Resources of Near-Earth Space
|Resources of Near-Earth Space, edited by John S. Lewis, Mildred Shapley Matthews, and Mary L. Guerrieri. © 1993 The Arizona Board of Regents. No part of this on-line book may be reproduced in any manner whatsoever without the written permission of the University of Arizona Press.
The National Space Society is proud to present this landmark book in cooperation with the University of Arizona Press. NSS supplied the volunteer labor to scan the book and create the PDF files which reside on the University of Arizona Press website. The Introduction and abstracts are available here in searchable text format, along with links to the complete PDF files for each chapter. Each chaper PDF is 1-3 megabytes in size.
C. R. STOKER,
NASA Ames Research Center
ABSTRACT: The physical and chemical properties of Martian surface soils are reviewed from the perspective of providing resources to support human activities on Mars. The relevant properties can only be inferred from limited analyses performed by the Viking Landers, from information derived from remote sensing, and from analysis of the SNC meteorites thought to be from Mars. Several lines of evidence suggest that the Martian surface is globally covered with a fine-grained soil having nearly uniform physical and compositional properties. Viking experiments characterized the physical properties of the soil well enough to allow preliminary designs for resource extraction equipment. The mineralogy of the soil has not been determined but the bulk elemental compositions determined by the Viking Lander X-ray Spectrometer analyses provide evidence for clay minerals (possibly smectites) or mineraloids (palagonite) admixed with sulfate and chloride salts. The soil unit contains materials bearing useful amounts of H2O, Fe, Al, Mg, S and Cl. Spectroscopic observations of Mars provide additional constraints on the composition of the soil and the best match to Martian spectra is obtained with certain terrestrial palagonites which contain poorly crystalline iron oxides. Many lines of evidence suggest that the SNC meteorites are samples of Martian crustal materials and thus provide information about the parent minerals from which Martian soil is derived. A number of trace mineral phases have been identified in the SNCs including carbonates, sulfates, and possible smectites. Martian surface materials can be used directly in a number of ways. Martian soil, with appropriate preconditioning, can probably be used as a plant growth medium, supplying mechanical support, nutrient elements, and water at optimal conditions to the plants. Loose Martian soils could be used to cover structures and provide radiation shielding for surface habitats. Martian soil could be wetted and formed into duricrete bricks with strength comparable to concrete for use in construction. Useful elements and compounds can be extracted from Martian soil. Water, one of the most valuable resources, probably exists in hydrated minerals although no specific mineralogical identifications have yet been achieved. Viking experiments showed that water evolved from Martian soils when they were heated to 500 C suggesting the soils contained at least —1% loosely bound water. Many minerals which might exist on Mars, including gypsum (21% H2O), kieserite (13% H20), goethite (10% H2O), and nontronite (5-6% H2O), contain tightly bound (structural) water which could be released by pyrolyses but the required energy input would vary with the identity and abundance of the mineral. The high sulfur content and the implication that sulfur may occur as a soluble salt suggests that sulfur can be readily extracted from Martian soil. Sulfur and sulfur-bearing compounds are used in the manufacture of a wide variety of useful substances including acids, bases, oxidizing and reducing agents, fertilizers, dyes, catalytic agents, detergents, solvents, explosives, etc. Machinable metals such as iron, magnesium and aluminum could also be extracted from Martian soils. Martian soil contains 18 wt% iron oxide which is likely to be in the form of poorly crystalline or nanocrystalline iron oxide minerals. The most important information needed to design resource extraction procedures is to determine the mineralogy of the Martian soil.
R. B. SINGER,
University of Arizona
ABSTRACT: Our knowledge of the composition of unaltered igneous crust on Mars is based on information from a variety of indirect sources. Two primary sources are reflectance spectroscopy and study of the SNC meteorites. Virtually all remote observations indicate that there is abundant unaltered basaltic crustal material exposed at or very near the present Martian surface, concentrated in low-albedo regions. Near-infrared reflectance spectroscopy provides compositional information about Fe2+-bearing igneous minerals such as pyroxenes, which have been consistently observed on the Martian surface. As estimated from spectral analysis, the composition averages relatively high-Fe, low- to medium-Ca clinopyroxene, with some regional variation. The SNC meteorites are a small and diverse group of relatively young igneous rocks generally thought to have originated in the crust of Mars. Shergotty, a basaltic meteorite from this group, is consistent in important mineralogic features with telescopic observations of low-albedo regions on the planet. Because shergottites formed as basalt flows or shallow cumulates it is reasonable that such materials would be exposed on the surface of their parent planet. Spectral analogs to the other two SNC meteorite families, the nahklites and chassignites, have not been detected at the Martian surface, consistent with their petrogenesis as higher-pressure cumulate assemblages. While the SNCs sampled relatively young igneous crust, there is evidence that the ancient crust of Mars is compositionally similar. Abundant ultramafic igneous rock at the Martian surface is neither required by nor consistent with the bulk of observational evidence. There is also no evidence for highly differentiated intermediate or acidic crust on Mars, and significant constraints on its possible abundance.
