How Might Asteroids be Colonized?

Since the mid-20th century, space enthusiasts and visionaries have looked to the asteroids as possible colonization sites. There are an estimated ten billion asteroids greater than 100 meters in diameter, and their combined surface area is much greater than that of the Earth. The largest asteroid, Ceres, has a surface area comparable to that of central Europe. The 32 largest asteroids are each 200 km or greater in diameter. There are an additional 100 billion asteroids between 10 and 100 meters in diameter. Many of these contain millions or billions of dollars worth of valuable resources.

It was Isaac Asimov who first suggested hollowing out asteroids prior to settling them. Unlike certain celestial bodies, for instance, Luna, some asteroids contain substantial carbon and volatiles such as water, both of which are necessary to sustain life. A hollowed-out asteroid would have an natural shield (the surface) to block out dangerous cosmic rays and micrometeorites, and if it could be spun around fast enough, the inner surface would have artificial gravity in regions perpendicular to the axis of rotation.

Although internal supports would be necessary to prevent an asteroid from collapsing under its own gravity, being of relatively low mass, even if one of these supports failed, it would not necessary kill everyone inside. With several artificial shield layers backing up the asteroid surface, there would be little reason to worry about a breach or unpredicted collapse.

Asteroids contain a huge amount of valuable materials, especially platinum group metals, which could fetch high prices if shipped down to Earth and sold here. This could become the basis for an inner solar system economy. Many of the most valuable metals on Earth long ago sank to its core, but on asteroids, these materials are readily available. As our global civilization continues to develop, many of the key resources could come from the asteroids rather than Earth itself.

As our population on Earth continues to grow at a rate of about 2% per year, eventually the planet will become too crowded to sustain everybody. The solution – colonize the inner solar system, particularly the asteroids. Perhaps the single greatest reason to colonize asteroids is their relatively low gravity – the amount of energy required to launch a package outside the gravity well of Earth is intimidatingly large, but on many asteroids, it is insignificant.

For more information, check out one of the most popular books on the subject, Mining the Sky: Untold Riches from Comets and Asteroids.