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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Lunar South Pole Illumination: Review, Reassessment, and Power System Implications

This paper reviews past analyses and research related to lunar south pole illumination and presents results of independent illumination analyses using an analytical tool and a radar digital elevation model. The analysis tool enables assessment at most locations near the lunar poles for any time and any year. Average illumination fraction, energy storage duration, solar/horizon terrain elevation profiles and illumination fraction profiles are presented for various highly illuminated sites which have been identified for manned or unmanned operations. The format of the data can be used by power system designers to develop mass optimized solar and energy storage systems. Data are presented for the worse case lunar day (a critical power planning bottleneck) as well as three lunar days during lunar south pole winter. The main site under consideration by present lunar mission planners (on the Crater Shackleton rim) is shown to have, for the worse case lunar day, a 0.71 average illumination fraction and 73 to 117 hours required for energy storage (depending on power system type). Linking other sites and including towers at either site are shown to not completely eliminate the need for energy storage.

Fincannon, James↗
NASA NTRS1993

Solar wind latitude variations and multiple scattering from Galileo interplanetary Lyman-alpha observations

The Galileo Ultraviolet Spectrometer Experiment (UVS) obtained a map of the celestial sphere from interplanetary Lyman-alpha (IPLA) on 13, 14 December 1990 during the Earth1 encounter. The Galileo spacecraft was near the downwind interstellar axis during the encounter and the map view directions filled the downwind hemisphere. The ratio between the observation and a single scattering model is attributed to a direct measurement of the multiple scattering correction required to model IPLA in the inner solar system. Analysis of this data set, referred to as an antisun map, shows that the solar wind charge exchange rate with interplanetary gas is 25 percent less over the solar poles than in the ecliptic at solar maximum. A model of the interstellar wind based on the antisun map observation exhibits a number density of atomic hydrogen far from the solar system, inside the heliosphere, of 0.16 +/- 0.05/cu cm.

Ajello, Joseph M.↗
NASA NTRS1972

Analyses of requirements for computer control and data processing experiment subsystems. Volume 1: ATM experiment S-056 image data processing system techniques development

The solar imaging X-ray telescope experiment (designated the S-056 experiment) is described. It will photograph the sun in the far ultraviolet or soft X-ray region. Because of the imaging characteristics of this telescope and the necessity of using special techniques for capturing images on film at these wave lengths, methods were developed for computer processing of the photographs. The problems of image restoration were addressed to develop and test digital computer techniques for applying a deconvolution process to restore overall S-056 image quality. Additional techniques for reducing or eliminating the effects of noise and nonlinearity in S-056 photographs were developed.

Source record↗
NASA NTRS1974

Pioneer spacecraft reliability and performance

The Pioneer 6 to 9 interplanetary spacecraft were launched in 1965, 66, 67, and 68. All continued to operate in orbits about the sun, gathering data on the solar system environment near one astronomical unit (AU) from the sun. Pioneer 10 was launched in March 1972, returned information about the planet Jupiter which it encountered in December 1973, and is now operating at six AU from the sun on a solar system escape trajectory. Pioneer 11, launched in April 1973, will encounter Jupiter in December 1974. The long-term mission success and performance of these programs (with emphasis on Pioneers 10 and 11) is reviewed in terms of these factors: philosophy of design for uncertain environments, simplicity in operation, redundancy, the test program, and the actual environment encountered.

Dixon, W. J.↗
NASA NTRS1974

The long life of Pioneer interplanetary spacecraft

The Pioneer 6 to 9 interplanetary spacecraft were launched in 1965, 66, 67, and 68. All continue to operate in various orbits about the sun, gathering data on the solar system environment. Pioneer 10 was launched in 1972, and is now more than halfway to Jupiter, with all systems performing their required functions. The paper reviews these programs and the few anomalies which have been observed. The long-term mission success is discussed in terms of possible causative factors: simplicity in design and operation, redundancy in function and in equipment, comprehensive development and acceptance tests, the mildness of the space environment, and luck.

