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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Study of meteoroid impact craters on various materials (A0138-1)

Interplanetary dust particles (micrometeoroids) are expected to form well-defined craters upon impacting exposed material in space. Studying the frequency and features of these craters will provide data on the mass-flux distribution of micrometeoroids and, to a lesser extent, on the velocity magnitude and direction. This experiment will study impact craters produced by micrometeoroids on selected materials (metals and glasses in the form of thick targets) to obtain valuable technological and scientific data. Specifically, the studies will focus on determining micrometeoroid composition and mass-flux distribution. Analyses will also be made on the distribution of impact velocity vectors.

Mandeville, J. C.↗
NASA NTRS1991

Study of meteoroid impact craters on various materials (AO 138-1). Attempt at dust debris collection with stacked detectors (AO 138-2)

Part of the Long Duration Exposure Facility (LDEF) tray allocated to French experiments, known as FRECOPA payload, was devoted to the study of dust particles. Two passive experiments were flown: one composed of a set of glass and metallic samples and one composed of multilayer thin foils detectors. In addition to these experiments, a broad variety of materials were exposed to the bombardment of microparticles and provide more data. Thick target experiment comprises selected metallic (Al, Au, Cu, W, Stainless Steel) 250 microns thick and glass surfaces 1.5 mm thick. Crater size distribution from these thick target experiments enable, with the aid of lab calibrations by solid particle accelerators, the evaluation of the incident microparticle flux in the near earth environment. The aim of the multiple foil penetration and collection experiment is primarily to study the feasibility of multilayer thin film detectors acting as energy sorters in order to collect micrometeoroids, if not in their original shape, at least as 'breakup' fragments suitable for chemical analysis. Foil thicknesses range from 0.75 to 5 microns of Al.

Mandeville, Jean Claude↗
NASA NTRS1992

Interplanetary meteoroid debris in LDEF metal craters

The extraterrestrial meteoroid residue found lining craters in the Long Duration Exposure Facility (LDEF) aluminum and gold targets is highly variable in both quantity and type. In typical craters only a minor amount of residue is found and for these craters it is evident that most of the impacting projectile was ejected during crater formation. Less than 10 percent of the craters greater than 100 microns contain abundant residue consistent with survival of a major fraction of the projectile. In these cases the residue can be seen optically as a dark liner and it can easily be analyzed by SEM-EDX techniques. Because they are rare, the craters with abundant residue must be a biased sampling of the meteoroids reaching the earth. Factors that favor residue retention are low impact velocity and material properties such as high melting point. In general, the SEM-EDX observations of crater residues are consistent with the properties of chondritic meteorites and interplanetary dust particles collected in the stratosphere. Except for impacts by particles dominated by single minerals such as FeS and olivine, most of the residue compositions are in broad agreement with the major element compositions of chondrites. In most cases the residue is a thin liner on the crater floor and these craters are difficult to quantitatively analyze by EDX techniques because the electron beam excites both residue and underlying metal substrate. In favorable cases, the liner is thick and composed of vesicular glass with imbedded FeNi, sulfide and silicate grains. In the best cases of meteoroid preservation, the crater is lined with large numbers of unmelted mineral grains. The projectiles fragmented into micron sized pieces but the fragments survived without melting. In one case, the grains contain linear defects that appear to be solar flare tracks. Solar flare tracks are common properties of small interplanetary particles and their preservation during impact implies that the fragments were not heated above 600 C. We are investigating the meteoroid fragments in LDEF metal craters to determine the properties of interplanetary dust and to determine if there are meteoroid types that are overlooked or otherwise undetected in cosmic dust collections obtained from the stratosphere and polar ice.

Brownlee, D. E.↗
NASA NTRS1972

Meteoroid impacts on Mars and the secondary particle environment

The degree to which the thin Martian atmosphere filters out meteoroids approaching the Martian surface was calculated by using a model of the meteoroid environment, a model of the Martian atmosphere, and equations of meteor physics. The secondary particle environment on the surface of Mars caused by the material ejected from meteoroid craters was modeled. The model consists of the mass distribution and the speed distribution of the secondary particles. Calculations were made of the penetration flux for aluminum structures on the Martian surface. The penetration hazard on the Martian surface was compared with the penetration hazard in space near Mars and on the lunar surface.

