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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 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

The record of Martian climatic history in cores and its preservation

Among the questions to be addressed by a Mars Sample Return Mission are the history of the Martian climate and the mechanisms that control the volatile cycles. Unfortunately, the evidence that bears most strongly on those issues lies in the volatile distribution in, and physical configuration of, a very delicate and volatile system: the uppermost Martian regolith. Some useful measurements to be made on returned samples of the regolith are identified, along with the many critical considerations in ensuring the usefulness of returned samples.

Zent, A. P.↗
NASA NTRS1989

Strain energy release rate as a function of temperature and preloading history utilizing the edge delamination fatique test method

Static laminate and tension-tension fatigue tests of IM7/8551-7 composite materials was performed. The Edge Delamination Test (EDT) was utilized to evaluate the temperature and preloading history effect on the critical strain energy release rate. Static and fatigue testing was performed at room temperature and 180 F (82 C). Three preloading schemes were used to precondition fatigue test specimens prior to performing the normal tension-tension fatigue EDT testing. Computer software was written to perform all fatigue testing while monitoring the dynamic modulus to detect the onset of delamination and record the test information for later retrieval and reduction.

Zimmerman, Richard S.↗
NASA NTRS1989

Orders of magnitude: A history of the NACA and NASA, 1915-1990

This edition brings up to date the history of U.S. agencies for space exploration, the NACA and NASA, from 1915 through 1990. Early aviation and aeronautics research are described, with particular emphasis on the impact of the two world wars on aeronautics development and the postwar exploitation of those technologies. The reorganization and expansion of the NACA into NASA is described in detail as well as NASA's relationship with industry, the university system, and international space agencies such as the ESA. The dramatic space race of the 1950 and 1960s is recounted through a detailed histroy of the Gemini and Apollo programs and followed by a discussion of the many valuable social/scientific application of aeronautics technologies, many of which were realized through the launching of successful satellite projects. The further solar system explorations of the Voyager missions are described, as it the Challenger tragedy and the 1988 return to space of the Shuttle program. Future plans are outlined for a cooperatively funded international space station to foster the ongoing study of space science.

Bilstein, Roger E.↗
NASA NTRS1988

The resurfacing history of Mars - A synthesis of digitized, viking-based geology

A global geologic map series of Mars was digitized at high resolution (1.846 sq km/pixel). It was found that the surface of Mars is predominantly volcanic. A resurfacing history was constructed by estimating the total extent of the geologic units. Eolian resurfacing was prevalent during the Late Amazonian Epoch, affecting 4.9 x 10 to the 6th sq km. It was found that resurfacing rates vary according to the absolute-age scheme used and generally decrease with time. Resurfacing rates were approximately 1000 sq km/yr during the Middle Noachian Epoch, one hundred to several hundred sq km/yr during the Late Noachian to Late Hesperian Epochs, and tens of sq km/yr or less during the Amazonian Period.

Tanaka, Kenneth L.↗
NASA NTRS1988

Bombardment history of the Saturn system

Crater distributions on Voyager images of Saturn's satellites are analyzed and models of relative cratering rates on these bodies are developed on the basis of orbital dynamics. A history of satellite bombardment, disruption, and resurfacing in the Saturn system is constructed, concentrating on Rhea. It is suggested that the surface of Rhea has approached saturation equilibrium for craters with diameters up to 32 km. Also, the disruption probabilities of Saturn's inner moons are estimated.

Lissauer, Jack J.↗
NASA NTRS1989

An ion microprobe study of the intra-crystalline behavior of REE and selected trace elements in pyroxene from mare basalts with different cooling and crystallization histories

The effects of crystallization interaction on the trace element zoning characteristics of pyroxenes are analyzed using electron and ion microprobe techniques. Four pigeonite basalts with similar isochemical composition, but different cooling rates and crystallization histories are studied. Pyroxene quadrilaterals displaying crystallization trends are presented. The crystal chemical rationalization of REE zoning, pattern shapes, and abundances are examined. The data reveal that the trace element zoning characteristics in pyroxene and the partitioning of trace elements between pyroxene and the melt are related to the interaction between the efficiency of the crystallization process, the kinetics at the crystal-melt interface, the kinetics of plagioclase nucleation and the characteristics of the crystal chemical substitutions in the pyroxene and the associated crystallizing phase.

