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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1963

Lunar Flight Study Series: Volume 7. Earth-Moon Transit Studies Based on Ephemeris Data and Using Best Available Computer Program: Principles for Reducing Earth-Moon Trajectory Analysis to Fundamentals - 2

This report presents an empirical investigation of earth-to-moon trajectories. The primary objective is to uncover relationships that result in the reduction of mission analysis or trajectory analysis problems to fundamentals. It is considered imperative that the results be accurate to the extent that any relationships that are uncovered are not brought about by simplifying or unrealistic assumptions. Consequently, the model used is as accurate as is presently available for use and the computations are performed under strict error controls. Procedures are reasonable from the engineering viewpoint. Some very helpful principles are uncovered. These may be briefly stated as follows: 1) Trajectories of constant flight time to the moon (in the 66 hour to 90 hour range), and arriving within a few minutes of the same time pass over a common point on the moon regardless of the arrival altitude and inclination, This common point of passage for such a family of trajectories is arbitrarily referred to as a VERTEX point; 2) These VERTEX points lie within a bounded region on the lunar surface as arrival time varies throughout the years, for a given flight time or flight time spread; 3) Increasing flight time results primarily in a longitude shift of the VERTEX point for a given arrival time; 4) Launch azimuth should be treated as a strong parameter regarding its influence on the vertex. Launch azimuth variations up to +/- 20 degrees about 90 degrees can shift the vertex as much as 3 degrees in latitude even when one is free to pick launch time, coast time, and S-IVB burn time appropriately with launch azimuth; and 5) The locus of periselenum, as arrival inclination takes on all possible values, is nearly circular about the vertex point for a given arrival altitude. A publication is now in preparation that applies these principles to much advantage in the solution of various trajectory analysis problems.

LUNAR FLIGHT↗
NASA NTRS1973

Acquisition/expulsion system for earth orbital propulsion system study. Volume 5: Earth storable design

A comprehensive analysis and parametric design effort was conducted under the earth-storable phase of the program. Passive Acquisition/expulsion system concepts were evaluated for a reusable Orbital Maneuvering System (OMS) application. The passive surface tension technique for providing gas free liquid on demand was superior to other propellant acquisition methods. Systems using fine mesh screens can provide the requisite stability and satisfy OMS mission requirements. Both fine mesh screen liner and trap systems were given detailed consideration in the parametric design, and trap systems were selected for this particular application. These systems are compatible with the 100- to 500-manned mission reuse requirements.

Source record↗
NASA NTRS1973

Earth resources applications of the Synchronous Earth Observatory Satellite (SEOS)

The results are presented of a four month study to define earth resource applications which are uniquely suited to data collection by a geosynchronous satellite. While such a satellite could also perform many of the functions of ERTS, or its low orbiting successors, those applications were considered in those situations where requirements for timely observation limit the capability of ERTS or EOS. Thus, the application presented could be used to justify a SEOS.

Lowe, D. S.↗
NASA NTRS1982

Complementary rare earth element patterns in unique achondrites, such as ALHA 77005 and shergottites, and in the earth

Abundances of major, minor, and trace elements are determined in the Antarctic achondrite Allan Hills (ALHA) 77005 via sequential instrumental and radiochemical neutron activation analysis. The rare earth element (REE) abundances of ALHA 77005 reveal a unique chondritic normalized pattern; that is, the REEs are nearly unfractionated from La to Pr at approximately 1.0X chondrites, monotonically increased from Pr to Gd at approximately 3.4X with no Eu anomaly, nearly unfractionated from Gd and Ho and monotonically decreased from Ho to Lu at approximately 2.2X. It is noted that this unique REE pattern of ALHA 77005 can be modeled by a melting process involving a continuous melting and progressive partial removal of melt from a light REE enriched source material. In a model of this type, ALHA 77005 could represent either a crystallized cumulate from such a melt or the residual source material. Calculations show that the parent liquids for the shergottites could also be derived from a light REE enriched source material similar to that for ALHA 77005.

Ma, M.-S.↗
NASA NTRS1983

On the determination of the coefficients of the Gaussian general theory of the Earth's magnetism for the year 1885 and about the relationship of the three Earth-magnetic elements

An attempt is made to judge the value of the Gaussian series for the Earth's magnetism. The computation employed to do this uses the method of the least and greatest coefficients. The number of unknown which had to be calculated from the individual groups was at most only four. All symbols of Gauss were retained.

Fritsche, H.↗
NASA NTRS1983

The measurement of the earth's radiation budget as a problem in information theory - A tool for the rational design of earth observing systems

The measurement of the earth's radiation budget has been chosen to illustrate the technique of objective system design. The measurement process is an approximately linear transformation of the original field of radiant exitances, so that linear statistical techniques may be employed. The combination of variability, measurement strategy, and error propagation is presently made with the help of information theory, as suggested by Kondratyev et al. (1975) and Peckham (1974). Covariance matrices furnish the quantitative statement of field variability.

