tag:blogger.com,1999:blog-73380704028872468572024-03-06T15:01:57.052-05:00Ramblings on the Future of HumanityArguments and discussions concerning various aspects of our future, both near term and for the far distant future. Topics include the threats to our continued existence, earth-impact asteroids, and a space-based civilization.Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.comBlogger53125tag:blogger.com,1999:blog-7338070402887246857.post-34315681659314603312011-07-07T07:51:00.001-04:002011-07-07T07:51:33.151-04:00Technologies for Asteroid Capture into Earth Orbit<p>The following is my presentation “Technologies for Asteroid Capture into Earth Orbit” given at the <a href="http://isdc.nss.org/2011/" target="_blank"><strong>International Space Development Conference</strong></a> in Huntsville, Alabama, on May 19, 2011.</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaMsrPxLFFgHo69TugNydiPFR7StIbTy3syUA1Brabr3x-ci1bywHpGs5sK6UNHFxfFiMZ8NAXeyCi7rarPtaIMYoP6N_TPFqfuYFdCGorLn-5UOJXa8ORkhBAQfDK5P7XS0ADgpMXnDQ/s1600-h/clip_image002%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image002" border="0" alt="clip_image002" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEio8QbAeGN3pjZOHNbJyZwo_Zxs3M8qy6aecV3bHx_KixusumMX1ZzcG5QFvdBaGXlUV1lljjMBvB-nEPCVahZraMEuaSdcW3lrbwvXbhi_Raiw4WiVyJ70ipVr1P4pc0-lBzzU2a3TBTA/?imgmax=800" width="364" height="274" /></a></p> <p>The focus of this presentation is on a specific technical approach which enables us to capture an asteroid using essentially current technologies; the missions, tools, and complications of that approach; and then some asteroid selection criteria and a few specific asteroid capture opportunities. </p> <p>Using the asteroid <a href="http://en.wikipedia.org/wiki/99942_Apophis" target="_blank"><strong>99942 Apophis</strong></a>, I outline a possible capture mission, its requirements, and a timeline.</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjNnEcYEGXxoSIv6tlpbDUqLlANGxVGtJ27YBytPCZSX0sy1tOzi6qL8Xno4zoWLIH1RZaIwOqrOUfdO4xZl9gOuOiYBKDK9eRWLmT8cUVF3VGGO0VSrpD-Pm2vNvKp4qC5UoPVD5zCblM/s1600-h/clip_image004%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image004" border="0" alt="clip_image004" src="http://lh3.ggpht.com/-DR5m4LZZ1eM/ThWcYAW1HkI/AAAAAAAAAGA/dQe4ma_uY68/clip_image004_thumb%25255B1%25255D.gif?imgmax=800" width="364" height="274" /></a></p> <p><strong>So why capture an asteroid?</strong> The main reason is to gain convenient access to its resources. Even a relatively resource-poor low-iron, low-metal <a href="http://www.meteoris.de/class/LL-Group.html" target="_blank"><strong>LL chondrite</strong></a> contains 20% iron, significant quantities of water and other volatiles in the form of minerals such as clays, and oxygen to burn. </p> <p>The asteroid Apophis (likely one of those LL chondrites) contains enough materials to construct about 150 <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2011/01/solar-power-satellite-design.html" target="_blank"><strong>five-gigawatt solar power satellites</strong></a><strong> </strong>at 25,000 tons of steel and silicon each, plus <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/10/designing-space-habitat.html" target="_blank"><strong>Kalpana One style habitats</strong></a> for 100,000 people, all shielded by the slag remaining after iron is smelted out of asteroid ore. The oxygen freed from iron compounds during smelting amounts to well over a million tons more than is needed for the habitats, valuable fuel mass for ion thrusters to move the habitats and solar power satellites into their chosen orbits and to spin them up.</p> <p>Of course, a space habitat providing food, water, oxygen, fuel, construction supplies, gravity, radiation shielding, and skilled human workers situated above much of the Earth’s gravity well is an ideal platform from which to continue the exploration and exploitation of space. </p> <p>And we should not forget that placing an asteroid into a stable Earth orbit prevents it from colliding with the Earth. </p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigUOMt1SqfSqdVIhKe9EB1f62MwQsWIUJ5H2rlPPykbb62uh0cm3A0AEnqEcFLoqxPv7Q1HnJ29Bm7xrWMEIr3rnigpR1V1DC86-QAslnIcOSqNdmHX1xjMJypekLOXmaymPRGTDPGlFY/s1600-h/clip_image006%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image006" border="0" alt="clip_image006" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUBRpjdARKO_9XvmbN4OlKrKGN8j9d7pBqJWIGt4bLJ7ctSg9-Ffo6vmu-pWl_jAiis4mXA3hnjMOl8vdG39ku3W-FMB9JmjY5tr1433FseTtpp3O0XsqjDf1AdWLovEypnjpca4SN5Xc/?imgmax=800" width="364" height="274" /></a></p> <p>So, <strong>how do we capture an asteroid?</strong> Even a tiny one masses millions of tons, and we don’t yet have the technologies to manhandle them and put them wherever we want. Luckily, we don’t have to. When a spaceship or asteroid passes close to a planet or large moon, its orbit is changed, sometimes dramatically.</p> <p>In principle, the Earth can impart a delta-V of up to 60km/s to an asteroid in orbit around the Sun, although in practice the limits are a small fraction of this. More importantly, small changes in the position or timing of an existing close approach are enormously magnified. </p> <p>We aren’t limited to the Earth, in that close encounters to other planets might be used to alter an asteroid such that it passes close to the Earth at a later time where its orbit can be further tuned by the Earth’ gravitational field.</p> <p>If we can adjust the asteroid’s orbit such that it makes a subsequent close approach to the Moon with a relatively low velocity, the resulting slingshot can drop that asteroid into an Earth orbit. The Moon can (in principle) remove up to 2 km/s of velocity relative to the Earth, although less is easier. </p> <p>A point I’d like to emphasize: In my opinion, gravitational slingshots are as much art as engineering, especially when considering the variations involved in multiple slingshots around one or more bodies. The people who dreamed up the Cassini and Messenger missions are both geniuses and artists, and I have every confidence that they can find suitable mission plans to capture any potentially hazardous asteroid into Earth orbit, although the missions may be very long and complex thanks to a shortage of appropriate close encounters and/or the need for significant changes to the asteroid’s orbital parameters.</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihYvcnFTJx1-mJ5yQRmIj_ML7iZsHcRX4ba3-qVm0uOSfHoBcywUAE0PpZJr3uCdY0LztsKH7F97Mndhcd-KVa0FF5Ce28fQjCQVuUvq25z8s0ZL4ejvxPmLYJFZP_OQdowbMOAdH-TdU/s1600-h/clip_image008%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image008" border="0" alt="clip_image008" src="http://lh4.ggpht.com/-sndiJtV16Js/ThWcbnkIJNI/AAAAAAAAAGQ/7wFnCVOcjyQ/clip_image008_thumb%25255B1%25255D.gif?imgmax=800" width="364" height="274" /></a></p> <p>When <strong>selecting an asteroid for a potential capture</strong>, the most important consideration is simply the proximity of an asteroid’s orbit to a useful keyhole through which the orbital engineers can design a capture mission in a reasonable timeframe. </p> <p>The second consideration is the size of the asteroid. Bigger is not better when a 1 kilometer asteroid masses fifty times as much as Apophis, and thus requires a fifty-fold increase in the product of mission time and fuel mass. On the other end, a small 120m LL asteroid massing 2 million tons (and relatively poor in useful metals and volatiles) still has sufficient materials to build a single small Kalpana One style habitat for 8,000 colonists plus a dozen 5 gigawatt SPSs. Thus I view 120 meters as the smallest asteroid worthy of (first) capture, since it is barely large enough to build a permanent habitat rotating at 3rpm for Earth-normal gravity and with adequate radiation and meteoroid shielding.</p> <p>Another consideration is the V-infinity of the asteroid, because slower asteroids are easier to move a distance large enough to make a significant difference in the slingshot. </p> <p>The potential magnitude of a gravity assist is also constrained by how close to the center of the Earth the asteroid passes – and I think it’s important to keep it out of the lithosphere. Also, for a rubble pile we don’t want to pass closer than the Roche limit or the asteroid may be torn apart by tidal effects, much as Jupiter’s tide tore the comet Shoemaker-Levy into 20 fragments. The actual Roche limit depends upon density, but is likely to be of the order of 20,000 kilometers for a rubble pile asteroid passing near the Earth, and perhaps 5,000 kilometers for the Moon.</p> <p>One might think that the composition of an asteroid would be the number 1 criteria, but in reality most asteroids should be quite valuable (see <em>Mining the Sky</em> by John S. Lewis). A common <a href="http://en.wikipedia.org/wiki/Carbonaceous_chondrite" target="_blank"><strong>carbonaceous chondrite</strong></a> might contain 25% nickel-iron mostly in the form of metal grains, 10% water, and several percent carbon plus everything else needed for life in space. But even a lowly LL chondrite will work.</p> <p>The last consideration here is the opportunity for intercept missions. We need to modify an asteroid’s orbit when it is easy, some months or years before the targeted close approach. This is difficult for a high-inclination or long-period asteroid because it might only approach closely enough to the Earth for low-delta-V intercept missions once every ten or a hundred years. But an asteroid with a two-year period might present suitable launch windows every two years. Also, for asteroids with periods close to a year and with low inclinations, there may be two launch windows per year as the asteroid passes inside and then outside the Earth’s orbit.</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkFl-L-9Liq3gBxFgFqJpHPuWob6tsf0zG4yotdE4TQwumkxABV40mHqDUWBtnMQdXM7q-toWSDgroCn2E4nUObWrk66e1DpoNwfxHbSo7i4XMZ4aIfwlpcOfYS7bYxHKdNaOxZVlW4kk/s1600-h/clip_image010%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image010" border="0" alt="clip_image010" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEimkENv35IEDonMT0YxWOLTuh9ax5KF0z8-1HyJWWceolVpm_rqbnkoVivtcw3Nw4mYDG17Y27vkJGD_ZoNJWxOEkNUELAMji4zPJnpvm0IT_EJmKHsZwk3zoHgv4ni0l5e6XYR0GTwJTQ/?imgmax=800" width="364" height="274" /></a></p> <p>This table presents <strong>some possible asteroid capture candidates</strong> as of 25-APR-2011, all brighter than 24<sup>th</sup> magnitude and expected to pass within 120 Earth radii in the next 50 years. Some of these may be eliminated by further refinement of their orbital parameters, while others can likely be added as new asteroids are discovered, or as orbits are corrected for known ones.</p> <p>The entries on this table were gleaned from the <a href="http://neo.jpl.nasa.gov/ca/" target="_blank"><strong>Near Earth Object Close Approach database</strong></a>. The various tables, databases, and lists at the NASA web site are inconsistent, sometimes even on the same page. For example, the orbit visualization tool often has significantly different closest approaches than the “close approach” data on the same page.</p> <p>A side note: Many asteroids have only been observed over a few days, resulting in large uncertainties in their orbital parameters. The shapes, diameters, and masses of most asteroids are estimated, not known. Diameters are estimated from an asteroid’s brightness and distance. But we can’t measure the actual albedo, and observations at multiple wavelengths are used to judge the asteroid class, and from that a typical reflectivity, and from that a formula results in an estimate of the diameter, and assuming an average density, we calculate the mass. This process has extremely large error bars. In April of 2010, radar imaging resolved the asteroid YU55. Previous estimates were that its diameter was 140 meters and its mass 4Mt. The actual measurement revealed a diameter of 400 meters and an estimated mass of 87Mt, a 22 fold mass increase.</p> <p>Let’s consider these asteroids.</p> <p><a href="http://en.wikipedia.org/wiki/99942_Apophis" target="_blank"><strong>Apophis</strong></a> is fairly well characterized, although it may not be an LL chondrite, and may therefore have a different albedo, diameter, and mass. As a candidate for Earth-orbit capture, it has the advantages of passing quite close, and relatively slowly, plus launch windows occur in Aprils and Octobers near close approaches, suitable for a 1, 1.5, 2, or 2.5 year mission. It masses 27 million tons, roughly twelve times larger than the minimum useful capture size.</p> <p><a href="http://en.wikipedia.org/wiki/(153814)_2001_WN5" target="_blank"><strong>2001 WN5</strong></a> is a bit on the large side, but it may pass about halfway between the Earth and Moon in 2028 which offers an opportunity to adjust its subsequent Earth approaches in 2037 and 2046. But being more than 20 times as large as Apophis means a lot of fuel is required, so 2001 WN5 will have to wait for a later, poorer opportunity, probably with a robotic mission. </p> <p><a href="http://en.wikipedia.org/wiki/2005_YU55" target="_blank"><strong>2005 YU55</strong></a> is three times as massive as Apophis, and approaches Earth, Venus, and Mars, giving multiple possibilities for gravity assists. Next year it will pass about 20% closer than the Moon’s orbit, but it won’t be that close again for quite a while. It makes frequent approaches, about every 11 years, with relatively close approaches in April of 2021, 2032, 2043 (etc), and in November of 2022, 2033, 2044 (etc). We can likely tune one close approach to allow a closer approach 11 years later that can lead to a capture 11 years after that.</p> <p><a href="http://en.wikipedia.org/wiki/(137108)_1999_AN10" target="_blank"><strong>1999 AN10</strong></a> is a large (50x Apophis), fast, and dangerous asteroid which will pass about as close as the Moon in 2027. It is large enough to build 7,500 5-Gigawatt Solar Power Satellites, or to house 2 million people in a 2 mile diameter habitat. Actually, we can solve Earth’s energy problem for the next thousand years AND build a habitat for one million people, with materials to spare. While it is difficult to capture, it should be worth the effort. </p> <p><a href="http://astronomy.activeboard.com/t32362246/asteroid-2009-wm1/?page=2&sort=newestFirst" target="_blank"><strong>2009 WM1</strong></a> is only half the size of Apophis, and should be easy to capture some fifty years from now at its next close approach.</p> <p>Lastly, <a href="http://en.wikipedia.org/wiki/(101955)_1999_RQ36" target="_blank"><strong>1999 RQ36</strong></a> is 7 times the size of Apophis and passes 1.2 Lunar distances from the Earth in 2060. It, too, won’t be easy to capture, but is also worth the effort.</p> <p>I’d like to point out that every one of these asteroids were placed into their current orbits by a slingshot around the Earth, a fact clear at a glance at the orbital simulation on the NASA web site. One of the principles of orbital mechanics is that an orbiting body (in a 2-body system) will always return to the altitude and velocity vector of its last orbit change. Ignoring hyperbolic orbits, one near Earth pass means more, until the body collides with the Earth or is deflected away by another planet. </p> <p>Note, too, that capturing Apophis in 2029 would provide ample fuel to capture those big asteroids a few decades later.</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiO4B6YxwDqwaZa_mi05Ydwr1UNjbxrqYCAZohvOP2Qt9OH9iyVTxOliOWXyENDxl9LaGShBDYnDVu7ia85ts7ufVvVr38zwycX9RGGChAIv0pwlEuIv91P00oaoer5AtEUDPR9aRMIXIc/s1600-h/clip_image012%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image012" border="0" alt="clip_image012" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEils5BBPmNSWugrsNpO1TZwg57SgyIZvaPJownBRWngPwzPGfI4_70B-fcfW7zrl0NPIxElQptWsq848wQgeLgof_rsvRWDfT-mA2KyyJcYCSfeJ8o1jNUMxE7eRK119k5SwqBIbPuQQXc/?imgmax=800" width="364" height="274" /></a></p> <p>But it seems that nothing is ever simple. Part of the problem is that we don’t really know much about asteroids. Many of them appear to be rubble piles, and in some cases these spin so rapidly that their shape is constrained by their spin, yielding flying-saucer shapes. Others are contact binaries which might be exceptionally awkward to manipulate. We have more options with solid bodies, but we can’t plan on that.</p> <p>So how do we apply thrust? Two ways come to mind: dock and push, or use a gravity tractor to pull. Gravity tractors can only apply tiny amounts of thrust, but that might work, especially on longer missions. It would also help to dangle heavier components such as nuclear reactors and fuel as close as possible to the asteroid, with the thrusters some distance away so they can aim off to the side without much loss of thrust efficiency. But a 1,700 ton mass dangling 170 meters from the center of Apophis would be needed to apply the necessary delta-V over a 10 month period. Gravity tractors generally require very long missions.</p> <p>We can dock with an asteroid and push against it in a traditional way, but there are complications due to microgravity and asteroid rotation. It is possible that a number of cables could be looped around the asteroid to hold the tugship securely in place. Even then, a spinning asteroid means that thrust can only be applied during a fraction of each rotation, wasting thrust and fuel to the extent that the applied thrust isn’t directed in the correct vector.</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjKMYiPv7x3yIt7j61hmcUcYsp26DwN25cr55e3mnF1Gdgq_j2vODzfE7070cNqhPj3GCEneUEr7RceZcwMj_m0lgzsJNvRBjqdkKGLVgkoTI5ULERC4oA6aEyMmGiQkIgVx3oCD56Ovc/s1600-h/clip_image014%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image014" border="0" alt="clip_image014" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRWiT9nNXAXVTSVeoqG6gLzMgqFEqlZjbkojC2E4htR4nxxCYaY68TTcMf43ZYE87vzRrfwtu3vRO7sKHuIRUFMzJZ-8DzjyQxiIj6PnrnJDmk01DTWDEXefocha7e8Vmtb_uKpQI83uA/?imgmax=800" width="364" height="274" /></a></p> <p>Let’s consider a specific example. The asteroid Apophis will approach Earth to within 30,000 kilometers on April 13, 2029, significantly inside the orbits of our geostationary satellites. If we do nothing, the Earth’s gravity will slingshot Apophis into a new orbit as it deflects it by about 28 degrees and boosts its velocity by 3.04 km/s. The result of this is that Apophis changes from a 0.89 year period Aten class asteroid orbiting mostly inside the Earth’s orbit to an Apollo class asteroid with a 1.167 year period and an orbit mostly outside of the Earth’s. I should point out that we don’t yet know with any degree of certainty exactly what the resulting orbit will be, because tiny changes in the position of closest approach have a huge impact on the resulting orbit. The period I’m quoting here corresponds to the keyhole that targets an Earth impact in 2036. </p> <p>My main point is that delaying Apophis’ arrival at the Earth’s orbit by changing its velocity by only 10 cm/s results in a 1.5 km/s reduction in delta-V - a velocity gain of a factor of 15,000. I chose that particular slingshot because it results in a semi-major axis of exactly 1 au, with a period of 1 year. I used a program named <a href="http://www.orbitsimulator.com/gravity/articles/what.html" target="_blank"><strong>GravitySimulator by Tony Dunn</strong></a> to model several Apophis orbit variations, and simultaneously to gain a true appreciation of the art and genius needed to find useful orbits.</p> <p>The <a href="http://www.nature1st.net/bogan/orbits/gravasst/orbitest.html" target="_blank"><strong>Tisserand criterion</strong></a> indicates that it’s possible to change Apophis’ eccentricity to zero at the same time, although that would result in an inclination of about 10.5 degrees, and requires a much larger delta-V. In any case, what we really want is not a near-Earth orbit, but rather a subsequent low-speed slingshot around the Moon to remove excess velocity and drop the asteroid into Earth orbit. That may require some finesse and multiple slingshots, but I’m confident it can be done. Look at the success of <a href="http://saturn.jpl.nasa.gov/index.cfm" target="_blank"><strong>Cassini</strong></a>, <a href="http://www.nasa.gov/mission_pages/messenger/main/index.html" target="_blank"><strong>Messenger</strong></a>, and other missions that have relied on gravity assist slingshots to achieve what once was considered impossible for our current technology.</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4GwkSvDFU0nLqztVrVUGRrbd_dcXNVUaRsgLEKm3PLXoi49k3-cJb-nGn42ZQfvP-wVeeAU6KTw-1hP-ciMOcXMrjG0Ob-mm1RQSXxjfBITK2E9IPGZNLTz2Cr30s67FnogY0X-QPqQw/s1600-h/clip_image016%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image016" border="0" alt="clip_image016" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_Txut6cIlz5z7kkziD9xDwrGsdkLMwf5vXzDVYO5U46hsS6OtVkyOnv8aaM8q8qMc9WNwDMBDUrHAcAis4fc3wWMh4-KV8RLOuv_t0PsaSUUig_yfcmpggLhV7iDwTBW4AbNS5pwlu9k/?imgmax=800" width="364" height="274" /></a></p> <p>We still need to give Apophis that 10 cm/s nudge. I don’t suggest abrupt changes from nuclear bombs or high-velocity impacts, partly because we need finesse to fine-tune the orbit, and that’s best done by the equivalent of titration. We need a tugship, a long-mission, highly fuel-efficient spacecraft to gradually move the asteroid into a new orbit. </p> <p><a href="http://en.wikipedia.org/wiki/Magnetoplasmadynamic_thruster" target="_blank"><strong>Magnetoplasmadynamic</strong></a> or <a href="http://en.wikipedia.org/wiki/VASIMR" target="_blank"><strong>VASIMR</strong></a> thrusters are likely the best choice to apply delta-V, as their high exhaust velocities reduce the total fuel mass needed, they can generate significant levels of thrust, and they should be able to achieve sufficiently high reliability.</p> <p>Of course, we need to push or pull the asteroid, which isn’t simple, partly because they are rotating, undoubtedly along an inconvenient axis. And they have enormous angular momentum which we can’t simply cancel. This means we’ll either have to dock – not land – at an appropriate location and thrust a fraction of the time, or use a gravity or magnetic tractor approach which might limit us to lower thrusts and longer missions.</p> <p>Note that ion thrusters take copious amounts of energy. 25 megawatts can be generated by a 300 by 300 meter solar array, or by a single compact nuclear module available commercially. We do have a lot of experience with high-power nuclear modules in submarines and aircraft carriers, so that’s an option I personally lean toward, but politics may dictate a less proven approach. Also, working fluids and cooling grids need to be addressed for nuclear or for solar dynamic electric generation.</p> <p>Given an appropriate power supply, we still need enough time and fuel to move an asteroid. So how much do we need?</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQGgNAtuGMyW2BXW4GXFuaGY6YjUghmrSxUXxnDNJPyXJFOjJjF6SP5Mc25-6hlQzmZ6E9hslYs4J4-iaAYGG0dxrNXKHajInhB4iNVx3hSETaTEWnpDbv9Jri4_PIh0OsZR2zRze-GhM/s1600-h/clip_image018%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image018" border="0" alt="clip_image018" src="http://lh6.ggpht.com/-oqbVK5dKfBw/ThWcgPaMcsI/AAAAAAAAAG4/EbRRFTZ6nAg/clip_image018_thumb%25255B1%25255D.gif?imgmax=800" width="364" height="274" /></a></p> <p>From our mission-time derived flight plan, we compute the needed delta-V, and conservation of momentum allows us to compute the needed momentum change and the product of fuel mass times exhaust velocity. The asteroid’s mass is a given, but we can choose to some extent our mission time, and thus the needed delta-V. Double the mission time, halve the delta-V.</p> <p>Note that doubling the exhaust velocity quadruples the needed energy (100 times the energy is needed for 10x velocity for a given amount of fuel). But doubling Vex also halves the fuel mass required, so the net effect is doubling the required power for a given thrust duration. At a specific impulse of 5000, consuming 55 tons of fuel over a 10 month period requires 5 megawatts of continuous power.</p> <p>With a lot of energy, we don’t need much fuel at all. These numbers are all well within our technological capabilities. Of course, additional fuel will be needed to deliver the tugship and its load of fuel to the asteroid, but again, the numbers are within our capabilities. We can do this.</p> <p>However, remember that Apophis is rotating and we may only be able to apply thrust half of the time. This doubles the thrust and power required.</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFQ2RVNrJUZkzHt8O3ScaCj3wgbvQnQnnUsEp29Qq8753-XnKDRYrhxDxzOHV5l7l5LRiO_XFvPGx2yowdJ9AkKDSOam-X911EglJHpYW__8P59eotIYhJyVcZsBwqGJKqTpzSnJltn4w/s1600-h/clip_image020%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image020" border="0" alt="clip_image020" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg87eWlNW89Hd41-dDV1RLqGUsbbM88-NxvUAjsONF5of-cKNPMXXXsa6yWQEt4V68Zc9uDcXQbk9vd9fFIjftZ_8IsqQvO_ye63c08FM2ZbFM95bhC7TZjA1RurnZQOd_3Cn8rcew5bpM/?imgmax=800" width="364" height="274" /></a></p> <p>I’m proposing a mission with two main phases and a three-year (or so) timeframe.</p> <p>The first phase is to launch the necessary components and assemble them in orbit, some time in 2027.</p> <p>The actual deep-space phase begins with a lunar slingshot for intercept injection in October of 2027, and docking with Apophis some 5 months later. This requires 3 km/s of delta-V, and about 15 tons of fuel.</p> <p>We would grapple Apophis, and apply 400 Newtons of thrust (enough to deliver 1.0 cm/s/month of acceleration) for half of every 30-hour day. Ten months of thrust consumes 55 tons of fuel. Then there is a three-month coast until the slingshot.</p> <p>The major slingshot must occur on April 13, 2029. The goal is to change Apophis’ orbit to achieve a lunar slingshot 1 year later to capture the asteroid into Earth orbit. Note that the initial thrust moves Apophis further from the Earth, and the subsequent lunar slingshot is necessarily even further out.</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6lb6OYz0CM1p-_8Y5OEXQ5yP_U_ayZynJRB3VO3xaF660aUQAjylr1Rd3gIeSFcHnfRIbQIqlVskdNjwN8CwrSrDu1Wig07RShWzZQEPFVMAhf2u5dlPLLA9LKev7f0EXgg5lxtTJf1M/s1600-h/clip_image022%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image022" border="0" alt="clip_image022" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8bb-VQ4cCnx9HDS3gYBeqr-j8DOg2uPmTGrM4tCj8fIXcgsQ25XigrYfE1qmHdmuN25s82D-ApMFKey0RnjkPn1ZYP9kVjykS0qP-1JQ9i7GKGWFiwYEgd1QKDGFjMf9JOkBFHXQtNbo/?imgmax=800" width="364" height="274" /></a></p> <p>I want to talk briefly about that tugship.</p> <p>It must support an extended deep-space mission, providing everything the crew needs to thrive. My supplies estimate assumes ammonia provides hydrogen for carbon dioxide recycling, and food to be dehydrated. </p> <p>My mission plan requires 55 tons of fuel to change the asteroid’s orbit, plus 15 tons for the intercept and docking, plus contingencies. I’d suggest at least 100 tons total, perhaps more. Note that if properly oriented, the fuel can provide significant radiation shielding during the trip to Apophis, and then the asteroid itself provides even more, especially if the crew quarters can be partially buried.</p> <p>We need to apply 200 newtons of thrust continuously for 10 months, or double that for half of the time. We’d need to double the power as well, 10 megawatts total. A 200 meter square array of 25% efficient solar cells generates 12 megawatts, the extra needed since ion thrusters aren’t 100% efficient.</p> <p>Lastly, we need some way to grab hold of the rotating asteroid. I suggest using 6 harpoons with 1-km lines launched around Apophis, the ends retrieved and securely tied to the tugship. This would function as an effective net and friction applies sufficient traction to apply thrust even at high angles of attack. We could break several of the lines and still hold on. Note that this is a good example of where people can easily accomplish a task which might be nearly impossible for an automated system.</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2ci-yeli3tAMSJxVm9ICSyHOM0dRYtqe3YwWwEtQj5sSe6EYgdA2UW8fsw3Eg1CqEjt3oOVv-9jAEp6tG5-V3sEPN-8qmyC9CWJwFnz-li-GeVS3OSLB7tzTwyiYEnFiZpf8TsequOzQ/s1600-h/clip_image024%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image024" border="0" alt="clip_image024" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilfyKH6MpTzpm1gvj1OTdIC4dcru5B-ClU2kexB2fXZeSVhq5GHzp8CAbyd4t7_l1TwuR4YCsYZEKmrVufW65cTZa9ziZINd0MwGkYY28djIfnwK2HEWa57Wud2qKn8SQtWVSmlW5lWCM/?imgmax=800" width="364" height="274" /></a></p> <p>This project plan assumes a separate launch of a construction shack housing six or more workers for several months.</p> <p>Their job is to assemble all of the components, as I’d expect at least 5 launches of 50+ tons each are required.