BRUCE M. JAKOSKY, University of Colorado
ABSTRACT: Water will be an important resource for future missions to explore Mars. As such, some understanding is required of the abundance and distribution of water in the Martian near-surface environment. As no technique has been used to date to map near-surface water in the Martian regolith or polar regions, our understanding of where the water is today depends on interpretations of observations which relate to the global history of water over geologic time and to the seasonal cycle of water in the atmosphere; in situ measurements are available at only two locations. These observations and the inferences from them are summarized in this chapter, along with the current best guesses as to where water can be found and what future observations might be used to locate water. Based on our current understanding of the Martian environment, the only sure source of water is in the polar regions; water or ice in the nonpolar regolith may be unavailable for mining or may be nonexistent. Additional observations might provide a more optimistic basis for finding water.
VICTOR R. BAKER, VIRGINIA C. GULICK and JEFFREY S. KARGEL, University of Arizona
ABSTRACT: From the perspectives of energy expenditure, ice is the most economical water resource to target for exploration on Mars. Theoretical stability criteria indicate the planetary- scale potential for ground ice poleward of about 40° latitude. Geologic indicators can constrain the exploration. Particularly useful in this regard are fluidized ejecta blankets, periglacial features, and relict glacial landforms. The relationship of such geomorphological indicators to the modern water resources is dictated by the processes responsible for water cycling in the Martian past and the extension of those processes to the present. The geomorphological evidence indicates extensive water cycling in the geologic past, involving either (1) atmospheric components leading to the formation of large ancient lakes or an ocean, or (2) hydrothermal activity. Exploration strategies can develop around the resource potential of hydrated minerals, hydrothermal systems, and ground ice based on an evolving practical experience as resources are discovered.
ALOYSIUS F. HEPP,
NASA Lewis Research Center
ABSTRACT: This chapter examines several novel proposals for CO2 reduction by chemical, photochemical, and photoelectrochemical means. Photolytic reduction of CO2 to CO and O2 can occur under mild conditions using a series of recently synthesized trinuclear nickel catalysts. We examine potential uses of CO, a by-product of CO, reduction, and carbon, as reducing agents in metal oxide processing to produce structural or power materials; CO2 produced in these reactions can then be recycled to generate O2 and CO. Reduction of CO2 with hydrogen produces methane through the Sabatier process. Further partial oxidation of methane can be carried out to produce acetylene, through the Sachsse process.The impact of such propellants on future missions to Mars is assessed.
CHRISTOPHER P. McKAY, NASA Ames Research Center
ABSTRACT: The human exploration of Mars can benefit from the availability of resources on the Martian surface that can be used to provide life support consumables. The key compounds O2, buffer gas (Ar/N2), and H2O are available on Mars and can be extracted from the atmosphere. Water may also be available from soil water and ground ice. The soil could be used as radiation shielding and could provide useful plant growth medium. Fairly autonomous processes can be designed to extract and stockpile Martian consumables. The utilization of O2, obtained from Martian atmospheric CO2 will probably be practical even on initial human missions. The ability to utilize these materials in support of a human exploration effort allows missions that are more robust and economical than would otherwise be possible.
