This post was originally published at October 22, 2011 at blogspot.com
The early proponents of space colonization, O’Neill in particulary, proposed an scheme in which we should first establish a base on the Moon. Because it is much cheaper to use resources from the Moon, then to import them from Earth. Only elements which cannot be found on the Moon in significant quantities, most notably the Moon lack large amounts of hydrogen, carbon and nitrogen (which are essential for life), should be imported from Earth to space habitats. According to O’Neill’s planning a few years after finishing the first habitats, we should move to the Asteroid belt. There we should have all necessary elements to our dispossal.
This scheme is based on the scientific knowledge of the 1970s. But sinds the 1970s scientists have discovered an astounishing amount of so called Near Earth Asteroids (NEA). The NEAs have a composition comparable to those in the Main Asteroid belt, actually most of those NEAs are main belt asteroids, which are ejected from the main belt as a result of the gravity of Jupiter. The existence of Near Earth Asteroids will change our colonization schedule.
There are Near Earth Asteroids with very Earthlike orbits, and therefore these are easy reach. Actually it is easier to get to the Near Earth Asteroids then the Moon, because a spaceship going to a NEA needs a lower delta v, then one underway to the Moon. Delta v, is a measure for the energy needed to reach a certain celestial body from Earth, for more information on this topic see here. In other words, in order to get to the NEAs one needs less fuel then to get to the Moon.
Not only are NEAs easier to reach, they also contain abroader spectrum of resources. If space colonists could use NEA resources, then they didn’t have to import anything from Earth. Of course in the beginning days of space habitization, space settlers should have to import some specialized goods from Earth (especially equipment needed to exploit NEAs), but this is also true in the original scheme of O’Neill. In the long run Spacers we be able to produce these goods themselves.
A third advantage of the Near Earth Asteroids is that they have a weaker gravity then the Moon (which is a sixth of Earth’s), so it is easier to get stuff from a NEA then from the Moon. Therefore less energy is needed to bring back useful material from the Near Earth Asteroids, then from the Moon. So using NEA resources made space colonization a lot cheaper.
We have seen that Near Earth Asteroids contain all resources a space colony needs, and that it is cheaper to exploit them instead of using Lunar resources, both in terms of accessibility and returning resources. Therefore it seems to be silly with today’s knowledge, still to promote that space colonists should first establish Moon bases.