Proceedings of the Tenth SSI/Princeton Conference on Space Manufacturing
May 15-18, 1991
Published by American Institute of Aeronautics and Astronautics and Space Studies Institute
Princeton Conferences
I. SPACE POWER
The Equatorial Plane — The International Gateway to Space. William C. Brown, Microwave Power Transmission Systems.
Abstract: The physical laws of electromagnetic radiation and orbital mechanics are providing an opportunity to construct an all-electronic transportation system in space by combining microwave power beaming and the use of the Equatorial plane. Taking advantage of this opportunity is thwarted by the present policies of our space-faring nations and agencies to continue to rely upon current modes of space transportation and provincial containment of those modes within regional boundaries. Resolving this conflict between the laws of nature and geopolitics can be accomplished through a growing appreciation of the merits of beamed power and a growing awareness of the inadequacies of our present propulsion and transportation paradigms to explore and exploit space. An evolutionary scenario in which the space transportation system could be realized through the commcercialization of space is presented. In this scenario a power station is established in equatorial low-Earth orbit for commercial use. It is supplied with low cost power beamed to it from transmitters on the equator. Through a natural evolutionary procedure the power station becomes a mobile transfer station to pick up cargo in LEO and to transport it to higher orbits, including geosynchronous orbit. The mobile transfer station, or interorbital vehicle, could also serve as a routinely recoverable stage for cargo destined for the moon or Mars.
The Environmental Impact of S.P.S.: A Social View. Gay Canough and Larry Lehman, ExtraTerrestrial Materials, Inc.
Abstract: The time is coming to promote Solar Power Satellites (SPS) as one good alternative to fossil fuel burning. We strongly suspect that the impediments to the implementation of SPS will NOT be technical, they will be political and social. Today, every means of generating electricity is being attacked by somebody. Of course, many concerns about power generation are legitimate. Coal burning does pollute the air and promote acid rain and nuclear power does generate difficult to store wastes. People talk about “risks” of this or that. What they should be discussing is “risk-benefit”. No means of generating power (or doing anything else in life for that matter) is without some risk. The real question is, does the benefit of having electricity from a given source out-weigh the risk? For SPS, it is very important to make sure that the environmental issues and possible public concerns are explored as much as possible before SPS comes to the attention of the general public. To do this, we must first gather from the experts, information on what are the possible hazards, both real and perceived, for SPS. All concerns must be addressed. Experts must be unified on explanations of what is and is not a hazard, why it is or isn’t and what to do about real hazards. This paper will address issues such as the environmental impact of microwave beams proposed from SPS to Earth, the space debris hazard posed by and to SPS, and other environmental issues. We will explore, not only the purely technical aspects of this, but also, some “what-ifs” that people are so good at worrying about and some ways to successfully market the SPS idea. It is no longer enough for experts to simply say “trust us” there is no hazard.
The Space Information Matrix: Defining the Critical Path. Robert I. Summersgill and Carole Kingsbury, The Space Information Matrix Project Team.
Abstract: There is at this time no analytic framework to guide our progress toward the “High Frontier”. Without a consistent way to determine where any research effort falls on the “critical path”, or how it relates to other efforts, deciding on priorities and assigning resources are serious long-term problems. The “Space Information Matrix” is a custom-designed source of coordinated information which can be used to structure choices among research projects, and among support allocations. Another of its functions is to correlate relevant projects with fields of study, noting importance, status, timeliness, personnel, and more. This means of organization makes gaps in research and heretofore unappreciated lines of investigation apparent, thereby allowing volunteers working toward space development to select appropriate tasks. As more and more decisions about importance, etc., are made, the critical path itself is developed and evolves. The field of space solar power research is used as an example of how this system can highlight needed research projects, both large and small.
Advanced Solar Heat Receivers for Space Power. Charles A. Lurio, Aerodyne Research, Inc.
Abstract: Solar heat receivers have been a part of many proposals for electric power generation and manufacturing in space. The technology for power system receivers was the subject of significant development work during the 1960s and, in recent years, for application to the space station program. The more recent work has largely followed the older concepts; however, design innovations leading to reduced mass and volume and improved thermal efficiency were pursued in research performed for NASA at Lockheed Sanders, Inc., a firm which had had considerable experience in the development of terrestrial receivers. Critical technology experiments were developed for a Stirling engine system receiver using fluoride phase change material (PCM) for energy storage during eclipse periods in low Earth orbits. The containers were designed to control void locations to prevent damage by PCM expansion during melting; the design was tested in drop tower experiments. The entire receiver cavity was conceived as a ‘cavity heat pipe’, transporting energy by evaporation of liquid sodium from a wick sintered to a nickel alloy hemisphere located at the focal zone of the solar concentrator. Two wick/hemisphere assemblies were fabricated; use of a wax impregnation technique reduced screen crushing during forming. A 2000K furnace to simulate solar flux conditions on the dome was built and tested.
Applications and Design Issues for a Lunar Surface-Based Mobile Solar Concentrator. Michael Magoffin and Ken Stone, McDonnell Douglas Space Systems Company.
Abstract: The mobility, autonomy, versatility, and use of local resources such as sunlight and lunar materials make a remotely controlled rover equipped with a solar concentrator an attractive unit to enhance the construction of a lunar base. This unit can reduce Earth-based logistics support and also minimize required EVA time by operating remotely. Applications of such a unit range from regolith stabilization for lunar landing pads and roadways to solar welding for construction on the moon. To start developing the solar technology needed for such a mobile concentrator, McDonnell Douglas Space Systems Company, Aluminum Company of America, and the Space Studies Institute have jointly demonstrated the use of concentrated solar energy in processing lunar soil simulants using a 75-kW solar concentrator. Relevant data from this research will be presented in this paper. This paper describes some applications of a remotely operated mobile solar concentrator for the establishment of a lunar base, general design requirements, and a conceptual design of one possible solar concentrator system to be used on the lunar surface.
II: LUNAR BASES
Lunar Excavation — What We Need to Know. Russell J. Miller, Colorado School of Mines.
