Clearly such a system could support major programs of lunar research, solar system research, and traffic to geosynchronous orbit or beyond. The facility proposed for LEO would initially emphasize the production of propellants for carrier vehicles. This would leverage the use of shuttle capacity (both volume and cargo mass) by reducing propellant (primarily oxygen, later fuels) and upper stage (e.g., OTV uplift. Oxygen could be provided for life-support systems and as 7/8 of the mass of water for human use and in other systems. Calculations indicate that if silanes (SinH2n+2) can be substituted for hydrocarbons in cargo rockets, then about ten times as much net mass could be delivered to LEO as is transported upward from Earth in the form of hydrogen (77). This assumes silane/LOX propulsion systems with specific impulse the order of 300 seconds. Mass left over after oxygen extraction would be suitable for glass/ceramic applications and as a source of metals. Mass multiplication (MM) is the ratio of “useful” non-terrestrial mass divided by the mass of equipment and consumables supplied from Earth to obtain the “useful” mass and use it. For the silane system MM > 10 seems possible. Other systems could have effectively infinite MM. High MM is a major need for growing space industry. MM can increase by building on Earth increasingly more efficient facilities which can be deployed in space. The more general approach is to use non-terrestrial materials to build in space more of the productive facilities which allow continual growth. This is referred to as “bootstrapping.” Learning to use lunar materials directly and for bootstrapping is clearly challenging. Because it is easier to reach LEO than the moon with both people and machines from Earth, it is sensible to demonstrate most of the initial utilization and bootstrapping just over our heads in LEO. Leo facility(ies) should concentrate on the use of lunar soils to build mass multiplying systems which can produce an ever-increasing range of products. These products could be expendables and other machine systems for production in space. Actively pursuing building in space with non-terrestrial resources would imply the following: • Full use of the 25 B$ investment in the Apollo program and the scientific knowledge of the moon and its resources that we have acquired since 1969; • Entry of many new people and skills into space programs both through public and new private efforts; • Creation of new incentives for shuttle development and use; • Support a program of expanded operations out of LEO into cis-lunar and deep space; • Tie more closely the exploration and exploitation of space (78); • Bring dramatically and continually to the attention of the American and world public, dynamic and growing space developments with continual new and unexpected opportunities (79,87); • Produce habitats and support systems which can safely protect life off Earth for long periods of time using solar energy and common silicate materials (this is needed for low cost manner exploration of the inner solar system — out to the asteroid belt); and • Force us to learn new ways, open-ended ways, of growing into space and on Earth. There will be analysts who object to using 15,000 $/hour labor (ie., astronauts' time in orbit) to do construction and development (72). However, this simply must be
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