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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Investigation of substrate-mounted thin-film meteoroid sensors for use in large area impact experiments

Two types of sensor designs were investigated: (1)a polysulfone dielectric film with vapor-deposited aluminum and gold sensor plates, bonded to a relatively thick aluminum substrate, and (2) an aluminum oxide (A1203) dielectric layer prepared on an aluminum substrate by anodization, with a layer of vapor-deposited aluminum providing one sensor plate and the substrate serving as the other plate. In the first design, specimens were prepared which indicate the state of the art for application of this type of sensor for elements of a meteoroid detection system having an area as large as 10 sq M. Techniques were investigated for casting large-area polysulfone films on the surface of water and for transferring the films from the water. Methods of preparing sensors by layering of films, the deposition of capacitor plates, and sensor film-to-substrate bonding, as well as techniques for making electrical connections to the capacitor plates, were studied.

Carollo, S. F.↗
NASA NTRS1973

Study of meteoroid detection systems applicable to the outer planets missions

Modifications to the Pioneer 10/11 meteoroid detection experiment to allow it to be used for outer planet missions were investigated. Both pressurized cells and metal-oxide silicon (MOS) penetration detectors are considered. Both the sensors systems and the electronics are treated. Investigation of the calibration and characterization of the MOS penetration detector is reported.

Brooks, A. D.↗
NASA NTRS1973

Production of lunar fragmental material by meteoroid impact.

The rate of production of new fragmental lunar surface material is derived theoretically on the hypothesis that such material is excavated from a bedrock layer by meteoroid impacts. An overlaying regolith effectively shields the bedrock layer from small impacts, reducing the production rate of centimeter-sized and smaller blocks by a large factor. Logarithmic production rate curves for centimeter to motor-sized blocks are nonlinear for any regolith from centimeters to tens of meters in thickness, with small blocks relatively much less frequent for thicker (older) regoliths, suggesting the possibility of a statistical reverse bedding. Modest variations in the exponents of scaling laws for crater depth-diameter ratio and maximum block-diameter to crater diameter ratio are shown to have significant effects on the production rates. The production rate increases slowly with increasing size of the largest crater affecting the region.

Marcus, A. H.↗
NASA NTRS1973

Space Tug Point Design Study. Volume 3: Design Definition. Part 2: Insulation, Meteoroid Protection, Structures, Mass Properties, GSE, Reliability and Safety

A study was conducted to determine the configuration and performance of a space tug. Detailed descriptions of the insulation, meteoroid protection, primary structure, and ground support equipment are presented. Technical assessments leading to the concept selection are analyzed. The tug mass properties, reliability, and safety assessments are included.

Source record↗
NASA NTRS1974

Description of the meteoroid detection experiment flown on the Pioneer 10 and 11 Jupiter flyby missions

The meteoroid detection experiment has the objective of measuring the population of 10 to the minus 9th power and 10 to the minus 8th power grams mass particles in interplanetary space with emphasis on making these measurements in the Asteroid Belt. The instrument design, which uses the pressurized-cell-penetration detection technique, and the tests involved in obtaining a flight-qualified instrument are described. The successful demonstration of flight-quality penetration detectors to function properly under long-term simulated space environments is also described.

Oneal, R. L.↗
NASA NTRS1975

Study to define low voltage and low temperature operating limits of the Pioneer 10/11 Meteoroid Detection Equipment (MDE) system

The Pioneer 10/11 meteoroid detection equipment (MDE) pressure cells were tested at liquid nitrogen (LN2) and liquid helium (LHe) temperatures with the excitation voltage controlled as a parameter. The cells failed by firing because of pressurizing gas condensation as the temperature was lowered from LN2 to LHe temperature and when raised from LHe temperature. A study was conducted to determine cell pressure as a function of temperature, and cell failure was estimated as a function of temperature and excitation voltage. The electronic system was also studied, and a profile of primary spacecraft voltage (nominally 28 Vdc) and temperature corresponding to electronic system failure was determined experimentally.