Abstract: The benefits of using nonterrestrial sources of bulk material and fuel for future missions have been well established. Accessing these resources from other bodies (planets, moons, asteroids or comets) in space requires the excavation and handling of materials before they can be processed into useful products. For bases or operations on planetary surfaces, site preparation will also require the excavation and handling of local material. Mining and excavation processes and equipment need to be defined early for accomplishing the required site preparation and resource recovery. For mining or construction on the Moon, we need to consider the physical properties or characteristics of the regolith and/or rock which will affect its excavatability and handling. This paper discusses the current state of knowledge on in situ lunar materials properties, how these properties will affect excavation for mining and construction, and identifies additional tests or missions required for optimum system definition.
Unit Operations in Lunar Mining. Richard E. Gertsch and Levent Ozdemir, Colorado School of Mines.
Abstract: Unit operations are the key to efficient terrestrial mining operations, and an excellent basis for a lunar mining research program. There are three basic unit operations in mining: fragmentation, excavation, and materials handling. Fragmentation breaks the in-situ material to excavatable size. Excavation moves the material to the materials handling system, which moves the material to the processing plant. Each unit operation is associated with specific mining machinery. Some equipment, such as front end loaders, work at one operation (excavation). Others, such as bucket wheel excavators, work at more than one operation (excavation and materials handling). Unit operations organizes and optimizes equipment selection and mine design. It matches the most economic mix of machinery to each unit operation. It accounts for the profound influence of the mining environment. Applying unit operations to the problems of building can provide an organized approach for selecting and designing the most economical lunar mine.
Factors Which Affect Heat Rejection System Design for Lunar Production Systems. Belinda Wong-Swanson, University of Arizona.
Abstract: This paper presents a radiation model of radiators on the surface of the moon. The driving factors on radiator area are the operating temperature and solar radiation. In addition five types of radiators are examined. Heat pipe radiators are currently the best type available due to its light mass, high reliability and wide operating temperature range. However liquid droplet radiators show tremendous potential because of its light mass, simple design and immunity to meteoroid puncture.
Attributes of a Lunar Communications Base. William A. Oran and Dennis E. Mateik, Bendix Field Engineering Corporation.
Abstract: The rationale for a lunar communications relay was established by analogy, based on previous and current studies of a Deep Space Relay Station (DSRS). Such a lunar relay/base would be best sited at a pole. Due to the parameters of the lunar orbit, a polar base would have to be somewhat dispersed to ensure simultaneous communications with the Earth and deep space missions. Based on photographs taken by the Lunar Orbiter, we have selected locations near the rim of crater Malapert and about 100 miles southwest of crater Amundsen as candidates for the principle elements required for a relay at the South Lunar Pole. The operation of several base configurations from an unmanned relay to a fully manned extraterrestrial control center were evaluated and it was noted, among other features, that the flexibility and usability of a base increases as the amount of manned interaction increases. This is not only due to the capability of maintaining, upgrading, and modifying systems, but also to synergistic features such as the capacity to use complex computer systems in deep space. Finally, we note that as the degree of manned involvement of the base increases, the opportunity to involve corporations from consumer industries also increases. This has the potential of not only reducing the overall cost to the government, but also increasing the competitiveness on Earth of U.S. made consumer products.
III: INTERNATIONAL CONSIDERATIONS
Mining Law for Outer Space. Wayne N. White Jr., University of California at Los Angeles.
Abstract: Existing international law allows public and private entities to appropriate minerals in outer space. At present, however, neither national or international laws specifically protect mining interests. The first section of this article describes the regime of international law which governs resource appropriation, including recent developments in the law of the sea and the law governing Antarctica. The second and third sections discuss the United States’ General Mining Law of 1872 (30 U.S.C. § 22 et seq.) and the S.S. Central America case (1989 A.M.C. 1955 (E.D. Va. 1989)), which allowed deep sea treasure hunters to perfect a claim by means of telepresence. In the final section of the paper, the aforementioned statute and case holding are analyzed as precedents for outer space. The author recommends mining laws which would clarify the legal status of miners prior to and during mining operations, as a means of encouraging mining investment.
From Flag Burnings to Bearing Arms to States Rights: Will the Bill of Rights Survive a Trip to the Moon? James E. Dunstan: Haley, Bader & Potts.
Abstract: The Bill of Rights, the first ten amendments to the U.S. Constitution, stands as the most important operative document of human rights and liberties ever created. On its 200th anniversary, it is appropriate not only to celebrate its durability but also to analyze its applicability into the next millennium and to The High Frontier. It should not be taken for granted that the Bill of Rights can be taken, in toto, to the Moon. The guiding precepts of individual rights and liberties may reguire significant adaptation to the harsh and near-immediately lethal environment of space. The purpose of this paper is to explore what changes in the Bill of Rights will be required to apply it to communities in space and on the Moon. Each of the first ten amendments will be analyzed, based on the language used in 1791, and on recent judicial interpretations of this language, to determine whether the present state of the Bill of Rights conflicts with immediate and intermediate needs of lunar “colonies.” The results are surprising and may be somewhat frightening to those who believe that a better and freer society can be established beyond the confines of the Earth. For although the Bill of Rights can be transported to the Moon, the balancing test between the rights of the individual and the interests of the state in keeping the colony alive will result in the limiting in degree of some rights we take for granted here on the Earth in the United States.
A Survey of Lunar Property Law. Yanai Z. Siegel, Rutgers Law School.
Abstract: A grant of title to an individual is the function of the state that claims sovereignty over the land. No state has claimed sovereignty over Earth’s Moon, and thus none may grant good title to any portion of it. There are five international law doctrines that allow sovereign states to acquire territory — conquest, cession, prescription, accretion and discovery – and two classes of land that are immune to sovereign claim: Res Communis (community property), and Res Nullius (“no-man’s land”), which are illustrated by Antarctica and the High Seas respectively. The five principal U.N. multilateral space treaties are reviewed with particular attention to the 1967 Outer Space Treaty and the 1979 Moon Treaty; treaty enforcement provisions severely limit states seeking to prosecute foreign nationals for perceived violations of international treaty provisions (e.g., lunar resource exploitation). An alternative basis for prosecution may be available using the “universal jurisdiction” doctrine on piracy, but only if the Moon is classified as Res Communis and lunar mining construed to constitute “depredation.” The 1967 Outer Space Treaty is characterized as a Res Nullius-style agreement; the 1979 Moon Treaty is characterized as Res Communis. Very few states have ratified the Moon Treaty, however.