Humes, D. H.↗
NASA NTRS1978

An estimate of particulates in the vicinity of a Shuttle orbiter due to meteoroid impact

An estimate of the magnitude of released particles in the vicinity of a a Shuttle (STS) Orbiter due to meteoroid impact has been completed. A calculation of the number of particles existing as surface contamination and released by such impacts has been performed. In addition, two estimates of the creation of new particles due to meteoroid cratering (backsplash) have been obtained. In each case, the total number of particles per day as a function of size without regard to velocity, as a function of velocity without regard to size, and as a joint distribution in size and velocity has been calculated.

Barengoltz, J.↗
NASA NTRS1985

Horizons and Opportunities in Lunar Sample Science

The Moon is the cornerstone of planetary science. Lunar sample studies were fundamental in developing an understanding of the early evolution and continued development of planetary bodies, and have led to major revisions in understanding of processes for the accumulation of planetesimals and the formation of planets. Studies of lunar samples have increased an understanding of impact cratering, meteoroid and micrometeoroid fluxes, the interaction of planetary surfaces with radiations and particles, and even the history of the Sun. The lunar sample research program was especially productive, but by no means have all the important answers been determined; continued study of lunar samples will further illuminate the shadows of our knowledge about the solar system. Further, the treasures returned through the Apollo program provide information that is required for a return to the Moon, beginning with new exploration (Lunar Geoscience Observer (LGO)), followed by intensive study (new sample return missions), and eventually culminating in a lunar base and lunar resource utilization. The few years during and following Apollo were a hectic time for lunar science. Since then, considerable maturation of the science and distinct changes in the mode of operation have developed. Funding (and hence the number of investigators) has naturally declined. Studies have become far more problem-oriented than descriptive. Many sample investigators have shifted their sights away from planetary evolution, for which the Moon holds considerable information, toward processes and materials in the pre-planetary solar nebula, for which the Moon has no direct evidence. Nonetheless, unique scientific opportunities are still supplied by the samples returned from the Apollo and Luna missions and by lunar meteorites. These 382 kg of samples constitute a priceless resource that still has enormous scientific potential. Continued interaction between NASA and the scientific community, especially through the advice of groups such as the Lunar and Planetary Sample Team (LAPST), is essential in maintaining the current level of excellence of the program. LAPST has reviewed its role, the role of the sample research community, and the perceived role of future researchers over the next decade in ensuring the effective use of lunar sample studies in space exploration and exploitation. The review encompasses: (I) lunar sample science; (2) lunar materials applications; (3) lunar sample studies and their relation to future space missions; and (4) lunar sample curation. Plans in all four areas are summarized in this document.

Source record↗
NASA NTRS1995

The Long Duration Exposure Facility (LDEF) photographic survey special publication

During the construction, integration, launch, retrieval and deintegration of the Long Duration Exposure Facility (LDEF), photographic surveys were made. Approximately 10,000 photographs were taken during the various phases of the LDEF project. These surveys are of technical and scientific importance because they revealed the pre and post flight conditions of the experiment trays as well as the spacecraft. Visual inspection of the photographs reveal valuable data such as space environment's effects and the earth atmosphere's effects post-retrieval. Careful files and records have been kept of these photographs. Each photograph has a Kennedy Space Center photo number or a Johnson Spaceflight Center photo number as well as a Langley Research Center photo number. The tray number, row number, and experiment number are also noted. Out of the 10,000 photographs taken, approximately 700 selected photographs were chosen for publication in a NASA Special Publication (SP) because they reveal the effects of space exposure to the viewer. These photographs will give researchers and spacecraft designers visual images of the effects of the space environment on specific materials, systems and spacecraft in general. One can visually see the degradation of thermal blankets, meteoroid craters, outgassing discoloration, atomic oxygen erosion, etc.

Oneal, Robert L.↗
NASA NTRS1991

Large craters on the meteoroid and space debris impact experiment

The distribution around the Long Duration Exposure Facility (LDEF) of 532 large craters in the Al plates from the Meteoroid and Space Debris Impact Experiment (S0001) is discussed along with 74 additional large craters in Al plates donated to the Meteoroid and Debris Special Investigation Group by other LDEF experimenters. The craters are 0.5 mm in diameter and larger. Crater shape is discussed. The number of craters and their distribution around the spacecraft are compared with values predicted with models of the meteoroid environment and the manmade orbital debris environment.

