Establishing Colonies Beyond Mars
Asteroids — those rocky objects that orbit the sun in a wide band between Mars and Jupiter — could serve as stepping-stones to the outer planets. There are only 100 asteroids larger than 125 miles (200 kilometers) across, but a billion or more may exist, making them one of the solar system's greatest resources [source: Rees].
But colonizing an asteroid would be even more challenging than building a base on Mars or the moon. Asteroids don't have much gravity, so astronauts would face serious health problems from living in that environment unless they created artificial gravity inside the base, possibly by continually spinning the entire habitat.
Because the asteroid belt is so far from the sun, solar arrays that powered such machinery would have to be gigantic. There also would be the problem of shielding the colonists from cosmic radiation. You might think that tunneling into the surface might provide some protection, but doing that would be tricky, because a lot of the objects that we call asteroids aren't actually solid rock, but basically bunches of space junk without much structural integrity [source: Allison].
But if we were going to colonize a smaller distant object, the dwarf planet Ceres, the largest object in the asteroid belt and the only dwarf planet in the inner solar system, might have some possibilities. NASA's Dawn probe discovered that the asteroid has an outer shell that's rich in water, in the form of ice and hydrates [source: NASA].
The Obama administration had an ambitious plan, the Asteroid Redirect Mission, which called for capturing part of an asteroid and bringing it back to the vicinity of the moon, so that astronauts could land on it and retrieve samples. But the project was cancelled in 2017 by the Trump Administration [source: Malik].
Are you ready to head beyond the solar system?