The Law of Space Resources: Exploiting the Final Frontier. Matthew A. Bille, University of North Dakota.
Abstract: In 1979, the United Nations devised a legal regime to govern exploitation of natural resources on the moon and other celestial bodies. The result was the pact commonly called the Moon Treaty. It has been ratified by only 13 nations, none of them major space powers. Thus, lunar mining today would take place in a legal as well as a physical vacuum. Any long-term space manufacturing plan will involve developing lunar resources. We cannot allow that development to be governed by anarchy, or, worse, by force. A legal regime governing lunar mining is in the interests of the United States. The choice for U.S. policymakers is whether to ratify the Moon Treaty or negotiate a new pact. American reluctance to accept the Moon Treaty is based on worst-case interpretations. A review of the Moon Treaty’s language, its alleged precedents, and the negotiating history of the Treaty shows those interpretations are unfounded. With the addition of an understanding explaining the American view of the disputed clauses, ratification of the Moon Treaty would be America’s best course of action.
IV: SPACE TRANSPORTATION AND SPACE EXPLORATION INITIATIVE
Cost-Effectiveness of Lunar Oxygen and Lunar Hydrogen in Future Space Transportation. Larry Redd, Martin Marietta Astronautics Group.
Abstract: The value of lunar produced propellants in an oxygen/hydrogen earth-moon transportation is presented in this paper. A figure of merit is established that expresses the cost that lunar propellant production should not exceed if these propellants are to compete with performing missions to the moon with all-earth propellants. The conclusions of this study are 1) lunar oxygen should be used for the return from the moon and for lunar landers, 2) less than 20 to 30% of the oxygen needs in low earth orbit for trips to the moon should be hauled back from the moon, and 3) lunar hydrogen, which requires processing of enormous amounts of lunar soil, does not appear to add significant benefits to the transportation system.
Induced Gravity Mars Transportation Systems: Configuration and Hardware Penalties. Stephen Capps, Robert Fowler, and Matthew Appleby, The Boeing Company.
b>Abstract: The need for an induced gravity environment in-transit to Mars is assessed based on current knowledge. Two possible alternatives to constant in-transit spinning, periodic spinning and Mars surface reconditioning are discussed and compared. Four propulsion options: cryogenic/aerobraking, solid core nuclear thermal, solar electric and nuclear electric are evaluated for concept adaptability to induced gravity, and salient differences from their micro-gravity counterparts are assessed. Configurations to the systems level are presented and accompanied by mass estimates. Hardware subsystems required for induced gravity vehicles, such as tether crawlers, tether reels, high-power roll-ring assemblies, etc. have been defined to a sufficient level of detail to confidently determine mass penalties. Results of this study show the mass penalties and complexity involved in producing an induced gravity environment.
Toward a Global Lunar Resource Survey: The Lunar Observer Mission. Rex W. Ridenoure, Jet Propulsion Laboratory.
Abstract: The present status of NASA’s Lunar Observer study effort at JPL is discussed in the context of an ongoing 20-year series of studies focused on defining a robotic, low-altitude, polar-orbiting mission to the Moon. The primary emphasis of the discussion is a review of the various systems-level factors that drive the overall mission plan. Selected top-level project and science requirements are summarized and the current mission and science objectives are presented. A brief description of the candidate science instrument complement is included. Several significant orbital effects caused by the lunar gravity field are explained and the variety of trajectory and maneuver options considered for both getting to the Moon and orbiting there are described. The baseline mission scenario that results is a single-spacecraft, single-launch scenario which includes a small subsatellite for lunar gravity field determination.
Lunar Resource Processing Using Solar Energy — A Research Project Status Report. John Garvey and Michael Magoffin, McDonnell Douglas Space Systems Company.
Abstract: Many candidate processes for utilizing lunar resources will require significant quantities of thermal energy. Concentrated solar energy is one potential source for such thermal inputs, particularly for surface operations that are of short duration and/or require a degree of mobility not available from centrally located nuclear systems. Because of the attractiveness of this energy option, McDonnell Douglas, the Space Studies Institute, and Alcoa Research Laboratories are conducting a joint research project to develop solar energy technology for lunar resource processing. In addition, McDonnell Douglas is also working with the Shimizu Corporation in the specific field of rock breaking. A key asset for this effort is a 75-kW thermal solar concentrator that McDonnell Douglas developed during a previous terrestrial energy program. This paper reports on the progress of this research in the areas of melting lunar simulant, postmelt processing, rock breaking and welding, and also identifies engineering issues that require attention in future research.
Material Processing with Hydrogen and Carbon Monoxide on Mars. Aloysius F. Hepp, Geoffrey A. Landis, and Diane L. Linne, NASA Lewis Research Center.
Abstract: This study examines several novel proposals for propellant production from carbon dioxide and monoxide and hydrogen. We also examine potential uses of CO as a fuel or as a reducing agent in metal oxide processing as obtained or further reduced to carbon. Hydrogen can be reacted with CO to produce a wide variety of hydrocarbons, alcohols, and other organic compounds. Methanol, produced by Fischer-Tropsch chemistry may be useful as a fuel; it is easy to store and handle because it is a liquid at Mars temperatures. The reduction of C02 to hydrocarbons such as methane or acetylene can be accomplished with hydrogen. Carbon monoxide and hydrogen require cryogenic temperatures for storage as liquids. Non-cryogenic storage of hydrogen may be accomplished using hydrocarbons, inorganic hydrides, or metal hydrides. Non-cryogenic storage of CO may be accomplished in the form of iron carbonyl (Fe(CO)5) or other metal carbonyls. Low hydrogen-content fuels such as acetylene (C2H2) may be effective propellants with low requirement for earth-derived resources. The impact on manned Mars missions of alternative propellant production and utilization is discussed.
Extending the Operational Altitude of Solar Sails Down to Space Station Altitudes with an Electrodynamic Tether. Richard Moss and Manuel Martinez-Sanchez, Massachusetts Institute of Technology.