ROBERT M. HABERLE, CHRISTOPHER P. McKAY, and
JAMES B. POLLACK, NASA Ames Research Center
ABSTRACT: Solar power is likely to play an important role in the coming exploration of Mars. As a resource it is cheap, in great supply, easy to convert into useful work, and lacks dangerous failure modes that can jeopardize the safety of future human outposts. Yet Mars is farther from the Sun and it has an atmosphere. In particular, dust storms are a major concern because they can literally envelop the entire planet, and can last for several months. Engineering studies of solar-powered systems designed to operate on the surface of Mars must carefully consider these aspects of the Martian environment. This chapter summarizes what is known about the Martian atmosphere as it relates to solar radiation at the surface. Thus, the composition of the atmosphere is reviewed and the gases and aerosols that affect the solar beam are identified and characterized, including dust particles and water ice clouds. A methodology is presented that enables the calculation of solar radiation at the surface. It is shown that although the presence of dust reduces the available energy, there still remains an appreciable diffuse component that can be utilized by solar collectors. Water-ice clouds have the same effect, but are of less concern than dust particles because of their generally lower optical depths, and greater scattering ability. It is estimated that the power requirements of a human outpost located at the Viking Lander 1 site (23°N) could be met with solar arrays about 30 by 30 m square, and about 1000 kg in mass. A system somewhat less than twice that size and mass could meet the power requirements for in-situ propellant production as envisioned in the "Mars Direct" scenario as proposed by Baker and Zubrin (1990). Thus, solar power is a viable energy source for future missions to Mars.
JEFFREY F. BELL and FRASER FANALE,
University of Hawaii
ABSTRACT: Data bearing on the composition of Phobos and Deimos are reviewed. Infrared spectroscopy indicates that neither satellite has significant amounts of bound water in its surface minerals. However, magnetospheric data from the Phobos 2 spacecraft can be interpreted as suggesting that the satellites are outgassing water vapor. Theoretical models indicate that if Phobos originally formed with an ice component, it could still retain an icy "permafrost" core at depths less than 100 m near the poles. A significant ice component is consistent with the surprisingly low density (1.9 g per cc) measured by Phobos 2; but a very high porosity (about 50%) could also explain this result. The most likely composition for Phobos and Deimos is a "CM3" carbonaceous-chondritelike assemblage of anhydrous silicates, carbon, organic compounds and ice. This composition suggests that the Martian satellites were originally formed in the outer asteroid belt and later captured by Mars. Our knowledge of Phobos and Deimos is still inadequate to evaluate intelligently their usefulness as resource bases, and another unmanned mission to Phobos is essential before any serious planning for its use is carried out.
BENTON C. CLARK, Martin Marietta Civil Space & Communications
ABSTRACT: Mars is endowed with an abundance of compounds containing most of the elements needed to manufacture propellants for transportation, whether by rocket, rover, or other means. Selection of the most suitable propellants involves a careful engineering evaluation, based upon the application (especially the energy requirements thereof) and the complexities that are involved in extracting the indigenous compounds and converting them to more useful ones.
JAMES B. POLLACK,
NASA Ames Research Center
ABSTRACT: Assuming commercial fusion power, heavy lift vehicles and major advances in genetic engineering, we survey possible late-21st century methods of working major transformations in planetary environments. Much more Earth-like temperatures may be produced on Mars by generating low freezing-point greenhouse gases (e.g., CO2, NH3, CFCs) from indigenous materials or by transporting them from elsewhere; on Venus by cancelling the greenhouse effect with high-altitude absorbing fine particles, or by a sunshield at the first Lagrangian point, and/or by sequestering or transforming CO2 at the surface; and on Titan by greenhouse and/or fusion warming. To produce global environments suitable for plants and animals, including humans, requires modifying the atmospheric composition and mass and altering the surface temperatures on these bodies. In general, engineering congenial worlds for plants is much easier than for humans, and is also a useful means of working further modification of the atmospheric composition, especially the establishment of several hundred mbar of O2 from H2O. Establishing global habitats suitable for humans will require the addition of at least several hundred mbar of N2 and O2 into the Martian atmosphere; the removal of most of the CO2 in Venus' atmosphere (most plausibly by forming carbonate minerals) plus the addition of large amounts of water; and the addition of several hundred mbar of O2 to Titan's atmosphere. Climatologically active abundances of some gases may be toxic to humans. It is not clear that any of these schemes are technically feasible (much less cost effective) with technologies projected for the end of the next century. They also raise disturbing questions about environmental ethics. Global warming on Earth has already led to calls for mitigation by planetary engineering—e.g., emplacement and replenishment of reflective or anti-greenhouse layers at high altitudes, or sunshields in space. But here especially we must be concerned about precision, stability, and inadvertent side-effects. The safest and most cost-effective means of countering global warming of the Earth—beyond, e.g., improved energy efficiency, CFC bans and alternative energy sources—is the continuing reforestation of —2.5 x 107 km2 of the Earth's surface. This can be accomplished with present technology.