People are starting to dream about the colonization of Space again. Elon Musk, the visionary CEO of SpaceX, has already weighed in on a settlement on Mars. Now an Austrian architect and engineer named Werner Grandl has published his own thoughts on how we might colonize space with a plan that does not mention Mars but rather focuses on the moon and Earth-approaching asteroids.

The first step would be to establish a Lunar Base and use it to mine the moon for its resources, metals ranging from iron to platinum group metals, helium 3 for future fusion power plants, and water for rocket fuel.

The lunar base could consist of a series of modules on the lunar surface or located underground, in a lava tube, protected from radiation and meteor strikes.

The next step would be to go to Earth-approaching asteroids, attach modules to them, and start mining them. If an asteroid happened to be 400 meters in diameter or greater, it could be hollowed out, a colony for about 2,000 people built inside, and then rotated to produce artificial gravity.

Mining and gravity are the keys. The moon and Mars have one drawback in that they have much lower gravity than Earth. People who live on these worlds will grow up accustomed to one-sixth and one-third gravity respectively and will be restricted in where else they can go.

A native born Martian or Lunarian may not be able to visit Earth without a great deal of medical intervention and conditioning.

The idea of free-floating asteroid colonies is a variant on an idea first developed in the late 1960s and then popularized in the 1970s and 1980s by the late Dr. Gerard K. O’Neill. The idea was that instead of setting down roots on another world with a hostile environment, build space-based colonies in which the environment can be controlled.

Using space resources, the number of such flying settlements would be virtually unlimited. The idea somewhat fell out of favor toward the end of the 20th Century, however. But with more efforts being directed to asteroid and lunar mining, the vision of colonies in space may be due for a revival.