Abstract: A systems study is presented of a propulsion system which uses an electrodynamic tether integrated into the structure of a solar sail vehicle. These propulsion systems are complementary to one another in that each functions well at spaceflight altitudes where the other can not. Such a mixed propulsion system would produce a spacecraft capable of flight from space station altitudes (= 450 km) to a deep space destination and return without the use of fuel. Three configurations of a solar sail-electrodynamic vehicle were studied. These configurations included both the square solar sail and heligyro, as well as both fixed and deployable electrodynamic tethers. It was found that decay times from low Earth orbit for solar sail vehicles depended on the mass to surface area ratio of the vehicle and, in general, were short. A drag to thrust ratio of .38 would be required for the vehicle not to lose orbital altitude during the orbit raising process when operating without batteries. An expression for the maximum thrust that a deployable electrodynamic tether can produce was developed. Orbital debris was shown to be a major concern, particularly for vehicle configurations using a deployable tether. The addition of a solar powered electrodynamic tether reduced the characteristic acceleration of the solar sail vehicle by a average of 38%. The further addition of batteries to permit operation in the planetary shadow reduced the characteristic acceleration an average of another 45%. Useful space missions, particularly for shuttling between the space station and a deep space destination, could be performed by a vehicle propelled by a mixed solar sail-electrodynamic tether propulsion system.
V: BIOMEDICAL CONSIDERATIONS
The Architecture of Artificial Gravity: Mathematical Musings on Designing for Life and Motion in a Centripetally Accelerated Environment. Theodore W. Hall, University of Michigan.
Abstract: Habitats support life; life demands motion. This paper uses mathematical derivations and computer simulations to examine environmental design for life and motion in artificial gravity. Although artificial gravity appears increasingly natural as the radius of rotation approaches infinity, it remains significantly unnatural at a kilometer radius. Environmental design may help the inhabitants to adapt by specifically responding to the unearthliness of the gravity. I propose that appropriate architectural forms should be derived not only from static geometric constraints, but also from the apparent dynamic behavior of hanging, falling, and moving objects, particularly with regard to concepts of verticality, horizontality, and modularity. This study reveals involute and catenary curves. If properly incorporated into the architecture, these curves may provide visual and tactile cues to aid the inhabitants in comprehending and adapting to their distorted gravity environment.
Surgery in Space: Surgical Principles in a Neutral Bouyancy Environment. Richard M. Satava, United States Army.
Abstract: The venturing forth of man into space confronts a surgeon with a new weightless environment. Operative procedures were performed on twenty rats in a simulated space environment using neutral buoyancy to identify those factors which could actually or potentially affect operative technique. There are three general areas of difference in simulated microgravity: Physical adaptation to gravity deprivation; tissue behavior, including bleeding; and the conduct of surgery. Without gravity, the tactile “feel” of objects is changed (“heavy” and “light” are meaningless terms) and proprioception is confused such that there is past pointing and over reaching of movements. Tissue planes tend to separate, and organs float and bob in the operative field making clamping, cutting and suturing different. Bleeding is a major consideration; surface tension tends to keep venous bleeding oozing along surfaces, while pulsatile arterial bleeding forms droplets, streamers and clouds depending upon the force of the bleeding. These factors and others interfere with surgical technique by obscuring vision with dispersion of blood, entanglement of sutures, lack of stabilization of organs, and floating of instruments into the operative field. The limitations of comparing neutral buoyancy to the true zero gravity of space are addressed. Further investigation for new surgical techniques in clinical surgery in space is needed.
A Conceptual Design for a Modular, High-Volume, Artificial-Gravity Crew Compartment in a Manned Mars Spacecraft. Howard Kleinberg, Spar Aerospace, Ltd.
Abstract: In this paper, a concept is proposed, which deals mainly with the crew compartment for the manned mission to Mars. Other assumptions regarding the configuration of the rest of the MHS are stated, in order to accommodate those of the Life-Section (LS), as appropriate. This concept satisfies certain requirements, some of which are assumed at this date. Among these requirements are large internal volume, artificial-gravity spin capability, crew protection from space radiation, and volume enough to carry and operate a closed ecological life support system (CELSS) to support the crew during a journey to and from Mars that may take as long as a year or more. This design will provide a large internal volume, while still being modular enough to be assembled in low Earth orbit. It will house the crew’s living and working quarters, the CELSS, and the interface between the LS and the rest of the spacecraft.
Extraterrestrial Intelligence? The Search Is On. Gary R. Coulter, NASA Headquarters
Abstract: On October 12, 1992, as the world celebrates the International Space Year and commemorates Columbus’ arrival in the New World, a significant step forward will be taken to answer the age old question “Are we alone in the universe?” On this date the NASA Search for Extraterrestrial Intelligence-Microwave Observing Project will initiate a search of the celestial sphere with special emphasis on the closest “solar-type” stars for radio signal eminating from extraterrestrial civilizations. When completed, in the year 2000, the NASA search will surpass the search volume all previous searched by a factor of 1010. The search will utilize the world’s largest radio astronomy telescopes as well as the space communications antennas of the NASA Deep Space Network (DSN). Led by the NASA Ames Research Center (ARC), the project will be implemented by scientists and engineers at ARC, the Jet Propulsion Laboratory (JPL) and selected investigators from the scientific community. After years of study, planning, review, software and hardware development and near misses with disaster, on Columbus Day, 1992, we will be able to say, “The search is on.”
VI: EXTERNAL TANKS AND SPACE STRUCTURES
Supporting the Infrastructure Requirements of a Spacefaring Civilization: An Overview of Possible Roles for the Space Shuttle’s External Fuel Tank in Future Space Infrastructure. Ronald D. Jones, Phillips Petroleum Company.
Abstract: Lunar outposts, solar power satellites, and human exploration of Mars are feasible goals for the dawn of the 21st century. However, these goals are unlikely to be realized without the development of something heretofore unknown in space exploration: the creation of a diverse collection of supporting infrastructure in low earth orbit (LEO). Such infrastructure will likely include manned and man tended laboratories, fuel storage depots, and orbiting hangers where large spacecraft can be assembled and refurbished. This paper examines potential roles the space shuttle’s discarded external fuel tanks might play in the creation of these “islands above the sky.”
