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Figure 5-35 — Growth of the lunar atmosphere for various constant gas addition rates. Comparable densities in the terrestrial atmosphere are indicated. Dashed lines indicate decay in the total mass if the gas source is shut off (after Vondrak, 1974).

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APPENDIX K: CHEVRON SHIELDS

Figure 5-36 — Cross section of the radiation chevron shield configuration.

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A particle radiation shield to transmit electromagnetic radiation in the visible region can be constructed out of right angle first surface mirrors made of aluminum. Figure 5-36 shows a cross section of such a shield.

Thus the average effective thickness of the chevron shield is the same as it would be if the mass were distributed uniformly to cover the same area.

If L is the separation between chevron mirror sections and d is the thickness of the mirrors, then the total cross sectional area of a chevron mirror is 2dL/cos 45°. If the mirrors were to be reformed as a uniform skin to cover the same area with the same mass of aluminum, the skin would have a thickness of 2d/cos 45° which is the path length traversed by a penetrating particle incident on the chevron shield at normal incidence.

When a chevron shield is used to admit light into a shielded region that contains a gas the individual angle mirrors must be connected by glass strips as shown in figure 5-36.

REFERENCES

1. Richardson, H. W.: The Economics of Urban Size, Lexington Books, Lexington, Mass., 1973.
2. Altman, P. L., and Dinner, D. S., editors: Metabolism; Federation of American Societies for Experimental Biology, Bethesda, Maryland, 1968.
3. Edwin, E.: Feast or Famine: Food, Farming, and Farm Politics in America, © 1974 Charter House, New York, pp. 123, 144, 165.
4. La Petra, J. W., and Wilson, R. S., editors: Moonlab, A Study by the Stanford/Ames Summer Faculty Workshop in Engineering Systems Design, June 24-Sept. 6, 1968, p. 123, NASA CR-73342.
5. Fontes, M. R.: Controlled-Environment Horticulture in the Arabian Desert at Abu Dhabi, Hort. Science, vol. 8, no. 1, Feb. 1973, pp. 13-16.
6. Popma, D. C.: Atmospheric Control Systems for Extended Duration Manned Space Flight, Biotechnology, a Conference held at Langley Research Center and Virginia Polytechnic Institute, Blacksburg, Va., Aug. 14-18, 1967, 1971, pp. 77-88, NASA SP-205.
7. Brink, D. L., and Bicho, T. G.: Comprehensive Studies of Solid Waste Management — Wet Oxidation of Organic Solid Wastes, SERL Report 71-1, Univ. of Calif., Berkeley, 1971.
8. Department of Commerce, Bureau of the Census; Industrial Census, 1972.
9. Glaser, P. E., Maynard, O. S., Mackovciak, J. J. R., and Ralph, S. L.: Feasibility Study of Satellite Solar Power Stations, NASA CR-2354, 1974.
10. Woodcock, G. R., and Gregory, D. L.: Derivation of a Total Satellite Energy System, AIAA Paper 75-640, 1975.
11. Hawkins, V. H.: Feasibility Study of Commercial Space Manufacturing Task II, Design Reference Mission, McDonnell Douglas Astronautics Company — East, DPD No. 515, May 1975.
12. Leith, H., Iverson, H. G., and Clemmer, J. B.: Extraction of Alumina by Leaching Melted and Quenched Anorthosite in Sulfuric Acid, U.S. Bureau of Mines, Report of Investigations 6744, 1966.
13. Russell, A. S., Jarrett, N., Bruno, M. G., and Remper, J. A.: Method for Carbon Impregnation of Alumina, Aluminum Company of America, Pittsburgh, Pa., May 21, 1974, U.S. Pat. 3,811,916.
14. Dell, M. J., Haupin, W. E., and Russell, A. S.: Metal Production, Aluminum Company of America, Pittsburgh, Pa., July 9, 1974, U.S. Pat. 3,822,195.
