Saturday, June 14, 2008

Our homes, the Comets

In previous posts, I have written about colonizing asteroids and then expanding into comets as an approach to reducing limits on the growth of human population. I pointed out that there are a trillion comets with diameters of one kilometer or more in our Oort Cloud.

I also hinted that comets contain everything we need for wealth and health. But exactly what is in a comet, anyway?

Land on an average comet. For each colonist, excavate a volume 10 meters by 10 meters by 10 meters (perhaps one fourth for recycling, one half for office/industrial/common space, one fourth for personal use--over 1000 square feet per person of living space). What have we excavated?

  • 400 tons of oxygen - plenty to breathe, enough to throw away (reaction mass / rocket fuel).
  • 100 tons of carbon - enough for building materials plus lots left over for things to grow and eat
  • 100 tons of hydrogen - all the water and energy you might want (I am assuming that we can get energy via hydrogen fusion at some point)
  • 70 tons of iron (or steel, if we add a little of our carbon)
  • 45 tons each of nitrogen and silicon
  • 30 tons of magnesium
  • 25 tons of sulfur (ok, I'm just trying to be complete)
  • 7 tons of aluminum
  • 5 tons of nickel
  • 100+ tons of other elements in smaller quantities

    Remember, that is per person. Does that sound like wealth to you? Note that each cubic kilometer of comet contains a million times that! If you take a slightly larger comet leaving the outside in place as radiation shielding, you have plenty of room for a population of a million people. In one small comet.

    Yes, I propose a comet based space civilization. All of the comets can be mined, through and through, but the smaller ones can be hollowed out and spun for gravity. Take a little of that carbon and spin it into carbon nanotube cables and wrap the comet to hold it together against the spin, and voila, you have a space habitat, warm, snug, and safe, with all the necessities of life including a form of gravity.

    Comets and asteroids are not at the bottom of gravity wells. Over 800 known asteroids are easier to reach (in terms of rendezvous Delta-V) than our own moon. And while they are far apart in distance, their energy distances are manageable (much closer than getting into low Earth orbit, generally much easier than landing on and leaving the moon).

    Some people don't believe in space colonization. For example, Charles Stross writes against it in the space cadets infesting the comments on this essay of mine. While many of his arguments are valid (and I, too, agree that the planets are poor choices), he misses the point that we need to expand into space, or humanity will stagnate and die. There are simply insufficient resources on Earth for a thriving, growing civilization. Perhaps Stross is content to let our computers own the future. Personally, I want people to own the future, not Intel and IBM.

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