Humes, Donald H.↗
NASA NTRS1995

Small craters on the meteoroid and space debris impact experiment

Examination of 9.34 m(exp 2) of thick aluminum plates from the Long Duration Exposure Facility (LDEF) using a 25X microscope revealed 4341 craters that were 0.1 mm in diameter or larger. The largest was 3 mm in diameter. Most were roughly hemispherical with lips that were raised above the original plate surface. The crater diameter measured was the diameter at the top of the raised lips. There was a large variation in the number density of craters around the three-axis gravity-gradient stabilized spacecraft. A model of the near-Earth meteoroid environment is presented which uses a meteoroid size distribution based on the crater size distribution on the space end of the LDEF. An argument is made that nearly all the craters on the space end must have been caused by meteoroids and that very few could have been caused by man-made orbital debris. However, no chemical analysis of impactor residue that will distinguish between meteoroids and man-made debris is yet available. A small area (0.0447 m(exp 2)) of one of the plates on the space end was scanned with a 200X microscope revealing 155 craters between 10 micron and 100 micron in diameter and 3 craters smaller than 10 micron. This data was used to extend the size distribution of meteoroids down to approximately 1 micron. New penetration equations developed by Alan Watts were used to relate crater dimensions to meteoroid size. The equations suggest that meteoroids must have a density near 2.5 g/cm(exp 3) to produce craters of the shape found on the LDEF. The near-Earth meteoroid model suggests that about 80 to 85 percent of the 100 micron to 1 mm diameter craters on the twelve peripheral rows of the LDEF were caused by meteoroids, leaving 15 to 20 percent to be caused by man-made orbital debris.

Humes, Donald H.↗
NASA NTRS1992

Large craters on the meteoroid and space debris impact experiment

Examination of 29.37 sq m of thick aluminum plates from the LDEF, which were exposed to the meteoroid and man-made orbital debris environments for 5.8 years, revealed 606 craters that were 0.5 mm in diameter or larger. Most were nearly hemispherical. There was a large variation in the number density of craters around the three axis gravity gradient stabilized spacecraft. A new model of the near-Earth meteoroid environment gives good agreement with the crater fluxes measured on the fourteen faces of the LDEF. The man-made orbital debris model of Kessler, which predicts that 16 pct. of the craters would be caused by man-made debris, is plausible. No chemical analyses of impactor residue that will distinguish between meteoroids and man-made debris is yet available.

Humes, Donald H.↗
NASA NTRS1994

Effects of the Venusian atmosphere on incoming meteoroids and the impact crater population

The dense atmosphere on Venus prevents craters smaller than about 2 km in daimater from forming and also causes formation of several crater fields and multiple-floored craters (collectively referred to as multiple impacts). A model has been constructed that simulates the behavior of a meteoroid in a dense planetary atmosphere. This model was then combined with an assumed flux of incoming meteoroids in an effort to reproduce the size-frequency distribution of impact craters and several aspects of the population of the crater fields and multiple-floored craters on Venus. The modeling indicates that it is plausible that the observed rollover in the size-frequency curve for Venus is due entirely to atmospheric effects on incoming meteoroids. However, there must be substantial variation in the density and behavior of incoming meteoroids in the atmosphere. Lower-density meteoroids must be less likely to survive atmospheric passage than simple density differences can account for. Consequently, it is likely that the percentage of craters formed by high-density meteoroids is very high at small crater diameters, and this percentage decreases substantially with increasing crater diameter. Overall, high-density meteoroids created a disproportionately large percentage of the impact craters on Venus. Also, our results indicate that a process such as meteoroid flattening or atmospheric explosion of meteoroids must be invoked to prevent craters smaller than the observed minimum diameter (2 km) from forming. In terms of using the size-frequency distribution to age-date the surface, the model indicates that the observed population has at least 75% of the craters over 32 km in diameter that would be expected on an atmosphereless Venus; thus, this part of the curve is most suitable for comparison with calibrated curves for the Moon.

