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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

A solar power system for an early Mars expedition

As NASA looks at missions that will expand human presence in the solar system, the power requirements for such missions need to be defined, developed and analyzed. One mission under consideration consists of a 40 day manned Mars surface expedition to perform science experiments. The mission time was centered around an aerocentric longitude (Ls) of 90 deg to lessen the probability of an occurrence of a local or planetary dust storm. The mission site was arbitrarily located at the Martian equator. The power requirements were assumed to be 40 kWe for life support and experiment power during the Martian day and 20 kWe for life support during the Martian night. A solar energy system consisting of roll-out amorphous silicon arrays and a hydrogen-oxygen regenerative fuel cell energy storage system was chosen for the study. The power available from a roll-out array, when plotted against time, approaches a cosine-like curve and depends on both array area and the amount of solar irradiance impinging on its horizontal surface. The array is sized to provide at least 20 KWe when the sun is 12.5 deg above the horizon and ramp up to 140 kWe peak power at Martian noon. In this configuration, the array is capable of supplying 40 KWe continuously to the user for the majority of the Martian day while supplying the excess energy to the electrolyzer portion of the energy storage system. A roll-out, pumped loop radiator system is used to dissipate the waste heat produced by the fuel cell. The power management and distribution system inverts the power from the individual solar array sub-modules and the fuel cell stacks and connects them to a 440 VAC single phase 20 kHz main bus. The total power system is comprised of 80 individual solar array modules with an integral bus and three energy storage modules consisting of fuel cell and electrolyzer stacks, reactant storage tanks, and a roll-out radiator. Power system mass, stowed volume, and deployed area were determined. Day/night power splits of 40/10 kWe, 40/30 kWe, and 40/40 kWe were also considered to determine the impact of a range of nighttime power requirements on the baseline system.

Mckissock, Barbara I.↗
NASA NTRS1989

A smaller scale manned Mars evolutionary program

This paper describes a concept for a manned Mars mission in which the parameters and trajectories are chosen to minimize the initial mass in earth orbit. The concept permits ready evolution from an initial modes step to full Mars surface operations. It uses a new heavy lift launch vehicle concept, the Shuttle Z.

Bekey, Ivan↗
NASA NTRS1989

Options for the human settlement of the moon and Mars

The evolutionary approach to space development is discussed in the framework of three overall strategies encompassing four case studies. The first strategy, human expeditions, places emphasis on highly visible, near-term manned missions to Mars or to one of the two moons of Mars. These expeditions are similar in scope and objectives to the Apollo program, with infrastructure development only conducted to the degree necessary to support one or two short-duration trips. Two such expeditionary scenarios, one to Phobus and the other to the Mars surface, are discussed. The second strategy involves the construction of science outposts, and emphasizes scientific exploration as well as investigation of technologies and operations needed for permanent habitation. A third strategy, evolutionary expansion, would explore and settle the inner solar system in a series of steps, with continued development of technologies, experience, and infrastructure.

Fairchild, Kyle O.↗
NASA NTRS1990

Low earth orbit infrastructure to accommodate manned lunar missions

In order to establish bases on the lunar and Mars surfaces, a significant amount of orbital infrastructure including assembly platforms, cryogenic fluids depots, and Space Station Freedom, will be required in LEO. These facilities will be required to perform a myriad of functions ranging from orbital demonstration of advanced technology systems and establishment of life science capabilities to servicing and refurbishment of reusable lunar transfer vehicles. This paper addresses the requirements levied on these facilities and provides an overview of potetial LEO infrastructure elements that satisfy various advanced manned missions. Of key importance to the success of the manned lunar mission are (1) the evolutionary growth of Space Station Freedom to serve as a transportation node and (2) the development of a Shuttle-derived launch vehicle to deliver mission elements to LEO.

Cirillo, William M.↗
NASA NTRS1992

Influences of CO2 sublimation/condensation processes on the long-term evolution of the Martian atmosphere

The accumulation process of frozen CO2 within the Martian regolith is analyzed. The boundary conditions are taken to be the periodically variable temperature at the Mars surface and the constant heat flux at the bottom of the regolith layers, some hundred meters thick. The mean value of temperature as well as its amplitude are assumed to be dependent on latitude and could be variable with the geological time scale. The flux of gaseous CO2 within the regolith is controlled by the mechanism of gas transport through the porous medium. An appropriate initial geometry of distribution of pores is assumed. The porosity and flux change due to condensation/sublimation processes. The equations of heat and mass transfer are solved numerically for a given latitude. Next, the local (over the parallel of latitude belt) annual balance of CO2 is calculated. The procedure is repeated over the whole Martian surface and next the total annual net flux is calculated.

