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 and one in Earth orbit. It is anticipated that near-closure (see chapter 5) will be achievable and that minimal human presence will be necessary. Interaction between lunar and Earth-orbiting components allows growth materials required by the orbital module to be supplied from lunar sources, thus greatly reducing supply costs. A major gain with respect to capital investment and production costs is that fewer materials must be flown up from Earth and that almost all the required on-site labor can be performed by automata.

Distributive benefits.
Certainly the SMF generates a number of indirect benefits for the public. It opens new horizons of knowledge, advantages American industry in international competition, provides new technologies, and reasserts the U.S. position of leadership in space. However, the public relates only vaguely to such interests, if at all. The establishment of a solar power satellite, on the other hand, is of more direct and tangible value. This kind of SMF product could have direct impact on energy costs now borne by the public and could lead to a visible decrease of dependence on foreign energy supplies.

Standards of living and public perceptions.
If the capital investments required are accounted for, the proposed mission can help to stabilize the American standard of living and eventually permit it to continue to rise. Energy scarcity is widely perceived as the root cause of current economic difficulties, a viewpoint stressed repeatedly by the media. Rampant inflation and unemployment, justly or unjustly, are traced directly back to the cost of energy. Recently, however, it has become increasingly apparent that the issue is not simply energy supply but also energy cost. Given the education the public already has received, it should not require too much additional effort to make people aware that their own short- and long-term interests are well-served by the SMF. The poor economic climate actually may prove an added fiscal impetus for the mission rather than a restraint.

4.1.3 Summary of Chapter Contents
The study team focused its efforts on four areas related to the nonterrestrial utilization of materials:


 * Material resources needed for feedstock in an orbital manufacturing facility (section 4.2)
 * Required initial components of a nonterrestrial manufacturing facility (section 4.3)
 * Growth and productive capability of such a facility (section 4.4)
 * Automation and robotics requirements of the facility (section 4.5)

Section 4.2 presents an overview of energy and mass available in the Solar System, with special attention to those resources which may be available in the near future and to possible space materials processing techniques. A lunar-to-LEO shuttle system utilizing silane fuel and an Earth-based electromagnetic catapult are possible candidates for the transportation of raw' materials and feedstock to low Earth orbit.

Scenarios for establishing an initial orbiting manufacturing facility are developed in section 4.3. To provide some basis for determining the minimum number and types of machines which might be available for space manufacturing and for constructing an automated shop capable of creating additional industrial equipment, a survey of basic manufacturing processes was performed by the team. "Starting kits" were conceptualized which might be useful in creating an ever-widening set of manufacturing devices requiring minimal initial inputs and using solar energy, vacuum, zero-gravity, and robotics to best advantage.

Section 4.4 demonstrates the growth and production potential of the Space Manufacturing Facility using the material resources and starting kits described earlier. Near-, mid-, and long-term examples of product manufacture are developed. These outputs, including Shuttle external tank conversion to simple structures (near-term), electronics components fabrication (mid-term), and the creation of space platforms, pure glasses, satellites, and robots (long-term), are presented as representative samples of SMF growth possibilities.

Section 4.5 concentrates on mission automat;on and machine intelligence requirements for an SMF. Limitations and functional demands of robotics in space are detailed. with recommendations for future machine intelligence developments. Mission technology drivers in major areas other than automation and machine intelligence are briefly summarized. Finally, section 4.6 provides a general discussion of the implications for society, potential consequences. and necessary sociocultural and political prerequisites for implementation of a space manufacturing mission.

4.2 Materials Background
A survey of Solar-System resources available to mankind in the near-, mid-, and distant-future is appropriate in evaluating the potential of the SMF mission concept. Such background is necessary to identify terrestrial and lunar resources, asteroidal materials, and various additional sources for space manufacturing feedstock. This section describes existing chemical extraction and materials processing alternatives including one new option identified during the course of the study large-scale electrophoretic lunar soil processing) and expanded possibilities for the metallurgy of native lunar basalts, followed by a consideration of materials transport both from the Moon to low Earth orbit using silane-based propellants derived in part from lunar materials, and from the surface of the Earth to LEO using a ground-based electromagnetic catapult (Mongeau et al., 1981).