</p> <p>-Two launches for the solar panels and supporting structures – total 100 tons</p> <p>-Two launches for the fuel and thruster assemblies – another 100 tons</p> <p>-One launch for the tugship (crew quarters) itself</p> <p>-The construction shack is a sixth launch, and the assembly crews, mission crew, and supplies are likely two more man-rated launches. Note I’m assuming the assembly crew is launched early, and the mission crew at the last minute, because the deep-space mission already requires a very long time. The number of people in each is an estimate, of course. While 6 workers may suffice to assemble the tugship during a two month project, double the people would simplify training, ease workloads, and provide significant redundancy. </p> <p>-Likewise with the deep-space mission crew. Two people may be able to handle the workload, but that is cutting it close. I’d suggest four at a minimum, and six is better. </p> <p><a href="http://lh5.ggpht.com/-PLqmIbq6_3M/ThWdvxIQCFI/AAAAAAAAAHU/ivKdVCI7Lgo/s1600-h/clip_image026%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image026" border="0" alt="clip_image026" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBDO9H0lG5dqmaFyDCx5xBQeXKNQBTeJ1pf8dx1TX_KiubjjZrb_8eiOfSpS6V6vnfaCL3uglqoF8Z4GnZJxKtvLd9bD0fkXJUh0NNB714XVWieZqsqYwMfET7pT-7M5pmmFHFy_PgrGA/?imgmax=800" width="364" height="274" /></a></p> <p>Continued research tops the list of the several logical <strong>next steps</strong> we should take. NASA is ideally suited for several of these, and the continuing search for <a href="http://neo.jpl.nasa.gov/neo/pha.html" target="_blank"><strong>potentially hazardous asteroids</strong></a> identifies the same candidate asteroids as a search for potentially capturable ones.</p> <p>We do need to address several legal issues, which pose a serious problem for Western civilization private enterprise. Key among this is the right to own and exploit objects in space. If a person or company does not have the right to exploit space-based resources, they can have no incentive to acquire them, and the future of humanity in space is effectively dead.</p> <p>We must also address the liability of moving asteroids. Certainly this should be done with the utmost care and intense oversight tempered with some sense of practicality. For example, the adjustment to Apophis orbit that I propose appears to pass through the 2036 impact keyhole. Does that mean we must move the orbit out and around that keyhole, or simply that we use reliable, even redundant systems, and closely monitor to track the potential need for additional intervention? I’m afraid that science and logic may have little to do with the outcome of that discussion.</p> <p>We need to design and build a tugship using thruster and power technologies available in an appropriate timeframe. Of course, that research is an excellent task for NASA’s <a href="http://www.nasa.gov/centers/marshall/home/index.html" target="_blank"><strong>Marshall Space Flight Center</strong></a>. I think the biggest challenge here might be in supporting deep-space, long-term missions with the human crews I believe are necessary to get the job done.</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbQGYScfH4lCCtU4bNMOFnUgftjHqzRHfeB6J4yQP4p_z29jDyjXtdujVlaoWcqmSkpDvEQIWMKaoke9W5GRTBIhmyf9kpwSYuGQHduyIjgANMtkc6fRM6TPd_aGsKTkXYK0jSsVG2Bps/s1600-h/clip_image028%25255B4%25255D.gif"><img style="background-image: none; border-bottom: 0px; border-left: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top: 0px; border-right: 0px; padding-top: 0px" title="clip_image028" border="0" alt="clip_image028" src="http://lh3.ggpht.com/-W0pgc6TCgA0/ThWdxKTFCuI/AAAAAAAAAHg/5SjrFY-C8Bo/clip_image028_thumb%25255B1%25255D.gif?imgmax=800" width="364" height="274" /></a></p> <p><strong>The bottom line is that we CAN capture asteroids into Earth orbit, thanks to the amplification of delta-V due to gravitational slingshots.</strong></p> <p>There are several candidate asteroids today, and there will be more tomorrow. Also, I did not look for opportunities where the asteroid close approach was to Venus, or Mars, or Mercury, and there is every chance that good candidates exist although longer missions (and an extra slingshot or two) would be required.</p> <p>The most important consideration to me is that capturing an asteroid such as Apophis places millions of tons of raw materials into Earth orbit where we need them to build solar power satellites, permanent orbiting habitats, and to advance humanity’s exploration and further exploitation of the vast resources of space.</p> <p>Lastly, we should never forget that capturing a potentially hazardous asteroid converts a dangerous threat into a resource of immense value.</p> <p>President Obama needs a grand goal for NASA and the nation in the next decades, one comparable to Kennedy’s “We choose to go to the moon in this decade.” I believe that capturing Apophis into Earth orbit is such a grand goal, with benefits to global energy and warming (via those solar power satellites), and to space exploration, and to permanent, self-sustaining habitats in space. And it removes a threat to the Earth.</p> <p>If you agree that we need a space-faring humanity and that exploiting asteroids is key, if you agree that sending cheap solar energy to Earth simultaneously helps humanity and reduces global warming, if you agree that we should act to prevent asteroid impacts on the Earth, then please share the word. Follow this link (<a href="http://www.stephendcovey.com/Apophis.htm" target="_blank"><strong>Project Apophis</strong></a>) and <a href="http://www.whitehouse.gov/CONTACT/" target="_blank"><strong>tell President Obama</strong></a> that he holds the key to the future of humanity in space, that capturing Apophis is feasible, affordable, solves many problems in a single step, and is a Grand Goal worthy of his – and this nation’s – focus. Thank you.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com24tag:blogger.com,1999:blog-7338070402887246857.post-34417298974847427762011-02-22T19:21:00.001-05:002011-02-22T19:21:18.010-05:00A Project Plan for Space Based Solar Power<p><strong>OVERVIEW OF A SPACE BASED SOLAR POWER PROJECT</strong></p> <p>In my post, <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2011/01/space-based-solar-power.html">Space Based Solar Power</a>, I present an overview of SBSP and its value to humanity. I also propose the use of asteroids for raw materials to reduce the cost to profitable levels. Still, the construction of the first Solar Power Satellite (SPS) is special, as we must incur all of the up-front (bootstrap) costs in addition to building the SPS itself.  I will demonstrate that it still can be a profitable venture. However, this project plan targets the initial construction of a dozen SPS’s, because the slag by-product of that much steel is the correct mass of shielding needed for a Kalpana-One style habitat for the workers (see my post, <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/10/designing-space-habitat.html"><strong>designing a space habitat</strong></a>).</p> <p>The approach I recommend is to capture an asteroid (see  <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2010/06/asteroid-capture-into-earth-orbit.html"><strong>Asteroid Capture into Earth Orbit</strong></a>) and use its resources to produce the steel and other materials needed to construct and operate a constellation of SPS’s.</p> <p>This approach has a relatively high up-front investment and results in a relatively low per-SPS cost. The project has many phases:</p> <ol> <li>Research & Development </li> <li>Capture a suitable asteroid into Earth orbit</li> <li>Launch Mining & Manufacturing Tools </li> <li>Launch Construction Shacks & Workers </li> <li>Construct & Deploy the SPS(s) </li> <li>Construct the Kalpana-One style Habitat(s) </li> <li>Repeat 5-6 as long as asteroid resources remain </li> </ol> <p>For the purposes of this post, I make several assumptions:</p> <ul> <li>we have chosen the asteroid 99942 Apophis, which also locks us into a 2029 timeline (project start in 2027, launch capture mission in early 2028). </li> <li>use of SpaceX’s Falcon 9 Heavy launch vehicle (announced with pricing, but not yet built, yet alone flown). </li> <li>pricing in 2011 dollars which must be adjusted for inflation. </li> <li>Worker launch costs initially average $24M/person, but in a 2031 timeframe human-rated transports will be built for the Falcon 9 Heavy (or eventually Falcon X Heavy) that can transport 30 to 100 people per launch into LEO at a price of $1,000,000 per ton (also per person).</li> <li>I ignore in-space worker salaries (small compared to launch costs)</li> <li>For income, I only consider Solar Power Satellites, ignoring tourism, the sales/rentals of housing and retail space, sales of propellants to outside parties, product placement, tie-ins, naming rights, or any other potential revenue sources.</li> </ul> <p><strong>RESEARCH & DEVELOPMENT</strong></p> <p>It may be an unreal oversimplification, but I will ignore the R&D costs for this project although they are large and unknown. I believe that NASA, the various governments, and the network of universities should bear this cost as part of their normal operations (supported by tuitions, taxes, and donations), although the more directed research will be borne by the corporations that will profit from the sales of related equipment and supplies. Known areas of research & development include:</p> <ul> <li>Heavy lift launch vehicles </li> <li>Space taxies / trucks (using ion thrusters to cheaply change orbits and to capture the asteroid) </li> <li>Long-term life support (recycling & farming in space) </li> <li>Zero Gravity Mining, Smelting, Refining, and Manufacturing (note need to recycle reagents and to capture and utilize bi-products such as CO2). </li> <li>Manufacturing Solar Photovoltaic Panels from asteroid materials </li> <li>High-efficiency Muilti-Gigawatt Microwave Transmitters / Receivers </li> <li>Large-scale in-space construction techniques (of SPS and habitats) with limited resources </li> </ul> <p><strong>CAPTURE A SUITABLE ASTEROID</strong></p> <p>How to capture an asteroid is largely covered by my previous post, <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2010/06/asteroid-capture-into-earth-orbit.html"><strong>Asteroid Capture into Earth Orbit</strong></a>, and a future post will detail the components of the capture project, including a proposed project breakdown of the needed components, launches, delta-v budgets, and a project timeline. </p> <p>The Asteroid Capture Project begins in 2027 with construction (in orbit) of a space tug. The tugship launch from LEO to intercept Apophis occurs in April of 2028, and the final Lunar slingshot of Apophis effecting capture into Earth orbit occurs 18 months later, in October of 2029. These dates are driven by orbital dynamics.</p> <p>A simplified overview of the Apophis Capture Project (using current or near-term launch vehicles) is:</p> <ol> <li>Launch tugship, fuel, solar panels to LEO: total 150 tons, needs 5 Falcon 9 Heavy launches ($500M); cost of tugship, etc. another $1.5B. This cost is lower than many space-based projects because of the extensive use of modular components assembled by humans in space(reducing the need for first-time perfection).</li> <li>Launch in-orbit assembly crew: 1 @ $100M, probably another $1B for training, tools, supplies, support staff. </li> <li>Launch mission crew & supplies: 1 @ $100M </li> <li>Intercept mission uses ion thrusters and a lunar slingshot to enter Apophis intercept trajectory in April 2028. </li> <li>2 months to intercept; 3 months of thrust to change Apophis orbit; 1 month of contingency; 6 months of coasting. After the slingshot around the Earth in April of 2029 there is another 6 months of coasting (with likely trajectory tweaking) before the final drop into Earth orbit via a Lunar slingshot in October, 2029. Capture Mission duration is a little over 18 months; with recycling of water & oxygen, 600 days of food & water & hydrogen (to recycle CO2) for a crew of 4 masses four tons; a similar mass is needed for the associated equipment (triply redundant). </li> </ol> <p>Total capture cost: $3.2B (ignoring R&D and ground support costs).</p> <p><strong>LAUNCH MINING & MANUFACTURING TOOLS</strong></p> <p>This is a big unknown, in that we don’t yet know how to best do mining, smelting, refining, and manufacturing in space (microgravity, necessity to recycle & save everything) from asteroid resources. We can make good guesses, however. Also, the facilities should grow over time, but the initial launches should suffice for starting manufacturing, especially since we are largely launching tools to make tools. After the initial launches, most of the needed additional equipment will be manufactured in space. These launches would begin in 2029; I expect the tugship will be used to transport these components from LEO to the asteroid now in Highly Eccentric Earth Orbit.</p> <ul> <li>Solar Power generator: 1 launch, $200M </li> <li>Mining facility (ore movers, grinders, separators): 2 launches, $400M </li> <li>Solar smelter, gas collection & refining, metal purification: 5 launches, $1B </li> <li>Steel production: 5 launches, $1B </li> <li>Rolling mill (girders, rods, sheet metal): 3 launches, $600M </li> <li>Finished metal product plant (nuts, bolts, rivets, connectors, pipes, tanks, etc.): 2 launches, $400M </li> <li>Silicon refinery, solar panel manufacturing (3 launches, $600M) </li> <li>Slag processing, shaping, rock wool production, & slag handling (1 launch, $200M) </li> </ul> <p>Total estimate is $4.4B for equipment and 22 launches, and this phase begins in 2029, ends in early 2030.</p> <p><strong>LAUNCH INITIAL WORKERS & THEIR CONSTRUCTION SHACKS</strong></p> <p>The initial workforce for all of the mining & manufacturing  equipment, even assuming significant automation, is considerable. I estimate 36 workers, needing 6 launches using Falcon 9’s and Dragon X capsules (total $600M) just to get started. Each crew member will likely require a ton or more of life support equipment and supplies.</p> <p>The Construction Shacks are the living quarters, recycling equipment, supplies, and solar panels for the initial mining and manufacturing workforce, intended to be buried beneath asteroid regolith for radiation and meteorite shielding (alternately regolith may be bagged and packed around the shacks). This will need to be repeated as the workforce grows (until a permanent habitat is at least partially completed).</p> <p>The Falcon 9 payload faring may be equipped to house up to 12, with room for supplies and equipment. Three of these would provide adequate housing and first-year supplies for the initial 36 workers, at a cost of $600M bringing the total cost to $1.2B ($33M/person).</p> <p>Subsequent workers initially have similar high launch and support costs, ramping down to $15M per-person as capacity grows to produce living quarters, water, and oxygen in space. When the interim habitat is ready and larger capacity people launchers (32 workers/launch) become available, per-worker launch costs should plummet to roughly $3M per person (in 2031), and as low as $1M per worker in subsequent years (with use of dedicated people-carrying spacecraft ferrying 100 workers into space per launch). Note that a 1 ton per worker mass allowance includes some essentials that cannot be easily fabricated in space, such as high-efficiency LEDs for the farms,  some fertilizers, and medical supplies. </p> <p>The workforce & construction shack launches could begin in late 2029.</p> <p>This initial 36 worker contingent will be sufficient to prove the feasibility of mining, refining, and manufacturing in space, but will be inadequate to achieve sufficient volumes of production for a timely project completion. </p> <p>A ramp up to 500 workers during 2030 should result in a steel production rate of roughly 100 tons per day, which in turn allows construction of the habitat pressure shell plus containers for the volatiles (oxygen, CO2, and H2O) in one year. At this point (an interim habitat consisting only of a spinning pressurized shell with partial radiation shielding), many of the workers can work without pressure suits, gravity prevents long-term health problems of zero-G living, and in-space production of food can begin.  </p> <p>Doubling the population and production annually allows the first SPS to be completed by the end of 2031 (when steel production is 200 tons per day, comparable to a small mill on Earth). 2032 should see 2 more SPS’s completed, and 2033 results in 4 more and completion of the habitat structure (with room for 8,000). By the end of 2033 the habitat capacity is reached, and the associated manufacturing facilities should be capable of building 8 SPS’s per year. Remember, it takes all of the slag associated with building the first 12 SPS’s to fully shield the habitat, which occurs during 2034. By the end of 2034, the first permanent habitat (8,000 person capacity) is complete, along with 15 Solar Power Satellites.</p> <p>The total worker cost through completion of the first SPS and the habitat shell would be $15B (by the end of 2031, a total of 1,500 workers). Adding 2,000 more workers in 2032 and 4,000 more workers in 2033 would cost only another $6B. </p> <p>This analysis has ignored the cost of salaries for space workers (and the cost of ground support). One reason to ignore the salaries is that they are insignificant compared to launch and equipment cost in the early years. </p> <p>Another reason to ignore them is that portions of each “salary” may be offset: workers may be charged for rent (or purchase of a condo), for food, water, recycling, even oxygen. The cost of living is very high in space, and salaries should reflect that, but the net cost of a worker is difficult to estimate. Many of the readers of this blog would likely volunteer to work for little more than the right to permanently live in space and be a part of humanity’s spacefaring future – I know I would. Very few of the workers would view these orbiting factories and habitats as temporary jobs and expect to return to Earth in a few years, especially if they were afforded the opportunity to buy a home and raise a family in the habitat.</p> <p><strong>CONSTRUCT & DEPLOY THE SPS</strong></p> <p>The construction of a Solar Power satellite requires multiple components, most of which will need to be built in orbit. For more details, see <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2011/01/solar-power-satellite-design.html">Solar Power Satellite Design Considerations</a>. The components are:</p> <ul> <li>Solar Panels (from high-grade silicon, in thin sheets such as commonly manufactured today) </li> <li>Steel structures to frame and aim the panels. </li> <li>Steel structures and motors to maintain alignment of the panels with the sun, and the antenna with the target Earth station. </li> <li>Microwave transmitting antenna </li> <li>Microwave transmitter </li> <li>Shield mass to protect the electronics from meteorite damage. </li> <li>Fuel to insert the SPS into the target geosynchronous orbit</li> </ul> <p>I expect that the motors and electronics (including the microwave transmitter) will be launched from Earth, for which I’ve budgeted $200M per SPS.</p> <p>A considerable amount of fuel is needed to move each newly constructed SPS from the near-Lunar location of its birth and insert it into an appropriate geostationary orbit. The total delta-V needed is roughly 2 km/s, the total mass is 25,000 tons, and even using 5,000 ISP VASIMR ion thrusters, 1,000 tons of fuel is needed. Luckily, that is a tiny fraction of the 15,000 tons of oxygen produced as a by-product of the smelting of iron ore into steel for each SPS. Also luckily, we’ll have a lot of power available, so the time required for this orbit change is limited largely by the number of ion thrusters (and thus the fuel flow rate) we wish to dedicate to this task. We’ll have plenty of oxygen to spare, so our ion thrusters should be optimized for this most available rocket fuel. </p> <p>Each SPS will require a matching ground receiving station consisting of a large (10+ kilometer) rectenna plus power conversion and distribution. These costs are only a guess, but I’d estimate that $1B each is more than enough. I have not included this portion of the per-SPS cost in my summary, as this cost would be born by the receiving local electric utility.</p> <p><strong>CONSTRUCT THE HABITAT</strong></p> <p>Another post details the <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/10/designing-space-habitat.html">Design of a minimum Kalpana-One style Habitat</a>: a 100-meter radius cylinder, 130 meters wide, spinning at 3rpm for 1G along the outer rim, lined with 3 meters of slag which provides excellent shielding against radiation and meteorites.</p> <p>The outer pressure shell is built using average strength (easily welded) steel plates nearly 1 inch thick, and masses approximately 28,000 tons. Completed first, once spun up it provides a shirt-sleeve environment with gravity, boosting the productivity and health of the workers.</p> <p>Over time, blocks of slag are brought inside to line the exterior walls, and interior structures are built as housing, workspaces, and farmland. Most of the volume is left open to eventually become a 12 acre cylindrical park. The core will be available as a low-gravity industrial and research space. Agriculture space (primarily for crops) is more than 5.5 million square feet; residential space is over 2.5 million square feet, there is 1.5 million square feet of offices / light industrial and a million square feet of storage and overhead space. The total internal structures including the outer 15 meters along the endcaps and perhaps 6 stories of rooms lining the cylinder rim, plus a 40 meter diameter core structure, masses 126,000 tons (a generous allowance). This is less tonnage than an Oasis Class Cruise Ship (225,000 tons carrying 8,000  passengers and crew) yet much more spacious. </p> <p>Power (6 kw/inhabitant or 50 megawatts total) is provided by solar panels lining the exterior surface of one endcap, plus a ring extending 100+ meters beyond the cylinder (effectively a 425-meter diameter solar panel array).  Additional power needed for exterior factories (such as the smelter) is included in their structures and allowances. The spin axis of the habitat points to the sun, requiring a massive gyroscope at the center of the habitat to slowly precess the spin axis at one revolution per year. </p> <p>Speaking of spin, it takes a lot of fuel and energy to spin up the habitat to 3rpm: about 1150 tons of fuel (oxygen) at an ISP of 5,000. Using 25 megawatts (half of the habitat’s available power), the spin up takes nearly 2 years. However, the empty shell (no shield mass) spins up very quickly; the majority of the energy is needed to maintain the spin as roughly a million tons of shield mass is gradually added to the habitat’s periphery.  </p> <p>Once complete, this habitat houses 8,000 workers / colonists, and provides all life-support needs. All of the steel (154,000 tons) and shield mass (1,600,000 tons of slag) are from the asteroid, along with the oxygen, water, and carbon needed for the life support system. The known components to be launched from Earth include the LED’s and other light sources for the farms and interior (see <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/11/lighting-our-space-habitats.html"><strong>Lighting our Space Habitats</strong></a>), various electronics, seeds, and perhaps 50 kilograms of nitrogen (per inhabitant) needed as fertilizer. </p> <p>There are no additional launch or equipment costs not included elsewhere (possibly excluding the ion thrusters needed for spin-up). </p> <p><strong>REPEAT</strong></p> <p>This project is an eight-year plan (5 years to the first SPS) culminating in the deployment of a permanent, self-sustaining habitat with a population of 8,000 and fifteen 5-gigawatt Solar Power Satellites in geostationary Earth orbit. By completion, the project will have consumed approximately 10% of Apophis, leaving  90% available to build additional habitats and Solar Power Satellites. </p> <p>The capacity will be in place to build additional Solar Power Satellites at the rate of 8 per year, but note that demand is much higher: current global electric demand would need 400 five-gigawatt SPS’s to fill, and total projected energy demand might require more than 4,000 by 2050 (most energy is used for heating, generally by burning fossil fuels). Apophis alone has sufficient resources to build up to 150 Solar Power Satellites (while building 10 habitats accommodating 8,000 people each), but in the long run additional asteroids will be needed.</p> <p>We should build additional habitats, including larger ones, as part of an ongoing project. We’ll likely need a “mining town” for each asteroid we capture, and an SPS construction / maintenance habitat just outside of geostationary orbit, and even a large habitat in low Earth orbit (as low as possible without serious atmospheric drag) as an Earth to LEO launch target and tourist destination. Good arguments can be made for additional habitats in various Lagrange points such as L5, and for transition orbits such as LEO to Geostationary, or to the Lagrange points. There may even be a 3:1 Lunar synchronous stable Earth orbit that visits L3, L4, and L5 in succession, 9.1 days apart – an ideal platform from which to host interplanetary missions, including to Mars.</p> <p><strong>SUMMARY</strong></p> <p>It all sounds time consuming and expensive: $22.8 Billion before that first SPS is operational. But remember, in 2032 that first SPS will generate $1.3B in cash flow (at a wholesale price of $0.03/kwh), in 2033 the 3 deployed SPS’s generate another $3.9B, in 2034 the 7 deployed SPS’s generate $9.1B, and subsequently the 15 SPS’s generate nearly $20B/year. The steel production rate is 800 tons per day, allowing 8 or more additional SPS’s to be built each year. The peak cash outlay is $25B with all investment repaid in 2035 – and huge net profits after that. </p> <p>Even considering only that first SPS, the total cost is comparable to the $5 billion per gigawatt that my local power company may spend on a nuclear power plant, without any need for radioactive waste disposal or refueling, and without quite as much local objection to the installation.</p> <p>Yes, I’ve been accused of being an optimist. Yes, it is likely to take longer than this project plan, due to unforeseen setbacks. Yes, I’ve ignored the cost of money in this analysis. I’ve even ignored the cost of bringing all these workers back to Earth (assuming they’d want to return). But even if it takes another year or two before breakeven, even if the costs might run 20% (or 100%) higher, even if you factor in the up-front R&D costs, even if you add a generous salary for every in-space worker plus free room & board, it is still a wildly profitable venture. </p> <p>And did I mention that Apophis has enough raw materials to repeat this project another nine times, at a fraction of the cost each (and completely funded by free cash flow)?</p> <p><strong><em>Is there an entrepreneur listening that likes the sound of <u>$200 Billion per year</u> of free cash flow for a measly $30 billion investment? And with the bonus of earning a permanent place in the history books as the party responsible for bootstrapping humanity’s move into the Solar System?!</em></strong></p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com10tag:blogger.com,1999:blog-7338070402887246857.post-27290333962434452242011-01-29T18:59:00.001-05:002011-01-29T19:00:52.695-05:00Solar Power Satellite Design Considerations<p>The major considerations driving solar power satellite design decisions are:</p> <ul> <li>location (geostationary, LEO, other)</li> <li>energy delivery method to Earth </li> <li>solar panel photovoltaic versus turbine generator (efficiency/cost tradeoff) </li> <li>size of an SPS (dimensions, mass, power) </li> </ul> <p><strong>LOCATION</strong></p> <p>Most studies recommend a geostationary orbit for Solar Power Satellites. This choice simplifies designs, and is the only choice that can deliver continuous power from a single SPS – the others require a constellation of satellites with any given ground station receiving power from a sequence of satellites. The disadvantages are that a relatively large transmitting antenna is required, and it takes more energy to reach those geostationary orbits.</p> <p>Another disadvantage is that it is inefficient to deliver power to high latitudes; multiple satellites with <a href="http://en.wikipedia.org/wiki/Molniya_orbit"><strong>Molniya orbits</strong></a> are one possible alternative.</p> <p>An SPS constellation in medium Earth orbit has been proposed, because of the lower cost to launch from Earth and the smaller size of the transmitting antenna. The disadvantages are that both the transmitting and receiving antennas may need to be dynamically aimed, plus the “dark” time due to passing through the Earth’s shadow is much greater, requiring still more satellites to deliver continuous power.</p> <p>The remainder of this post will focus on geostationary locations, which have been studied more thoroughly.