Kossacki, K.↗
NASA NTRS1991

A mission design for International Manned Mars Mission - From the 1991 International Space University (ISU) Design Project

The International Space University (ISU) conducted a study of an international program to support human exploration of Mars as its annual Design Project activity during its 1991 summer session in Toulouse, France. Although an ISU Design Project strives to produce an in-depth analysis during the intense 10-week summer session, the International Mars Mission (IMM) project was conducted in a manner designed to provide a learning experience for young professionals working in an unusual multidisciplinary and multinational environment. The breadth of the IMM study exceeds that of most Mars mission studies of the past, encompassing political organization for long-term commitment, multinational management structure, cost analysis, mission architecture, vehicle configuration, crew health, life support, Mars surface infrastructure, mission operations, technology evaluation, risk assessment, scientific planning, exploration, communication networks, and Martian resource utilization. The IMM Final Report has particular value for those seeking insight into the choices made by a multinational group working in an apolitical environment on the problems of international cooperation in space.

Mendell, Wendell W.↗
NASA NTRS1991

Induced gravity Mars transportation systems configuration and hardware penalties

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 microgravity 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.

Capps, Stephen↗
NASA NTRS1992

Preliminary design of a meteoroid/orbital debris shield system for a Mars mission spacecraft

A preliminary design of a spacecraft shield system to defeat meteoroids and orbital debris during a Mars mission is presented. The mission scenario is first defined in terms of stage times which include LEO, transit, low-Mars orbit, and Mars surface periods. The environment definitions for earth-orbital space debris, planetary meteoroids, and interplanetary meteoroids are next introduced. Shield system design approaches incorporate stochastic simulation, hydrocode analyses, hypervelocity impact testing, and optimization techniques. Structural design trades presented include spacecraft configuration, mission schedule, penetration risk, and total standoff distance between the bumper and wall.

Robinson, J. H.↗
NASA NTRS1992

A U.S. perspective on the human exploration and expansion on the planet Mars

A NASA perspective on the human exploration of Mars is presented which is based on the fundamental background available from the many previous studies. A hypothetical architecture of the Mars surface system is described which represents the complete spectrum of envisioned activities. Using the Strategic Implementation Architecture it is possible to construct a thoughtful roadmap which would enable a logical and flexible evolution of missions. Based on that architecture a suite of Martian surface elements is proposed to provide increasing levels of capability to the maturing infrastructure.

Roberts, Barney B.↗
NASA NTRS1992

Mars observer radio science (MORS) observations in polar regions

MORS observations will focus on two major areas of study: (1) the gravity field of Mars and its interpretation in terms of internal structure and history and (2) the structure of the atmosphere, with emphasis on both temperature-pressure profiles of the background atmosphere and small scale inhomogeneities resulting from turbulence. Scattering of cm wavelength radio signals from Mars' surface at highly oblique angles will also be studied during the primary mission; nongrazing scattering experiments may be possible during an extended mission. During the MORS primary mission, measurements of the spacecraft distance and velocity with respect to Earth based tracking stations will be used to develop models of the global gravity field. The improvement in knowledge of the gravity field will be especially evident in polar regions. The spatial and temporal coverage of atmospheric radio occultation measurements are determined by the geometry of the spacecraft orbit and the direction to the Earth. Profiles of atmospheric temperature and pressure will extend from the surface to altitudes of 50 to 70 km.

Simpson, Richard A.↗
NASA NTRS1993

Mars transfer vehicle studies

Earth-to-Mars distances vary from 60 to 400 million kilometers over a 14-year cycle. This complicates Mars mission design as a function of calendar time. Stay times at Mars are also strongly driven by opportunities for a return flight path which are within the limits of delta-V associated with practical space vehicles. The biggest difference between Mars and lunar transfer missions is mission time, which grows from a few days for the moon, to as much as a few hundred days for Mars missions. As a result, modules for similarly sized crews must be much larger for Mars missions that for transfer to lunar orbit. Technology challenges for one Mars mission scenario analyzed by Boeing include aerobrakes, propulsion, and life support systems. Mission performance is very sensitive to aerobrake weight fraction and, as a result, there is an incentive to use high performance materials such as advanced composites and thermal protection systems. Lander aerobrake would be used twice (for both planetary capture and descent to the Mars surface), and it would need to survive temperatures up to 3500 degrees.