Dixon, W. J.↗
NASA NTRS1976

Asteroids and comparative planetology

The state of knowledge concerning the asteroids is reviewed and discussed in terms of the relationship of the asteroids with other solar system bodies. The data on spectral reflectances of asteroids are examined, and their implications for comparative planetology are discussed.

Matson, D. L.↗
NASA NTRS1978

The High Energy Astronomy Observatory X-ray Telescope

The High Energy Astronomy Observatory-Mission B (HEAO-B) is a satellite observatory for the purpose of performing a detailed X-ray survey of the celestial sphere. Measurements will be made of stellar radiation in the range 0.2 through 20 keV. The primary viewing requirement is to provide final aspect solution and internal alignment information to correlate an observed X-ray image with the celestial sphere to within one-and-one-half arc seconds. The Observatory consists of the HEAO Spacecraft together with the X-ray Telescope. The Spacecraft provides the required attitude control and determination system, data telemetry system, space solar power system, and interface with the launch vehicle. The X-ray Telescope includes a high resolution mirror assembly, optical bench metering structure, X-ray detectors, detector positioning system, detector electronics and aspect sensing system.

Miller, R.↗
NASA NTRS1981

Solar-site test module

Report describes small test set which interrogates solar-energy data acquisition systems. Lightweight, portable set includes microcomputer with keyboard, alphanumeric display, printer, cassette recorder/player for storing programs and data, and cable for connection to Site Data Acquisition System (SDAS). Unit is operated by BASIC program and Assembly language. Report is specific to DOE/NASA application yet contains general information to assist in designing similar units.

Kissel, R. R.↗
NASA NTRS1985

Effects of temperature on remotely sensed mineral absorption features

The present paper provides the results from a series of laboratory experiments which were conducted to investigate the variable spectral behavior of diagnostic Fe(++) crystal field absorptions in common rock-forming minerals as a function of temperature. The general goal of the study is to refine existing techniques of mineralogic and chemical characterization, based on specific optical behavior which has been measured and correlated in a systematic way. It is pointed out that the presented work, taken together with a number of recent studies, provides new information on the manner in which specific features of mafic minerals combine in rocks and soil spectra, taking into account also variations of identification and subsequent interpretation as a function of planetary surface temperature. The obtained results are directly applicable to interpretation of remotely sensed data for many solar system objects, particularly Mars, asteroids, the moon, earth, and Mercury.

Singer, R. B.↗
NASA NTRS1987

Noiseless coding for the magnetometer

Future unmanned space missions will continue to seek a full understanding of magnetic fields throughout the solar system. Severely constrained data rates during certain portions of these missions could limit the possible science return. This publication investigates the application of universal noiseless coding techniques to more efficiently represent magnetometer data without any loss in data integrity. Performance results indicated that compression factors of 2:1 to 6:1 can be expected. Feasibility for general deep space application was demonstrated by implementing a microprocessor breadboard coder/decoder using the Intel 8086 processor. The Comet Rendezvous Asteroid Flyby mission will incorporate these techniques in a buffer feedback, rate-controlled configuration. The characteristics of this system are discussed.

Rice, Robert F.↗
NASA NTRS1991

Interstellar initiatives

Issues related to space exploration beyond the solar system are introduced and discussed including the interstellar medium and interstellar probes and communication. The characteristics of the interstellar medium cannot be accurately predicted, and four probes are described that are intended to travel beyond the solar system and transmit data regarding the interstellar medium. Interstellar communication is shown to be technically feasible with existing technology, and the problems associated with manned interstellar travel are listed. Factors limiting the possibilities of such travel include propulsion options, energy requirements, and the amount of time required for a given mission to a nearby star. Interstellar space is shown to be of interest to astronomers because of the possibilities of long-baseline observations in a clean observational environment.

