Space trade

[1] Several people have considered trade within the Solar System as one of the ways in which the colonization of Mars is both important and can be made self-sufficient.

Robert Zubrin, of Lockheed Martin Astronautics, in a paper on the economic viability of colonizing Mars,[2] puts forward interplanetary trade as one way in which a hypothetical Martian colony could become rich, pointing out that the energy relationships between the orbits of Earth, Mars, and the asteroid belt place Mars in a far better position for involvement in any future asteroid mining trade than Earth.

Jim Plaxco, in a paper putting forward the case for colonizing Mars,[3] mentions that Phobos and Deimos can be developed, in the long term, from being short-term testbeds for the techniques of asteroid mining and staging posts for colonization of Mars itself, into key trading posts in interplanetary trade, again because of their favourable position within the Solar System.

It is theorized that if different locations within the Solar System become inhabited by humans, they would need to transport valuable resources between different planets, moons and asteroids.

That threatens the possibility of conducting business in a genuinely common currency and of enforcing debt agreements incurred by governments.