Woodcock, Gordon↗
NASA NTRS1992

Electrical and Chemical Interactions at Mars Workshop. Part 2: Appendix

The objectives of the workshop were the following: (1) to identify issues related to electrical and chemical interactions between systems and their local environments at Mars; and (2) to recommend means of addressing those issues, including the dispatch of robotic spacecraft to Mars to acquire necessary information. Presentations about Mars' surface and orbital environments, Space Exploration Initiative (SEI) systems, environmental interactions, modeling and analysis, and plans for exploration are presented in viewgraph form.

Source record↗
NASA NTRS1992

Results from a Si(Li) gamma ray detector stack for future Mars missions

We present Monte Carlo analysis and experimental data from a novel lithium-drifted silicon detector stack for gamma ray spectroscopy instrumentation in future Mars surface landers and other planetary missions. The Monte Carlo analysis shows full energy photopeaks even in the range of about 100 keV to 2 MeV where, in Si, Compton scattering dominates the absorption processes. Laboratory data is shown for an experimental detector stack of four planar Si(Li) devices, each 5 mm thick with an active area 2 cm in diameter. All the experimental data were collected with maximum temperature of the stack at 175 K. Background reduction is achieved by using the detector of the stack closest to the source in anticoincidence. We present a comparison of experimental data from the stack with the Monte Carlo model for Cs-137 (662 keV). Agreement is shown to be good, with a full energy photopeak clearly seen (FWHM about 10 keV). Experimental stack data is also shown for multiple peaks at 511 keV (Na-22) and 662 keV (Cs-137). The peaks are clearly resolved (FWHM 10 keV), and are compared with the results obtained using a 8 percent resolution, 3 in. x 3 in. NaI(TI) device (FWHM about 50 keV).

Hubbard, G. S.↗
NASA NTRS1993

A sensitive continuum analysis method for gamma ray spectra

In this work we examine ways to improve the sensitivity of the analysis procedure for gamma ray spectra with respect to small differences in the continuum (Compton) spectra. The method developed is applied to analyze gamma ray spectra obtained from planetary mapping by the Mars Observer spacecraft launched in September 1992. Calculated Mars simulation spectra and actual thick target bombardment spectra have been taken as test cases. The principle of the method rests on the extraction of continuum information from Fourier transforms of the spectra. We study how a better estimate of the spectrum from larger regions of the Mars surface will improve the analysis for smaller regions with poorer statistics. Estimation of signal within the continuum is done in the frequency domain which enables efficient and sensitive discrimination of subtle differences between two spectra. The process is compared to other methods for the extraction of information from the continuum. Finally we explore briefly the possible uses of this technique in other applications of continuum spectra.

Thakur, Alakh N.↗
NASA NTRS1993

Rover imaging system for the Mars rover/sample return mission

In the past year, the conceptual design of a panoramic imager for the Mars Environmental Survey (MESUR) Pathfinder was finished. A prototype camera was built and its performace in the laboratory was tested. The performance of this camera was excellent. Based on this work, we have recently proposed a small, lightweight, rugged, and highly capable Mars Surface Imager (MSI) instrument for the MESUR Pathfinder mission. A key aspect of our approach to optimization of the MSI design is that we treat image gathering, coding, and restoration as a whole, rather than as separate and independent tasks. Our approach leads to higher image quality, especially in the representation of fine detail with good contrast and clarity, without increasing either the complexity of the camera or the amount of data transmission. We have made significant progress over the past year in both the overall MSI system design and in the detailed design of the MSI optics. We have taken a simple panoramic camera and have upgraded it substantially to become a prototype of the MSI flight instrument. The most recent version of the camera utilizes miniature wide-angle optics that image directly onto a 3-color, 2096-element CCD line array. There are several data-taking modes, providing resolution as high as 0.3 mrad/pixel. Analysis tasks that were performed or that are underway with the test data from the prototype camera include the following: construction of 3-D models of imaged scenes from stereo data, first for controlled scenes and later for field scenes; and checks on geometric fidelity, including alignment errors, mast vibration, and oscillation in the drive system. We have outlined a number of tasks planned for Fiscal Year '93 in order to prepare us for submission of a flight instrument proposal for MESUR Pathfinder.