Shearer, C. K.↗
NASA NTRS1989

Pressure-time history of pylon wake signature on a pusher propeller in flight

Miniature, high-frequency, pressure transducers were mounted on a pusher propeller at 3/4 and 90-percent radii. Time-history of fluctuating surface pressure over 700 revolutions and 26 flight conditions reveal intriguing phenomena. The anticipated pylon wake signature manifests itself as a negative pressure pulse over extended portions of the suction surface. The phenomenon further develops into a primarily random turbulence signature at 80-percent chord and interestingly may reevolve as a coherent wake signature further downstream. A new type of periodic disturbance of long time-scale, compared to propeller period-of-revolution, is discovered at positions beyond 0.6 chord on the suction surface in the transonic regime.

Farokhi, Saeed↗
NASA NTRS1989

The origin, composition and history of cometary ices from spectroscopic studies

The spectroscopic analysis of pristine cometary material provides a very important probe of the chemical identity of the material as well as of the physical and chemical conditions which prevailed during the comet's history. Concerning classical spectroscopy, the spectral regions which will most likely prove most useful are the infrared, the visible and ultraviolet. Newer spectroscopic techniques which have the potential to provide equally important information include nuclear magnetic resonance (NMR) and electron spin resonance (ESR). Each technique is summarized with emphasis placed on the kind of information which can be obtained.

Allamandola, L. J.↗
NASA NTRS1989

Cosmogenic nuclides in cometary materials: Implications for rate of mass loss and exposure history

As planned, the Rosetta mission will return to earth with a 10-kg core and a 1-kg surface sample from a comet. The selection of a comet with low current activity will maximize the chance of obtaining material altered as little as possible. Current temperature and level of activity, however, may not reliably indicate previous values. Fortunately, from measurements of the cosmogenic nuclide contents of cometary material, one may estimate a rate of mass loss in the past and perhaps learn something about the exposure history of the comet. Perhaps the simplest way to estimate the rate of mass loss is to compare the total inventories of several long-lived cosmogenic radionuclides with the values expected on the basis of model calculations. Although model calculations have become steadily more reliable, application to bodies with the composition of comets will require some extension beyond the normal range of use. In particular, the influence of light elements on the secondary particle cascade will need study, in part through laboratory irradiations of volatile-rich materials. In the analysis of cometary data, it would be valuable to test calculations against measurements of short-lived isotopes.

Herzog, G. F.↗
NASA NTRS1989

Thermal histories of the samples of two KOSI comet nucleus simulation experiments

Temperatures recorded during two KOSI comet nucleus simulation experiments strongly suggest that heat transport by vapor flow into the interior of the sample is very important. Two comet nucleus simulation experiments have been done by the KOSI team in a big space simulator. The thermal evolution of the sample during insolation and the results of simplified thermal evolution calculations are discussed. The observed thermal histories cannot be explained by a simple model with heat transferred by heat conduction at a constant conductivity, so a coupled heat and mass transfer problem was considered. The porous ice matrix was assumed to have a constant thermal conductivity and to be in thermal equilibrium with vapor in the pores, the internal pressure being the vapor pressure. The vapor was modelled as an ideal gas because, at the temperatures relevant to the problem, the mean free path length of the vapor molecules is large in comparison with the pore dimensions. The heat capacity at constant volume per unit mass of the two phase mixture was also assumed constant. The vapor was allowed to flow and transfer heat in response to an internal pressure gradient.

Spohn, T.↗
NASA NTRS1989

Asteroid collisional history - Effects on sizes and spins

The effects of asteroid collisional history on sizes and spins of present-day objects are discussed. Collisional evolution studies indicate that collisions have altered the spin-rates of small bodies, but that the largest asteroids may have retained their primordial rotation rates. Most asteroids larger than 100 km diam have probably been shattered, but have gravitationally recaptured their fragments to form a rubble-pile structure. Large angular momentum asteroids appear to have Maclaurian spheroidal or Jacobi-ellipsoid-like shapes; some of them may have fissioned into binaries. An integrated size and spin collisional evolution model is presented, with two critical parameters: one which determines the spin rates for small fragments resulting from a shattering collision, and the other determines the fraction of impact angular momentum that is retained by the target.