Aluminum Salvage Station For External Tanks (ASSET). Curtis H. Spenny, James N. Haislip, Robert E. Linscott, William Raynes, Michael Skinner, and David VanMatre, Air Force Institute of Technology.
Abstract: The purpose of this study is to determine whether the External Tanks of the Space Transportation System, when carried into low earth orbit, can be reduced economically to a form of readily usable construction material. A scenario is assumed in which the first tank is partially dismantled and then becomes the facility for dismantling additional tanks, storing product and constructing space structures. A set of tools is identified to autonomously accomplish the tasks of cutting, transport of crude stock, removal of spray-on foam insulation, and product storage. Astronaut setup and takedown of tools is required for each tank reduction. Power requirements are determined for the reduction task and an electrical power system is specified. An orbit model projects the annual facility fuel requirements, predicts the orbital decay of the facility, and estimates the orbital decay rates of any debris which may escape during the salvage operation. Life cycle costs are projected based upon reducing four tanks per year. It is shown that more than 52,000 pounds of structural aluminum, primarily in the form of I-beams and strip, can be salvaged annually in a manner that is cost competitive when compared to equivalent products delivered as orbiter payload. The reduction concept is specific to the External Tank. However, any launch system with comparable thrust to payload ratios will in general have expendable structural material taken nearly to orbit.
Commercial Platforms from the External Tank. Thomas C. Taylor, William A. Good, David Nixon, and Art Overman, Global Outpost, Inc., and Michael Simon, Man Technologie.
Abstract: GLOBAL OUTPOST, Inc. proposes the development of resources available from an external tank of the space shuttle placed in low earth orbit with NASA cooperation. The tank is unique in many ways. Two are discussed in the paper. First, the external tank is a source of base metal for the beginnings of several new industries in orbit. One industry is the large scale materials processing without containers using the attributes of space. Second, is the development and use of the interior pressure vessel capability of the external tank combined with microgravity. Neither new industry is an adaption of earth based process, but research leading to new industries not possible on earth. To support the utilization of the resources of the ET, a cost effective method for the recovery of the tank must be developed and implemented. The tank is salvaged with a privately financed subsystem package or kit placed on the tank by NASA in orbit. GLOBAL OUTPOST, Inc. has isolated 68 different commercial services capable of being offered from a relatively simple commercial service platform using the external tank as a strongback. Some of the services offered can be helpful to researchers and later industrialists in developing the resources of the tank. The external tank derived platform is an outpost in the emerging global space commercialization industry. The platform proposed is a minimum cost, man visited facility aimed at attracting commercial ventures seeking a cost effective access to the resources of the space shuttle external tank.
Space Base I: Building a Large Space Station Using External Tank Technologies. James M. Snead, Beavercreek, OH.
Abstract: This paper proposes a unique, near-term, moderate-cost approach for building a large, multi-use space station in low Earth orbit through the utilization of Space Shuttle External Tank technologies. This large space station, called Space Base 1, is designed for crew sizes starting at 25 with provisions for expansion to about 170. It has sizeable research laboratories, variable gravity processing and training facilities (simultaneously from zero to Mars g-levels), recreational and physical fitness facilities, individual crew quarters, agricultural facilities, and a partially-closed life support system. Space Base 1 is constructed from specially fabricated versions of the External Tank which are launched into orbit via an unmanned version of the Space Shuttle transportation system similar to NASA’s proposed Shuttle C. By using this approach, only eight launches of this unmanned system are required to place the station’s modules and equipment into orbit for an initial crew size of 25. Four regular manned Shuttle missions are required to transport the construction crews and initial operating crew to the station. Space Base 1 would be suitable as the low Earth orbit development, training, and logistics base to support the proposed Space Exploration Initiative’s manned Lunar and Mars exploration programs. Its large physical size with facilities for a large crew make it suitable to support a robust program of exploration and the expansion of manned activities in Earth orbit.
Selected On-Orbit Applications for Large Rocket Propellant Tanks. David L. Christensen, Wyle Laboratories.
Abstract: Described are several on-orbit applications for large rocket propellant tanks after they have fulfilled their primary function. Included are several examples for potential use of large tanks as used by the space shuttle and recommendations for implementing broader use in space of large propellant tanks in the future. Current plans to modify and use the space shuttle external tank as a key element of the new National Launch System are also discussed, and a proposal is made for incorporating certain “orbital utilization” features into the core element during the redesign phase.
VII: ADVANCED CONCEPTS
Advanced Communications Technology Satellite (ACTS). Mark S. Plecity, NASA Lewis Research Center, and Mark E. Nail, NASA Headquarters.
Abstract: The NASA Advanced Communications Technology Satellite (ACTS) provides high risk technologies having the potential to dramatically enhance the capabilities of the satellite communications industry. This experimental satellite, which will be launched by NASA in 1993, will furnish the technology necessary for providing a range of services. Utilizing the ACTS very high gain hopping spot beam antennas with on-board routing and processing, Very Small Aperture Terminal (VSAT) digital networks which provide on-demand, full mesh connectivity, 1.544 MBPS services with only a single hop can be established. The high gain spot beam antenna at Ka-band permits wide area, flexible networks providing high data rate services between modest-size earth terminals. This service is being considered in the U.S. for such applications as interconnecting supercomputers. This paper provides an overview of ACTS and discusses the value of its technology for these communication applications as well as others.
Helium-3 Mining of Uranus. Dani Eder, Boeing Aerospace and Defense Group.
Abstract: Extraction of He3 from the Moon has been proposed. The Moon is a very poor grade of ore (parts per billion) for this material. Examination of other potential sources in the Solar System reveals Uranus as a potential site with higher grade ore. Two mining concepts, orbital scoop mining and in-situ extraction, are compared, and the latter selected on the basis of He3 returned per Earth initial mass in orbit invested. Obtaining He3 from Uranus should be considered the baseline approach rather than getting it from the Moon.
A General Approach to Interstellar Flight. Erik T. Paterson, University of British Columbia.