Parker, C. D.↗
NASA NTRS1976

Results of the asteroid-meteoroid particle experiment on Pioneer 11

The Asteroid-Meteoroid Detector, an electro-optical instrument that detects and measures particles in space by sensing the sunlight reflected from them, is part of the payload of both the Pioneer 10 and 11 spacecraft. The Pioneer 11 instrument is essentially identical to that on Pioneer 10, with some minor modifications. Reduction of the Pioneer 11 data was complicated by the failure of one of the four sensor channels at about 1.1 AU from the sun. Detailed analysis yielded 51 events between 1.0 and 3.5 AU, which were used to determine the particle concentration distribution in that region of space. Weighted curve-fitting of the results shows agreement with the concentrations derived from Pioneer 10 to within about a factor of two. As with the Pioneer 10 results, the exponent of the size dependency varies from about -1.7 for 100-micron radius particles to about -3.2 for 10-cm bodies. The instrument, its operation, and the method of data analysis are reviewed.

Soberman, R. K.↗
NASA NTRS1978

Albedos and size distribution of meteoroids from 0.3 to 4.8 AU

Observational data are compared on the distribution of very small micrometeoroids (1 billionth to 1 hundred-millionth g), the scattering source function of the zodiacal light, the distribution of larger micrometeoroids (at least 1 hundred-thousandth g) as observed from Helios A and Pioneer 10, and the distribution of meteoroids from the sample seen from earth. The experiments, analyses, and simulations involved in obtaining these data are described in detail. It is shown that the various groups of data can be reconciled only by small albedos that decrease outward from 0.1 to at least about 3.3 AU for the particles which produce both the zodiacal light and the observed meteors. The results also indicate that there must be a maximum in the distribution of the larger particles somewhere between the orbits of earth and Jupiter. It is suggested that a search for fireballs in Jupiter's atmosphere by the television cameras of the MJS 77 mission should aid in locating this maximum.

Cook, A. F.↗
NASA NTRS1978

Meteoroids from periodic comet d'Arrest

The predicted anomalous tail of periodic comet d'Arrest was photographed and photometrically studied. The derived particle-size distribution function varies inversely according to slightly higher than the 4-th power of the size. Particle dimensions span a few orders of magnitude, the mean size being in the general range of 0.01 to 0.1 cm depending on the assumed bulk density. The determination of the amount of the ejected dust is complicated by large uncertainties in the particle albedo. The product of the particle albedo and of the production rate of meteoroids that remain gravitationally bound to the solar system is found to be about 3000 g/s at the time of maximum activity and some 200 g/s when averaged over the comet's revolution period. The contribution of the comet to the interplanetary dust cloud is insignificant, unless the albedo of the debris from the comet is as low as 0.1 percent.

Sekanina, Z.↗
NASA NTRS1978

New lunar microcrater evidence against a time varying meteoroid flux

An attempt to measure the relative times of formation of 25 microcraters on lunar rock 60015 is discussed which was carried out as part of a study of the flux of interplanetary dust and possible time variations of that flux over periods of 1000 to 1 million yr. The data obtained could indicate that the formation rate of 100-micron-sized pits was lower in the past as compared with the formation rate of micron-sized pits, that the flux of particles forming 100-micron-sized pits may have varied relative to that of particles forming micron-sized pits, or that 100-micron-sized pits are forming now at a higher rate, relative to the formation rate of accretionary disks, than in the past. The last suggestion is shown to be almost untenable, and the overall results are found to lead to a logical paradox. It is concluded that the attempt probably failed and that the reason for failure raises serious questions regarding the use of lunar rock surfaces as meteoroid detectors.

Hartung, J. B.↗
NASA NTRS1979

Meteoroid Protection Methods for Spacecraft Radiators Using Heat Pipes

Various aspects of achieving a low mass heat pipe radiator for the nuclear electric propulsion spacecraft were studied. Specific emphasis was placed on a concept applicable to a closed Brayton cycle power sub-system. Three aspects of inter-related problems were examined: (1) the armor for meteoroid protection, (2) emissivity of the radiator surface, and (3) the heat pipe itself. The study revealed several alternatives for the achievement of the stated goal, but a final recommendation for the best design requires further investigation.

Ernst, D. M.↗