</p> <p><strong>MICROWAVE ENERGY DELIVERY TO EARTH</strong></p> <p>The minimum size of an SPS is driven by the size of the energy transmitter and the Earthside receiving station. While several alternatives have been considered, the best option appears to be beaming microwaves to Earth receiving stations from geosynchronous orbit. To achieve sufficiently narrow beams that arrive at sufficiently low energy densities (so as not to cook anything in their path), we’ll need a transmitting antenna one kilometer wide. </p> <p>The receiving station is larger at 10 kilometers east-to-west and as long north-to-south as necessary to appear circular from the SPS (a 10 kilometer circle at the equator, a 10 by 15 kilometer oval at 30 degrees latitude, 10 by 20 kilometers at 45 degrees latitude, perhaps 10 by 30 kilometers at 60 degrees). Note that 60 degrees latitude is approximately the limit of feasibility due to both the size of the receiving array and the amount of atmosphere that must be traversed. Luckily, this supports serving the vast majority of the global population, excluding only the Artic regions, Alaska (U.S.A.), northern Canada, and the European Nordic countries and northern Russia. Note that St. Petersburg (Russia), Helsinki (Finland), Stockholm (Sweden), and Oslo (Norway) are near the limits of servable destinations.</p> <p>An Earth-side energy density of 23 mW/cm² (chosen as safe for all life forms) equates to 5 gigawatts as a minimum power limit near the equator and proportionally more at higher latitudes. Building smaller SPS systems can be done, but the antenna arrays would not be smaller (or cheaper), and thus would be less cost-effective. Note that some sources suggest a minimum size of 4 gigawatts. In any event, at 2.45 Ghz (the highest frequency with negligible absorption by rain, snow, clouds, and people), a one-kilometer transmitter could not possibly focus higher intensities upon the Earth, making this a safe and non-military technology. </p> <p>The likely technology for the receiving station is a rectenna array, a network of many simple wires with diodes. It can be deployed above cropland (and herds of cattle, even forests) with only minor loss of productivity of the farm. Receiver losses will be of the order of 10%, much less than typical long distance power transmission.</p> <p>A side point: direct-to-home power transmission is perfectly feasible. A home rooftop rectenna could easily capture 5 or 10 kilowatts of power, several times the average household demand. The problem is all the power wasted between rooftops, including undesirable electric currents induced in most metals and wiring. But perhaps this is not a problem in a military environment, where an energy beam could be directed to the conflict zone, not as a weapon, but for providing electrical power wherever needed. This also has direct military applications: SPS powered drones could fly indefinitely.</p> <p><strong>HOW BIG IS A SOLAR POWER SATELLITE?</strong></p> <p>So how big is the SPS itself? That depends critically on the efficiency of solar energy capture and thus the technology used. There are two likely technologies: solar cells (photovoltaic) and solar dynamic (mirrors and gas or steam turbine powered generators). Both methods take advantage of the near-constant sunlight (only shadowed by the Earth for a few total hours near midnight twice a year, and never for more than 75 minutes at a time) – a net 99% availability. Also, the intensity of solar energy in space is greater than on the Earth’s surface due to the lack of air to absorb energy. About 950w/m<sup>2</sup> strikes the Earth’s surface at noon on the equator on a clear day, while in orbit the solar energy density is 1367w/m<sup>2</sup> all of the time.</p> <p><strong>Solar Photovoltaic versus Solar Dynamic</strong></p> <p><strong>Solar cells</strong> vary hugely in cost and efficiency. Common cells convert about 10% of the incoming energy to electricity. But modern cells convert 20% (thin film) to 40% (optimized) of the incoming energy. Caltech claimed to achieve 85% in a highly experimental demonstration in March of 2010. We don’t know what technology will be the most cost-efficient. Note that 25% efficiency implies a 4km by 4km photovoltaic array would generate 5 gigawatts in orbit, although it would take a 4.25km square array to deliver 5 gigawatts to the Earth assuming an 80% efficiency in the transmitter / receiver. </p> <p><strong>Solar dynamic</strong> may be more efficient, as large, low-cost mirror arrays focus the sun’s heat on a boiler driving a turbine electric generator. The mirrors are relatively inexpensive, and the cost will be dominated by the need to remove the waste heat using large cooling arrays. But the efficiencies are quite high, typically 40% to 50% (potentially even higher, depending upon the fluid used). Ordinary steam turbines can achieve 40% efficiency. Hybrid designs with a gas turbine followed by a steam turbine can achieve 60% or higher efficiency. The problem with solar dynamic is that moving parts imply mechanical failures. These units would likely require a nearby crew for maintenance – something easily provided from a space-based habitat. Note that at 60% efficiency, a circular mirror of 2.8 km diameter (or a 2.5 km square array) is sufficient for a 5 gigawatt SPS.  </p> <p>Solar dynamic has other advantages: lightweight flexible mirrors (such as ordinary aluminum foil) are not significantly affected by radiation, ultraviolet light, or micrometeor punctures. Disadvantages include that the turbines and generators are heavy, high-tech components that may have to be launched from the Earth. Also, the working fluid in the gas/steam turbines may not be cheaply available. The only gas available in large quantities is oxygen, which is very corrosive to many metal surfaces, at least until we capture the resources of a live or extinct comet which is likely to contain enormous quantities of water and ammonia.</p> <p><strong>PHYSICAL SIZE OF A SOLAR POWER SATELLITE</strong></p> <p>Using assumptions listed above, the width of an SPS might range from 2.5km to 4.25km, or as large as 6.75km if we use the cheapest solar cell technologies. But 4.25km looks like a reasonable target. Note that at geosync orbital distances, these would be as visible as the larger planets, and easily resolved with binoculars. Once hundreds were in orbit, they would appear as an arc of lights to anyone who looked up on a clear night. </p> <p>There is also a nearby 1.0km microwave transmitting antenna, visible using binoculars. One problem is that the solar cells must always point at the sun while the transmitting antenna must always point to the Earth side receiving station. Proposed solutions include:</p> <ul> <li>use the same structure with phased array techniques to steer the beam (always pointed at the sun), difficult for certain orientations; </li> <li>use separate structures with some connecting mechanism that rotates one or both arrays; </li> <li>use a smaller integrated array of a 1km transmitter (always pointing to the Earth) backed by a (fixed) 1km photovoltaic array, and a separate large mirror to track the sun and focus its light on the back of the transmitter. While appealing in several respects, this does have its own problems: dissipating roughly 15kw of waste heat per square meter, which implies a blackbody temperature of 240<sup>o</sup>C if there is no additional radiating surface (it couldn’t be a manned structure, and would have to cool off prior to maintenance). The mirror and the transceiver would have different orbits – one would require constant adjustments. Lastly, it would be difficult to focus sufficient light on the transceiver near local noon each day. But some clever engineer may find a solution to all these problems. </li> </ul> <p><strong>MASS OF A SOLAR POWER SATELLITE</strong></p> <p>Using modestly optimistic assumptions for solar photovoltaic panels, supporting structure, power collection, and for the microwave transmitter and its own antenna, I estimate a total mass of 25,000 tons for a five-gigawatt SPS. Early estimates were closer to five times higher, and some optimists currently estimate that thin film panels would weigh one-fifth as much, although a supporting structure and the transmitter must also be considered. Note that if the solar panel array is 4km on a side, then 1.0 kg/m<sup>2</sup> of panels, structure, and wiring results in a total mass of 16,000 tons, leaving the remainder of my mass allowance for the transmitter, its antenna, and other support structures.</p> <p>A 1.0kg/m<sup>2</sup> mass allowance solar cells, wiring, and structure seems like a significant challenge, requiring a substrate similar to a sheet of paper in thickness. Note that a silicon wafer sliced 1.0mm thick weighs 2.3kg/m<sup>2</sup>. However, the typical thickness of photovoltaic silicon wafers today is only a tenth that, and thus weighs 0.23kg/m2, leaving adequate allowance for structural components and wiring. </p> <p>When using the resources of an asteroid to build the Solar Power Satellite, the mass of the photovoltaic panels is only a minor concern, as there is more than enough silicon and iron in even a small asteroid to build them as crudely as desired. Indeed, using a convenient asteroid allows the construction of large and inefficient but presumably simple and reliable solar power satellites. The final technology choice may be one of minimum labor costs or total time-to-market. Those tradeoffs are not simple, because using a less efficient technology (that is simpler to produce) implies a significantly larger structure with more materials and thus more time and effort to build.</p> <p>But by using an asteroid for raw materials, we at least have choices to make beyond “is it even feasible?” Launch costs of people and tools to bootstrap the process will be high enough as it is, but having the cheap and convenient asteroidal resources in orbit where we need them gives us the flexibility to try not just one approach, but several approaches and learn which is the best way to deliver clean and cheap energy to the inhabitants of Earth.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com2tag:blogger.com,1999:blog-7338070402887246857.post-63941210414095519842011-01-23T10:08:00.001-05:002011-01-23T10:08:00.266-05:00Space-Based Solar Power<p>Many people have written pages, papers, even entire books on the subject of Space Based Solar Power. Certainly many of the authors are better qualified than I am. What my posts add to the mix is the cost reduction and simplicity gained by using an asteroid captured into Earth orbit for the bulk of the materials. </p> <p>Also, some of my sources are more recent than many older papers – which makes a huge difference. For example, my earlier posts used a figure of 125,000 tons for a 4 gigawatt SPS, based upon references quoting 20,000 tons per gigawatt, plus structure and the transmitter. But more recent sources propose a very lightweight design requiring only 1,000 tons per gigawatt – a 20-fold reduction. For these posts, I’ll be using an intermediate figure of 5,000 tons per gigawatt, or a total of 25,000 tons for a 5 gigawatt SPS (measuring 4 km on a side).</p> <p>Even with current high launch costs, at least one company believes they can build a cost-effective SBSP system using all Earth-sourced materials. I don’t see how, since fifty to a hundred or more 100-ton payload launches would be required. But the people with their money on the line have put more thought into justifying the ROI, and I wish them well. </p> <p>More commonly, pundits believe that Lunar materials (typically using a launch-rail system to lower the cost of launching materials from the Moon) might reduce the total cost to an acceptable level for as few as 50 to 100 SPSs (to amortize the costs of landing a great deal of equipment and people on the Moon).</p> <p>Asteroidal resources are much more readily available, and several sources have proposed robotic mining missions to various asteroids (chosen for a low net delta-V, especially for returning material to Earth orbit). Some proposals return raw material to Earth orbit for processing; others return materials processed to some degree (such as iron). Robotic missions are often assumed to eliminate life-support and radiation shielding costs.</p> <p>Note that a 100-meter radius Kalpana One style habitat (housing and feeding up to 8,000 residents) can be built from a single 120-meter asteroid, along with 12 five-gigawatt Solar Power Satellites, using the slag from iron smelting as radiation shielding.</p> <p>My proposal (see <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/08/capturing-apophis.html">Capturing an Asteroid</a>) is to use gravitational slingshot maneuvers (around the Earth, the Moon, or even Mars or Venus when appropriate) to capture <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/10/choice-of-asteroids.html">one or more asteroids</a> into Highly Eccentric Earth Orbit (HEEO), then to launch the tools needed to mine the asteroid, smelt it into valuable materials, and build the SPS network in orbit. Of course, this is simply a logical extension of the proposals to return asteroid raw materials to Earth orbit. I propose to send the whole asteroid (which we can do given the extraordinary special circumstance of an existing close approach of an asteroid).</p> <p>This approach requires large numbers of people in space, because people are good at problem solving. Using robotic approaches requires that the engineers anticipate all possible contingencies, and, speaking as an experienced computer programmer, I absolutely guarantee that we will never succeed at anticipating every possibility. </p> <p>But people are resourceful, and their ingenuity will solve all of the little problems, and likely the big ones that crop up, as well. The number of people needed is huge, because each SPS is itself huge (kilometers wide), and there is a lot of work required. We’ll need to smelt ore into steel at impressive rates (but typical of a foundry on Earth). We’ll need to form that steel into plates, girders, pipes, tanks, cables, etc.. We’ll also need tables, and chairs, and sinks, and toilets. It’s expensive to bring those things up from Earth.</p> <p>We’ll need to use part of that steel (and much of the slag) to build habitats for space workers (see <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/10/designing-space-habitat.html">Designing a Space Habitat</a>). We’ll need to produce magnesium for mirrors (assuming turbine-driven electric generators) or silicon for solar voltaic cells (or both – we won’t know what is best until we try). We’ll need to weld or bolt all the pieces together into immense structures, and then maintain them (because parts fail, regardless of how well-built they are). We are likely speaking of thousands of people to build that first SPS, and thousands more to build and maintain a network of them.</p> <p>Carbonaceous chondrite asteroids and extinct comets certainly contain everything needed. These comprise at least 75% of all asteroids, although they are relatively rare among Earth-crossing ones. However, any undifferentiated asteroid (such as ordinary chondrites) should suffice. All of these contain vast quantities of iron, oxygen, and magnesium. Most asteroids will contain small but significant quantities of carbon and hydrogen, easily extracted by simple heating. The asteroids to avoid are those from parent bodies that melted and differentiated, since that would isolate most metals into an iron core, and deplete the volatiles, leaving ore as poor and dry as moon rocks.</p> <p>HOWEVER, there are significant ground-based costs to consider as well. In addition to building an SPS with a microwave transmitter to deliver power to an Earth station, we must build that ground station, which (in principle) is easy and low-tech, but is still large (and thus expensive, partly because of land-use costs), plus we must build the power distribution network to get the electricity to the consumer. I do not have a good handle on this cost, which I am certain will vary tremendously from site to site, as it should be much cheaper where land is cheap (and power is not needed), and will be much more expensive close to major cities where the power is needed but land is expensive plus there is always resistance to putting the receiving rectenna in our back yards.</p> <p>Note that the receiver may typically require an oval roughly three miles wide and six long, but it is sparse and may be placed over a farm with little impact on crops or livestock below. It may also be place in a forest just above the treetops, where it would not even be all that visible. As a very rough estimate, I will assume that the ground-side costs will equal the in-orbit costs per SPS, although I will also plan that all of the up-front capital costs are for the SPS itself (a simplistic approach that ignores the cost of lawyers and politicians).</p> <p>My next post will discuss specific design considerations for a Solar Power Satellite.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com1tag:blogger.com,1999:blog-7338070402887246857.post-70240085827185504612011-01-21T10:52:00.001-05:002011-01-23T10:11:19.836-05:00Economics of Solar Power Satellites<p>Reading my local paper yesterday, I learned that the cost of building new, modern, nuclear power plants was much higher than I had thought. The Jacksonville Electric Authority (JEA) is considering a 20% share of a new 2 Gigawatt plant – at a cost of $2 Billion. The total cost of the plant is $10 Billion – or $5 Billion per gigawatt.</p> <p>This seems horribly expensive, but the resulting steady, cheap, zero-carbon electricity apparently makes the capital investment worth while.</p> <p>The cost is indeed high, which is good news for Space Based Solar Power: it may be possible to profitably launch the components directly from Earth to build a Solar Power Satellite (just barely).</p> <p>But as I have argued in previous posts, there is a much less expensive way to build Solar Power Satellites: build them in orbit using asteroids which provide all the raw materials we need (just add tools and workers).</p> <p>As a side benefit of great importance to most of the readers of this blog, my plan requires the building of permanent orbiting space habitats, self-sufficient, rotating for gravity, and using the slag from iron smelting as radiation shielding – a topic I’ve discussed before.</p> <p>My next several posts will discuss various aspects of Space Based Solar Power built using asteroid materials, from some high-level design considerations to construction techniques and ultimately to revenue generation and return on investment. </p> <p>I am more convinced than ever that we can expand humanity into space using ground-based profit motive, with benefits of lower energy costs, near-zero carbon emissions, and, did I mention, <strong><em>HUGE PROFITS</em></strong>?</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com3tag:blogger.com,1999:blog-7338070402887246857.post-12262862529741398542010-06-03T20:14:00.001-04:002010-06-03T20:14:14.057-04:00Asteroid Capture into Earth Orbit<p>(This long post is the presentation I delivered at the <strong><em>International Space Development Conference</em></strong> in Chicago on May 30, 2010. Links to additional information have been added, and overhead slides have been deleted.)</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhK2EDsJbtnMhqe4-lkoCilMurBJS8XCR7lg93suKP8f1PlNllYTUBdzdtHXvtn25e2vvXXqaqDC-FinjTmwrVmuumlGSOt67uyAVfBkdfxpUTjS5B8jYnV1_6yhYwjKRHVTh-_b3mQ7MY/s1600-h/clip_image002%5B9%5D%5B3%5D.gif"><img style="border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px" title="clip_image002[9]" border="0" alt="clip_image002[9]" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIjXTCTbMXwWF4orHMYAHPTGD3UUVYLJqzJOnw_JSht5Pk8Wm6wkTXabcX-vEszcMu5az9iUcGPI1-zh04QSr0jACnKhDFJmqdndgPf6jzsVpY1GyMqXxaZNdB3f_vT9KZKwHn5mUFCwM/?imgmax=800" width="364" height="274" /></a></p> <p><strong>Why capture an <a href="http://www.galleries.com/rocks/asteroids.htm">asteroid</a>?</strong> The main reason is to gain convenient access to its resources. Even a relatively resource-poor low-iron, low-metal LL chondrite contains 20% iron, significant quantities of water and other volatiles in the form of minerals such as clays, and oxygen to burn. And the best place to have those resources is in Earth orbit where they will have the greatest value. I will show how an investment of perhaps $20B will result in a trillion dollars worth of resources – a fifty-fold gain, with tremendous benefits for all of humanity humanity.</p> <p>For example, the asteroid Apophis (likely one of those LL chondrites) contains enough materials to construct about 125 five-gigawatt solar power satellites at 25,000 tons of steel each, plus <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/10/designing-space-habitat.html"><strong>Kalpana One style habitats</strong></a> for 100,000 people. The slag remaining after iron is smelted out of asteroid ore works nicely as the radiation shield, of which we’ll need 200 tons per person. The oxygen freed from iron compounds during reduction (1 ton of oxygen per 3 tons of iron) amounts to well over a million tons more than is needed for our habitats, and I expect we’ll use that oxygen as fuel mass for ion thrusters to move the habitats and solar power satellites into their chosen orbits.</p> <p><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/10/designing-space-habitat.html"><strong>Kalpana One style habitats</strong></a> are basically stubby cylinders spinning for gravity, with outer hulls containing 10 tons of radiation shield per square meter to provide protection against radiation and meteoroids similar to what we have on the surface of the Earth (which, not coincidentally has 10 tons of atmosphere above every square meter). </p> <p>Of course, a space habitat providing food, water, oxygen, fuel, construction supplies, gravity, radiation shielding, and skilled human workers and situated above much of the Earth’s gravity well is an ideal platform from which to continue the exploration and exploitation of space. </p> <p>And we should not forget that <strong><em>placing an asteroid into a stable Earth orbit prevents it from colliding with the Earth</em></strong>. In the long run, I believe that humanity will view Earth-crossing, potentially hazardous asteroids as low-hanging fruit, and each future discovery of an asteroid on a possible collision path will be followed by a gold-rush style race culminating in another new moon for our planet. Of course, each of these new moons will be somewhat temporary, as we convert its resources into more and larger habitats, solar power satellites, and other, perhaps undreamed of tools for the advancement and protection of humanity.</p> <p></p> <p><a href="http://lh6.ggpht.com/_WNHiVAIBXv8/TAhFNlHz79I/AAAAAAAAACI/aUcYcN7XkLo/s1600-h/clip_image002%5B11%5D%5B3%5D.gif"><img style="border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px" title="clip_image002[11]" border="0" alt="clip_image002[11]" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLVadWDvug98auUmeirAE5VGt4O_eKxaIFvxU0s114MeBFBnNZ8r-VNogMr8o-pSIVvDl7CNtUXlAhk8FdwmQyeFWLxe1BHRiCv0GmZ7UWfxHGb2h4bVneVXaqJD0-7__dfoWf2YFPdVk/?imgmax=800" width="364" height="274" /></a></p> <p><strong>So, how do we capture an asteroid?</strong> Even a tiny one masses millions of tons, and we don’t yet have the technologies to manhandle them and put them wherever we want. Luckily, we don’t have to. When a spaceship or asteroid passes close to a planet or large moon, its orbit is changed, sometimes dramatically.</p> <p>In principle, a slingshot around the Earth can impart a delta-V of up to 60 km/s to an asteroid in orbit around the Sun, although in practice the limits are a small fraction of this. More importantly, very small changes in the position or timing of an existing close approach are enormously magnified. </p> <p>We aren’t limited to the Earth, in that close encounters to other planets might be used to alter an asteroid such that it passes close to the Earth at a later time where its orbit can be further tuned by the Earth’ gravitational field.</p> <p>If we can adjust the asteroid’s orbit such that it makes a subsequent close approach to the Moon with a relatively low velocity, the resulting slingshot can drop that asteroid into a highly eccentric Earth orbit. The Moon can (in principle) remove up to 2 km/s of velocity relative to the Earth (although less is easier). Note that dropping the velocity of an asteroid to about .25 km/s (tangential) near the Moon’s orbit would result in an orbital period of about 9 days with perigee inside the geostationary orbits.</p> <p>A point I’d like to emphasize: In my opinion, gravitational slingshots are as much art as engineering, especially when considering the variations involved in multiple slingshots around one or more bodies. The people who dreamed up the Cassini and Messenger missions are both geniuses and artists, and I have every confidence that they can find suitable mission plans to capture any potentially hazardous asteroid into Earth orbit, although the missions may be very long and complex thanks to a shortage of appropriate close encounters and/or the need for significant changes to the asteroid’s orbital parameters.</p> <p><a href="http://lh5.ggpht.com/_WNHiVAIBXv8/TAhFOdxDNFI/AAAAAAAAACQ/uTBtbPFMv94/s1600-h/clip_image002%5B13%5D%5B3%5D.gif"><img style="border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px" title="clip_image002[13]" border="0" alt="clip_image002[13]" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEisdkhQBTctxbgRl82nVa5wFpLDrh4F_CXc3NCN8jdGzLl0oWdXoGZ-To1aXq_lhCRLADFfhDAlz5Gsv1vctmXKMFPkI0ai6GiMdMdRcROjsQ-j_9FobxFqtGmYn8nAUOpM1mZ8njjuXR8/?imgmax=800" width="364" height="274" /></a></p> <p></p> <p><strong>Let’s consider a specific example.</strong> The asteroid Apophis will approach Earth to within 30,000 kilometers on April 13, 2029, significantly inside the orbits of our geostationary satellites. If we do nothing, the Earth’s gravity will slingshot Apophis into a new orbit as it deflects it by about 28 degrees and boosts its velocity by 2.66 km/s. The result of this is that Apophis changes from a 0.89 year period Aten class asteroid orbiting mostly <em>inside</em> the Earth’s orbit to an Apollo class asteroid with a 1.167 year period and an orbit mostly <em>outside</em> of the Earth’s. I should point out that we don’t yet know with any degree of certainty exactly what the resulting orbit will be, because tiny changes in the position of closest approach have a huge impact on the resulting orbit. The period I’m quoting here corresponds to the keyhole that targets an Earth impact in 2036. </p> <p>My main point is that delaying Apophis’ arrival at the Earth’s orbit by changing its velocity by only 7.5 cm/s for six months results in a 1.4 km/s reduction in delta-V - a velocity gain of a factor of 20,000. I chose that particular slingshot because it results in a semi-major axis of 1 au, with a period of 1 year (and somewhat ahead of the Earth in its orbit). I used a program named GravitySimulator by Tony Dunn to model several Apophis orbit variations, and simultaneously to gain a true appreciation of the art and genius needed to find useful orbits. </p> <p>The Tisserand criterion indicates that it’s possible to change Apophis’ eccentricity to zero at the same time, although that would result in an inclination of about 10.5 degrees. In any case, what we really want is not a near-Earth orbit, but rather a subsequent slingshot around the Moon to remove excess velocity and drop the asteroid into a true Earth orbit. That may require some finesse and multiple slingshots, but I’m confident it can be done. Look at the success of Cassini and Messenger and all the other missions that have relied on gravity assist slingshots to achieve what once was considered impossible for our current technology.</p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixtFH8txi-eiW2GxYBB9kVqhyphenhyphengeztjRl7W3U_3q4l4HoR_FRbDwXbBH-tNTKwKgDrv6bNBni3OS2W3_UB3A4zRiCl4RrtVwzwwp_dceqBS8eKwvC2tmVAHrelb-Gwgr-k-3JNtjpK0NNI/s1600-h/clip_image002%5B15%5D%5B3%5D.gif"><img style="border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px" title="clip_image002[15]" border="0" alt="clip_image002[15]" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjewFtJS3utBhuSUUNnmMOsW3WI8g_zNYid_TSIeqerqNj4pn4n9CVN-48fE79K4HLA_eRsUbbB88r7uhcbNVxFiNfWXYiT3JHfKWyECz8NR3N4kEZIaX3T-nJR4mY5grwIE0lCr1a3HpQ/?imgmax=800" width="364" height="274" /></a></p> <p><strong>We still need to give Apophis that 7.5 cm/s nudge.</strong> I don’t suggest abrupt changes from nuclear bombs or high-velocity impacts, partly because we need finesse to fine-tune the orbit, and that’s best done by the equivalent of titration. We need a tugship, a long-mission, highly fuel-efficient spacecraft to gradually move the asteroid into a new orbit. </p> <p>Robotic missions may make a lot of sense in the future, because asteroid orbit changes are necessarily long-term missions. But until we figure out how to do it from actual experience, I think the ingenuity of real humans is needed to figure out what really works, out there in space, on the job. But manned missions have problems, too, largely revolving around the life support needs of fragile humans who need oxygen, water, and food to survive.