Abstract: There have been many proposed schemes for achieving human interstellar flight, all suffering from defects such as 1) inappropriate objectives, 2) lack of economic justification, and 3) an overfocus on purely technical considerations (including extreme byways in advanced Physics), ignoring the human factors. This paper explores a scenario involving a simpler approach, based upon the presupposition that no planetary civilization can mount an interstellar venture. The Space community is very familiar with the features of the Space colonies/settlements proposed by O’Neill and his associates. A low enough acceleration applied to any such colony for long enough can allow it to be moved from any point in the Solar System to any other, provided enough raw materials are carried for the duration of the flight, and the initial population is low enough to prevent unacceptable population density by the time of the arrival at the destination. During such a flight the great majority of the people aboard would not experience much difference from their lives before the start of the flight. Having gained experience with such flights within the Solar System, a civilization consisting of such mobile colonies will find little difference for flights beyond the Solar System, merely requiring a greater initial reserve of raw materials and a relatively lower initial population. This has implications for 1) the Fermi Paradox, and 2) the U.F.O. problem.
The Aresian Well: Piping Martian Volatiles to the Inner Solar System. Alastair J. W. Mayer, Space Pioneers
Abstract: This paper discusses the exportation of Martian polar cap volatiles (primarily water, but including other compounds of H, C, O and N) by means of a pipeline from the icecap to the equator, and thence up a “beanstalk” or orbital tower extending beyond Mars-synchronous orbit, where they are released at Mars escape velocity. Such a beanstalk could be fabricated, for Mars, of graphite fiber with a low 1.1:1 taper. Cost of such Martian volatiles in near-Earth space would be less than that of launching them from Earth.
Application of Expert System Modeling to Space-Based Construction and Manufacturing. Steve D. Jolly, University of Colorado.
Abstract: This paper explores an issue of vital interest to any endeavor involving the assembly or construction of hardware in space, including manufacturing. The issue is the assessment of constructability, specifically involving the creation and measurement of preferred assembly sequences in a Computer Aided Design computing environment on Phase A space designs. A preliminary theoretical mathematical model is developed to try and explain the human planner’s expert behavior, while simultaneously driving the consideration, selection and development of a knowledge-based, domain-dependent prototype Expert System. The possible assistance of Operations Research algorithms and Fuzzy Reasoning expert systems are briefly discussed in the context of model development. The majority of the following is based on preliminary findings from the author’s dissertation, unpublished and currently in work at the University of Colorado.
A.R.C.: Asteroid Resource Colony: An Inhabited Mining Colony Design Concept. Claudio Veliz, Architect.
Abstract: The methods by which human beings colonize the balance of the solar system is open to wide speculation. This is just one exercise in the field of options. A team of New York architects and engineers took first place with their submission of a design to inhabit an asteroid. Sponsored by the National Space Society, the competition was held in 1989. The design concept is inspired by the precedent of American Indian hunting economies: making full use of the available resources. In the scheme, an automatic mining complex attaches to an asteroid and, while mining its interior, uses the extracted material to manufacture building materials in turn used to assemble the rest of the habitat elements. The unused portions of the mined material is propelled back to low earth orbit, via mass driver, for commercial trade.
VIII: SPACE BIOSPHERES
Bioregenerative Technologies for Waste Processing and Resource Recovery in Advanced Space Life Support Systems. Dennis Chamberland, NASA Kennedy Space Center.
Abstract: The development of a bioregenerative advanced space life support system, often described as a Controlled Ecological Life Support System (CELSS), will require the development of highly controlled biological systems for production of water, oxygen and food. “Wastes” will be processed and returned as resources to the system. Such a developmental scheme will demand that these biologically based engineering systems be interactive to other physical and biological systems and that they be minimally buffered, and continuously and highly controlled. In investigating the spectrum of available conventional bioregenerative technologies, aerobic and anaerobic bioreactors are considered. The use of activated sludge reactors for biomass conversion show promise of reduction and conversion of inedible plant solids as well as other soluble wastes into a suitable biomass for possible use in feeding fish in an aquaculture system. Similarly, a thermophilic anaerobic reactor, such as a fluidized bed, immobilized cell reactor, may be useful for the relatively fast biological conversion of plant solids into soluble products and ultimately into useful resources ranging from carbon dioxide to methane. These systems must be engineered to optimize the conditions necessary to encourage the biological conversion processes desired and achieve rapid recovery of resources from states traditionally thought of as unusable wastes. Such processes will have important spin off potentials for use on earth.
The Design and Visualization of a Space Biosphere. Al Globus, Computer Sciences Corporation.
Abstract: Lewis One is a qualitative space biosphere design. It is intended to house 10,000 residents in a cylinder large enough for a 1g rotating habitat module and construction facilities to reproduce the module. The shielding, exterior, and construction bays are non-rotating. Lewis One is compared to the Bernal Sphere space colony designed in the 1970s. Lewis One is visualized using state of the art computer graphics hardware and software to produce a three dimensional, animated, lighted, shaded, texture mapped surface model. One may interactively ‘fly’ outside and inside the structure to examine features of interest. Interactively controlled planar cutaways at any location and/or orientation are available. Visualization provides insight into, and feedback on, the design to drive improvements and communicate design concepts.
Progress Report on the Biosphere 2 Project. Mark Nelson, Space Biospheres Ventures.
Abstract: The Biosphere 2 Project has focussed on the development of technologies and integrated testbeds for bioregenerative life support systems. Individual technologies have included soil bed reactors for air purification, aquatic plant/microbial systems for recycling wastewater nutrients and sustainable agricultural systems for supplying complete human nutritional needs in closed ecological systems. In addition, unique analytic laboratory and computer systems for automation/data collection and analysis have been developed for the project. The 480 cubic meter Biosphere 2 Test Module has permitted evaluation during four years of operation of individual subsystems as well as “all up systems testing” for the first totally bioregenerative life support experiments involving humans. Construction has been completed for the 3.15 acre, 7 million cubic foot Biosphere 2 facility. Biosphere 2 will be a pioneering experiment in the long-term sustainability of complex bioregenerative systems, including technical and life systems with a crew of eight people. For the first time, such a facility will include a diversity of internal ecosystems (rainforest, savannah, desert, marsh, ocean and agriculture) making it a valuable laboratory for studies pertinent to global ecology as well as a ground-based testbed for those needed for space habitation.