Herrick, Robert R.↗
NASA NTRS1993

Interplanetary meteoroid debris in LDEF metal craters

We have examined craters in Al and Au LDEF surfaces to determine the nature of meteoroid residue in the rare cases where projectile material is abundantly preserved in the crater floor. Typical craters contain only small amounts of residue and we find that less than 10 percent of the craters in Al have retained abundant residue consistent with survival of a significant fraction (greater than 20 percent) of the projectile mass. The residue-rich craters can usually be distinguished optically because their interiors are darker than ones with little or no apparent projectile debris. The character of the meteoroid debris in these craters ranges from thin glass liners, to thick vesicular glass containing unmelted mineral fragments, to debris dominated by unmelted mineral fragments. In the best cases of meteoroid survival, unmelted mineral fragments preserve both information on projectile mineralogy as well as other properties such as nuclear tracks caused by solar flare irradiation. The wide range of the observed abundance and alteration state of projectile residue is most probably due to differences in impact velocity. The crater liners are being studied to determine the composition of meteoroids reaching the Earth. The compositional types most commonly seen in the craters are: (1) chondritic (Mg, Si, S, Fe in approximately solar proportions), (2) Mg silicate. amd (3) iron sulfide. These are also the most common compositional types of extraterrestrial particle types collected in the stratosphere. The correlation between these compositions indicates that vapor fractionation was not a major process influencing residue composition in these craters. Although the biases involved with finding analyzable meteoroid debris in metal craters differ from those for extraterrestrial particles collected in and below the atmosphere, there is a common bias favoring particles with low entry velocity. For craters this is very strong and probably all of the metal craters with abundant residue were caused by asteroidal dust impacting at minimum velocities.

Brownlee, D. E.↗
NASA NTRS2017

A Comparison of Results from NASA's Meteoroid Engineering Model to the LDEF Cratering Record

NASA's Long Duration Exposure Facility (LDEF) has provided an extensive record of the meteoroid environment in low Earth orbit. LDEF's combination of fixed orientation, large collecting area, and long lifetime imposes constraints on the absolute flux of potentially hazardous meteoroids. The relative impact rate on each of LDEF's fourteen surfaces arises from the underlying velocity distribution and directionality of the meteoroid environment. For the first time, we model the meteoroid environment encountered by LDEF over its operational lifetime using NASA's Meteoroid Engineering Model Release 2 (MEMR2) and compare the model results with the observed craters of potentially hazardous meteoroids (i.e. crater diameters larger than approximately 0.75 mm). We discuss the extent to which the observations and model agree and how the impact rates across all of the LDEF surfaces may be utilized to help calibrate future versions of MEM.

Ehlert, S.↗
NASA NTRS2017

A Comparison of Results From NASA's Meteoroid Engineering Model to the LDEF Cratering Record

NASA's Long Duration Exposure Facility (LDEF) has provided an extensive record of the meteoroid environment in Low Earth Orbit. LDEF's combination of fixed orientation, large collecting area, and long lifetime imposes constraints on the absolute flux of potentially hazardous meteoroids. The relative impact rate on each of LDEF's fourteen surfaces arises from the underlying velocity distribution and directionality of the meteoroid environment. For the first time, we model the meteoroid environment encountered by LDEF over its operational lifetime using NASA's Meteoroid Engineering Model Release 2 (MEMR2) and compare the model results with the observed craters of potentially hazardous meteoroids (i.e. crater diameters larger than approximately 0.6 mm). We discuss the extent to which the observations and model agree and how the impact rates across all of the LDEF surfaces may suggest improvements to the underlying assumptions that go into future versions of MEM.

Ehlert, S.↗
NASA NTRS1994

Morphology of meteoroid and space debris craters on LDEF metal targets

We measured the depths, average diameters, and circularity indices of over 600 micrometeoroid and space debris craters on various metal surfaces exposed to space on the Long Duration Exposure Facility (LDEF) satellite, as a test of some of the formalisms used to convert the diameters of craters on space-exposed surfaces into penetration depths for the purpose of calculating impactor sizes or masses. The topics covered include the following: targe materials orientation; crater measurements and sample populations; effects of oblique impacts; effects of projectile velocity; effects of crater size; effects of target hardness; effects of target density; and effects of projectile properties.

Love, S. G.↗
NASA NTRS1983

Crater ejecta scaling laws - Fundamental forms based on dimensional analysis

Self-consistent scaling laws are developed for meteoroid impact crater ejecta. Attention is given to the ejection velocity of material as a function of the impact point, the volume of ejecta with a threshold velocity, and the thickness of ejecta deposit in terms of the distance from the impact. Use is made of recently developed equations for energy and momentum coupling in cratering events. Consideration is given to scaling of laboratory trials up to real-world events and formulations are developed for calculating the ejection velocities and ejecta blanket profiles in the gravity and strength regimes of crater formation. It is concluded that, in the gravity regime, the thickness of an ejecta blanket is the same in all directions if the thickness and range are expressed in terms of the crater radius. In the strength regime, however, the ejecta velocities are independent of crater size, thereby allowing for asymmetric ejecta blankets. Controlled experiments are recommended for the gravity/strength transition.

Housen, K. R.↗