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NASA NTRS1989

Exploration case studies

NASA's Office of Exploration has undertaken four case studies for prospective expansion of manned space activities beyond earth orbit. The subjects of these studies are (1) an expedition to the Martian moon Phobos; (2) a three-mission expedition to Mars; (3) the construction of a man-tended lunar observatory; and (4) the construction of a lunar outpost to serve as the basis for construction of a Martian outpost. The fourth alternative would follow the recommendation of the National Commission on Space for the creation of a 'bridge between worlds' in which explorers would develop ways in which to 'live off the land' in a space environment.

Underwood, Jimmy M.↗
NASA NTRS1989

Beyond earth's boundaries

The USA has adopted the long-term goal of exploring the space frontier, including establishing human settlements beyond Earth orbit. This article describes four candidate missions for developing pathways into the Solar System which have been identified by NASA's Office of Exploration: human expeditions to Phobos and Mars, a lunar observatory and a lunar outpost to assist Mars explorations. The requirements placed upon near-term programmes by each of these missions are outlined and the elements necessary for a long-term implementation strategy are analysed.

Alan Ladwig↗
NASA NTRS1989

NASA's plans for manned missions to the moon and Mars

Issues, problems, and potential solutions of the lunar and Mars missions which will be undertaken in the first decade of the next century are discussed. Arguments are made for the feasibility and usefulness of a lunar base, and an evolutionary approach to a manned Mars mission involving a preliminary mission to Phobos is outlined. The Shuttle Z concept for both moon and Mars missions which involves a dual use of a spacecraft transfer stage operating also as a booster third stage is defined.

Bekey, Ivan↗
NASA NTRS1989

Human exploration mission studies

The nation's efforts to expand human presence and activity beyond Earth orbit into the solar system was given renewed emphasis in January of 1988 when the Presidential Directive on National Space Policy was signed into effect. The expansion of human presence into the solar system has particular significance, in that it defines long-range goals for NASA's future missions. To embark and achieve such ambitious ventures is a significant undertaking, particularly compared to past space activities. Missions to Mars, the Moon, and Phobos, as well as an observatory based on the dark side of the Moon are discussed.

Cataldo, Robert L.↗
NASA NTRS1989

First measurements of plasma waves near Mars

Preliminary results from electric field measurements in the environment of Mars using the plasma-wave system on board Phobos 2 are reported. Electron-plasma oscillations observed upstream of the bow shock correspond to a solar-wind density of 2/cu cm. The shock-foot boundary was crossed up to three times on each orbit. The shock ramp was detected at altitudes between 0.45 and 0.75 Mars radii R(M) above the planetary surface. The density increased by about a factor of two at the ramp. The shock position, although variable, seems to be consistent with previous measurements. The downstream magnetosheath contained broadband electric-field noise below the plasma frequency. The boundary of th obstacle, or plasmapause, was crossed at altitudes of the order of 0.28 R(M); the cold plasma density was highly variable within the planetopause and reached the unexpected value of 700/cu cm on the third orbit, at 0.25 R(M) altitude. Bursts of waves with frequencies below the electron cyclotron frequency occur within the planetopause.

Grard, R.↗
NASA NTRS1990

A model of the energetic ion environment of Mars

Because Mars has a weak intrinsic magnetic field and a substantial atmosphere, instruments on orbiting spacecraft should detect a population of energetic heavy planetary ions which result from comet-like ion pickup in the solar wind and magnetosheath convection electric fields, in addition to those that might result from processes internal to a Martian 'magnetosphere.' Although this ion exosphere has been previously discussed in the literature, detailed predictions that might be directly applied to the interpretation of data are not available. Here a test particle model is used to construct a global picture of Martian pickup ions in the Mars environment. The model makes use of the recent Nagy and Cravens (1988) model of the Martian exosphere and Spreiter and Stahara's (1980) gas dynamic model of the magnetosheath. The pickup of ions originating at Phobos is also considered. Notable properties of the resulting ion distributions include their near-monoenergetic spectra, pancake pitch angle distributions, and large gyroradii compared to the planetary scale.

Luhmann, J. G.↗
NASA NTRS1990

Stability of the Martian atmosphere - Possible role of heterogeneous chemistry

A new hypothesis is proposed for recycling Martian CO to CO2. The same hypothesis can satisfactorily explain the recently observed depletion in CO in the middle atmosphere of Mars. The mechanism involves oxidation of CO through heterogeneous chemistry in the presence of aerosols. It is further suggested that H2O ice aerosols in the atmosphere of Mars are particularly effective in this process. The thrust for suggesting this mechanism came from the extensive presence of aerosols in the Martian atmosphere and relatively low CO mixing ratios in the low to middle atmosphere detected by the Phobos spacecraft.