Biological Life Support System for Mars Mission. Josef Gitelson, Institute of Biospherics, USSR Academy of Sciences.
Abstract: Out of the life elements necessary for a biological life support system, a very favorable starting selection are the hydrogenous bacteria. They can synthesize biomass, assimilating CO2 and hydrogen and release all of the energy of oxidation of hydrogen to water. The volume of culture to ensure the life support of man and to utilize his natural excretions in continuous cultivation may be less than twenty meters. The power of electrical energy expended on this one-man basis is 0.62 for water electrolysis and involves 0.2 kilowatts for technical needs. In total then about one kilowatt per man. The equipment and technology of cultivating hydrogenous bacteria culture is detailed in the work in our institute.
IX: NONTERRESTRIAL RESOURCES
Hydrogen Reduction of Lunar Simulants for the Production of Oxygen in a Continuous Fluid-Bed Reactor. Robert O. Ness, Laura L. Sharp, and Brian D. Runge, University of North Dakota, and Christian W. Knudsen and Michael A. Gibson, Carbotek, Inc.
Abstract: As humankind moves toward the settlements of the twenty-first century, more resources and basic raw materials are needed for the development of self-sufficient bases on the Moon and Mars. One of the most important factors in the development of cost-effective and autonomous life support and transportation systems is the production of oxygen from indigenous materials. Carbotek, Inc., of Houston, Texas, has been developing a process that reduces ilmenite via the following reactions: (1) FeTiO3 + H2 —> Fe + TiO2 + H2O; (2) H2O + electricity —> H2 + O. Detailed kinetic work has been accomplished using lunar simulants and is currently being conducted on lunar soil samples in a differential fixed-bed flow reactor by Carbotek. The simulant results have previously been reported. The next step was to evaluate several critical elements and the bubble formation in the bed under 1/6 g for the purpose of scaleup. This was done in February 1989 on NASA’s KC-135 research aircraft. Currently, the University of North Dakota Energy and Environmental Research Center (UNDEERC) and Carbotek are conducting tests in a 1-lb/hr continuous fluidized-bed reactor system and a batch system. These tests will verify fluidized solids behavior during reaction using lunar simulant. Batch tests will be conducted on MLS-1 provided by the University of Minnesota. Continuous tests will then be conducted at the 1-lb/hr scale. Temperatures will be investigated between 900° and 1,000°C at several residence times. An on-line mass spectrometer will be used to determine moisture concentrations in the product gas stream. Further analysis will include SEM-PC for elemental mapping and determining pore structure and the temperature effect on sintering. A Mossbauer analysis will be done to determine the iron forms. Also, small amounts of sulfur and H2S will be added to determine if a hydrogen recycle stream will cause a buildup of H2S, or if the sulfur will be tied up with the iron in the rutile by-product.
Lunar Oxygen Production by Pyrolysis of Regolith. Constance L. Senior, Physical Sciences, Inc.
Abstract: Oxygen represents one of the most desirable products of lunar mining and manufacturing. Among the many processes which have been proposed for oxygen production, pyrolysis stands out as one which is uncomplicated and easy to bootstrap. Pyrolysis or vapor-phase reduction involves heating regolith to temperatures sufficient to allow partial decomposition and vaporization. Some metal oxides give up oxygen upon heating, either in the gas phase to form reduced gaseous species or in the condensed phase to form a metallic phase. Metal-containing species in the gas phase can be collected by condensation and thus separated from oxygen. Based on preliminary experiments and equilibrium calculations, the temperatures needed for pyrolysis are expected to be in the range of 2000 to 2200 K, giving total gas pressures of .0001 to 0.1 torr. Bulk regolith can be used as a feedstock without beneficiation with concentrated solar radiation supplying most of energy needed. Further, selective condensation of metal-containing species from the gas phase may yield metallic iron and silicon as byproducts from the process.
Lunar Production of Oxygen by Electrolysis. Rudolf Keller, EMEC Consultants.
Abstract: Two approaches to prepare oxygen from lunar resources by direct electrolysis are discussed. Silicates can be melted or dissolved in a fused salt and electrolyzed, with oxygen evolved at the anode. Direct melting and electrolysis Is potentially a very simple process, but high temperatures of 1400 – 1500 °C are required, which aggravates materials problems. Operating temperatures can be lowered to about 1000 °C by employing a molten salt flux. In this case, however, losses of electrolyte components must be avoided. Experimentation on both approaches is progressing.
Design of an Automated Process Control System for Lunar Oxygen Production. Brian D. Runge and Tom Stokke, University of North Dakota.
Abstract: As industry begins to utilize the resources and special operating conditions available in space, the need for automated process control and data acquisition systems will become critical. In recent years, there has been significant growth in the field of PC-based process control systems. While PC-based systems may not be selected as the final control system in a full-scale plant, their extreme flexibility and programming power do offer excellent opportunities for simulating and testing the control schemes that will be needed. It also seems natural that such systems be utilized in pilot-scale testing of space- or moon-based processing plants, in part due to their small size and weight, but more importantly for the ease with which they can be modified to correct for changing system parameters often encountered in the early testing of any new process. This paper presents a working design for the control system of a lunar oxygen plant. This design is similar in scale and function to a process control scheme currently used in the control of an operational coal gasification pilot plant. A similar automated control system is also employed by a bench-scale hydrogen reduction of ilmenite for oxygen production system presented at this conference by Robert Ness in another paper.
Glass-Ceramics from Lunar Resources. B. D. Fabes and W. H. Poisl, University of Arizona.
Abstract: Homogeneous glasses were formed by melting and quenching simulated ilmenite-extracted lunar regolith. The viscosities and crystallization behavior of the glasses were investigated to identify optimal compositions and processing temperatures for fabricating glass-ceramics. The glasses were subsequently crystallized by heating in air. With moderate control of the crystallization process, pore-free, homogeneous, polycrystalline ceramics with a thin residual glass phase surrounding each grain were made. This glass-ceramic material had a much higher tensile strength (215 MPa) than the uncrystallized parent glass (125 MPa).
Identifying the Challenges of a Lunar Materials Processing Plant. Barbara Altenberg and H. A. Franklin, Bechtel Group, Inc.
