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Transportation Economics of Extraterrestrial Resource Utilization

By Andrew Hall Cutler and Mari Leilani Hughes


It is assumed that the utilization of space shuttle external tanks as an extraterrestrial resource is economical, as it would be ridiculous to discuss the use of lunar or asteroidal resources if this were not true. [Gramlich Disagrees -- `Shuttle is Uneconomical'] Due to the restricted composition and limited nature of this resource, the exploitation of lunar and asteroidal resources is worthy of consideration. Several conclusions can be drawn from a consideration of the economics of mining the moon and asteroids. It is shown that production of lunar oxygen or steel for use in LEO is economically justified in the near future, and is superior to the use of asteroidal resources. Production of lunar hydrogen, if feasible, is not desirable from an economic standpoint until a lunar oxygen producing facility is on line and delivering oxygen to LEO. In determining economic feasibility high mass payback ratios are not particularly important. Low initial capital investment is more important. Thus steel for uses such as SDI is a more economical product than oxygen for propulsive or other uses. It is found that optimizing and comparing selected physical parameters such a delta V or Isp does not in general lead to the most economical system. Two major questions are identified which have a major impact on extraterrestrial materials utilization economics. These are minimum achievable ratios of dry mass to loaded mass for the transport vehicles, and the ability to manufacture at the mine mouth. Dry to fully loaded vehicle mass ratios must be less than 6% or so if there is any hope for economical transportation. The ability to perform manufacturing at the mine mouth is probably dependent on human presence for repair.