</p> <p>Ion thrusters such as VASIMR engines are likely the best choice to apply delta-V, as their high exhaust velocities reduce the total fuel mass needed, and they should be able to achieve sufficiently high reliability.</p> <p>Of course, we need to push or pull the asteroid, which isn’t simple, partly because they are rotating, undoubtedly along an inconvenient axis. And they have enormous angular momentum which we can’t simply cancel. This means we’ll either have to dock – not land – at an appropriate location and thrust a fraction of the time, or use a gravity tractor approach which might limit us to lower thrusts and longer missions.</p> <p>In addition, ion thrusters take copious amounts of energy. 25 megawatts can be generated by a 300 by 300 meter solar array, or by a single compact nuclear module available commercially. We do have a lot of experience with high-power nuclear modules in submarines and aircraft carriers, so that’s an option I personally lean toward, but politics may dictate a less proven approach.</p> <p>Given an appropriate power supply, we still need enough time and fuel to move an asteroid. </p> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmBJ569g9nfmeLivOJ_U3DT5j8tU6qPR1VFeV66Y70ZfjG8UGl-MX8FxWekb5B7cbu-X_pyJMX7P_ZWlrpGxADQHBCUti4HNYaEVg4WcrXhF53guC9yThBCswkceoluW3nS8cHjxdG7i0/s1600-h/clip_image002%5B17%5D%5B3%5D.gif"><img style="border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px" title="clip_image002[17]" border="0" alt="clip_image002[17]" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLVjSIv-E78l0I7rldjULBVJKLpLM8JBcQhstyRZ5TjcXp9aEJmvagfdmKpJNuyxW_YXw5keFRhyphenhyphenE2hroDMZDvjOpvoPgu-qVF76zziZVNOzgdp7uQalye0_g265BYWaGMz4Q6VGdIa00/?imgmax=800" width="364" height="274" /></a> <p><strong>So how much fuel do we need?</strong> As a first approximation, we can pick a specific keyhole, which targets a change in position at a future time. From the mission lead time, we easily compute the needed asteroid delta-V, and conservation of momentum allows us to compute the needed momentum change - the product of fuel mass times exhaust velocity. The asteroid’s mass and the needed delta-S (for this example) are givens, but we can choose to some extent our mission time.</p> <p>Note that doubling the exhaust velocity quadruples the needed energy; 100 times the energy is needed for 10x velocity.</p> <p>Let’s look at our Apophis example. That 200 second delay over a six month mission requires a fuel mass that varies by a factor of ten depending upon the exhaust velocity. With a lot of energy, we don’t need much fuel at all, barely 4 tons. With a specific impulse of 5,000, we only need 41 tons. These numbers are all well within our technological capabilities. Of course, additional fuel will be needed to deliver the tugship and its load of fuel to the asteroid, but again, the numbers are within our capabilities. We can do this!</p> <p></p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIAfC3ZNAy79RIRT3iJLdZFe_gDSKD92we2eMTFj3oTIJIUXjhN8CxffOLK7Ddmef-d1Ut4JY5euhXkYKupn438MnrPkdL7mQE2H7MrQBHc1jW7DAUHRYgN4LbWCt4uUyWNu9qMOIQeUo/s1600-h/clip_image002%5B19%5D%5B3%5D.gif"><img style="border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px" title="clip_image002[19]" border="0" alt="clip_image002[19]" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjeuudIEdW39rl_cF3ea6tpVQ7a6aqP2DXUNEbrzzFbS09QhnrXRTKKoOHj7L4MYvneXXUPArhy9GxOSvlqsfJGy05t7VrpGSJ0pzI3-A95uChyphenhyphenA9D_d3WeSVxxVcqrw3_a3BLx6Xe_8Ko/?imgmax=800" width="364" height="274" /></a></p> <p><strong>But it seems that nothing is ever simple.</strong> Part of the problem is that we don’t really know much about asteroids. Many of them appear to be rubble piles, and in some cases these spin so rapidly that their shape is constrained by their spin, yielding flying-saucer shapes. Others are contact binaries which might be exceptionally awkward to manipulate. We have more options with solid bodies, but we can’t plan on that.</p> <p>So how do we apply thrust? Two ways come to mind, dock and push, or use a gravity tractor to pull. Gravity tractors can only apply tiny amounts of thrust, but that might work best, especially on longer missions. It would also help to dangle heavier components such as nuclear reactors and fuel as close as possible to the asteroid, with the thrusters some distance away so they can aim off to the side without much loss of thrust efficiency.</p> <p>We can dock with an asteroid and push against it in a traditional way, but there are complications due to microgravity and asteroid rotation. It is possible that a number of cables could be looped around the asteroid to hold the tugship securely in place. Even then, a spinning asteroid means that thrust can only be applied during a fraction of each rotation, wasting thrust and fuel to the extent that the applied thrust isn’t directed in the correct vector.</p> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSUTybs4NWOJSdkcvfGZpnpFuLIrIIFuuOSIXpfNvmOyHmPzPjKmfj6tmn81dvvwiiAQiYt-2CwyYNkZNhfLjIW6UY9x7DYtklBNzXzZTm1Kf_DNc50J9ucipS5H18Bz_-Sfc8FqV3RaQ/s1600-h/clip_image002%5B21%5D%5B3%5D.gif"><img style="border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px" title="clip_image002[21]" border="0" alt="clip_image002[21]" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidN67UjoFG9H6phoq_hFzAorGPioCJYNNSEgGIPeIH8UBfoRtu5er4GRZc7MSWColZ6uX2SGhhBd92sXaeGriW2c1TExZNSh75pAMq6_wiA1Td7DElw5vXRZoQyAl0TlgmqwDsrutXEwI/?imgmax=800" width="364" height="274" /></a> <p><strong>There are other complications.</strong> As I mentioned before, gravity assists are hugely complex computations and the solutions are driven as much by creativity and imagination as by brute force calculations. There are many potential asteroid candidates, potentially multiple bodies to slingshot past, and multiple slingshots may be needed, as with the Cassini and Messenger missions.</p> <p>At this point we don’t know enough about any of the potentially capturable asteroids, especially regarding their orbital parameters. Position uncertainties for most potential impacts for objects in the Potentially Hazardous Object database are in the tens of thousands of Earth radii once we go out twenty or more years. The uncertainties are not just due to the usual suspects of position and velocity, because things like albedo and asteroid spin have significant impacts over long periods. We would certainly need to know the true present course of an asteroid before undertaking any deflection efforts, accurately enough to eliminate any reasonable near-term possibility of an Earth impact. However, I believe that any deflection mission with a significant net reduction in impact probability over the next hundred (or thousand) years may be acceptable.</p> <p>We’ll also need to address problems of mining, refining, and manufacturing in zero-gravity which may require entirely novel approaches. This is another area where human ingenuity will be vital, as I don’t think we’ll know what the problems and solutions are until we try something that doesn’t work the first time.</p> <p>The last complication I’ll mention is that this is largely a bootstrap effort, with most of the costs up-front and the benefits and profits significantly in the future. But I’m optimistic, and I believe that an investment of as little as $20 billion, as described in <strong><em><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2010/03/economics-of-life-in-space.html">The Economics of Life In Space</a></em></strong>, will result in annual revenue of about 1.3 billion dollars (wholesale electricity at $0.03/kwh) for <em>each</em> of the 125 SPSs we could build from Apophis. After building the first few solar power satellites, the revenue stream becomes self-sustaining with no additional investment required, although the population and infrastructure in space would continue to grow. </p> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5ANswRWfJk3DVgHT6PSNUeE38ZL1JBHjX_M9Xg8KYhdicCM7xhSzCcpr-m5tb_CJ5a-1iErg5K0p18Bgh_YHNQbiY05WD-aN2K1hHMhrKR5rNYfziJ2RhVSEuPHtEGhyshKoRyDAxBQY/s1600-h/clip_image002%5B23%5D%5B3%5D.gif"><img style="border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px" title="clip_image002[23]" border="0" alt="clip_image002[23]" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIdFu-IVm0WGQ_vm79FnCUMG-AbDkvssVUjUX9mmIas0Z6YMkTcfx-eqlRVE1dzLTyQs3aX1Z73PE4lcwxO2Lj-dBGJtFCAAGB465X3CjwT8pHUxxOFzfKGBwrOVQWDRQfexmOuqa7Tvo/?imgmax=800" width="364" height="274" /></a> <p><strong>Lets discuss some of the selection criteria for choosing asteroids for potential capture into Earth orbit.</strong> </p> <p>The most important consideration is simply the proximity of an asteroid’s orbit to a useful keyhole through which the orbital engineers can design a capture mission in a reasonable timeframe. </p> <p>The second consideration is the size of the asteroid. Bigger is not better when a 1 kilometer asteroid masses fifty times as much as Apophis, and thus requires a fifty-fold increase in the product of mission time and fuel mass. On the other end, a small 120 meter LL asteroid massing 2 million tons (and relatively poor in useful metals and volatiles) still has sufficient materials to build a single small Kalpana style habitat for 8,000 colonists plus twelve 5-gigawatt SPSs, and requires one tenth the fuel (all else being equal). Thus I view 120 meters as the smallest asteroid worthy of capture, since it is barely large enough to build a permanent habitat rotating at 3rpm for Earth-normal gravity and with adequate radiation and meteoroid shielding. We will need at least that many miners, steel-workers, welders, SPS construction workers, and support personnel such as farmers to build the infrastructure and solar power satellites.</p> <p>Another consideration is the V-infinity of the asteroid, because slower asteroids are easier to move a distance large enough to make a significant difference in the slingshot, and less asteroid delta-V will be needed. </p> <p>The potential magnitude of a gravity assist is also constrained by how close to the center of the Earth the asteroid passes – and I think it’s important to keep it out of the lithosphere. Worse, for a rubble pile we don’t want to pass closer than the Roche limit or the asteroid may be torn apart by tidal effects, much as Jupiter’s tide tore the comet Shoemaker-Levy into 20 fragments. The actual Roche limit depends upon density, but is likely to be of the order of 20,000 kilometers for a rubble pile asteroid near the Earth, and perhaps 5,000 kilometers for the Moon.</p> <p>One might think that the composition of an asteroid would be the number 1 criteria, but in reality most asteroids should be quite valuable. Of course, a common carbonaceous chondrite might contain 25% nickel-iron mostly in the form of metal grains, 10% or more water, and several percent carbon plus everything else needed for life in space. But even a lowly LL chondrite will work.</p> <p>The last consideration here is the opportunities for intercept missions. We need to modify an asteroids orbit when it is easy, some months or even years before the targeted close approach. This is difficult for a high-inclination long-period asteroid because it might only approach closely enough to the Earth for low-delta-V intercept missions once every ten or a hundred years. But an asteroid with a two-year period might present suitable launch windows every two years. Also, for asteroids with low inclinations, there may be two launch windows in a year as the asteroid passes inside and then outside the Earth’s orbit.</p> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhi80nFKXAaphKw-XBBFxWI-ObIuB6fSw5Lpo4dpBA2bG9Vi5SGk1tFBBIrBqWpzKIuegtvqFMejKcpajop8N_KiGaUGjorATzQVNmwNbjc7OrbDAzDgaQmQTgQRB9m-AWLAlIBvEJnw94/s1600-h/clip_image002%5B25%5D%5B3%5D.gif"><img style="border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px" title="clip_image002[25]" border="0" alt="clip_image002[25]" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhlMVmGx5KDqtCPjTv_UmFqqQhU48bqrPr6Uu6_iYvbfGgK2emmDtJal1PEXaVbQx5yDo1e8Hz7fYOQR7bNMXVDZbEwhR6sIO5oSujjd91W_ksBEx-9_tRqd5a-Cqys_mqI_m5gpynyhqw/?imgmax=800" width="364" height="274" /></a> <p><strong>This table presents some possible candidates as of mid May.</strong> Some of these will be eliminated by further refinement of their orbital parameters, while others can likely be added as additional asteroids are discovered, or as orbits are corrected for known ones.</p> <p>The entries on this table were gleaned from the Near Earth Object Close Approach database. Note that the various tables, databases, and lists at the NASA web site are inconsistent, sometimes even on the same page. For example, the orbit visualization tool often has significantly different closest approaches than the “close approach” data on the same page.</p> <p>A side note: Many asteroids have only been observed over a few days, resulting in large uncertainties in their orbital parameters. The shapes, diameters, and masses of most asteroids are estimated, not known. Diameters are estimated from an asteroid’s brightness, distance, and albedo. But we can’t measure the actual albedo, and observations at multiple wavelengths are used to judge the asteroid class, and from that a typical reflectivity, and from that a formula results in an estimate of the diameter, and assuming an average density, we calculate the mass. This process has very large error bars. In April, radar imaging resolved the asteroid YU55. Previous estimates were that it’s diameter was 140 meters and its mass 4 million tons. The actual measurement revealed a diameter of 400 meters and an estimated mass of 87 million tons, a 20x mass increase.</p> <p><strong>Lets consider these asteroids.</strong></p> <p><strong>Apophis</strong> is fairly well characterized and has a very close approach on 13-Apr-2029, although it may not be an LL chondrite after all, and may therefore have a different albedo, diameter (currently 270m), and mass (currently 27 Mt - million tons). As a candidate for Earth-orbit capture, it has the advantages of passing quite close (4.6 Earth radii), and relatively slowly (V-infinity of 5.87 km/s), plus a launch window occurs each April 13<sup>th</sup> near the close approaches and is thus suitable for a one-year mission. Missions to improve our knowledge can be launched in 2013 and 2021.</p> <p><strong>2007 RY19</strong> is noted as having possible very close approaches in some databases, but not in others, and the error bars are very large. The best opportunity may be 03-Dec-2024. Its mass (1.8Mt) makes it easy to move, and intercept missions can be launched every 7 years or so. </p> <p><strong>2001 WN5</strong> is a bit on the large side at 646 Mt, but it will pass about halfway between the Earth and Moon in 26-Jun-2028, which may offer an opportunity to adjust its subsequent orbit that we shouldn’t pass up, even if the actual capture couldn’t happen for a decade or two more. This asteroid is large enough to build thousands of SPSs and habitats for at least 2 million people.</p> <p>At 87 megatons, <strong>2005 YU55</strong> is three times as massive as Apophis, and approaches Earth, Venus, and Mars, giving multiple possibilities for gravity assists. Next year it will pass about 20% closer than the Moon’s orbit, but it won’t be that close again for quite a while (depending upon its new orbit after the Earth slingshot). In its present orbit, it makes frequent approaches, about every 5 years.</p> <p><strong>2006 WB</strong> is a small asteroid that won’t pass very closely (nearly 2.5 lunar distances) on 26-Nov-2024, but it is small, and we can possibly adjust its orbit for subsequent passes. Note that its mass is poorly constrained, with different databases estimating its mass differently by a factor of four, from 0.5 Mt to 3.0 Mt. </p> <p><strong>1994 WR12</strong> also approaches Mercury and passes Earth every 2 years in a nearly 3:2 synchronous orbit. Its next close approach is on 26-Nov-2021, and it has a perfect size at 2 megatons (120 meter diameter) making this an early practice possibility for changing an asteroid orbit. It doesn’t pass very closely at all, however, coming no closer in 2021 than 8 times the Moon’s distance.</p> <p>I’d like to point out that every one of these asteroids were placed into their current orbits by a slingshot around the Earth, a fact clear at a glance at the orbital simulation on the NASA web site. One of the principles of orbital mechanics is that an orbiting body (in a 2-body system) will always return to the location and velocity vector of its last orbit change. Ignoring hyperbolic orbits, one near Earth pass means more, until the body collides with the Earth or is deflected away by another planet. </p> <a href="http://lh4.ggpht.com/_WNHiVAIBXv8/TAhFTpRZGKI/AAAAAAAAADI/_wSCiq8HbdE/s1600-h/clip_image002%5B27%5D%5B3%5D.gif"><img style="border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px" title="clip_image002[27]" border="0" alt="clip_image002[27]" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg__9yaQJIpxnRFz-Cl3H-_w7CYmDFfJpDQcWcNVSBpQ8aj7m2yrPKHG2qDk2bdNSeRHcao9DgSbfnawsSdUOwiHBNK4kt4glEDRBIKLndNtflJigAYRebtfddrauyqT9y2Ccv-ffjJWEM/?imgmax=800" width="364" height="274" /></a> <p><strong>A legitimate question to ask is, will NASA undertake an effort such as capturing an asteroid into Earth orbit?</strong> Personally, I think it’s unlikely, because (at least as I have envisioned it) this is a commercial endeavor. Certainly NASA would not build solar power satellites, although we can task NASA with related aspects of human habitation in space, including habitat design, launch vehicles and tugships, farming, space operations, and other research projects that advance humanity into the Solar System. We might even get NASA to capture an asteroid into Earth orbit as one way to avoid a future Earth impact. I strongly encourage this, as NASA is an excellent organization to make sure the orbital capture is done right (if expensively), and then NASA could sell the exploitation rights to private enterprise and recoup all mission expenses.</p> <p>China does not face the same political constraints and the Chinese government could easily choose to capture an asteroid and build habitats and solar power satellites. </p> <p>The United Arab Emirates certainly has the funds to capture an asteroid and build a fleet of solar power satellites. And actually, I can’t envision a more appropriate use for the oil wealth they’ve accumulated. While they haven’t demonstrated the technologies to execute such a mission themselves, they could certainly fund it, buying themselves the resources to build that fleet of solar power satellites, and converting the dwindling stream of oil revenue into a growing stream of solar energy revenue.</p> <p>Capturing and exploiting an asteroid such as Apophis can be done by private enterprise. I estimated the required investment as about $20 billion, which is certainly within the capabilities of the largest companies. And the prospect of a revenue stream of $150 billion per year should excite their CFOs.</p> <p>Ignoring the profit motive for a moment, we should also consider that there are other possible reasons to invest in space habitats, specifically: to promote a way of life. There are many churches with the capacity to fund this effort, yielding a platform in the heavens, and a starting point to go forth and multiply. Certainly the resources available in the asteroids and comets dwarf to insignificance the Earth’s resources, so in the long term, the only thing that counts is that move into space. </p> <p>And whether NASA, China, the UAE, private enterprise, or even some other organization steps forward to undertake this mission, capturing an asteroid is an incredible prize, as is the building of a the first large permanent colony in space -- accomplishments which will permanently record its founders in the history books.</p> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEge6QMJW-e7e16bXS6E5ePHes9tMeFu4ZtVTuS8BT__wC5xoHl1ti2QWYQQ2mPrn3oeOdLTHlzMBm_xzZ8TIr_OvOantWYjochPIYe6hsNDM0z6MyW1P8iacOMD8rMqkiA0KOQCAyQuqwo/s1600-h/clip_image002%5B29%5D%5B3%5D.gif"><img style="border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px" title="clip_image002[29]" border="0" alt="clip_image002[29]" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdB16Nbxv7eDUSS5ckfZXsKZiOudp5JfR7sezO5sXvQXdqzZZKWLkk5DEwKGzo2edrAdEhQvJoiq1zCDHAX2czZ80CVinA5T1E3fi8MzYge9qPF78ySrpb6CunQwejvNKxC4-17cxICm0/?imgmax=800" width="364" height="274" /></a> <p><strong>Continued research tops the list of the several logical next steps we should take.</strong> NASA is ideally suited for several of these, and the continuing search for potentially hazardous objects identifies the same candidate asteroids as a search for potentially captureable ones. We need much better knowledge of their orbits, size, and composition; we need to explore slingshot opportunities; and we need to seriously advance our ability to move permanently into space via closed-loop recycling of everything.</p> <p>We also need to address several legal issues, which pose a serious problem for Western civilization private enterprise. Key among this is the right to own and exploit objects in space. If a person or company does not have the right to exploit space-based resources, they can have no incentive to acquire them, and the future of humanity in space is effectively dead.</p> <p>We must also address the liability of moving asteroids. Certainly this should be done with the utmost care and intense oversight tempered with some sense of practicality. For example, the example adjustment to Apophis orbit that I propose here appears to pass through the 2036 impact keyhole. Does that mean we must move the orbit out and around that keyhole, or simply that we use reliable, even redundant systems, and closely monitor to track the potential need for additional intervention? I’m afraid that science and logic may have little to do with the outcome of that discussion.</p> <p>Someone needs to design and build a tugship using thruster and power technologies available in an appropriate timeframe. I think the biggest challenge here might be in supporting deep-space, long-term missions with the human crews I think are necessary to get the job done.</p> <p>Lastly, we should refine the cost estimates for space based solar power from in-orbit asteroid resources and using a variety of technologies, although this is certainly a commercial endeavor.</p> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1SLmsv3B5kSjJQDNja0PqZ7x7rOLb1h8ovmGpwfGc3WizK7mQ_ogqqNSpxlNaBgodOdgBRJcaku9QOrzDDcvyzLfx0QwEqxw6OKDQcKKz5K-BKnofsrZ7j_EAFoqeX0WfEs4dN01Tr30/s1600-h/clip_image002%5B31%5D%5B3%5D.gif"><img style="border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px" title="clip_image002[31]" border="0" alt="clip_image002[31]" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6yIs3GhW8BV0eMu9B5fYy6EECbh4bT3-oXsSvrI7rGLmpy87qZ8QcxOgQsih0LmGh2Al_pPPGua2yC-AMQ6IZj1BDmliJ3ZnEozW4Kyi40pWXqlAQWmh-7otGNBPhWEIXu6cBAWd9Q-U/?imgmax=800" width="364" height="274" /></a> <p><strong>The bottom line is that we CAN capture asteroids into Earth orbit, thanks to the amplification of delta-V due to gravitational slingshots.</strong></p> <p>There are several candidate asteroids today, and there will be more tomorrow. Also, I did not look for opportunities where the asteroid close approach was to Venus, or Mars, or Mercury (let along Jupiter), and there is every chance that many more good candidates exist, although longer missions would be required.</p> <p>The most important consideration to me is that capturing an asteroid such as Apophis places millions of tons of raw materials into Earth orbit where we need them to build solar power satellites, permanent orbiting habitats, and to advance humanity’s exploration and further exploitation of the vast resources of space.</p> <p>Lastly, we should never forget that capturing a potentially hazardous asteroid converts a dangerous threat into a resource of immense value.</p> <p>My personal web page, <a href="http://www.StephenDCovey.com"><strong>www.StephenDCovey.com</strong></a>, gives too much information on my background and other ventures. But it also contains link called “<a href="http://www.stephendcovey.com/Apophis.htm">Project Apophis</a>” which very briefly summarizes this presentation, and concludes with a call to action via a link to the Office of the Whitehouse. </p> <p><strong>President Obama needs a grand goal for NASA and the nation</strong> in the next decades, one comparable to Kennedy’s “We choose to go to the moon in this decade.” I believe that <strong>capturing Apophis into Earth orbit is such a grand goal</strong>, with benefits to global energy and warming (via those solar power satellites), and to space exploration, and to permanent, self-sustaining habitats in space. <strong>And it removes a threat to the Earth.</strong></p> <p>If you agree that we need a space-faring humanity and that exploiting asteroids is key, if you agree that sending cheap solar energy to Earth simultaneously helps humanity and reduces global warming, and if you agree that we should act to prevent asteroid impacts on the Earth, then please share the word. Follow that link and tell President Obama that he holds the key to the future of humanity in space, that capturing Apophis is feasible, affordable, solves many problems in a single step, and is a Grand Goal worthy of his – and this nation’s – focus. Thank you.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com14tag:blogger.com,1999:blog-7338070402887246857.post-32628882864374187102010-03-13T14:49:00.001-05:002011-01-23T10:11:19.836-05:00The Economics of Life In Space<p><strong>For mankind to move into Space, it must be</strong></p> <ul> <li>Affordable in the short term </li> <li>Profitable in the mid term </li> <li>Self-sustaining in the long term </li> </ul> <p>Each of these should be analyzed in more detail, even if they are self-evident to the optimists among us. Even the definition of short, mid, and long term are subject to discussion, but for these purposes the points above are self-defining.</p> <p><strong><font size="3">The long term</font></strong> will begin when Earthbound civilization is no longer necessary for a space faring humanity. By not necessary, I don’t mean not useful: I expect that the cradle of mankind will always be an important part of humanity’s heritage. But at some point the continued expansion of humanity will no longer depend upon Earth resources. This has happened to every expansion of humanity (or a branch of civilization) at some point or another. For example, when Europeans colonized the Americas, the new territories may have initially profited by sending goods to the home country and depended upon tools and technologies created there, but eventually the continued expansion of the frontier no longer depended upon the Motherland. This may take longer (perhaps much longer) in space than on Earth, because the environment is hostile, a high level of technology is needed to survive there, and technological civilizations are complex. It may take tens of thousands of people living in space, or it may take tens of millions to replicate all of our technology. But it <em>will</em> happen.</p> <p><strong><font size="3">The mid term</font></strong> will be the period when Earth profits from investments in space, and in some sense this will be a Golden Age of immense profits, rapid growth, unbridled enthusiasm and optimism. Many people have proposed many different potential sources of profit, but two stand out: tourism and Solar Power Satellites (SPSs).</p> <p><strong><font size="3">Space Tourism</font></strong> is perhaps an indirect Earth profit generator. As long as launch costs are high (even as cheap as $500/pound), it will only be affordable by the wealthy. But most of the expenses are Earth-bound, and every million dollars spent on Space Tourism will contribute perhaps $2.5M to the Earth’s economy, supporting 25 to 50 families on Earth.  Remember, you can’t spend money in space; every dollar spent on the space program is ultimately spent on Earth, and will continue to be until a space civilization can thrive on its own.</p> <p><strong><font size="3">Space-Based Solar Power (SBSP)</font></strong> would directly benefit civilization on Earth, in multiple ways. Not only through stable, low-cost, zero pollution electric power, but also since the construction of Solar Power Satellites and the construction of Earth receiving stations would stimulate the Earth’s economy. Note that SBSP can provide cheap power to remote areas, including many of the poorest nations on Earth. Note that, as with space tourism, every dollar spent on SBSP (both construction and operation) is a dollar spent on Earth. The fact that a large-scale SBSP network would be enormously profitable for some corporations or nations in no way reduces its value to the Earth’s economy. And low-cost reliable power directly contributes to the wealth of the recipient. In a sense, reducing the use of fossil fuels (and the resulting global warming) is only an indirect benefit of SBSP.