Atreya, S. K.↗
NASA NTRS1989

Human pathway to the solar system in the 21st century

Some proposed space exploration missions are examined. Consideration is given to requirements for human expeditions to Phobos and Mars and for establishing a lunar observatory and a permanent, self-sufficient facility on Mars. Earth-to-orbit transportation, propellant management, extraterrestrial construction and operations, life support technology, space transfer systems, and automation and robotics are examined in terms of proposed missions.

O'Handley, Douglas A.↗
NASA NTRS1990

Human exploration mission studies

This paper describes several case studies of human space exploration, considered by the NASA's Office of Exploration in 1988. Special attention is given to the mission scenarios, the critical technology required in these expeditions, and the extraterrestrial power requirements of significant system elements. The cases examined include a manned expedition to Phobos, the inner Martian moon; a human expedition to Mars; the Lunar Observatory; and a lunar outpost to early Mars evolution.

Cataldo, Robert L.↗
NASA NTRS1990

Venus mantle-Mars planetosphere - What are the similarities and differences?

An overview of data concerning the mantle and planetosphere regions of Mars and Venus is presented, emphasizing data from the Phobos 2 mission. It is shown that there are significant similarities between the mantle/planetosphere regions on the two planets. These similarities include a transition region between the magnetosheath and the ionosphere dominated by heavy, planetary ions, and a transition region in which the electron population is different from both the shock solar wind and the photoelectron populations. Also, on both planets, a magnetic signature near the transition boundary and the presence of low frequency electric waves within the transition region are observed.

Nagy, Andrew F.↗
NASA NTRS1990

A model of the ion wake of Mars

Observations from the Phobos spacecraft suggest that, for the most part, the Martian magnetotail is induced instead of intrinsic. Test particle techniques are used to determine how the associated ion wake might appear to detectors behind Mars if it is produced primarily by planetary ions picked up by the solar wind in the dayside exosphere. The results suggest that low energy pickup ions populate the inner wake, while a more energetic component is present in the outer magnetosheath and adjacent solar wind.

Luhmann, J. G.↗
NASA NTRS1990

An approach for targeting landers and penetrators using orbital optical navigation

Onboard orbital optical navigation data is analyzed with the purpose of generating topographic maps for selecting a landing site. It is suggested that a near-real time orbit-determination process be used for solving a large set of parameters including the spacecraft orbit and primary-body gravity field, the rotational properties of the planetary body, the coordinates of surface features, and the camera-pointing and orientation angles of each picture. A batch-sequential formulation of the standard least-squares problem is employed, along with backward smoothing and a square-root formation filter. An experiment in which over 100 images of Phobos are processed to estimate about 2000 parameters is presented, with emphasis on coordinate systems, transforming points on the reference surface to images in the picture, parameter estimation, and cartographic accuracy.

Wang, Tseng-Chan↗
NASA NTRS1990

Achievable space elevators for space transportation and starship acceleration

Space elevator concepts for low-cost space launches are reviewed. Previous concepts suffered from requirements for ultra-high-strength materials, dynamically unstable systems, or from danger of collision with space debris. The use of magnetic grain streams solves these problems. Magnetic grain streams can support short space elevators for lifting payloads cheaply into Earth orbit, overcoming the material strength problem in building space elevators. Alternatively, the stream could support an international spaceport circling the Earth daily tens of miles above the equator, accessible to advanced aircraft. Mars could be equipped with a similar grain stream, using material from its moons Phobos and Deimos. Grain-stream arcs about the sun could be used for fast launches to the outer planets and for accelerating starships to near lightspeed for interstellar reconnaisance. Grain streams are essentially impervious to collisions, and could reduce the cost of space transportation by an order of magnitude.

Pearson, Jerome↗
NASA NTRS1989

Theoretical predictions of volatile bearing phases and volatile resources in some carbonaceous chondrites

Carbonaceous chondrites are usually believed to be the primary constituents of near-Earth asteroids and Phobos and Diemos, and are potential resources of fuels which may be exploited for future planetary missions. The nature and abundances are calculated of the major volatile bearing and other phases, including the vapor phase that should form in C1 and C2 type carbonaceous chondrites as functions of pressure and temperature. The results suggest that talc, antigorite plus or minus magnesite are the major volatile bearing phases and are stable below 400 C at 1 bar in these chondritic compositions. Simulated heating of a kilogram of C2 chondrite at fixed bulk composition between 400 and 800 C at 1 bar yields about 135 gm of volatile, which is made primarily of H2O, H2, CH4, CO2 and CO. The relative abundances of these volatile species change as functions of temperature, and on a molar basis, H2 becomes the most dominant species above 500 C. In contrast, Cl chondrites yield about 306 gm of volatile under the same condition, which consist almost completely of 60 wt percent H2O and 40 wt percent CO2. Preliminary kinetic considerations suggest that equilibrium dehydration of hydrous phyllosilicates should be attainable within a few hours at 600 C. These results provide the framework for further analyses of the volatile and economic resource potentials of carbonaceous chondrites.