15. Haupin, W. E., and Racunas, B. J.: Preparation of Alkali Metal Chloride Melt for Use in Electrolysis of Aluminum Chloride, Aluminum Company of America, Pittsburgh, Pa., Sept. 25, 1973, U.S. Pat. 3,761,365.
16. King, L. K., Knapp, L. L., Schoener, R. C., Kloap, N., Starner, B. M., and Remper, J. A.: Recovery of Solid-Selectively Constituted High Purity Aluminum Chloride From Hot Gaseous Effluent, Aluminum Company of America, Pittsburgh, Pa., Jan. 15, 1974, U.S. Pat. 3,786,135.
17. Russell, A. S., Knapp, L. L., and Haupin, W. E.: Production of Aluminum, Aluminum Company of America, Pittsburgh, Pa., April 3, 1973, U.S. Pat. 3,725,222.
18. Nishioka, Kenji, Arno, Roger D., Alexander, Arthur D., and Slye, Robert E.: Feasibility of Mining Lunar Resources for Earth Use: Circa 2000 A.D., vols. I, II, Ames Research Center, vol. 1, NASA TM X-62,267; vol. 2, NASA TM X-62,268, 1973.
19. Dalton, C., and Hohmann, E.: Conceptual Design of a Lunar Colony, 1972 NASA/ASEE Systems Design Institute, University of Houston, MSC, Rice University NASA Grant NGT 44-005-114, NASA CR-129164.
20. Mansfield, J. M., Dolan, T. J., Carpenter, R. B., Jr., and Johns, R. G., Jr.: Lunar Base Synthesis Study, vols. I, II, III, Space Division, North American Rockwell Document Number SD-71-477, Contract Number NAS8-26145, May 1971, NASA CR-103127, NASA CR-103131.
21. Wetherill, G. W.: Solar System Sources of Meteorites and Large Meteoroids, Ann. Rev. of Earth and Planetary Science, vol. 2, 1974.
22. A Preliminary Structural Analysis of Space-Base Living Quarters Modules to Verify a Weight Estimating Technique, NASA MSC-O1-542, MSC, Houston, Texas.
23. Dugan, G. L., Golueke, C. G., Oswald, W. J., and Rixford, C. E.: Photosynthetic Reclamation of Agricultural Solid and Liquid Wastes, SERL Report No. 70-1, University of California, Berkeley, 1970.
24. Rechcigl, M., editor: Man, Food, and Nutrition, © 1973, CRC Press, Cleveland, Ohio, p. 122.
25. Aldrich, D. G. Jr.: Research for the World Food Crisis, © 1970, A.A.A.S., Washington, D.C., pp. 81, 89.
26. Zelitch, I.: Photosynthesis, Photorespiration, and Plant Productivity, © 1971, Academic Press, New York, pp. 270-271.
27. D'Amario, L. A., and Edelbaum, T. M.: Minimum Impulse Three-Body Trajectories, AIAA Journal, vol. 12, no. 4, pp. 455-462, 1974.
28. Freeman, J. W., Jr., Fenner, M. A., Hills, H. K., Lindeman, R. A., Medrano, R., and Meister, J.: Suprathermal Ions Near the Moon, Icarus, vol. 16, no. 2, April 1972, pp. 328-338.
29. Freeman, J. W., Jr., Hills, H. K., and Vondrak, R. R.: Water Vapor, Whence Comest Thou? Geochim. Cosmochim. Acta, Suppl. Proceedings of the 3rd Lunar Science Conference, Cambridge, Mass., MIT Press, vol. 3, 1972, pp. 2217-2230.
30. Vondrak, Richard R.: Creation of an Artificial Lunar Atmosphere, Nature, vol. 248, no. 5450, April 19, 1974, pp. 657-659.
31. Vondrak, Richard R.: Environmental Impact of Large Space Facilities, paper submitted to Proceedings of Princeton University Conference, Meeting No. 127, on Space Manufacturing Facilities, Princeton University, May 1975 (in preparation).

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BUILDING THE COLONY AND MAKING IT PROSPER

For the functioning system described in the previous chapter to become a reality much preparatory work must take place to fill in the gaps in current knowledge. Initial efforts toward space colonization begin on Earth, move into low Earth orbit (LEO) and continue later to the lunar surface, the site of the mass catcher (L2), and finally to the site of the colony (L5).