</p> <p>Also note that SBSP would be expensive to build and launch from Earth; it will likely be affordable only when we can use space-based resources to build Solar Power Satellites (see my post, <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/08/capturing-apophis.html">Capturing Apophis</a>). But once built, Earth’s civilization benefits for the indefinite future.</p> <p><strong><font size="3">The short term</font></strong> is the period – however long – when Earthbound civilization must invest in space. This includes the period when we are beginning to build a network of Solar Power Satellites, or space habitats for living, or space hotels for tourism. While any long-term space-based habitat is likely to produce its own power, food, water, and oxygen (recycling wastes in a closed cycle), most other needs must be met using tools and technologies imported from Earth, including LED’s for lighting the farms, computers, communication equipment, high-technology space suits, VASIMR rocket motors, vitamins, pharmaceuticals, medical equipment. The list is endless, although the relative need and value tails off rather quickly.</p> <p>More importantly, <strong>the Short Term</strong> is the period while the costs of launching people, tools, and bootstrap resources into space exceed the profit derived from space-based enterprises, primarily SBSP. But the cost of bootstrapping a space-based civilization is an investment, pure and simple, yielding enormous profits for those clever and resourceful enough to make that investment. </p> <p><strong><em>The revenue from a single SPS is of the order of $1 Billion per year</em></strong>, suggesting that an investment of even $100 Billion to build and deploy a hundred SPS’s would be wildly profitable. Yet it would cost a fraction of that to capture an asteroid such as Apophis into Earth orbit, and to launch sufficient people and tools to turn that asteroid into a habitat and a factory to build Solar Power Satellites. Note that Apophis is too small to build more than about a dozen SPSs (assuming half of its mass is reserved for habitats). Yet it is more than large enough to bootstrap the process and support the ongoing space-based resources needed to capture additional asteroids to build thousands of SPSs and habitats for millions of people.</p> <p>Let’s estimate some numbers:</p> <ul> <li>$2 Billion: <strong>Commercialize the technologies to capture an asteroid</strong> (large-scale VASIMR, long-duration space flight)</li> <li>$2 Billion: <strong>Launch the capture equipment and team</strong>. This will result in the capture of an asteroid such as Apophis into a highly-eccentric Earth orbit after a period of a year or two.</li> <li>$2 Billion: <strong>Develop the processes and tools needed to mine, smelt, and process asteroid material into steel, oxygen, and hopefully CO2 and water</strong>. Other valuable materials are a bi-product. There are many unknowns, including the raw materials themselves, and zero-gravity smelting, and recycling of effluent gases such as carbon dioxide. Nothing should be vented / wasted.</li> <li>$2 Billion: <strong>Launch the solar smelters, mining equipment, and tools</strong> to process iron ore into steel plates, girders, cables, etc.. Part of this is launching a small fleet of VASIMR tugs, fueled by excess oxygen from the smelters and using solar power for energy, to boost cargo and people from LEO to the HEEO of the captured asteroid. To a degree, this is launching the tools to build the tools to build the tools….</li> <li>$2 Billion: <strong>Launch the people and habitat resources</strong> (LED lights for farms, solar panels for power, initial supplies of oxygen, food, and water, pumps and recycling equipment, ….)</li> </ul> <p>Okay, so I used nice round numbers to get the total cost around $10 Billion. It may even be accurate to within a factor of two. In reality, I’d expect on-going costs of continuing launches of additional people and resources, perhaps $2 Billion per year for the 5 years I expect it would take to build the infrastructure and that first Solar Power Satellite, but then you get another one built every year, and the continuing influx of people and resources builds additional SPSs every year after that.</p> <p>My expected cost to get that first habitat and first solar power satellite operational is of the order of $20 Billion. But then the investment starts to multiply, and by the time you’ve invested $30 Billion, you’d have 30 Solar Power Satellites in production and your investment ROI is 100% per year (ignoring ground-based costs of receiving and distributing the power, which might be as much as another billion per satellite). Actually, by the time you have two SPSs (ignoring ground costs) or four SPSs (assuming $1B/satellite in ground costs) in operation the operation is self-sustaining and doesn’t require additional capital investments, yet the profits continue to grow.</p> <p>Assuming the chosen asteroid is Apophis (but see <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/10/choice-of-asteroids.html">A Choice of Asteroids</a>), the first $10 billion would be spent by 2030, the first SPS operational in 2035 (after spending another $10 Billion), and the entire operation is wildly profitable by 2040 (by which time you’ve invested $30 Billion but your satellites are earning you $30B/year). It sounds like a great investment for my IRA.</p> <p>A lot of research is needed, and a lot of talent. We need to solve these problems:</p> <ul> <li><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/11/farming-in-space.html"><strong>Farming in Space</strong></a> (total closed-system recycling)</li> <li><strong>micro-gravity mining</strong></li> <li><strong>zero-gravity smelting</strong> of ores using recycled reducing agents and probably direct solar power</li> <li><strong>zero-gravity refining</strong> (separation of metals, slags, and effluent gases into valuable component parts)</li> <li>zero-gravity rapid capture and separation of gases from iron and steel production (we can’t afford to waste that carbon dioxide).</li> <li>zero-gravity metal forming (turning steel into girders, rods, plates, cables, etc.)</li> <li>Welding of large structures in space.</li> <li>Low-cost, human-friendly space suits (ie, <strong>skin suits</strong>) for hard-working people.</li> <li><strong>VASIMR</strong> (or similar rocket technologies) to use the excess oxygen from the production of iron as a rocket fuel for in-orbit shuttles and to capture asteroids. Oxygen is the primary bi-product of steel production from ore (other than slag, and assuming recycling of carbon), with a ton of oxygen freed for every three tons of iron produced. Thus the 75,000 tons of steel needed for a habitat for the first 8,000 people yields 25,000 tons of oxygen. Building each 180,000 ton SPS (4 km on a side) yields 60,000 tons of excess oxygen. That’s a lot of rocket fuel.</li> <li><strong>Low-cost launch to LEO</strong>. Part of this may be the economy of scale, as very large heavy-lift rockets are much cheaper per ton to orbit than smaller rockets. I believe this entire operation is highly profitable and sustainable if the launch cost to LEO is $1 million per ton or less. While NASA and the Space Shuttle (or its proposed replacements) can’t approach this cost, commercial private-sector efforts can. And the scale of this project is large enough to justify those investments.</li> </ul> <p>There are a myriad other problems to be solved, but most of them are engineering efforts, not R&D projects. They will still require a lot of talented people, and many more people will be needed to work in space – thousands of them, of every persuasion. Miners. Steel workers. Welders. Electricians. Plumbers. Mechanics. Farmers (lots of farmers). Doctors and nurses. Pharmacists. Cooks. Wait staff. Bartenders. Construction workers. Janitors. Barbers and cosmetologists. Massage therapists. Truck drivers & bus drivers (but we’ll call them space ship pilots). Clerks. Accountants. I suspect a lot of movies might be made in space, so add actors and all those people listed in the credits for your favorite movie. And where lots of people go, families happen. So we’ll also need day care workers. Teachers. Playgrounds. Schools. Police. We might even need a manager or two. Counselors. And a divorce lawyer. </p> <p>If you have a skill, you’re probably needed in space. <strong><font size="3">Welcome to the future.</font></strong></p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com1tag:blogger.com,1999:blog-7338070402887246857.post-79671138368307919552010-02-26T14:02:00.001-05:002010-02-26T14:02:59.445-05:00I Hope I’m Wrong …<p>I’ve argued that the future of humanity necessarily involves a future in space. There, we won’t have the room restrictions, resource restrictions, and catastrophe likelihoods that we’ll have so long as we’re confined to the surface of a single planet. There, a single nuclear, or nanotech, or biotech mistake won’t wipe us all out in the blink of an eye.</p> <p>But to bootstrap into a space-faring civilization takes a huge commitment. Space travel (at least from the surface of the Earth)takes a LOT of energy, which (on average) we don't have to spare. Space travel (and bootstrapping our future) also takes money, which we also (on average) don't have to spare. </p> <p>One key point of my proposed "space faring future" is that we will need fusion energy, which potentially solves the energy problem. We aren't there, yet, but there is hope. Out as far as the Asteroid Belt, solar energy can handle our needs, but in the very long term (think a thousand years) we’ll need to expand beyond there.</p> <p>A second key point is that a future in space for humanity is not likely to involve a lot of travel to and from planetary surfaces. Landing deep in a gravity well and launching into space from deep in a gravity well is extremely expensive. I also don't believe that we will colonize Mars or even our moon to any great degree - there's just very little value in that, and a great deal of expense. </p> <p>That's why I expect that humanity's future will be asteroid and comet based. Comets (and carbonaceous asteroids) provide all of the raw materials (including hydrogen and deuterium for fusion power) that we might need for a space-based civilization, in a readily accessible form. It is relatively cheap and easy to land/take-off from their negligible gravity wells. </p> <p>However, to get there in the first place (especially with enough infrastructure to build a high-tech industrialized society) will take a lot of energy, which we aren't likely to have to spare until we perfect fusion energy. </p> <p>I have another very important point, which I haven’t elaborated on the past, largely because it is too depressing. </p> <p>I don't believe that the USA will be a significant part of humanity's future. We have too many well-meaning people who think our wealth should be spent in other ways, such as feeding the poor, burying excess carbon dioxide, low-income housing, building giant levees around all of our low-lying coastal cities, and (most importantly) preserving the status quo. They want to preserve what we have, or restore what we had, instead of building the future. </p> <p>I believe that humanity's move into a space-based civilization will be funded by either extremely wealthy dictatorships (think oil sheiks) or other dictatorships that care more about results than about their people or damaging the environment - think China. </p> <p>You see, we have more than enough wealth to create a comet-based space faring civilization. We could do it now IF we didn't mind launching large nuclear reactors into space (a nuclear submarine is quite similar to a spaceship, a nuclear-powered aircraft carrier could carry more than enough infrastructure and people to colonize an asteroid). </p> <p>We don't have the needed wealth or energy ON AVERAGE. But there are people (or countries or companies or churches) that have enough wealth that, should they so choose, they could bootstrap the process, and in that way insure their own place in history. </p> <p>It WILL happen. At least I hope it will - the alternative is likely to be the more-or-less slow demise of humanity, as our per-capita energy falls, as our per-capita wealth averages globally, as billions of people starve and technology fails. </p> <p><strong><em>The status-quo is not an option.</em></strong> In an ideal world, we would find a way to raise the global per-capita wealth to something like what we currently enjoy in western civilization (likely making US much wealthier than at present). In an ideal world, we would find a way to do that while reducing humanity's impact on our global ecology (sounds impossible to me). In an ideal world, we would find ways to feed our burgeoning population while leaving most of the world's natural resources untouched (some people argue that we have no right to take the food that sustains the other carnivores of the world, such as sharks, wolves, crocodiles, hyenas, etc.). Other people would argue that it is more important to preserve the endangered spotted sand flea than to build power plants, factories, or housing. </p> <p>I don't think it is likely to happen in our current society. We have too many people who want to globally average our wealth, too many people more concerned with reducing our impact on the world than on building our future, too many people more focused on taking the wealth of others than on creating their own wealth. </p> <p>The status quo is likely to lead to a greatly reduced impact of humanity on the global ecology. That will automatically happen when civilization fails and billions starve and we are reduced to a few tens of millions of people living on the edge of starvation in a non-technological world. The remainder of the world (non-human) is likely to recover quite nicely (perhaps minus a few thousand species that have or will die out because of our impact). </p> <p>At some point in the future, SOME dictator will decide to move HIS society into space, "screw the masses". It WILL happen, and that dictator will thus insure his place in history. The USA is likely to be a small reference in a footnote about a failed civilization, otherwise forgotten. </p> <p>My personal attitudes (I'm normally a perpetual optimist) and beliefs (I'm intelligent enough to see that there are extremely serious problems in the world) are in conflict. I see that we DO have the resources, but not the will to expend them, and our excess resources are dwindling.</p> <p>It would cost us a few billion to capture an asteroid, a few billion more to turn it into a factory for Solar Power Satellites (helping the Earth below), a few billion more to create permanent habitats in orbit. The total expenditures ($10B-$20B for this one project) would be less than we spend annually on pet food, or cosmetics. We spend 10 times this on gasoline every year to fuel our bad driving habits and oversized cars. The largest source of wasted wealth may be our excess expenditures on health care: The USA spends DOUBLE the dollars per person on health care than do the 2 dozen counties with better health care (as measured by their longer average life spans). This is a waste of roughly $600 billion, of which perhaps 20% is due to malpractice insurance and procedures instituted only to prevent malpractice claims (not medically necessary). A tiny fraction of this ANNUAL expense would fund humanity’s future in space.</p> <p>There are so many solutions that we don’t have the will to implement. High-density urban living. Public transportation. Electric cars. Health care without waste. Eating more vegetables and less beef. Recycling (really, we just need less of a wasteful attitude as represented by our use of disposable packaging). Solar power. Geothermal power. Travelling-Wave nuclear reactors (that consume radioactive waste). </p> <p>Question: What do YOU believe are the long-term goals of civilization? What SHOULD we spend our wealth on?</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com2tag:blogger.com,1999:blog-7338070402887246857.post-43174314959127639242009-11-18T15:38:00.001-05:002009-11-18T15:38:27.399-05:00Lighting our Space Habitats<p>In previous posts (<a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/10/designing-space-habitat.html">Designing a Space Habitat</a> and <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/11/farming-in-space.html">Farming in Space</a>) I’ve argued that we do not want to use “natural sunlight” to illuminate our habitat and grow our crops. There are three primary reasons: </p> <ul> <li><strong>Simplicity</strong>: We must have radiation (and meteor) shielding of about 10 tons per square meter of surface. A complex chevron array of mirrors would be needed to reflect light around this shield, plus mirrors would need active positioning to track the sun. Joints between windows, shield, and structure would be subject to thermal cycling, introducing failure points.</li> <li><strong>Room</strong>: We don’t have enough surface area to position our farms on the inner surface of our habitat where reflected sunlight could be most easily directed. Artificial lighting allows growing crops in rooms with very low ceilings, supporting 5 to 10 times the population in the same size structure.</li> <li><strong>Thermal</strong> <strong>Efficiency</strong>: Natural sunlight is largely heat, and heat dissipation is the primary limiting factor in the size and population density of a large space habitat. Every watt admitted or generated in the interior must be radiated away. The interior will be warmer than the blackbody radiating temperature of the exterior.</li> </ul> <p>There are other considerations as well. Much of natural sunlight is not photo-synthetically active radiation (PAR). Plants appear green because they reflect this wavelength of light and do not utilize it (chlorophyll has absorption peaks in the red and blue regions of the spectrum). From an energy efficiency standpoint, natural sunlight is relatively poor (worse when considering infrared and ultraviolet which comprise 55% of the sun’s energy flux). Only 1%-2% of solar energy is converted into biomass by plants, compared to 8%-16% of the energy of optimized LED light sources (C4 plants - including crops such as wheat, corn, rice, barley, oats, and sugarcane -  have higher efficiency than C3 plants).</p> <p>Sources for this information offer a wide variety of opinions. For LED lighting, see the research articles at <a href="http://ledgrowlightsoutlet.com/led-grow-light-research-and-development.html">LED Grow Lights Outlet</a>. For sulfur microwave lights, see <a href="http://ncr101.montana.edu/Light1994Conf/5_10_MacLennan/MacLennan%20text.htm">MacLennan et al</a>. For a discussion of photosynthetic efficiency, see <a href="http://www.aeiveos.com/~bradbury/Papers/PhotosyntheticEfficiency.html">R.J.Bradbury</a>.</p> <p>Using available information on LED grow lights, optimal plant growth is achieved using approximately 72 PAR watts per square meter. As indicated in my earlier post <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/11/farming-in-space.html">Farming in Space</a>, we should conservatively allocate 64 square meters per person to maintain a good (largely vegetarian) diet. This equates to 4600 watts per person to grow crops.</p> <p>We’ll need additional illumination. According to <a href="http://www.engineeringtoolbox.com/light-level-rooms-d_708.html">The Engineering Toolbox</a>, direct sunlight provides over 100,000 lux, and full daylight 10,000 lux. An overcast day (1000 lux) is equivalent to the needed light level in a store or a detail-intensive workspace. A normal work (office) environment may only require 500 lux, and home illumination and classrooms only 250 lux. Hallways are even less, perhaps 100 lux. A reasonable average is about 500 lux, which requires 250 watts of white light for my proposed habitat space of 50 square meters per person (ignoring the farms and central park).</p> <p>The central park area requires much more light – enough to grow plants, and the park will need a white light spectrum. In addition to recreation, the park will grow fruit and nut trees. We have a lot of space to be brightly illuminated, about 10 square meters per person at 10,000-20,000 lux (half of the time), requiring an average of 350-700 watts per person (assuming doped <a href="http://en.wikipedia.org/wiki/Sulfur_lamp">sulfur microwave lamps</a>).</p> <p>One last point: contrary to current public opinion, I predict that the lights in a permanent space colony will provide moderate (non-zero) levels of ultra-violet light. During exposure to sunlight (containing UV light), human skin produces large amounts of vitamin D, a nutrient vital to health. See the non-profit <a href="http://www.vitamindcouncil.org/">Vitamin D Council</a> for additional information about the value of this vitamin. <em>“Current </em><a href="http://www.vitamindcouncil.org/research.shtml"><em>research</em></a><em> has implicated </em><a href="http://www.vitamindcouncil.org/vdds.shtml"><em>vitamin D deficiency</em></a><em> as a major factor in the pathology of at least 17 varieties of cancer as well as heart disease, stroke, hypertension, autoimmune diseases, diabetes, depression, chronic pain, osteoarthritis, osteoporosis, muscle weakness, muscle wasting, birth defects, periodontal disease, and more.”</em> Vitamin D deficiency may only be the most obvious result of a lack of full-spectrum light in our lives. </p> <p>Humans evolved to require gravity, and sunlight, and a varied diet. Until we learn otherwise, we need to replicate the conditions of life on Earth very closely in our new homes in space.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com16tag:blogger.com,1999:blog-7338070402887246857.post-14411207210985632702009-11-06T11:06:00.001-05:002009-11-06T11:06:57.753-05:00Farming in Space<p>In previous posts I’ve described plans for <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/10/designing-space-habitat.html">space habitats</a> which include allowances and techniques for the closed system recycling we will need to establish self-sustaining life in space.</p> <p>This post describes in some detail just what is needed, and where I found the information. Fundamentally, we will need to provide recycling for nearly everything in space. </p> <p>Humans breathe oxygen which is plentiful in the form of oxides and silicates, but rare as the free element in space. We each need a bit less than a kilogram of oxygen per day (0.83kg on average, more under high work loads). Note that processes such as smelting metallic ores use heat and a reducing agents such as carbon to turn metal oxides into the metal plus oxides such as CO2. Green plants turn the CO2 into carbon (or carbohydrates), freeing the oxygen, and the carbon can be fed as raw material into the smelter. The only net products of smelting are metal (such as iron) and oxygen.</p> <p>Humans consume water for drinking, food growth and preparation, cleaning, even entertainment. Since hydrogen is in short supply (until we can gather and use the resources of a comet, in which case we’ll have more than enough to throw away), we’ll need to carefully recycle water. Each human drinks or eats about 2.6 kg of water daily; more is needed for hygiene and growing crops, a lot more.</p> <p>Working humans need to eat, on average, about 2500 Calories per day (some estimates suggest 2000, my wife’s diet suggests 1500). This can be provided by about 540 grams (dry weight) of food (50g protein, 70g fats, 420 carbohydrates).</p> <p>The total consumption of a human is about 4 kilograms of oxygen, water, and food per day, and it should come as no surprise that that the same human produces 4 kilograms of waste (in the form of carbon dioxide, exhaled water, sweat, urine, and feces) per day.</p> <p>Also unsurprising is that green plants (such as algae) can take those 4 kg of wastes and produce the needed food and oxygen with only the addition of energy in the form of light.</p> <p>The complications arise from the need for a balanced, nutritious, and tasty diet containing all of the essential amino acids and fatty acids, and from the fact that we do not digest all portions of plants. Cellulose (fiber) is undigestible,  and we don’t even attempt to eat most of the plant material of a crop (stems, roots, leaves, bark). </p> <p>The ecosystem we create in space must be perfectly balanced. When plants produce food for us to eat, they simultaneously produce the exact amount of oxygen needed to metabolize that food. But they also produce those stems, roots, leaves, etc., and excess oxygen to match. All of that extra plant matter <em>must</em> be fed to some other animals (such as rabbits or goats), or to fungi, or to bacteria, <em>or burned</em>. The excess CO2 must be captured and fed back to the growing plants of the next crop, because we don’t exhale enough CO2 to feed the plants, only enough to grow the food we ate – a fraction of the total plant material.</p> <p>Note that we can meet all of our dietary needs by growing a variety of algae such as blue-green algae including spirulina, and chlorella.</p> <p>Somewhat surprising is how little water is needed to grow adequate volumes of algae – as little as 6 to 10 liters per person. This is due to the extremely high growth rates of alga under optimal conditions.</p> <p>However, an algae diet is not only boring, it doesn’t taste good. It is likely to only be used for long space missions where space and payload is at a premium, and even then at least 4 varieties must be cultivated to meet our dietary requirements.</p> <p>Whether we are growing alga or traditional crops, much of human waste is not readily usable as fertilizer. Portions are, and some bacteria excel at producing nitrates out of urea and ammonia. But much solid waste cannot be so easily processed. Luckily, a technique is available to solve the problem: a Supercritical Water Oxidizer applies high pressure, modest temperatures, and oxygen to burn the carbohydrates to water and CO2, freeing nitrates and mineral salts in the process. This is called the Zimmerman Process.</p> <p>The process boils down to:</p> <ol> <li>feed CO2 and light to growing plants</li> <li>harvest human-edible feedstuffs</li> <li>feed much of the rest to animals such as rabbits, goats, and chickens, as well as vegetarian fish such as tilapia.</li> <li>burn the rest of the plant matter to produce CO2 and ash (which is fertilizer)</li> <li>feed food byproducts (and table scraps) to animals such as chickens or pigs (which when harvested produce still more byproducts)</li> <li>use that Supercritical Water Oxidizer on animal and human wastes to convert them back into CO2 and fertilizers for the plants.</li> <li>Condense water out of the air for drinking, and recycle irrigation water (which holds excess fertilizers) for plants.</li> </ol> <p>Remember, as we are growing crops we need to feed them extra CO2 (much more than humans exhale), and store the excess oxygen they produce; we’ll restore the balance when we burn the crop residues and wastes. The “burning” doesn’t have to be an open fire. Feeding crop residues to goats counts as burning, as does using the plant matter as a reducing agent in the production of iron – both produce CO2 and free the water in the carbohydrates.</p> <p>What crops should we grow? In general, dwarf varieties of grains, beans, and vegetables will satisfy most of our needs. We’ll have bread and pasta from wheat, rice, soybeans, oatmeal, lettuce, tomatoes, melons, potatoes, sweet potatoes, onions, herbs, etc.. I’m sure we’ll grow strawberries and other fruits, and eventually our parks will also serve as a source for nuts and fruits such as apples. I’m also quite certain we’ll grow grapes for wine, barley and hops for beer, coffee, and tea. Some human appetites insist on being satisfied.</p> <p>That does leave the question of space. Just how big must our farm be? According to T.A. Heppenheimer’s excellent book <em><a href="http://www.amazon.com/gp/product/0811703975?ie=UTF8&tag=amethystgalle-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0811703975">Colonies in Space</a></em>, the answer is derived from existing studies and experiments in high-intensity farming. Using dwarf varieties that have also been selected for short planting-to-harvest times, using interplanting (sowing the next crop before the current one is harvested), and optimizing CO2, water, light, and humidity, Heppenheimer calculates that 60 acres of farmland will support ten thousand people. This is only about 25 square meters per person.</p> <p>I propose to average less than half that efficiency and allocate 64 square meters per person to include space for crop tending, to support a greater variety of foods, and to allow some extras to feed goats (for milk, cheese, and meat), rabbits (for meat), and chickens (for eggs and meat). Note that crops don’t require high ceilings; a single meter is good enough (on average), yielding a volume requirement of 64 cubic meters per person. This is less than the 100 cubic meters per person of living space I recommend in <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2009/10/designing-space-habitat.html">Designing a Space Habitat</a>, where I also recommend about 33 cubic meters of workspace volume and an equivalent amount of overhead.