Source record↗
NASA NTRS1993

Bench checkout equipment for spaceborne laser altimeter systems

This paper addresses the requirements for testing and characterizing spaceborne laser altimeter systems. The Bench Checkout Equipment (BCE) system, test requirements, and flow-down traceability from the instrument system's functional requirements will also be presented. Mars Observer Laser Altimeter (MOLA) and the MOLA BCE are presented as representative of a 'typical' laser altimeter and its corresponding test system. The testing requirements of other or future laser altimeter systems may vary slightly due to the specific spacecraft interface and project requirements. MOLA, the first solid-state interplanetary laser altimeter, was designed to be operational in Mars orbit for two Earth years. MOLA transmits a 7.5 ns pulse at a wavelength of 1.064 microns with a 0.25 mr beam divergence and a pulse repetition rate of 10 Hz. The output energy is specified at 45 mj at the beginning of mapping orbit and 30 mj at the end of one Martian year. MOLA will measure the laser pulse transit time from the spacecraft to the Mars surface and return to a resolution of 1.5 meters.

Smith, James C.↗
NASA NTRS1993

Thermal studies of Martian channels and valleys using Termoskan data: New results

The Termoskan instrument onboard the Phobos '88 spacecraft acquired the highest-spatial-resolution thermal data ever obtained for Mars. Included in the thermal images are 2 km/pixel midday observations of several major channel and valley systems, including significant portions of Shalbatana Vallis, Ravi Vallis, Al-Qahira Vallis, Ma'adim Vallis, the channel connecting Valles Marineris with Hydraotes Chaos, and channel material in Eos Chasma. Termoskan also observed small portions of the southern beginnings of Simud, Tiu, and Ares Valles and some channel material in Gangis Chasma. Simultaneous broad band visible data were obtained for all but Ma'adim Vallis. We find that most of the channels and valleys have higher inertias than their surroundings, consistent with Viking IRTM-based thermal studies of Martian channels. We see for the first time that thermal inertia boundaries closely match all flat channel floor boundaries. Combining Termoskan thermal data, relative observations from Termoskan visible channel data, Viking absolute bolometric albedos, and a thermal model of the Mars surface, we have derived lower bounds on channel thermal inertias. Lower bounds on typical channel thermal inertias range from 8.4 to 12.5 (10(exp -3) cal cm(exp -2) s(exp -1/2)K(exp -1)) (352 to 523 in SI units). Lower bounds on inertia differences with the surrounding heavily cratered plains range from 1.1 to 3.5 (46 to 147 in SI units). Atmospheric and geometric effects are not sufficient to cause the inertia enhancements. We agree with previous researchers that localized, dark, high inertia areas within channels are likely eolian in nature. However, the Temloskan data show that eolian deposits do not fill the channels, nor are they responsible for the overall thermal inertia enhancement. Thermal homogeneity and strong correlation of thermal boundaries with the channel floor boundaries lead us to favor noneolian overall explanations.

Betts, B. H.↗
NASA NTRS1994

Mars power system concept definition study. Volume 1: Study results

A preliminary top level study was completed to define power system concepts applicable to Mars surface applications. This effort included definition of power system requirements and selection of power systems with the potential for high commonality. These power systems included dynamic isotope, Proton Exchange Membrane (PEM) regenerative fuel cell, sodium sulfur battery, photovoltaic, and reactor concepts. Design influencing factors were identified. Characterization studies were then done for each concept to determine system performance, size/volume, and mass. Operations studies were done to determine emplacement/deployment maintenance/servicing, and startup/shutdown requirements. Technology development roadmaps were written for each candidate power system (included in Volume 2). Example power system architectures were defined and compared on a mass basis. The dynamic isotope power system and nuclear reactor power system architectures had significantly lower total masses than the photovoltaic system architectures. Integrated development and deployment time phasing plans were completed for an example DIPS and reactor architecture option to determine the development strategies required to meet the mission scenario requirements.

Littman, Franklin D.↗