PREPARATORY WORK

Critical gaps in present knowledge and experience, such as physiological limitations of a general population and dynamics of closed ecological systems, require extensive basic research before space colonies can be established. Parallel engineering efforts are also needed to develop suitable techniques, processes, and materials for colonization of space. Pilot plants for extraction of materials, for fabrication in space, and for power production are necessary to provide design and operations experience. Finally, transportation systems, in particular the mass launcher and catcher, and the rotary pellet launcher which are necessary for transporting lunar ore to L5, must be developed early in the space colonization effort.

This chapter describes the projected preparations, operations, schedules, and costs to establish a permanent colony in space. While not optimized with respect to any criterion, they have been conservatively developed to demonstrate feasibility. The sequential activities needed for space colonization and the costs for such a program are summarized in figures 6-1 and 6-2.

Also included in this chapter is a discussion of the satellite solar power stations (SSPS's) as a potential economic justification for space colonization. If production of SSPS's were to become the central activity of space colonists, several modifications of the system logistics would be likely.

There are three sites for research, development, demonstration, testing and evaluation (RDDT&E): Earth, LEO, and the lunar surface. There is no activity at L5 during these activities because LEO provides a similar environment to L5 but at one quarter the cost. This is because materials must come from the Earth during this preparatory work and it would cost more to transport them to L5 than it does to LEO.

Activities on Earth

Systems not requiring zero-g can be developed in pilot plants on Earth. These include systems for materials extraction and fabrication, power generation, transportation, and habitation. Techniques for processing lunar soil into structural materials are especially critical for the colonization program since they differ significantly from those currently used on Earth (see chapter 4, appendices I and J). Those processes which require vacuum can be tested on a small scale on Earth. In addition, many of the large subsystems, while ultimately dependent upon the features of the locale in space, may be studied or partially developed on Earth. For example, a large facility or manufacturing plant may use lighter structures and different heat radiators in space; nevertheless, its internal processes can be studied in detail on Earth. These preliminary RDDT&E efforts are critical milestones for most major elements of space colonization.

Both nuclear and solar power sources of large scale must be developed, even though solar electric power is generally preferred since a specific plant mass of 14 t/MW is estimated for solar plants as compared to 45 t/MW for unshielded nuclear generators. Nuclear power is planned for the station in LEO and for the lunar base so that continuous power can be supplied during frequent or prolonged periods of being in shadow.

Two basic transportation systems must be developed; one to lift large and massive payloads, the other to transport lunar ore to L5. The first system includes a heavy lift launch vehicle (HLLV) capable of lifting 150 t to LEO; an interorbital transfer vehicle (IOTV) with a 300 t payload for missions from LEO to high orbits; e.g., to L2, L5, or to lunar parking orbit; and a lunar landing vehicle (LLV) with a 150 t payload capacity. These vehicles can be developed using the technology developed for the space shuttle. Development of the lunar mass accelerator, the mass catcher at L2, and the interlibration transfer vehicle (ILTV) is less certain but is still expected to use current technology.

Major research, as opposed to the above technological development, is required on physiological effects and ecological closure. The physiological effects that are amenable to research on Earth include long-term exposure to reduced total atmospheric pressure, to reduced pressures of certain gases, and effects of rotation on vestibular function. Research into questions of ecological closure is vital to the long-range colonization of space. The mix and quantity of flora and fauna needed to maintain closure or partial closure together with humans must be quantified. Moreover, research into intensive agricultural techniques is important in the colony's efforts to provide its own food. Particular attention must be directed to microbial ecology; the varieties, amounts, and interactions of bacteria and other microbes needed for healthy agriculture, animals, and people, are today imperfectly understood.

Activities at LEO

Pilot plants for materials extraction and fabrication, techniques for materials assembly, solar and nuclear power generation systems, the mass catcher, the ILTV and IOTV, and the habitats are all tested in LEO which provides vacuum and zero-g with relatively rapid access from Earth. Research on physiological effects of rotation and reduced gravity is conducted there also.