</p> <p>In that previous post, I assumed that 3 levels of living space would be allocated for the farms, but that may not be the best option. Rather, the farms are the primary source of waste heat. All that light energy ends up as heat and must be dissipated. The end caps of our cylinder expose a great deal of surface, so it makes the most sense to place our primary heat sources – the farms - adjacent to them. Using 8 meters along both end caps as our farms provides 64 cubic meters per person, independent of the size of our habitat (as long as we use the Kalpana geometry). Many plants need little gravity, indeed aquaculture (raising algae and fish) may require none, and these may be placed near the center. I expect that we’ll place livestock near the outer rim, as their needs for gravity are likely to mirror our own.</p> <p>A future post will describe the lighting needs of the crops, and the technologies we’ll use to provide it.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com10tag:blogger.com,1999:blog-7338070402887246857.post-65164837217630342012009-10-29T18:41:00.001-04:002009-10-29T18:41:49.205-04:00Designing a Space Habitat<p>A range of designs have been proposed for space habitats. Some appear to be mostly artistic concepts, others are much more serious. They include:</p> <p>(From Wikipedia <a href="http://en.wikipedia.org/wiki/Space_habitat">http://en.wikipedia.org/wiki/Space_habitat</a>)</p> <ul> <li><a href="http://en.wikipedia.org/wiki/Bernal_sphere">Bernal sphere</a> - "Island One", a spherical habitat for about 20,000 people. </li> <li><a href="http://en.wikipedia.org/wiki/Stanford_torus">Stanford torus</a> - A larger alternative to "Island One." </li> <li><a href="http://en.wikipedia.org/wiki/O%27Neill_cylinder">O'Neill cylinder</a> - "Island Three", the largest design. </li> <li><a href="http://en.wikipedia.org/w/index.php?title=Lewis_One&action=edit&redlink=1">Lewis One</a><sup><a href="http://en.wikipedia.org/#cite_note-3">[4]</a></sup> A cylinder of radius 250m with a non rotating radiation shielding. The shielding protects the micro-gravity industrial space, too. The rotating part is 450 long and has several inner cylinders. Some of them are used for agriculture. </li> <li><a href="http://www.nss.org/settlement/space/2007KalpanaOne.pdf">Kalpana One, revised</a><sup><a href="http://en.wikipedia.org/#cite_note-4">[5]</a></sup>A short cylinder with 250 m radius and 325 m length. The radiation shielding is 10 t/m<sup>2</sup> and rotates. It has several inner cylinders for agriculture and recreation. </li> </ul> <p>There are other well-known structures from science fiction literature, including</p> <ul> <li>Rama (a 20x50km rotating cylinder) from Arthur C. Clarke’s novel, <em>Rendezvous With Rama</em> </li> <li>Space Station V (from the movie <em>2001: A Space Odyssey</em>) </li> <li>Babylon 5 </li> </ul> <p>Of these, the most complete design is “Kalpana One, Revised,” which properly accounts for issues such as shielding and rotational stability. Most designs presume that it is best to provide windows to admit natural sunlight, but there are many reasons to prefer artificial light sources, primarily involving heat, but also the need for shielding. For adequate shielding from radiation and meteors, the outer walls of the habitat must mass about ten tons per square meter. While transparent quartz windows could be built of this thickness, most designs involving natural sunlight use mirrors to deflect sunlight around shields of stone. But the admitted heat is the real problem (discussed below).</p> <p>In my previous posts, including <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/05/our-first-colonies-in-space.html">Our First Colonies In Space</a>, <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/05/life-in-asteroid.html">Life in an Asteroid</a>, and <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/06/our-homes-comets.html">Our Homes, the Comets</a>, I assumed that we would tunnel into asteroids and comets, enclose and spin them for gravity if they were small enough, or build spinning structures inside them if they were too large.</p> <p>But while writing a sequel to my short story <em>Apophis 2029</em>, I realized that the best choice was simply to build one or more space habitats from the raw materials of the asteroids and comets. I came to this conclusion because of considerations for effective use of space, the stresses of spinning large objects for gravity, and (most importantly) thermal dissipation.</p> <p>People consume energy in their homes, workplaces, and travel. Much more important, food requires a large amount of energy in the form of light for growing crops. After extensive research on plant needs, high-intensity farming, and lighting technologies, I concluded that the minimum light levels needed requires 4 kilowatts of very-high-efficiency LED lights to grow the food for one person (assuming a primarily vegetarian diet – you need more to grow additional crops for livestock). Add to that the per-capita electric consumption in the U.S.A. of about 1.5 kilowatts, add a little more for contingencies, and I realized we need to plan on 6 kilowatts of energy consumption for every human aboard the habitat.</p> <p>That’s not too bad, especially considering that readily available solar power can easily provide such levels and at a modest cost.</p> <p>But energy consumption turns into heat, and heat must be radiated away. The bottom line is that we must allot 19 square meters per person of surface area assuming black body radiation at a temperature of 0 degrees C. It does not help to plant little radiators all over the surface, as they interfere with each other. All that matters is the apparent size of the habitat from a distance, and how closely it approaches the ideals of a black body radiator. Of course, we could use active cooling to heat radiators to much higher temperatures while cooling the interior, but I prefer passive techniques so that a failure of the cooling system doesn’t rapidly result in cooking the inhabitants.</p> <p>There goes my idea that a million people could thrive in a cubic kilometer of comet. There is plenty of room, more than enough materials. Unfortunately, their waste heat would rapidly boil their home away.</p> <p>Also, solar light has a large content of heat – and that excess, too, must be radiated away. Sunlight is not energy efficient for growing crops in a thermos bottle (which is what a habitat in space effectively is).</p> <p>So, my revised plan calls for 20 square meters of surface <em>per person</em>. Also, to provide radiation and meteor shielding equivalent to the Earth’s surface requires 10 tons of shielding per square meter of surface – and thus 200 tons of shield mass <em>per person</em> (regolith is fine, slag works well and is dense, ice is best as long as it doesn’t boil away). But the needed surface area and shield mass per person are constants.</p> <p>My earlier thoughts on structure did not consider rotational stability, and the folks that designed Kalpana One came up with some very strong arguments that a spinning cylinder is best, and that the width of the cylinder should be 1.3 times the radius. Thus, a cylinder of radius 100 meters (spinning at 3 rpm for 1 G gravity along the outer rim) should be 130 meters wide. That gives a 1-G living area of a little over 80,000 square meters, a total surface area of over 144,000 square meters, and thus a maximum population of 7,200. This structure provides 11.25 square meters (121 square feet) per person of 1-G living space. Is that enough?</p> <p>It’s comparable to the space provided (per person) in many hotel rooms and cruise ships. But few couples want to live in a 242 square foot efficiency for long, although 28 sm (300 sf) studio apartments are common in many expensive cities.</p> <p>There is no need to live only on the outer 1-G surface. Assuming 3-meter intervals, the next level up provides 97% of a G. Surely that is adequate. And now we have 22.5 square meters per person of available living space, equivalent to 450 square feet per couple – or 900 square feet for a family of 4. A third living level raises the per-person space to over 33 square meters – 675 sf per couple – 1350 sf for a family of four. Not spacious, but certainly comfortable.</p> <p>Humans need space for living, working, and of course for growing food. We must allot some space for office space, work space, schools. A single level should suffice (11 square meters per person), partly because some people will work in the farms, or in their homes, or outside the habitat entirely (such as in the mines, the smelters, the steel mills, the solar power satellites, etc.).</p> <p>Each person requires approximately 64 cubic meters for crops, but crops don’t require 3-meter ceilings. Allocating 2 levels for agriculture may be tight, but 3 levels is more than enough and provides some excess capacity for the production of meat, milk, and eggs.</p> <p>We need a little more space for overhead: storage, aisles, conduits for air, water, sewage. So we add an 8th level for good measure. That still leaves an interior cylinder with a radius of 75 meters as a park or recreation area. It has 3/4ths of a G of gravity. The opposite side is more than 500 feet overhead – it will feel spacious enough, and 15+ acres of playgrounds, hiking paths, trees, and grass will provide a little bit of Earth in space.</p> <p>But there’s no need to leave the end caps – the walls of our cylinder – as bare metal. We should build offices, low-gravity facilities (perhaps hospitals), hotels, etc. along those walls. Allocating 15 meters of depth along each end-cap for such purposes still leaves a hundred-meter-wide park, now with only 12 acres of usable space, 100 meters wide by 470 meters around. The lowest level of the end caps is a perfect place for shops and restaurants.</p> <p>The above ramble describes the capacity of a 100-meter radius cylinder, spinning at 3 rpm to provide Earth-normal gravity. This spin rate is often considered the maximum for a rotating space habitat, as most people (but not all) can adjust to it. More people can adjust to 2 rpm, and essentially everyone has no problem with 1 rpm.  So how much room do we get with these and larger structures? Can they be built?</p> <p>This table shows the size, possible population, and mass (in kilotons or kT) of the external steel shell, the internal steel infrastructure, and the shield (total mass of steel shell plus rock). Note that once the steel shell reaches a mass of 10 tons per square meter, additional shielding is not needed. For a reference point, the total mass of steel in a modern aircraft carrier is about 60,000 tons, about 20% less than the smallest habitat. The dimensions given are of the habitable volume; the outer walls are assumed to be an extra 5 meters in thickness to provide the volume needed to contain the shield mass (but that extra external area raises the maximum population as well). The thickness of the outer steel shell is also given, in meters, and it ranges from 3cm (1.2 inches) in the 100 meter cylinder to 1.31 meters (4 feet) in the largest. The table also shows the percentage of the asteroid Apophis needed to build this structure, or alternatively the minimum size of a rocky asteroid large enough to build it. *Note that the largest structure would require a nickel-iron asteroid, as there is no rocky shield mass needed.</p> <table border="0" cellspacing="0" cellpadding="0"><tbody> <tr> <td width="89">RPM</td> <td width="86">3.0</td> <td width="80">2.5</td> <td width="87">2.0</td> <td width="104">1.5</td> <td width="81">1.0</td> <td width="88">0.8</td> <td width="97">0.4</td> </tr> <tr> <td>Radius</td> <td>100</td> <td>143</td> <td>224</td> <td>398</td> <td>895</td> <td>1,590</td> <td>4,621</td> </tr> <tr> <td>Width</td> <td>130</td> <td>186</td> <td>291</td> <td>517</td> <td>1,163</td> <td>2,067</td> <td>6,007</td> </tr> <tr> <td>Population</td> <td>8,087</td> <td>16,010</td> <td>38,005</td> <td>117,491</td> <td>585,398</td> <td>1,839,804</td> <td>15,457,797</td> </tr> <tr> <td>Central Park</td> <td>100</td> <td>156</td> <td>261</td> <td>487</td> <td>1,133</td> <td>2,037</td> <td>5,977</td> </tr> <tr> <td>Ceiling</td> <td>150</td> <td>236</td> <td>397</td> <td>745</td> <td>1,739</td> <td>3,131</td> <td>9,191</td> </tr> <tr> <td>Acres</td> <td>12</td> <td>29</td> <td>80</td> <td>281</td> <td>1,529</td> <td>4,949</td> <td>42,625</td> </tr> <tr> <td>Steel Shell (kT)</td> <td>38</td> <td>105</td> <td>385</td> <td>2,092</td> <td>23,258</td> <td>129,560</td> <td>3,154,722</td> </tr> <tr> <td>(thickness)</td> <td>0.03</td> <td>0.04</td> <td>0.06</td> <td>0.11</td> <td>0.25</td> <td>0.45</td> <td>1.31</td> </tr> <tr> <td>Steel Structure (kT)</td> <td>36</td> <td>71</td> <td>168</td> <td>519</td> <td>2,584</td> <td>8,117</td> <td>68,166</td> </tr> <tr> <td>Shield (kT)</td> <td>1,580</td> <td>3,096</td> <td>7,216</td> <td>21,406</td> <td>93,822</td> <td>238,401</td> <td>0</td> </tr> <tr> <td>Total Mass (kT)</td> <td>1,653</td> <td>3,273</td> <td>7,769</td> <td>24,018</td> <td>119,664</td> <td>376,078</td> <td>3,222,888</td> </tr> <tr> <td>% Apophis (27 mT)</td> <td>6.12%</td> <td>12.12%</td> <td>28.78%</td> <td>88.95%</td> <td>443.20%</td> <td>1392.88%</td> <td>11936.62%</td> </tr> <tr> <td>min.asteroid</td> <td>107</td> <td>134</td> <td>179</td> <td>260</td> <td>445</td> <td>651</td> <td>924*</td> </tr> </tbody></table> <p>It is clear that Apophis contains enough raw materials to build habitats supporting 125,000 colonists in up to 16 structures. It is interesting that a 1-kilometer nickel-iron asteroid (of which there are approximately 50,000 in the main belt) provides enough iron that (adding the resources of a small carbonaceous chondrite for carbon, oxygen, and water) a 9x6 kilometer cylinder could be built, supporting over 15 million people. Still larger structures may be constructed; steel has adequate tensile strength for structures large enough to support a billion people, but they become wildly inefficient, requiring nearly 10 times the steel per person.</p> <p>I plan additional posts providing details on farming in space, on solar power satellites, and on the economics of life in space. It is clear that space habitats are feasible, and that commerce based upon tourism and the construction and maintenance of solar power satellites can pay for it. The obstacles are the difficulty of the bootstrap process: </p> <ul> <li>capturing an asteroid such as Apophis into Earth orbit </li> <li>Launching the tools to mine the riches of the asteroid, the tools to smelt its ores into steel and other valuable materials, the tools to shape that steel into the plates, beams, and girders needed to build things </li> <li>Launching the people to make it possible with enough consumables to get past the bootstrap. </li> <li>Designing and implementing closed-system recycling facilities capable of efficiently converting human wastes (and crop residues) into food, oxygen, and water. </li> </ul> <p>Once enough infrastructure is in place, the colony should not need the addition of oxygen, water, food, or structural materials. High tech tools will be needed, including whatever is needed to construct solar cells, but the raw materials would already be in place. The Earth will export technology, tools, vitamins, pharmaceuticals, and people. In exchange, the Earth will receive bountiful energy from the Sun, with zero carbon footprint.</p> <p>But that, too, will take time, energy, and especially people. In the long run, the demand for people in orbit is likely to exceed our capabilities of putting them there. And that, too, is the subject of a future post.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com36tag:blogger.com,1999:blog-7338070402887246857.post-50209896928909078302009-10-23T20:02:00.001-04:002009-10-23T20:02:13.807-04:00A Choice of Asteroids<p>I began researching this post believing that Apophis (with its April 13, 2029 close approach) was our best opportunity to capture the resources of an asteroid for humanity and the space program.</p> <p>Soon I realized that the selections are bountiful (or frightening, depending upon your point of view).</p> <p>NASA maintains several valuable web sites and services, including </p> <ul> <li>the Potentially Hazardous Object list (over a thousand) at <a href="http://neo.jpl.nasa.gov/orbits/">http://neo.jpl.nasa.gov/orbits/</a> (where you can display an orbit animation)</li> <li>the Small Body Database Browser at <a href="http://ssd.jpl.nasa.gov/sbdb.cgi">http://ssd.jpl.nasa.gov/sbdb.cgi</a> which lists 3,000+ comets and 400,000+ asteroids</li> <li>the Near Earth Object Program at <a href="http://neo.jpl.nasa.gov/">http://neo.jpl.nasa.gov/</a></li> <li>The Sentry Risk Table at <a href="http://neo.jpl.nasa.gov/risk/">http://neo.jpl.nasa.gov/risk/</a> listing PHOs in order of threat. Apophis is currently #4, not based upon 2029 or 2036 but the 2068 approach.</li> </ul> <p>As I described in my post <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/08/capturing-apophis.html">Capturing Apophis</a>, these objects are far too large for us to simply man-handle. We must use finesse, or more precisely, we must use the gravitational influence of a body such as the Earth to do most of the work for us. We can nudge small to medium size bodies a bit given months or years of head start. So, we need objects that pass close by, perhaps within the orbit of the Moon.</p> <p>Plus, I’m interested in objects we can capture in my lifetime.</p> <p>Here is a list of potential asteroids. Their distance of closest approach is given in Earth radii (1 Er = 6400 km). For reference, the Moon averages 60 Er (Earth radii) away. This list is in order of close approach date.</p> <ul> <li>2005 YU55 passes at 25 Er on 8-Nov-2011. It’s 120 meters across, masses 3 million tons. I wish it passed later – it would make a wonderful practice asteroid but we’re not likely to be able to launch a deflection mission in time.</li> <li>2008 UV99 passes at 7.16 Er on 30-Mar-2019, is 400 meters wide and masses 87 million tons.</li> <li>2001 FB90 passes at 13 Er on 24-Mar-2021, is 349 meters wide and masses 58 million tons.</li> <li>2007 RY19 passes within 0.89 Er on 12-Mar-2024, is 110 meters wide, masses 1.8 million tons. </li> <li>2001 CA21 passes at 6.41 Er on 9-Oct-2025, is 677 meters wide and masses 422 million tons.</li> <li>2001 WN5 passes at 37.5 Er on 26-Jun-2028, is 780 meters wide, massing 646 million tons.</li> <li>Apophis 99942 passes at 5.86 Er on 13-Apr-2029, is 270 meters across and masses at least 25 million tons.</li> <li>2007 FT3 passes at 22 Er on 03-Oct-2030, is 340 meters wide, masses 54 million tons.</li> <li>2009 UN3 passes at 19 Er away on 09-Feb-2032, is 919 meters wide massing just over a <em>billion tons</em>.</li> </ul> <p>Note that the sizes are estimates based upon the apparent brightness of the asteroid. None of these have been imaged and measured. The masses are estimates based upon a spherical body of that size with a density of 2.6 tons per cubic meter (partly porous). A solid body would mass more, nickel-iron much more.</p> <p>This list is not exhaustive, and some of these asteroids may be moving too fast (or not have suitable advance rendezvous orbits) for our purposes. But all 9 of these pass close enough to the Earth that their subsequent orbits are changed by the Earth’s gravity, and a relatively small nudge can be used to control a gravitational slingshot and choose its subsequent path. Some may require multiple slingshots and many elapsed years before they can be parked in a suitable orbit, but even the smallest of these (2007 RY19 at 1.8 million tons) contains enough resources to pay for the effort many times over.</p> <p>There are many other asteroids from which to choose. A number of asteroids are in horseshoe or spiral orbits near the Earth, and may make suitable low delta-V rendezvous targets. Many more are easier to reach (in terms of required delta-V) than the surface of the Moon. Some of these are nickel-iron asteroids, others may be extinct comets containing huge amounts of ice. One estimate is that 6% of asteroids may be extinct comets.</p> <p>We need better observations of all of the above objects. If one were a carbonaceous chondrite or an extinct comet, its value would be immensely greater due to the high content of carbon and water – the stuff of life. If one was nickel-iron then that, too, would have extra value. But all asteroids have great value once they’ve been captured into a stable Earth orbit, as all of them contain oxygen, silicon, magnesium, and iron. </p> <p>Clearly, we don’t need to fight over these trillion-dollar resources. There are enough potentially valuable asteroids to share. </p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com6tag:blogger.com,1999:blog-7338070402887246857.post-56654778719559601622009-10-15T18:23:00.001-04:002009-10-26T19:09:10.823-04:00Recipe for a Space Habitat<p>To build permanent habitats for people to live in space will require several needs to be addressed:</p> <ul> <li>Living space providing adequate room plus radiation and meteor protection</li> <li>Gravity or its equivalent</li> <li>Oxygen to breathe</li> <li>Water to drink</li> <li>Food to eat</li> <li>Something profitable to justify life in space</li> </ul> <p>Luckily, some of these are easily addressed, as certain asteroids have all the resources we need, including the majority of the asteroids in the belt – the carbonaceous chondrites.</p> <p><strong>STEP 1:</strong> Capture an asteroid into a useful orbit. The next great opportunity is the asteroid Apophis 99942, which will be in a location suitable for capture in 2029. See my post, <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/08/capturing-apophis.html">Capturing Apophis</a> for details. The good news is that Apophis contains 50 million tons of resources, including 10 million tons of iron, 15 million tons of oxygen,  12 million tons of magnesium, and perhaps 8 million tons of silicon. The bad news is that we presently believe that Apophis is an LL Chondrite, low in volatiles including water, carbon, and nitrogen, also relatively low in calcium, aluminum, and titanium. Available carbon is likely less than 0.2%, water less than 1%. Still, half of these values equates to 50,000 tons of carbon and a quarter-million tons of water.</p> <p>How much water and carbon is needed? Studies of high-intensity farming techniques suggest that about a half-ton each of carbon and hydrogen are needed <em>per person</em> to grow crops for food and oxygen recycling. This is equivalent to about 3 tons of carbon dioxide and 5 tons of water, per person, much of which will be contained in the growing plants of our farms. Plants are, after all, carbohydrates. We also need significant amounts of nitrogen (for proteins), and phosphorus as well as various trace elements. But all of these are abundant in ordinary asteroids except carbon, hydrogen, and nitrogen. The most common asteroids, carbonaceous chondrites, contain these volatiles in abundance.</p> <p>Still, it is clear that even a dry rock like Apophis contains enough raw materials to support as many as 50,000 people.</p> <p><strong>STEP 2:</strong> Establish a temporary beachhead. An empty shuttle tank works great. </p> <p>An empty Space Shuttle SLWT External Fuel Tank has a hydrogen tank 8.4m by 29.5m (97x27’), and an oxygen tank 16.6m by 8.4m (54x27’); these function nicely as pressurized crew quarters. If the hydrogen tank is converted to recycling (growing plants and recycling wastes), its 1493 cubic meter volume could support about 36 people who reside in the oxygen tank volume (553 m^3), or about 15 cubic meters per person (2x2.5x3m). </p> <p>You bury the tank for radiation and meteor protection. Five meters of regolith gives about the same protection as Earth sea level; we could get by with three meters on top.</p> <p><strong>STEP 3:</strong> Mine the asteroid and use a solar furnace (or other techniques) to smelt it into useful metals and free oxygen. Also, the first gases emitted when you heat up the regolith are CO2 and H2O. Save them. And note that all the leftover slag is extremely valuable as radiation shielding for the habitat we want to build, so don’t throw it away, either.</p> <p>To yield enough water and carbon dioxide to grow food for one person, you’d need to process only 50 tons of ore from a carbonaceous chondrite like the Murcheson meteor, but more like 500 tons if Apophis is truly an LL chondrite. You’ll get a little excess carbon which lets you make steel instead of just iron. 100 tons of steel.  As a bi-product, you’ll end up with perhaps 25 tons of oxygen, which you’ll want to save, also. This is a good use for a few more empty shuttle external fuel tanks. We’ll be using oxygen as fuel, I suspect, in VASIMR type thrusters powered by solar energy.</p> <p><strong>STEP 4:</strong> Establish a farm in that empty hydrogen tank (or in several of them as the colony grows). My estimates of needed space are based upon 64 square meters per person of crop area, using high-intensity techniques, and using LED light sources. I also assume hydroponic techniques instead of soil, because it’s easier to recycle the root mass. We won’t use soil (even if it’s free and abundant) until we have a huge surplus of carbon and water to waste.</p> <p>Note that we need to feed extra CO2 to the growing crops – humans don’t produce enough to grow everything we need, because of the small fraction of plant material that is edible. We’ll even be burning the dried crop residue to create CO2, or turning it into coke (carbon) to improve the efficiency of iron production.</p> <p><strong>STEP 5:</strong> Start building Solar Power Satellites. You’ve got the steel, and all the magnesium you could want, plus more than enough silicon. A square kilometer array of solar panels or collectors intercepts a gigawatt, yielding a net 200 megawatts to <a href="mailto:Earth@$0.01-0.02/kwh">Earth</a>. But why stop at a gigawatt? You’re building in outer space where it is simple to build large structures. </p> <p>A circular array with a 1.6km radius would yield 4 gigawatts of power to be beamed to Earth from geosync orbit. Each generates $1B per year in wholesale electricity (at $.03/kwh). With no energy costs – just maintenance.</p> <p>The steel & other raw materials for each one consumes about 1% of Apophis’ regolith. By the time you’ve built 50 of them, your revenue is $50 billion a year, and you’ve only consumed half of Apophis.</p> <p><strong>STEP 6:</strong> While you are building Solar Power Satellites in one factory, you can be building a large, permanent, self-sustaining habitat in another. Many designs have been proposed, and I, personally, like a rhombic triacontahedron. It is constructed from 30 identical rhombic steel plates. A simpler design (but more difficult to build) is a cylinder. Both would be spun for gravity. </p> <p>For radiation and meteor shielding, you need about the same mass of shield as the Earth provides us: 10 tons per square meter. That’s about 5 meters of regolith, or 3 meters of slag (which is nice and dense). I realized that this much mass, spinning at one G along the periphery of a sphere (which is close to a rhombic triacontahedron) exerts an outward force entirely equivalent to a pressure vessel, whose characteristics are well known. To contain a force of 15 tons per square meter (3 tons of which is air pressure), a spherical pressure vessel 100 meters in radius only needs to be about an inch thick, masses about 25,000 tons of steel. </p> <p>The limiting factor for population is likely to be heat dissipation. Using very high efficiency LED light sources to grow our food, and minimizing all wasted energy interior to the structure, we need about 20 square meters of cooling area per person (assuming passive cooling – the only safe kind). Thus, a 100 meter radius habitat, spinning at 3rpm for 1 G, has sufficient area for a population of about 6,000 people. It takes about 4 tons of steel per person to build the pressure vessel. Since the area per person is constant (20 square meters), and the amount of shielding per unit area is constant (10 tons per square meter), each person needs 200 tons of shielding. Thus the habitat for 6,000 people requires a 25,000 ton steel pressure vessel, plus probably that much again for internal structures, plus 1,200,000 tons of shield mass. This is 2.5% of Apophis – we could build 20 of these with the half left over from building 50 solar power satellites.</p> <p>Spinning at 3rpm is too fast, you say? If the radius of our vessel is increased to 225 meters (yielding 1 gravity with a 2 rpm spin), our pressure vessel needs to be 5.6 cm (2.25 inches) thick, and requires nearly 300,000 tons of steel. But it now is large enough to support a population of over 30,000 people. And its construction consumes 12.5% of Apophis. Yes, we can still build 4 of these: one in Apophis orbit, one above geosync as the ideal place to maintain those solar power satellites, and I’m sure we can find places to stash the other two. How about L4 and L5?