Ganguly, Jibamitra↗
NASA NTRS1990

Volatile-bearing phases in carbonaceous chondrites: Compositions, modal abundance, and reaction kinetics

The spectral and density characteristics of Phobos and Deimos (the two small natural satellites of Mars) strongly suggest that a significant fraction of the near-earth asteroids are made of carbonaceous chondrites, which are rich in volatile components and, thus, could serve as potential resources for propellants and life supporting systems in future planetary missions. However, in order to develop energy efficient engineering designs for the extraction of volatiles, knowledge of the nature and modal abundance of the minerals in which the volatiles are structurally bound and appropriate kinetic data on the rates of the devolatilization reactions is required. Theoretical calculations to predict the modal abundances and compositions of the major volatile-bearing and other mineral phases that could develop in the bulk compositions of C1 and C2 classes (the most volatile rich classes among the carbonaceous chondrites) were performed as functions of pressure and temperature. The rates of dehydration of talc at 585, 600, 637, and 670 C at P(total) = 1 bar were determine for the reaction: Talc = 3 enstatite + quartz + water. A scanning electron microscopic study was conducted to see if the relative abundance of phases can be determined on the basis of the spectral identification and x ray mapping. The results of this study and the other studies within the project are discussed.

Ganguly, Jibamitra↗
NASA NTRS1991

Kinetics of volatile extraction from carbonaceous chondrites: Dehydration of talc

Carbonaceous chondrites are believed to be the primary constituents of near-Earth asteroids and Phobos and Deimos, and are potential resources of fuels that may be exploited for future planetary missions. Calculations of equilibrium phase relations suggest that talc (Ta) and antigorite (Ant) are likely to be the major hydrous phases in the C1 and C2 meteorites (Ganguly and Saxena, 1989), which constitute the most volatile rich classes of carbonaceous chondrites. The dehydration kinetics of talc are studied as a function of temperature, grain size, composition and fluid fugacity, as part of a systematic study of the reaction kinetics of the volatile bearing phases that are either known or likely to be present in carbonaceous chondrites. The dehydration kinetics were investigated at 1 bar, 775 to 875 C by monitoring the in-situ weight loss as a function of time of a natural talc. The talc platelets had a dimension of 0.8 to 1 micron. The run durations varied from 233.3 hours at 775 C (48 percent dehydration) to 20.8 hours at 875 C (80 pct. dehydration). The results can be adequately represented by a given rate equation. Theoretical analysis suggests that the reduction in the concentration of H2O in the environment of dehydrating talc, as would be encountered in processing chondritic materials, will have negligible effect on the rate of dehydration, unless there is a change of reaction mechanism owing to the presence of other volatile species.

Bose, Kunal↗
NASA NTRS1991

Survey of resource opportunities and critical evaluation of economic requirements

A series of mission analyses were performed to evaluate human mission to Mars and the moon with and without the aid of planetary resource utilization. The types of trade studies that are considered include the use of resources to manufacture propellant, food, habitat atmospheric gases, and lander habitat structure. Also, the potential for export of resources from the moon, Mars, Phobos, Deimos, and selected asteroids is also examined. In all cases, mass leveraging is evaluated. For certain cases, economic factors are evaluated as well. It is concluded that some uses are highly leveraging on the mission, whereas others have lesser impact and, therefore, should be afforded lesser priority in resource utilization studies. This survey is made with a consistent set of scaling laws for spacecraft propulsion and habitation systems and subsystems, and therefore, provides a rational basis for comparing different resource locations and use strategies.

Clark, Benton C.↗
NASA NTRS1991

Mass budget for mining the moons of Mars

The mass budget is detailed for system architectures that use rocket fuels of propellants derived from Deimos and Phobos to transport 10000 ton payloads of exofuel (exoatmospheric fuels) or exomass (exoatmospheric mass) to earth orbits. A point design for the system architecture is used that includes a self-sustaining cycle, which requires no materials from earth, and an infrastructure, which must be emplaced to start the cycle. Both the use of steam rockets and the use of liquid oxygen and liquid hydrogen is examined. It is shown that a system delivering 10000 tons of payload to a highly elliptical earth orbit requires approximately 23000 tons of water for use by nuclear heated steam rockets to effect completely propulsive, round trip maneuvers. It is also shown that about 8000 tons will be available for sale at low earth orbit, each cycle, and that the number of cycles can number in the tens before critical components are replaced.

Zuppero, Anthony↗