Davis, Donald R.↗
NASA NTRS1990

Volume loss and defluidization history of Barbados

A history of pore volume loss and defluidization of accreted sediments of the basal complex of Barbados island is presented. The structural evolution of the basal complex and evidence for past and present volumetric changes are addressed by examining varied phenomena, with emphasis on porosity-depth data. The empirical findings are used to consider questions such as the position-age profile of pore volume loss relative to other deformation components in the growing prism and the type of loading that principally caused pore volume loss.

Speed, R.↗
NASA NTRS1990

Thermal history of Mars and the sulfur content of its core

A model for thermal evolution of the Martian mantle and core and for the evolution of the Martian magnetic field is developed by expanding the planetary thermal history model of Stevenson et al. (1983) and using the energy balance equations from that work. Several parameter values are chosen differently from those of the Stevenson model, including those for mantle density, core radius, core density, central pressure, and pressure at the core-mantle boundary. The model is further modified to allow calculations of lithosphere thickness through time. According to the model, the core contains a light alloying constituent, assumed to be sulfur. The results of calculations show that a small Martian magnetic field can be generated by a weakly convecting liquid core.

Schubert, Gerald↗
NASA NTRS1990

Constraints on early events in Martian history as derived from the cratering record

Constrains on early events in Martian history are derived using the planet's cratering record. Variations in the shapes of the crater size-frequency distribution curves are interpreted as indicative of the size-frequency distribution of the production populations, thus providing information about the age of the unit relative to the end of the heavy bombardment period. Results from the analysis of craters superposed on heavily cratered units across the Martian surface provide constraints on the hemispheric dichotomy and the early erosional conditions on Mars.

Barlow, Nadine G.↗
NASA NTRS1990

Resurfacing history of Tempe Terra and surroundings

The resurfacing history of the Tempe Terra region is examined on the basis of an analysis of cumulative frequency curves for individual terrain units within Tempe Terra and its surroundings. The results of the analysis, which was carried out using the techniques of Neukum and Hiller (1981), suggest that three major resurfacing events occurred in this region, with crater retention ages N(1) (the cumulative number of craters larger than 1 km diameter per million square kilometer) of (242,100), (95,700), (20,800), and (5500). These results are interpreted as indicative of three major resurfacing events occurring in this region, ending at N(1) = (95,700), (20,800), and (5500). It is shown that it is possible to extend this technique to derive not only ages for major resurfacing events, but the minimum extent of the now-buried surfaces and the thickness of the materials involved in each major resurfacing event.

Frey, Herbert V.↗
NASA NTRS1991

X-15: the Perspective of History

The linkages between the Apollo 11 voyage to Tranquility Base and the 199 flights of the X-15 aircraft are discussed. Accomplishments of the X-15 program and a history of aircraft developments that led up to the X-15 are presented.

Hallion, Richard P.↗
NASA NTRS1991

Water on Mars: Volatile history and resource availability

The existence of water on Mars is undisputed today. Measurements of atmospheric water vapor have shown that the abundance varies with location and season in a systematic way which depends on processes of exchange with the polar caps, regolith, and atmosphere. Channels, which give the appearance of having been carved by water or of having had water involved in their formation, appear in various locations on the surface; some were formed by catastrophic outflow of water from beneath the surface, while others form valley networks which give the appearance of having formed over long periods of time primarily early in the planet's history. The north polar residual cap consists of water ice, possibly containing an amount of water equivalent to a global layer several tens of meters thick. Finally, water is observed within the regolith, as adsorbed water or as water of hydration.

Jakosky, Bruce M.↗
NASA NTRS1990

Creating a rocket-building institution - The history of the Marshall Space Flight Center

This paper will examine the early history of NASA Marshall Space Flight Center to identify major changes in the Center during the period that it was responsible for developing the Saturn family of launch vehicles. The principal conclusion is that the unique change experienced by Marshall during the Saturn era was its shift from an in-house, self-sustaining organization to an institution responsible for managing the Saturn-related performance of a nationwide network of aerospace contractors.

Wright, Michael D.↗