</p> <p>Sorry, but if you want to spin at 1 rpm (radius of 890 meters), it takes all of 2 Apophis-size asteroids to provide the needed raw materials and would have living space to support about 500,000 people. But it takes more steel per person the larger you build it – there is no economy of scale, as larger and larger pressure vessels take more and more steel per unit area (and thus per person). But as long as we are doing the math, if you raise the radius to 4 kilometers, your steel shell must be a full meter thick, and itself provides all the shield you need.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com1tag:blogger.com,1999:blog-7338070402887246857.post-89198504351589949062008-10-31T08:11:00.001-04:002008-10-31T12:06:18.972-04:00Evolution<p>Evolution - or survival of the fittest (or luckiest) - is a readily provable fact, and one not limited to species: Evolution also applies to ideas (memes) with areas as diverse as religion, music, fairy tales, and urban legends. </p> <p><strong>The concept of evolution is simple:</strong> That which successfully reproduces, survives. If pressures (due to competition or predation) limit the growth of something which has a natural variation (a choice of religions, or music genres, or tales, or an ecosystem, or apes), those variants which most successfully reproduce will succeed versus those less suitable, or less lucky.</p> <p>Note how few successful religions abound which forbid sex. <em>There have been short term experiments in this direction.</em> More subtly, religions that don't have a strong philosophy of proselytism tend to be dominated by those that do. <strong>Remember, survival of the fittest is really just survival of those that successfully reproduce. </strong>See <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/06/purpose-of-life.html">The Purpose of Life</a>.</p> <p>Evolution of species continues today. Mankind is forcing change, which drives evolution. Some of this is merely speeding long term trends (such as reduced success of amphibians in general, or the loss of many marginal species like the spotted owl). Other changes are more worrisome (such as the evolution of anti-biotic resistant bacteria).</p> <p>Especially with animals (including humans), there are <strong>two forces that dominate evolutionary pressures.</strong> In addition to reproductive success due to <strong>superior survival characteristics,</strong> there is reproductive success due to <strong>sexual selection</strong> (ie, how members of each sex choose mates). More colorful animals are easier to find, and the most showy male is likely to get the most females and successfully reproduce even though he is also the most visible to predators and ends up living a shorter life. Sexual selection may also explain extremely large sauropod dinosaurs; perhaps the males/females liked (or could see) tall females/males better - and sought them as mates - leading to runaway selection for this feature.</p> <p>Even mankind continues to evolve in several ways, and indeed demonstrates evidence of very recent evolution.</p> <p>For example, there is strong evidence that people have been evolving for external sexual characteristics. Human females have proportionally larger breasts, narrower waists, and broader hips than other primates. (As a human male, I do love that shape.) Human males have shapes that illustrate upper body strength, and have a penis that is larger in proportion to body size than any other ape. Apparently males have been selecting for large breasts and hips (especially in contrast to waist size). And women have been selecting men with broad shoulders, large muscles, and a big penis. And bad boys, at that.</p> <p>Watching many reality shows (and especially MTV) suggests that human females are still actively selecting for strength, size, and sexual prowess; intelligence is clearly not a requirement. Likewise for human males, actively selecting voluptuous, athletic females with exotic eyes, long hair, and aggressive sexual attitudes.</p> <p>Our technology is also having a significant effect on the human specie: we are becoming less diverse, as our ability to travel globally is reducing regional and racial disparities at measurable rates. In a few thousand years, there may be no remaining significant racial differences at all as we continue to interbreed and blend. Personally, I think this is a good thing.</p> <p>We are also enabling the survival and allowing the reproduction of humans who would never live to adulthood without technology and/or large social organizations to care for them. I think this is a bad thing (when genetically caused), as I prefer that our children be smarter, stronger, and healthier. I know many people find my attitude offensive, but really, people, it is not in humanity's best long term interest to support or encourage the reproduction of serious genetic defects or low intelligence. Again, see my post<strong> </strong><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/06/purpose-of-life.html"><strong>The Purpose of Life</strong></a>.</p> <p>A few other rambles:</p> <p>Humanity is the ocean's most effective predator, and our fishing techniques are rapidly changing (evolving) fish to have less desirable characteristics. Fish are maturing younger and at smaller sizes as we select only the largest (previously most successful) fish. Fish that humans like to eat are being selected out - made extinct - versus undesirable, bony, badly tasting, or hard-to-capture fish. A tight school of fish may have worked to confuse dolphins or sharks, but it is an bright sonar target easily capture by our mile-wide nets today. And small and mid-size fish that avoid schooling behaviors make poor (unprofitable) targets. </p> <p>Note that the world's most successful plants and animals are those whose evolution has made them desirable food for humans (cows, chickens, pigs, wheat, corn, rice, etc.). Then we help them thrive and reproduce, in numbers far exceeding natural populations. </p> <p>Some people have argued against the use of windmills as a source of renewable electric power, based upon the fact that the turning windmills kill many birds. Tear down the windmills, drill for oil, save the birds. The reality is that more birds are killed by cars and trucks on the highway. (The activists would probably like to outlaw cars and trucks, too.)</p> <p>I believe in the value of evolution: the birds that learn to avoid the rotating windmill blades will survive and reproduce. We can already see this effect along our highways: fifty years ago it was much more common to hit a bird on the highway, even though speeds were significantly lower then. Think of it as evolution in action (thank you, Larry Niven).</p> <p><strong>Last, the implications of evolution to a field near and dear to my heart: science fiction.</strong></p> <p>Contrary to nearly every movie alien, any intelligent life we meet in outer space will not be highly effective carnivorous killing machines. Au contraire, they will be (on their home planet) relatively weak and defenseless, needing superior intelligence to survive and reproduce. A dominant carnivore, or a herbivore that does not need to fear predation due to successful defenses (armor, size, quills, poisons) <em>will cease to evolve.</em> Every intelligent alien ever depicted with huge fangs, great strength, speed, armored skin, etc.,  is absurd, as they would never have evolved intelligence. </p> <p>No, the most intelligent species will be those that are slow, weak, need protection from the elements, need to build and use tools to thrive, and need a civilization to defend against the superior strength, speed, and teeth of their planet's versions of lions, and tigers, and bears.</p> <p>Of course, there is some evidence that intelligence is not a long term survival characteristic. <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/07/fermi-paradox-where-are-they.html"><strong>We haven't yet met a single intelligent alien.</strong></a></p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com0tag:blogger.com,1999:blog-7338070402887246857.post-57101819077528804282008-10-26T08:06:00.001-04:002008-10-26T08:06:21.293-04:00The Earth's Fragile Ecology<p>Most of my readers know that I'm fundamentally an optimist (see <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/05/i-am-optimist-we-will-have-future.html">I am an optimist</a>), and that I believe that science and technology (along with human ingenuity) can and will solve most (hopefully <em>all</em>) of our problems caused by technology and the resulting global population growth.</p> <p>But it won't be easy, or cheap.</p> <p>Most people seem unaware of the major ecological problems we face, focusing instead on a few relatively minor (but well publicized) potential problems such as <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/07/global-warming.html">Global Warming</a> or loss of biodiversity.</p> <p>Here are a few more for your consideration.</p> <p><strong>Loss of topsoil:</strong> Globally, current farming techniques results in topsoil being lost to erosion at rates far greater than natural replenishment. Topsoil (the only part of the Earth's regolith that can readily support crops) is being lost at a huge rate, resulting in reduced crop yields and even desertification in some areas. Currently, the recommended solution is to globally convert to no-till farming, which has the problem of requiring greatly increased use of herbicides and insecticides with their attendant and largely unknown long term effects.</p> <p><strong>Ocean anoxia:</strong> The huge influx of topsoil and fertilizer into the oceans is producing larger and more frequent dead zones, where nearly everything larger than a bacteria dies due to lack of oxygen. All of the nutrients lead to bacterial blooms which consume all free oxygen, and while some mobile fish can swim to the surface to gulp oxygenated water or swim out of the region, bottom dwellers and the myriad small critters that comprise the bulk of the food chain have no such ability. They die, and so do other life forms that depend upon them. This process happens to thousands of square miles every year, and the area and event duration is increasing.</p> <p>Overfishing: The oceans are being depleted of desirable foodstocks are rates far greater than can be maintained. Already, many once common seafoods are becoming rare, and many fisheries are now effectively ocean deserts, completely devoid of large fish. At present, there are two approaches to solve the problem. One is to create huge "no fishing" zones to serve as replenishment stocks for the regions around them. This works in the short run (assuming enforcement by fast, armed ships), but eventually the fish will evolve to avoid fishing zones. The second solution is one that our leaders have done completely backwards. They have established minimum take sizes, where the fisherman is allowed to keep only fish above a certain size. Sounds good at first, as the young fish are allowed to live, feed, and grow. Unfortunately, there is something called evolution. Fish which once grew quickly to a large size (to avoid predation) are now evolving to grow more slowly and to reproduce at a much smaller size (avoiding predation by the most effective ocean predator, us). As a consequence, reproductive success is reduced, and the remaining fish are becoming less and less desirable. The solution? Capture (and eat) medium sized fish, encouraging these species to grow quickly to a large (safe) size and to produce large numbers of offspring to ensure that enough of them escape us to maintain their species. But this will take technology, and leadership.</p> <p><strong>Falling water tables:</strong> Everyone has heard of (or experienced) the relative and growing shortage of fresh water. Many people don't realize how serious the problem has become. Many cities (especially in desert areas but including many water-rich areas such as Orlando, Florida, USA) are pumping fresh water out of the ground at rates much greater than natural replenishment. Eventually the wells will run dry. Going deeper is often not a solution because of salt water, no water, or pollutants such as oil, lead, or arsenic. Along the oceans, pumping fresh water out of the ground encourages salt water incursion, a serious problem. One side effect of excessive ground water pumping is that springs dry up, and rivers that once ran to the ocean now shrivel and disappear. Water wars will result when cities / states / nations consume the fresh water that other downstream cities / states / nations need to survive.</p> <p><strong>Chemical pollution:</strong> To me, the most serious pollution issue is from the long term unanticipated side effects of biochemicals we create and dump into the environment. These include insecticides, herbicides, drugs, hormones, and especially antibiotics. We don't understand the long term effects of insecticides and herbicides; we ignore the possible unintended effects of long exposure to low doses of hormones and many other drugs (traces of which can be detected in many or most municipal water supplies), and we are rapidly breeding (thanks to evolution and the overuse of antibiotics) new bacteria (and likely viruses) which are immune to all known antibiotics. This alone could result in a plague which could destroy most human life.</p> <p><strong>The growth of cities:</strong> We tend to put cities (especially large, growing ones) at the worst possible places: in river valleys, along flatland floodplains, along the mouths of rivers. The same places that are the best possible farmland. We <em>should</em> build them on mountains, in deserts, rocky, hilly terrain, even floating on the oceans. Leave the good farmland to farming. Leave the river deltas for farming and allow the annual floods that replenish their topsoils and ecologies. Our cities continue to grow at alarming rates, covering the surrounding land with buildings and asphalt. And polluting or burying the former topsoil in the process.</p> <p>Are there long term solutions? My favorite is to move humanity off of Planet Earth and into space habitats. See <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/05/colonizing-solar-system.html">Colonizing the Solar System</a> and <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/06/population-unlimited.html">Population Unlimited</a>. Unfortunately, I expect that humanity will tend to continue to exploit the Earth in ever greater degree until the point is reached where most of the population will abruptly die. And <em>then</em> the survivors just might be smarter and do it right the next time. That, my friend, is evolution in action.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com3tag:blogger.com,1999:blog-7338070402887246857.post-89065618751610532212008-10-24T13:01:00.001-04:002008-10-24T13:01:12.239-04:00ECONOMICS 101<p>Some fundamental tenants, followed by discussion and ramifications:</p> <ol> <li>There is no such thing as savings. </li> <li>Money is not real (although it is a valuable accounting tool). </li> <li>Prices are set by supply and demand. </li> <li>Any attempt by people or governments to change any of the above is doomed to failure. </li> </ol> <p><strong>There is no such thing as savings,</strong> other than to store food or other supplies in a larder. <em>We all live off of the current productivity of workers.</em> For you to retire, you must convince someone else to work on your behalf (to provide you with food, clean water, sanitation,  energy, health services, everything you need). At the beginning of life, your parents did that. At one time, we would depend upon our children to provide for our old age. Investing in children was investing for retirement. But that time has past.</p> <p>In today's society, we <em>save</em> for our retirement and therefore depend upon society to care for us. The only way that works is if:</p> <ol> <li>We invest a portion of our current work productivity in infrastructure (capital) so that other, future, workers can be more productive. (In exchange, we expect those future workers to support us in the future via a fraction of their increased productivity.)</li> <li>A large enough fraction of the population is working in primary production to provide for the non-workers. </li> <li>The population dynamic is such that the future expected number of retirees is proportional to the future number of primary workers. <strong><em>This does not match reality!</em></strong> </li> </ol> <p><strong>Money is not real.</strong> Actually, money can be real, if it consists of coins or other valuable items (gold coins are real, as are gems and many other commonly recognized commodities). Paper money, or a coin whose value is based on a promise, is not real. Unfortunately, governments can print more money or stamp more coins. This dilutes the value of the existing currency, making it proportionally less valuable. Note that the total value of the good and services in the economy remains unchanged - only the number (accounting value) associated with the measurement of the economy increases.</p> <p>The picture is not really so simple, but it will serve our purposes. The great thing about the concept of money is that it creates an accounting tool that allows us to share productivity, to allow a civilization to work together (some farmers, some miners, some builders, some engineers, etc.) where each of us can achieve greater productivity in a narrow field than any of us could if we each had to provide for all of our needs. Can a farmer build a house or a car? Can an engineer raise cattle and chickens for meat, milk, eggs? Yes, but not as well as a professional. And that, my friends, is the true source of wealth.</p> <p><strong>Prices are set by supply and demand. </strong>This is always true in the long run, although short term variation due to greed, fear, stupidity, and the delays needed to change production will happen. Capitalism works, for the most part, but it is slow to respond to changing markets. If oil prices jump, economic theory says that exploration, production, and distribution will increase supply to match (or exceed) demand. However, it takes years to find new sources of oil, drill the wells, build the distribution networks, the refineries, etc.. </p> <p>The government should have a role in pricing, to ensure fair competition, avoid fraud, and to make certain that the consumer fairly pays all costs associated with a commodity. For example, if a bottle of water is sold to the consumer, the price (manufacturing, distribution, and taxes) should reflect the total life cycle cost of that bottle of water, including the renewability of the water source (no dropping water tables stealing water from the future), and the disposition of the bottle (the cost of disposal or recycling - don't dump our current waste on our children).</p> <p><strong>Any attempt by people or governments to change any of the above is doomed to failure.</strong> History is full of failed attempts to control an economy. Price fixing invariably leads to shortages. Government attempts to define production invariably result in reduced choice and quality, with higher prices. Printing more money causes inflation. And since there is no such thing as savings, it is incredibly stupid to "invest" social security funds in government debt. All such debts must be repaid by taxes on future workers, whether you call them social security taxes or anything else. Who could come up with this concept? Unless the worker's funds are invested in things resulting in future productivity gains (which can include factories, research, infrastructure), this scheme is doomed to failure. Yes, I'm in favor of privatizing social security, just as I'm against the concept of government debt (except in the short term as a balancing mechanism). Unfortunately, it may be too late.</p> <p>However, in our current economic environment I support government investment in real estate or other businesses (as well as research), because only then can we boost real worker productivity and escape the fragile house of cards we live in.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com2tag:blogger.com,1999:blog-7338070402887246857.post-40420918308412390272008-08-25T23:38:00.001-04:002008-08-25T23:38:43.586-04:00Threats to our Future<p>This post contains a list of what I consider to be the most serious threats to the future of humanity, as of today. It should be considered an incomplete and open-ended list; I'm certain that each of us can think of additional threats.</p> <p>Note that I'm not considering threats to our civilization and/or way of life. There are many more of those. Rather, I want to limit this discussion to threats that can end all human life.</p> <p>There are four main categories in two dimensions: the first dimension is simply natural disasters or man-made ones. The second dimension is things we can control versus things we can't. There may not be any entries in the list for "man made disasters we can't control", so perhaps we should qualify that as things we can't <em>fix</em>.</p> <p><strong>1) Natural Disasters we can't control/fix:</strong></p> <ul> <li>Nearby supernova or gamma ray burst or passing black hole: Nothing we can do about any of these, so don't worry about them. </li> <li>Super Flare from the Sun: Our sun won't go nova or expand into a red giant for billions of years, but there is a possibility that it could have a major hiccup and blast the Earth with searing heat or sterilizing levels of radiation. Sea life would survive, as would any people lucky enough to be in submarines. It's too bad those tend to be men only; we also need women to save the species. Solution: co-ed submarine crews.</li> <li>Large Igneous Event: These have caused mass extinctions in the past, and might in the future. Not much we can do here, either, as long as we all live on the surface of the Earth. </li> </ul> <p><strong>2) Natural Disasters we <em>can</em> control/fix:</strong></p> <ul> <li>Snowball Earth: At least twice in the Earth's history we have had global cooling so extreme that the oceans have completely frozen over, causing the loss of all surface life, and likely the loss of all oxygen. The solution is simple: <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/07/global-warming.html">Global Warming</a>. </li> <li>Comet or Asteroid Impact: There are millions of comets and asteroids large enough to destroy all human life, possibly all life <em>period</em> on the face of the Earth. Some of these will eventually strike the Earth; this is inevitable unless we take <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/08/capturing-apophis.html">active steps</a> to prevent such a catastrophe. We may have years or millennia before the big one hits, but we may not have enough advance notice to do something about it, unless we start building the infrastructure now. We need a very well-funded Space Watch program to find these objects years before they might obliterate us, and given enough advance notice, current technologies are likely to prove sufficient to avert disaster. </li> </ul> <p><strong>3) Man-made disasters we <em>can't</em> control/fix: </strong>(these are things that we create, but have no effective control over, and no natural defenses against)</p> <ul> <li>Experiments gone wrong: While I'm a firm believer that nothing will go wrong when the LHC begins operation, I can't guarantee that all scientific experiments will have a similar result. If we knew the results in advance, we wouldn't need to perform the experiment now, would we? For example, if someone managed to create a nanometer-diameter black hole and drop it into the Earth, it would eat away at our planet and grow until it consumed the entire planet -- and there's not a damn thing we could do about it, even if we had hundreds or thousands of years before the disastrous end.</li> </ul> <p><strong>4) Man-made disasters we <em>can</em> control/fix.</strong> </p> <ul> <li>Nanotech gone bad: While it may be remotely possible to create a self-replicating nanite that will reproduce until all possible resources are consumed, burying humanity in 3 feet of gray goo,this is so difficult that I'm not worried about it. We can't create a reasonably self-powered machine that could live off of the environment at present. We cannot build a complex small machine that can self-replicate. Or even a big machine. In any case, this problem is well described, and guidelines exist to insure that any replicating machine will have limits built into it (such as a critical and rare raw material).</li> <li>Strong, malevolent AI (see <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/05/likely-coming-technological-singularity.html">The (likely coming) Technological Singularity</a>) poses a very real threat, but one which may be difficult to realize, and one that we could choose to avoid by limiting computers to sub-human intelligence. Even if such an AI existed, there is a possibility of negotiation and co-existence so long as its intelligence and capabilities remain within the grasp of human understanding. But once we have made a machine significantly more intelligent than any human, we risk losing control. We will become the pets, to be neutered and/or put down at the convenience of the AI.</li> <li>Biotech Terrorism: To me, this is <em>the</em> thing to worry about. It is completely within the realm of possibilities that a small group, even an individual, could tailor a virus or bacterium to create an airborne disease of unparalleled lethality, one that was immune to our natural defenses, one that could wipe us all out. My friend Jeff Carlson has written an excellent  techno-thriller (<a href="http://www.amazon.com/gp/product/044101514X?ie=UTF8&tag=amethystgalle-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=044101514X" target="_blank">Plague Year</a>) about an engineered viral organism that kills nearly all warm-blooded life on Earth, and the most unbelievable part is that it was designed with a weakness that could be exploited such that we might survive. What if those designers had made a mistake and the self-destruct mechanism failed? Or the bug evolved and the mechanism failed due to a minor mutation?</li> </ul> <p>Did you note the traditional really big things that I don't think threaten humanity?</p> <ul> <li>Nuclear War (and the threatened Nuclear Winter): Contrary to the hype we've all heard, we do <em>not</em> have enough nuclear weapons to destroy humanity, or even to create a nuclear winter. Many natural disasters release much more energy or release much more pollution. Yes, we <em>do</em> have the capability of destroying civilization as we know it, and even of killing more than 90% of humanity. But some of us will survive, live on, and rebuild civilization. An all-out nuclear war would merely set us back a few thousand years.</li> <li><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/07/global-warming.html" target="_blank">Global Warming</a>: Warming up the Earth by 5 or 10 degrees would eventually melt the ice caps, raise the oceans by 200+ feet, drown coastal cities, states, even entire nations. It would radically disrupt the ecology, and hundreds or thousands of species would face extinction. The expense of dealing with such a catastrophe greatly exceeds trillions of dollars. But in the big picture, this is an inconvenience, a forced change. Human casualties would be in the noise range, likely fewer than the toll from malaria.</li> <li>Overpopulation: Another serious problem, overpopulation has well-known natural controls: starvation and disease. Once half of everyone is dead, we no longer have a problem. Works for lemmings, too. The species survives. Note that the opposite problem, underpopulation, is much more serious (if it happens), because it is difficult to recover from the loss of genetic diversity. We'll lose some big cats (such as cheetahs) because they have insufficient genetic diversity to survive a nasty disease.</li> </ul> <p>Please, propose your own threat to the future of humanity. </p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com0tag:blogger.com,1999:blog-7338070402887246857.post-33104331896538288112008-08-14T12:31:00.001-04:002009-10-22T06:13:11.163-04:00Capturing Apophis<p>Past blog posts of mine have described many aspects of the expansion of human civilization into space.</p> <ul> <li><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/05/colonizing-solar-system.html">Colonizing the Solar System</a></li> <li><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/05/our-first-colonies-in-space.html">Our First Colonies in Space</a></li> <li><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/05/life-in-asteroid.html">Life in an Asteroid</a></li> <li><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/06/population-unlimited.html">Population Unlimited</a> (resource limits of comets)</li> <li><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/06/our-homes-comets.html">Our homes, the Comets</a></li> <li><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/06/next-steps-in-colonizing-solar-system.html">Next Steps in Colonizing the Solar System</a></li> <li><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/07/near-future-space-industries.html">Near-future Space Industries</a></li> <li><a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/08/animals-in-space.html">Animals in Space</a> (both pets and food animals)</li> </ul> <p>Today I'd like to focus on the orbital mechanics of capturing an asteroid, specifically <a href="http://en.wikipedia.org/wiki/99942_Apophis">99942 Apophis (aka 2004 MN4)</a>.