In the previous post, I argued that the asteroids are our logical first choices for a space based civilization.
However, the asteroid belt itself is not the best place to start. The asteroid belt is relatively far away--asteroids mostly reside in a wide range of orbits between Mars and Jupiter. But not all of them. Millions more reside in the Lagrange points in Jupiter's orbit. Thousands more orbit inside of Mars' orbit, some inside Earth's orbit. Many of these have highly eccentric orbits that would be difficult to reach. But not all.
Rather, our first choices should be Earth-crossing asteroids, the same asteroids that NASA is cataloging because they pose a potential threat to Earth. Given proper timing, some of these are even easier to reach than the moon.
Yes, I believe that instead of finding potential killer asteroids, we should be finding potential homes for humanity. These are the same asteroids! Given enough time, we can easily change an asteroid's orbit, potentially by something as simple as painting it a different color such as white or black.
But the very fact that an Earth-crossing asteroid may closely approach the Earth gives us additional options. We can use the gravitational pull of the Earth and/or the moon to change the asteroid's orbit, making large changes possible.
A particularly exciting option is the possibility of capturing an asteroid into Earth orbit. A captured asteroid puts vast resources into easy reach, protecting the earth from a future impact at the same time. Even a small Earth-crossing asteroid such as Apophis (only 300 meters wide) contains fifty million tons of material, potentially including millions of tons of water, iron, carbon, nitrogen and other materials valuable to life in outer space.
In addition to raw materials, an asteroid provides protection. By placing the colony inside the asteroid, the inhabitants are protected from meteors, solar flares, and cosmic rays. Fifteen or twenty feet of rock should provide the same degree of protection as our atmosphere on Earth.
Instead of worrying about how to deflect asteroids away from the Earth, I propose that we worry about how to place them into nice, safe, useful Earth orbits from which they could never again impact our planet.
There may be other first choices, but Apophis has been well-studied. After all, scientists briefly feared in 2004 that Apophis was on a 2029 collision course with Earth. Now, they fear that Apophis will miss in 2029 but may still strike in 2036. This asteroid is small enough for us to deflect, and will come closer than our geosynchronous satellites on April 13, 2029, giving us an ideal opportunity to tune its orbit.
I propose that we deflect Apophis just enough so that we can capture it into earth orbit (possibly after a slingshot or two with the moon). Then teams can be sent there to mine its resources, smelt them into valuable materials (including rocket fuels), and build a permanent space habitat, one suitable for thousands of worker/colonists and their families. Depending upon its composition, the materials readily available in Apophis can reduce the cost of exploring the solar system by a factor of five or ten.
That way, we turn a potential catastrophe into a treasure. I have written a short story, APOPHIS 2029, to that effect. When it is published, be sure to read it!