Abstract: For frequent travel to and from the Moon, manufacture of liquid oxygen propellant on the lunar surface has been identified as a big “pay-back” technology. Production of other products from resources available on the Moon will also be valuable. The art of bringing together manufacturing with research, design, and development for application on the lunar surface is a chemical process engineering challenge. Given the extremes of the lunar environment, ideas for the structure and siting of a lunar pilot plant designed to manufacture useful products from lunar resources are presented and the unique challenges associated with designing operating plants based on three processes are described.
Propellant Manufacturing on Mars: Issues and Implications. Malcolm A. LeCompte, Aerodyne Research, Inc., and Julie P. Stets, Bull Information Systems.
Abstract: The benefits to be derived from manufacturing chemical rocket propellants from native resources on the Martian surface are so great that it will almost certainly be a component of any future manned Mars exploration program. The types of chemical propellants possible for manufacture are suggested by the location, abundance and state of the Martian volatile inventory. Carbon Monoxide and Oxygen, obtained and produced from atmospheric carbon dioxide, may be the most accessible bi-propellant, but is lowest in energy. Methane and Oxygen and cryogenic-Hydrogen and Oxygen require either finding large amounts of Martian water, or importing hydrogen. However, they offer operational advantages that may militate for their early introduction in a Mars exploration program. The occurence of volatiles and their accessibility on or near the Martian surface will be discussed with regard to their exploitation for propellant manufacture. The possibility of manufacturing four different types of propellant will be introduced. The immediate advantages of each option, and its impact for longer term programs will be compared. The prospects for, and benefits to be derived from, an evolutionary program of propellant manufacture will be discussed. An optimal scheme for a variety of manned Mars programs, as suggested by the propellant options, will be proposed, including sprint, long-duration exploration, and settlement. Neural network based analysis techniques are being investigated as a means to perform simulations for evaluating long term strategies and cost/benefit studies among the programs suggested.
POSTER SESSION
Magnetic Radiation Shielding: An Idea Whose Time Has Returned? Geoffrey A. Landis, Sverdrup Technology, Inc.
Abstract: One solution to the problem of shielding crew from particulate radiation in space is to use active electromagnetic shielding. Practical types of shield include the magnetic shield, in which a strong magnetic field diverts charged particles from the crew region, and the magnetic/electrostatic plasma shield, in which an electrostatic field shields the crew from positively charged particles, while a magnetic field confines electrons from the space plasma to provide charge neutrality. Advances in technology include high-strength composite materials, high temperature superconductors, numerical computational solutions to particle transport in electromagnetic fields, and a technology base for construction and operation of large superconducting magnets. These advances make electromagnetic shielding a practical alternative for near-term future missions.
Tether Methods for Reactionless Orbital Propulsion. Geoffrey A. Landis, Sverdrup Technology, Inc.
Abstract: In space, limits on transportation effectiveness are set by requirements for reaction mass, since reaction mass must be carried on board and often comprises the majority of the launch mass of a space system. Thus, applications where a tether can be used for propulsion with no requirement of reaction mass are extremely attractive for space development. It is a remarkable fact that tethers can be used to increase orbital energy with no requirement for reaction mass.
Impact of Agricultural Mass Flow Fluctuations on the Lunar Base Environment. Nickolaus Leggett and Judith Fielder, Reston, VA.
Abstract: Operating a lunar base agricultural system is a complex activity with many factors to take into consideration. One serious factor that must be considered is the mass flow fluctuations engendered by the cultivation, harvest, and crop waste recycling of various types of food crops. It appears that in the interests of reducing mass flow fluctuations through the agricultural system, it would be preferable to cultivate primarily short term continuous or long term continuous crops. Initial lunar base agricultural systems should substitute potatoes in lieu of surge crops both for ease of technological operation and for the reduced impact this crop type has on the lunar base environment.
A Possible Path of Evolution of a Concept for an Automated Multipurpose Materials Extraction Facility. Howard O. Kleinberg, Spar Aerospace, Ltd.
Abstract: Long-term habitation of space will eventually require use of off-Earth resources to reduce long-term program costs and risks to personnel and equipment due to launch from Earth. Extraction of oxygen from Lunar soil is a prime example. This paper presents the results of an examination by Spar Aerospace of a plasma-separation concept as part of a materials extraction facility that might be used in space. Such a process has the far-reaching potential for extracting any or all of the elements available in soil samples, extraction of oxygen from lunar soil being the near-term application. This paper also examines the range of uses of each generation of plasma-processing technology for both terrestrial as well as extra-terrestrial applications, as the technology evolves. The following topics are discussed: automated soil-gathering using robotics; automated soil pre-processing; plasma dissociation and separation of soil, and collection of sorted elements in an automated process; containment of gases, storage of pure elements, metals; automated shipment of materials to manned base, or pick-up site; the projected ‘generations’ of plasma-processors, and their applications to activities both on earth and in space.
Renewing Lunar Hydrogen with Polar Power Rings. Graham S. Galloway, Spiral Survey Expedition, Thunder Bay, Ontario
Abstract: Lunar Ice and its contained Hydrogen are sought to supplement lunar development. The discovery of Polar Ice would identify a valuable finite resource. Plans to adapt to eventual ice resource depletion can be accelerated in the event ice is not discovered. A glance at the factors proposed in Ice accumulation point towards the development of a small renewable resource, with the density of hydrogen in solar wind as the rate limiting factor. Since much solar wind is in the form of ions is it possible to influence solar wind to a useful extent by the application of Magnetic and electrical fields, perhaps to enhance both the density of solar wind on the lunar surface and direct the wind to ion collection plates by deflecting the ions away from areas where solar wind is a waste or undesirable (a partial radiation shield) using Bussard ram scoops or Matloff/Fennelly Electromagnetic Ion Scoops on the lunar surface, or producing an adjustable Lunar Magnetosphere. The collection and conversion of Solar energy to electrical energy is suggested as a tool to modify the Solar wind to our advantage. The solar power collection system is a pair of Rings, one at each pole, at North and South latitudes of 70 to 85 degrees, as a circular grid of photovoltaic collectors.
