Drexler wrote long ago: ...History thus joins with common sense to suggest that space development — not national prestige — is the engine that will open a road to the stars

Chris writes: The use of resources from Mars fits within the defintion of space development resources. It's only that people like Drexler see the Moon or the Minor Planets as raw materials...

Drexler wrote long ago: Mars fits in poorly. To advance space development, we need cheap resources in near-Earth space. The Moon is obvious and attractive: the velocity increment needed to escape the Moon and bring materials to near-Earth space is fairly low, and the Moon holds oxygen, rock, metals, and (perhaps) water at the poles. What is more, it can best absorb any politically-inspired mania for a planetary base, being close enough to do so at a comparatively modest cost. The asteroids are less obvious to the casual eye, but more attractive: the velocity increment needed to bring materials from suitable asteroids is lower than that of the Moon, and asteroids contain oxygen, rock, water, hydrocarbons, steel, nickel, cobalt, and precious metals.

Chris writes: With the use of IRSU and Mars resources you loose most of the "advantages" of the Moon and the Minor Planets except proximity and learning more about potential impactors...

All resourses will be used and whether a space based or planet based expansion happens I don't think we are anywhere near that Era. We still are exploring the resourses!

BTW, no model of a historical nature seems to capture all the aspects of Space, whether its the history of air travel, trains or ships and what people did with them... The Chinese had many of religious, political and the Emperor's own personal reasons for building the fleet and later sculling them and to call it all "national prestige " is to render that part of Dexler's argument absurd!

--Chris Vancil