Barkstrom, B. R.↗
NASA NTRS1987

Comparison of relativistic effects in barycentric and Earth-centered coordinates and implications for determination of GM for Earth

The results of an investigation of relativistic effects which have an influence on the determination of GM sub E (M sub E is the mass of the Earth, G is the Newtonian gravitaional constant) are summarized. The detailed arguments and derivations are discussed. The Parametrized Post-Newtonian (PPN) coordinates; Eddington-Clark (EC) coordinates; a coordinate system based on barycentric dynamical time (TBC coordinates); and Local Inertial coordinates are discussed.

Ashby, Neil↗
NASA NTRS1987

Earth materials research: Report of a Workshop on Physics and Chemistry of Earth Materials

The report concludes that an enhanced effort of earth materials research is necessary to advance the understanding of the processes that shape the planet. In support of such an effort, there are new classes of experiments, new levels of analytical sensitivity and precision, and new levels of theory that are now applicable in understanding the physical and chemical properties of geological materials. The application of these capabilities involves the need to upgrade and make greater use of existing facilities as well as the development of new techniques. A concomitant need is for a sample program involving their collection, synthesis, distribution, and analysis.

Source record↗
NASA NTRS1989

Earth observations during Space Shuttle flight STS-26: Discovery's mission to earth - September 29-October 3, 1988

During the late September-early October, 1988 flight of the Space Shuttle Discovery, astronauts took 1505 photographs of earth using handheld cameras. The resulting pictures provide an overview, not available from any other source, of dynamic environmental phenomena on five continents. The Discovery photographs show that: (1) atmospheric clarity has improved in the Northern Hemisphere, (2) widespread burning of natural vegetation throughout the Southern Hemisphere continues to generate immense smoke palls and extensive sedimentation in rivers and estuaries, and (3) although the drought in Africa was partially relieved by heavy rains in autumn, 1988, Lakes Chad and Nasser are at the lowest levels ever seen from space.

Wood, C. A.↗
NASA NTRS1990

Characteristics of the earth's radiation budget derived from the first year of data from the Earth Radiation Budget Experiment

The first year of broadband Earth Radiation Budget Experiment (ERBE) data is analyzed for top-of-the-atmosphere regional variations of outgoing longwave (LW) flux and planetary albedo for total scene as well as clear-sky conditions. The annual variation of radiative parameters is examined for February 1985 through January 1986 for selected regions, latitude zones, and the entire globe. Results show significant seasonal variations for both LW fluxes and albedo. A broad longwave flux maximum (with a relative minimum corresponding to the intertropical convergence zone in the middle) covers the tropics and the subtropics with its center moving about 20 deg in latitude between seasonal extremes. Minimum albedo (about 20 percent) occurs within 15 deg of the equator. In the tropics and midlatitudes, there is a tendency toward higher albedos during the summer. Larger albedos at the higher latitudes are caused by solar zenith angle effects and by increased snow and ice cover. Net warming occurs between 35 deg N and 35 deg S latitude near the equinoxes and in a 90-deg-wide latitude band at the solstices centered around 35 deg latitude in the summer hemisphere. This energy surplus at lower latitudes coupled with an energy deficit in the poleward regions is the primary driver of atmospheric circulations. For the year, the global net radiation is nearly in balance.

Gibson, G. G.↗
NASA NTRS1991

A rapid method of estimating the collision frequencies between the earth and the earth-crossing bodies

The present study examines a very fast method of calculating the collision frequency between two low-eccentricity orbiting bodies for evaluating the evolution of earth-orbiting objects such as space debris. The results are very accurate and the required computer time is negligible. The method is now applied without modification to calculate the collision frequencies for moderately and highly eccentric orbits.

Su, Shin-Yi↗
NASA NTRS1991

Earth observations during Space Shuttle flight STS-35 - Columbia's Mission to Planet Earth, December 2-10, 1990

Some of the most significant earth-viewing imagery obtained during Space Shuttle Columbia's flight STS-35, December 2-10, 1990, is reviewed with emphasis on observations of the Southern Hemisphere. In particular, attention is given to environmental observations in areas of Madagascar, Brazil, and Persian Gulf; observation of land resources (Namibia, offshore Australia); and observations of ocean islands (Phillipines, Indonesia, and Reunion). Some of the photographs are included.

Lulla, Kamlesh P.↗
NASA NTRS1991

Application of precise altimetry to the study of precise leveling of the sea surface, the Earth's gravity field, and the rotation of the Earth

Our program includes five research items: (1) determination of a precision geoid and gravity anomaly field; (2) precise leveling and detection of tidal changes of the sea surface and study of the role of the tide in the global energy exchange; (3) oceanic effect on the Earth's rotation and polar motion; (4) geological and geophysical interpretation of the altimetry gravity field; and (5) evaluation of the effectiveness of local tracking of TOPEX/POSEIDON by use of a laser tracker.

Segawa, J.↗