Drysdale, Alan↗
NASA NTRS1995

The classical tests in Kaluza-Klein gravity

The possible existence of extra dimensions to spacetime can be tested astrophysically using Kaluza-Klein theory, which is a natural extension of Einsteins's general relativity. In the simplest version of the theory, there is a standard class of five-dimensional solutions that are analogous to the four-dimensional Schwarzschild solution. However, even a small departure of the extra dimension from flatness affects the first or dominant part of the potential, making it possible to test for the existence of an extra dimension. Data from the solar system indicate that in our region of space the terms due to the fifth dimension are small (less than or equal to 0.1%) compared to those due to the usual for dimensions of spacetime. However, the parameters of Kaluza-Klein theory are not universal constants and can vary from place to place depending on local physics. Hence other astrophysical systems may serve as better laboratories for investigating the possible existence of extra dimensions.

Kalligas, D.↗
NASA NTRS1997

Beginning Research with the 1.8-meter Spacewatch Telescope

The purpose of Spacewatch is to explore the various populations of small objects within the solar system. Spacewatch provides data for studies of comets and asteroids, finds potential targets for space missions, and provides information on the environmental problem of possible impacts. This grant provided some of the funds to implement Spacewatch operations on the new 1.8-m Spacewatch Telescope.

Gehrels, Tom↗
NASA NTRS1999

Laboratory Simulations of Martian and Venusian Aeolian Processes

With the flyby of the Neptune system by Voyager, the preliminary exploration of the Solar System was accomplished. Data have been returned for all major planets and satellites except the Pluto system. Results show that the surfaces of terrestrial planets and satellites have been subjected to a wide variety of geological processes. On solid- surface planetary objects having an atmosphere, aeolian processes are important in modifying their surfaces through the redistribution of fine-grained material by the wind. Bedrock may be eroded to produce particles and the particles transported by wind for deposition in other areas. This process operates on Earth today and is evident throughout the geological record. Aeolian processes also occur on Mars, Venus, and possibly Titan and Triton, both of which are outer planet satellites that have atmospheres. Mariner 9 and Viking results show abundant wind-related landforms on Mars, including dune fields and yardangs (wind-eroded hills). On Venus, measurements made by the Soviet Venera and Vega spacecraft and extrapolations from the Pioneer Venus atmospheric probes show that surface winds are capable of transporting particulate materials and suggest that aeolian processes may operate on that planet as well. Magellan radar images of Venus show abundant wind streaks in some areas, as well as dune fields and a zone of possible yardangs. The study of planetary aeolian processes must take into account diverse environments, from the cold, low-density atmosphere of Mars to the extremely hot, high- density Venusian atmosphere. Factors such as threshold wind speeds (minimum wind velocity needed to move particles), rates of erosion and deposition, trajectories of windblown particles, and aeolian flow fields over various landforms are all important aspects of the problem. In addition, study of aeolian terrains on Earth using data analogous to planetary data-collection systems is critical to the interpretation of spacecraft information and places constraints on results from numerical models and laboratory simulations.

Greeley, Ronald↗
NASA NTRS2006

Critical Evaluation of Chemical Reaction Rates and Collision Cross Sections of Importance in the Earth's Upper Atmosphere and the Atmospheres of Other Planets, Moons, and Comets

We propose to establish a long-term program of critical evaluation by domain experts of the rates and cross sections for atomic and molecular processes that are needed for understanding and modeling the atmospheres in the solar system. We envision data products resembling those of the JPL/NASA Panel for Data Evaluation and the similar efforts of the international combustion modeling community funded by US DoE and its European counterpart.

Huestis, David L.↗
NASA NTRS2014

Alteration of Lunar Rock Surfaces through Interaction with the Space Environment

Space weathering occurs on all ex-posed surfaces of lunar rocks, as well as on the surfaces of smaller grains in the lunar regolith. Space weather-ing alters these exposed surfaces primarily through the action of solar wind ions and micrometeorite impact processes. On lunar rocks specifically, the alteration products produced by space weathering form surface coatings known as patina. Patinas can have spectral reflectance properties different than the underlying rock. An understanding of patina composition and thickness is therefore important for interpreting re-motely sensed data from airless solar system bodies. The purpose of this study is to try to understand the physical and chemical properties of patina by expanding the number of patinas known and characterized in the lunar rock sample collection.

Frushour, A. M.↗