</p> <p>Apophis is the near-earth asteroid that made the headlines in 2004 because of it's feared potential impact on Earth on Friday, April 13, 2029. Additional observations revealed that Apophis will miss by a hair (passing closer to earth than our geosynchronous satellites), but its orbit will be changed by that close approach such that there is a small chance of an Earth impact on April 15, 2036. </p> <p>Apophis is a small asteroid, only about 300 meters in diameter (approximately 1,000 feet). This is too small to create an ELE (Extinction Level Event, to borrow a phrase from the movie <em>Deep Impact</em>), but it <em>could</em> devastate an area the size of Connecticut, or strike the ocean creating tsunamis that would kill millions of people and destroy trillions of dollars worth of property. Note that if we do nothing, Apophis will almost certainly strike the Earth some day, although perhaps not for thousands of years. We must take steps to prevent that catastrophe.</p> <p>Luckily, one method of preventing a future Earth impact is to place the asteroid into Earth orbit, from which a future Earth impact is impossible. The near-Earth pass will result in a <a href="http://en.wikipedia.org/wiki/Gravitational_slingshot">gravitational slingshot</a>, changing its orbit.</p> <p>As it passes near us in 2029, Apophis will be moving approximately 5 km/s slower than the Earth in its orbit around the sun, dropping in toward the orbit of Venus (and ignoring, for the moment, the additional speed it will gain dropping into our gravity well). If we do nothing, the near-miss will speed up Apophis by a few km/s, turning it from an <a href="http://en.wikipedia.org/wiki/Aten_asteroid">Aten Asteroid</a> (a near-Earth asteroid whose orbit is primarily inside of the Earth's) into an <a href="http://en.wikipedia.org/wiki/Apollo_asteroids">Apollo Asteroid</a> (one whose orbit is close to the Earth's orbit, at least on average).</p> <p>My own rough calculations indicate that if we speed up Apophis by a relatively small amount, such that it passes even closer to the Earth, then it will gain even more speed from its slingshot around our planet. A deflection into an orbit nearly co-circular with the Earth's will also speed it up to approximately Earth's orbital speed (a 5 km/s velocity increase is needed--well within the range of possibilities). Apophis only needs to reach closest approach about 500 seconds earlier than on the current orbit, still passing 10,000 kilometers above the Earth's surface. </p> <p>It will have too much speed (due to the earth's gravity well) and will speed away (and outward), but will return to the vicinity of the Earth with a low enough speed that another slingshot around the moon will drop Apophis into Earth orbit. As a result of these two slingshot maneuvers, Apophis will have an orbit whose apogee is near the moon, and whose perigee (closest approach) can be tuned by small adjustments in its orbit before it performs the Lunar slingshot.</p> <p>Over time, some additional velocity should be removed (by ion thrusters or other propulsion methods) so that its orbit is entirely within the moon's orbit, or some other permanently stable orbit. We don't want it crashing into the moon, either. Apophis is a far too valuable resource to waste.</p> <p>I'm confident that the orbital changes needed to capture Apophis are within current technology capabilities, although more detailed analysis is certainly needed. And this is an opportunity that should not be missed: a billion dollar mission to capture Apophis will result in a trillion dollar resource in high-Earth orbit, and avoid a trillion dollar catastrophe at the same time. </p> <p>Apophis masses perhaps 50,000,000 tons. While the largest percentage is oxygen, approximately 20% is metals (primarily iron). It contains large amounts of magnesium and aluminum, and significant quantities of hydrogen (think millions of tons of <em>water</em>). It contains more than enough silicon to build all of the power satellites we'll ever need.</p> <p>Who could pass that up? If not NASA and the U.S. government, then perhaps the Chinese, or Dubai. Or even private enterprise; this project is well within the funding capabilities of large corporations or even a few individuals. Perhaps Bill Gates would like to have a private moon around the Earth. Or the Disney corporation (I'm thinking Disneymoon), or Hyatt Hotels (I'd love to stay at the Apophis Hyatt some day).</p> <p>Any takers?</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com20tag:blogger.com,1999:blog-7338070402887246857.post-72068148902979693152008-08-05T09:42:00.002-04:002008-12-06T07:55:52.128-05:00The Future of Sex<p>Yes, there will be sex in the future. You weren't worried about that, were you?</p><p><strong>But will technology affect our enjoyment of sex?</strong> Will it be like in Demolition Man, where the sex act avoids physical contact and the exchange of body fluids? Or will it be like in (name the movie) where virtual sex is rampant and some people orgasm to death?</p><p>Sex toys are one area Moore's Law hasn't affected, but some day that will change in a huge way.</p><p>A realistic virtual reality simulation allowing people to experience sex with others (real or imagined) would be worth <em>billions</em>.</p><p>While porn would be the early adapter of "feelies", they would change the way all movies are made and presented.</p><p><strong>What about virtual sex between virtual people?</strong> If our brains are uploaded into computers, I'll bet that someone figures out how to implement virtual sex that is largely indistinguishable from the real thing (at least to the participants). </p><p>Or is it truly the same? How will virtual self-representations affect virtual sex? Many people in gaming choose avatars not related to their physical appearance. That might be even more true when it comes to sex play. I'm sure that ED won't be an issue, nor will premature ejaculation. Or size. (Never mind. I was just told that size doesn't matter).</p><p><strong>How about sex in space?</strong> In space, no one can hear you scream. (No, wrong movie.) In orbit or other zero-gravity environments, sex would be more difficult, a challenge. As I point out in <em>Apophis 2029</em>, while possible, sex in free-fall is awkward and likely tiring. It's still worth the effort, I'm sure, but it <em>is</em> different. Straps, hand-holds, and surfaces to thrust against would be important. Vital, even.</p><p>So, yes, I believe there <em>will</em> be sex in the future. Hopefully it will be between between consenting adults, and at least occasionally result in children. After all, if we stop having children (see <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/06/purpose-of-life.html">The Purpose of Life</a>), soon there would be no more sex in our future. </p>Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com0tag:blogger.com,1999:blog-7338070402887246857.post-77264466347470875362008-08-02T08:16:00.001-04:002009-10-26T19:09:41.395-04:00Animals in Space<p>In the long run, the animals whose populations grow will be those that either prove themselves valuable to humans or that prove hard to eliminate. In a resource-starved highly over-populated Earth, the choice of who survives--human or animal--is likely to be won by the human (ignoring the impact of sub-species such as attorneys).</p> <p>The animals we take with us as our civilization expands into the cosmos are likely to be numerous. Those limited to a meager existence in zoos and parks can't be viewed as successful, but at least their lives will be in a rather pleasant captivity. Modern zoos are more like a Hyatt Regency than Alcatraz for their occupants.</p> <p>Humans will likely keep our pets, the <strong>dogs</strong> and <strong>cats</strong> that provide us with love and companionship. Cats seem especially suited to a life in zero gravity--I have no problem imaging cats thriving in such an environment. Dogs, to me, seem to need gravity for happiness (running, jumping) but they'll adapt, I'm sure.</p> <p>The other animals we take with us are those domesticated ones <em>that taste good</em>. We are, after all, omnivorous, and no amount of processing is likely to give an algae cake the taste and texture of a steak. I could be wrong, and there is a huge efficiency drop if we choose to eat animals instead of plants, but it seems that in a wealthy society, we'll find a way to raise <strong>cattle</strong> for meat and milk, <strong>chickens</strong> for meat and eggs, <strong>pigs</strong> for bacon and ham. </p> <p>Better (more efficient) choices exist for meat animals; <strong>goats</strong> produce much more milk per pound of food consumed, <strong>rabbits</strong> much more meat. Chickens are quite efficient as-is. But you can't prepare a prime rib from rabbit. Still, these choices are likely to be early winners, in some cases because they eat different parts of the plant than we humans.</p> <p>Seafood will likely be available, also. We already raise <strong>salmon</strong>, <strong>catfish</strong>, and other seafood in farms. These are likely to do quite well in space, at least as long as we can find and utilize large volumes of water (I like comets). We'll miss many foods from the top of the food chain (such as tuna, swordfish and the like), but varieties of others are likely to be plentiful, possibly even critters such as shrimp and lobster.</p> <p>My question for today is, how many animals will succeed against our will (such as mice, or pigeons, or ants, or roaches)? Or what others must we bring along because they are a necessary part of the ecology? For example, must we use bees for pollination? Earthworms to churn the soil? </p> <p><strong>Here's a scary thought:</strong> What if there is some pest whose presence is necessary for long-term health, such as the mosquito? Some of them can't reproduce unless they've consumed human blood, but has any human <em>ever</em> reproduced before being bitten by a mosquito? </p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com2tag:blogger.com,1999:blog-7338070402887246857.post-33085623030803228642008-07-30T11:23:00.001-04:002011-01-23T10:11:19.837-05:00Near-future Space Industries<p>Many people have written about commercial opportunities in space. The big ones are power satellites (beaming zero-carbon-footprint energy to earth), zero-G industrial processes (things that can't be cheaply made in a gravity field, such as foamed steel), and tourism (I'm looking forward to Disneymoon, and that first Hyatt with an out-of-this-world view).</p> <p>Another significant opportunity exists in communication satellites and research. It is much cheaper to maintain / repair / service satellites from an orbit near them. It's even cheaper to build them there. Send the expensive components to low Earth orbit, assemble them in space, and launch to a higher geo-synchronous orbit using in-space resources (fuel made from asteroids & comets). It is much cheaper. An asteroid-based satellite assembly factory in a thousand-mile-high orbit could easily perform those functions. Another asteroid near geo-synch orbit could perform maintenance functions. </p> <p>Astronomers take note: such a space-based satellite assembly factory could also build a really huge space telescope by assembling a collage of launchable mirror segments. Imagine the resolving power and light-gathering capabilities of a fifty-meter version of the Hubble Space Telescope. Add the convenience of a nearby maintenance crew that could swap out new instruments for old, replace failing gyroscopes, perform routine repairs. If desired, the maintenance crew could be positioned permanently between the sun and the telescope to shade it from those pesky thermal cycles due to the contrast between the sun's heat and the cold of space.</p> <p>In the long run, the biggest space industry is likely to be the same as on Earth: people, their entertainment, their housing, their food and water (and air), and information. As mankind expands into the cosmos, there is no need to make money by sending products home to Earth, just as the economy of the USA is not entirely dependent upon sending products back to mother Europe. An expanding population creates its own wealth as there are always opportunities for us to help one another (and make a buck in the process).</p> <p>In the relatively near term, supporting Earth's needs will be paramount and will fund the expendables and technologies needed to thrive in space. Soon after, mining, housing, and food (recycling) will be the major industries. But after the space population exceeds some critical threshold (I don't know if it is ten thousand, or a million, or even tens of millions), it will become completely self-sustaining. Expanding humanity's presence in space will become the fundamental driving force of the space-based economy. And from then on, there's no looking back.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com0tag:blogger.com,1999:blog-7338070402887246857.post-75164851092080509452008-07-29T10:15:00.001-04:002008-07-29T10:15:33.115-04:00The Future of Religion<p>Can any topic have more opinions?</p> <p>Religion seems to be built into us, possibly as a result of the knowledge of our own mortality. It's hard to believe that my consciousness, my mind, is in any way a physical manifestation of my brain and that it could simply stop when I die. Surely, I will go on and survive my physical death. </p> <p>However, logic tells me that my consciousness is a result of the processes in my brain, and when I <em>die</em>, <em>I'll</em> be dead.</p> <p>As the average level of freedom increases around the globe, two effects related to religion are apparent:</p> <ol> <li>The percentage of people claiming to be religious is decreasing (likely due to an increased tolerance toward those who don't share our personal beliefs), and </li> <li>The number of religions seems to be increasing. </li> </ol> <p>In the past, religions were founded by charismatic leaders, who convinced others to follow in their footsteps.</p> <p>Today, many religions (some of which claim <em>not</em> to be religions) are based upon logic, either as rationalizations of combinations of other religions, or as the result of people with similar beliefs getting together and deciding that "this is the way that makes sense".</p> <p>We can all hope that someday in the not-too-distant future humanity will be above the petty conceits that have led to past and present religious wars.</p> <p>But then what?</p> <p>Like all non-extinct organisms, successful religions have survival tenets. (See <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/06/purpose-of-life.html">The Purpose of Life</a>.) For a (generic) church, long-term survival means reproducing the church, growing the congregation. For some, that means having children and keeping those children in the fold. For others, it means spreading the word. Indeed, many of the most successful religions have the attitude that anyone not believing as I do is surely doomed, thus justifying wars and conquest to convert the non-believers. Sometimes the wars are overt (The Crusades, or a Jihad). Sometimes they are peaceful (Christian missionaries come to mind). However, they all strive to convert non-believers to the "one true religion" of the warrior. </p> <p>My critique group (while working on my story currently titled <em>Ghost Rights</em>) posed a number of question related to religion. Such as, is it still needed? <em>Ghost Rights</em> deals with the uploading of human brains into computers, resulting in effective immortality. (See <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/07/immortal-dilemma.html">Immortal Dilemma</a>.) If this is indeed possible, the big question becomes <strong>does effective immortality eliminate the need for religion in our lives?</strong></p> <p>I personally think not. There will always be those who believe that there must be something better out there, reachable automatically by ending what we have now. There will always be those who don't believe that a human soul can be duplicated into a machine, that God's creation cannot be copied by technology (yes, this ignores the fact that humans are copied biologically every second of every day). And there will always be those who don't believe that the copy in the machine is really me. I'm one of the latter, I'm afraid. </p> <p>Personally, I believe that the human attraction toward religion is based upon our recognition of mortality, and I don't think that is going away in the next few million years.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com0tag:blogger.com,1999:blog-7338070402887246857.post-51848851227120923112008-07-25T11:38:00.001-04:002008-07-25T11:38:47.326-04:00Singularity Revisited<p>I've been lurking & posting on other blogs lately (such as <a href="http://www.tor.com">www.tor.com</a>), and the primary topic has been <a href="http://en.wikipedia.org/wiki/Technological_singularity">The Technological Singularity</a>, whether or not it might happen, how many singularities have already happened in human history, and whether it will have a positive or negative impact on humanity.</p> <p>For my basic position and additional references, see my post, <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/05/likely-coming-technological-singularity.html">The (likely coming) Technological Singularity</a>.</p> <p>Most of the discourse boils down to:</p> <ol> <li>Can <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/05/moore-wall.html">Moore's Law</a> <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/07/more-on-moore-law.html">continue</a> and is a resulting technological singularity inevitable?</li> <li>Will this be a "rapture of the nerds" where humanity (or at least a significant fraction thereof) will participate? </li> <li>(Not so important) What is the impact of the singularity concept on the literature of science fiction?</li> </ol> <p>The optimists, including <a href="http://en.wikipedia.org/wiki/Vernor_Vinge">Vernor Vinge</a> who first used the term "singularity" in this context, and <a href="http://en.wikipedia.org/wiki/Ray_Kurzweil">Ray Kurzweil</a>, firmly believe in computers augmenting human intelligence, memory, and communication, leading to a time of superhuman intelligence with unforeseeable results. Thus, a "singularity".</p> <p>Even some optimists have qualms: <strong>In 1993, Vinge himself said, "Within thirty years, we will have the technological means to create superhuman intelligence. Shortly after, the human era will be ended."</strong></p> <p>Much modern science fiction either deals with the "post-human" era--after the singularity--or proposes reasons why the singularity never happened.</p> <p>The pessimists, including notables such as <a href="http://en.wikipedia.org/wiki/Bill_Joy">Bill Joy</a>, fear the singularity. Joy wrote an article for Wired Magazine called <a href="http://www.wired.com/wired/archive/8.04/joy_pr.html"><i><strong>Why the future doesn't need us</strong></i></a>. It is thoughtful, and frightening.</p> <p>I'm a pessimist; I fear the rise of the machines. I believe that these technological advances are coming. It will be up to us to make sure that our technologies are used to improve humanity, not destroy it.</p> <p>I also see fundamental problems controlling advanced AI. We have <em><strong>no friggin' idea</strong></em> how to program morality, or ethics, or respect, or love, let alone <a href="http://en.wikipedia.org/wiki/First_Law_of_Robotics">Asimov's Laws</a> into our computers. We have a hard enough time teaching it to people. Have you ever been robbed, or mugged, or threatened? At least you haven't been murdered, <em>yet</em>.</p> <p>I see problems with the controlling extreme advances in computer technology. Assume, for the moment, that advanced AI is possible, given expected improvements in computers and possible improvements in software. The person/company/country with superhuman intelligence on his/their side will have an <em>enormous</em> advantage over his/their competitors. <strong>Human greed <u>will</u> overwhelm caution</strong>, at least part of the time. It will take a huge, powerful, global governmental agency to control the technologies and prevent catastrophe. </p> <p>In the long run, the most powerful government agency <em>becomes</em> the government.</p> <p>As humanity (hopefully) expands into the cosmos, I see this one, all-powerful agency being the sole unifying force of humanity. Because it only takes a single malevolent superhuman entity to wipe out us all. And in the long run, the only thing that matters is survival (see <a href="http://ramblingsonthefutureofhumanity.blogspot.com/2008/06/purpose-of-life.html">The Purpose of Life</a>).</p> <p>I look forward to humanity's advancement, but I fear our extinction. Once <a href="http://en.wikipedia.org/wiki/Hard_AI">hard AI</a> is possible, fighting it will be a perpetual struggle.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com0tag:blogger.com,1999:blog-7338070402887246857.post-81907234641838954402008-07-21T15:45:00.001-04:002008-07-21T17:25:17.139-04:00Immortal Dilemma<p>I've come up with many ideas for my "ghost story" world, in which people can choose to have their brains copied into a computer. In this world, the process of reading a brain involves taking it apart and recording all of the neuron structures, synaptic paths, whatever else impacts how the brain works, and is necessarily destructive. You can't survive the brain dump, so I simply assumed that people would wait until near death to get uploaded into a computer.</p> <p>After all, the computer program may have my memories, my personality, my attitudes and behaviors, and certainly behaves as though it's me, but I'm still dead, in my opinion. Still, even as a copy, it thinks it's me, and therefore in some sense perhaps it is. Your biological body dies, and your consciousness  wakes up in a simulation.</p> <p>The quandary is that the brain dump records all aspects of the brain <em>at the time of the dump</em>. Do it too late and it fails. Do it too soon and, well, did I mention that it's an irreversible choice? You're giving up on any additional <em>real</em> life that you may have experienced.</p> <p>But delaying too long is a potential problem. If you don't get to the hospital in time, you're dead forever. If you have a stroke and some part of your brain dies, the upload will have the same flaws. You can't get back to a healthy brain and memory. Likewise with dementia. Once those memories are lost, they may be lost forever.</p> <p><em>And forever is a long time if you're immortal.</em></p> <p>So when is the right time to leave your mortal body? </p> <ol> <li>Never?</li> <li>In the hospital as they declare you dead? </li> <li>When you're ready to retire? </li> <li>When you seriously start thinking about your mortality?</li> <li>When your kids have left the nest and you're at the top of your career? </li> <li>As soon as you can afford the (presumably expensive) procedure?</li> <li>Or when you're at your peak of creativity, which might be at 25 or so?</li> </ol> <p>Remember, your immortal self is captured at the moment of the brain dump. You can still learn, but you can't easily recapture lost capabilities or memories. </p> <p>Also, should the time you choose to upload vary with your present (or post-death) career? If you can do your job in front of the computer, not having a body shouldn't slow you down. Lawyers, consultants, webmasters, writers, management, stock broker, and a thousand other jobs can be done by the dead. Possibly even better than by the living.</p> <p>Time to think and vote.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com3tag:blogger.com,1999:blog-7338070402887246857.post-26172509463322132008-07-18T08:42:00.001-04:002008-07-21T17:25:17.139-04:00The Speed of Life<p>I've written a story about a future in which our minds (memories, personality, consciousness) are uploaded into computers when we approach death. (Not before: the readout process is destructive and you would not survive).</p> <p>Personally, I think that understanding the brain is not going to happen, but that doesn't keep us from simulating it, from creating a large and powerful neural network sufficient to model every aspect of the human brain. We don't need to understand how the brain "thinks" any better than we do now; we simply need to provide the inputs, outputs, and a sufficiently large, fast, impressionable (teachable) model. This is largely how computer neural networks work today, but on a trivially small scale.</p> <p>One common perception is that the resulting computer would be placed into a (potentially humanoid) robot, so that the person would continue to function much as in biological life, but now mechanical/electronic. Personally, I don't think this is likely. For the near future, robots are difficult to implement. Energy storage, strength, speed, dexterity are all issues that we have evolved to handle well and that are extremely difficult to implement using the motors and actuators that we can build. </p> <p>There is another problem: why should the electronic implementation of the mind be limited to occupying a physically present (robotic) body? Virtual reality simulations of an environment would offer much greater freedom, including virtual travel, conventions, sex, whatever. Note that a physical body is necessarily limited to responding to its environment by the needs of physical response times. Virtual reality has no such restriction.</p> <p>One of the interesting aspects of this approach is <em><strong>the speed of life</strong></em>: how rapidly does the person in the computer experience the reality of the world? I'm pretty certain that when Moore's Law makes the next generation of computers run twice as fast and that means the person in the computer experiences reality twice as fast, not that they become twice as smart.</p> <p>I see potential problems of the difference in speed when it comes to communicating with (slow) humans, or older generations of uploaded personalities, problems which will get worse as technology improves. Do you like to spend time with really slow people? It becomes frustratingly difficult to engage in meaningful dialog, on both sides. Note that I do not anticipate "improving" consciousness; you would not be able to carry on a half-dozen simultaneous conversations any more than you can today. We would find ourselves using buffered communication channels, such as email or voice mail.</p> <p>Back to the robot issue: a very fast implementation of a human mind in a human sized real-world responding robot would be awkward at best, maddeningly boring at worst. I'd rather experience the virtual world at a normal (to my greatly sped-up mind) speed--blindingly faster than you slow biological humans. </p> <p>The reality of minds in many different speeds of computers might lead to a caste system. It might also lead to a world where the young and fast have huge performance advantages over the old and slow, with serious implications for jobs. I guess we'll have to pay for continuous upgrades, or fall behind. Great story ideas; I've already written one and outlined two others.</p> <p>But wetware (or breeders, or humans--whatever you want to call us) will always run as slow as we do today. Our "speed of life" is built into us by our biology and environment.</p> <p>Human perception speed is not the only possible speed. Other animals may perceive the world much differently than we do. Have you ever watched a hummingbird eat or fight? Their motions and reaction times are incredibly fast. They think we are slow. Likewise, a tortoise may perceive us as fast. A tree views a tortoise as imperceptibly fast.</p> <p>What about alien biologies? Aliens could be around us now, but running at such a faster (or slower) speed that we don't perceive them as existing, let alone as intelligent. Larry Niven wrote <em>The Slow Ones</em>. Robert L. Forward wrote <em>Dragons Egg</em> about the inhabitants of the surface of a neutron star who experience life incredibly faster than humans. </p> <p>Is it possible that our forests are intelligent creatures with trees the equivalent of neurons and fungi are neural transmitters? Such intelligences would experience thoughts many orders of magnitude slower than us; I doubt we'd ever recognize them.</p> <p>I would argue that a human brain cell is alive but not intelligent. Would an intelligent species of bacteria recognize that a human was intelligent? I think not; the scale and speed of life is too different.</p> Stephen D. Coveyhttp://www.blogger.com/profile/12946494775268235149noreply@blogger.com0