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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 NTRS2019

Simulating Space Weathering in the Transmission Electron Microscope via Dynamic in Situ Heating and Helium Irradiation of Olivine

The chemical composition, microstructure, and optical properties of grains on the surfaces of airless bodies are predominantly altered by micrometeorite impacts and solar wind irradiation. These processes drive space weathering and result in the formation of features including chemically-altered, amorphous grain rims, Fe nanoparticles (npFe), and vesiculated grain textures. These characteristics have been identified in returned samples from the surfaces of the Moon and asteroid Itokawa. In order to advance our understanding of the formation of these microstructural and chemical features in returned samples, we have simulated space weathering processes for a variety of materials via laboratory experiments. These experiments include ion irradiation to simulate solar wind exposure and laser irradiation and in situ heating to simulate micrometeorite impacts. While these experiments have provided considerable insight into the formation mechanisms of many space weathering features, they are predominantly static and typically performed separately. Here we present results from the simulated space weathering of olivine grains via He irradiation and dynamic heating, both performed in situ inside the transmission electron microscope (TEM). These experiments allow for the real-time observation of chemical and microstructural changes resulting from the superposed effects of ion irradiation and pulsed heating.

Thompson, M. S.↗
NASA NTRS2019

Coordinated Analysis of an Experimentally Space Weathered Carbonaceous Chondrite

The surfaces of airless bodies experience solar wind irradiation and micrometeorite impacts, a process collectively known as space weathering. These mechanisms alter the chemical composition, microstructure, and optical properties of surface materials and considerable work has been done to understand this phenomenon in lunar and ordinary chondritic materials. However, ongoing sample return missions Hayabusa2 to asteroid Ryugu and OSIRIS-REx to asteroid Bennu have prompted the need to study the effects of space weathering on hydrated, organic-rich materials, especially in the context of early results. Understanding space weathering of these samples is critical for properly interpreting remote sensing data during asteroid encounters, for sample site selection, and for the eventual study of returned samples. We can better understand space weathering of carbonaceous materials by simulating these processes in the laboratory. Recent experiments have shown that the changes in spectral characteristics of carbonaceous chondrites are not consistent among experiments, suggesting additional work is needed before these results can inform our understanding of spectral variations on asteroidal surfaces. Similarly, substantial work remains to characterize the chemical and microstructural effects of these processes in order to correlate these features with spectral changes. Here, we build on our previous work, presenting new results of the pulsed laser irradiation of the Murchison (CM2) meteorite to simulate micrometeorite impacts and the progressive space weathering of carbonaceous surfaces.

Thompson, M. S.↗
NASA NTRS2024

Influence of Ductility on the Performance of Lunar Habitat Structures Under Recurrent Disturbances

This research examines how ductility affects the durability of lunar surface structures against recurring disturbances like moonquakes, micrometeorite impacts, and thermal cycles over an extended period. The structural performance at various levels of ductility was determined by adjusting material parameters and the thickness of a reference multilayered dome structure. Moonquake and micrometeorite impact-induced lateral displacements were estimated using a reduced-order model under a control-oriented dynamic computational modeling framework. The study considered the degradation of the metallic dome’s strength properties over time due to thermal cycles. Fragility curves were generated by assessing the likelihood of reaching three predefined damage levels as a result of multiple hazards. Additionally, a discounted cash flow analysis was conducted to incorporate a financial aspect into the performance comparison. The findings revealed that structures with sufficient ductility capacity have a lower probability of sustaining severe damage or collapsing within a shorter time frame. Hence, having ductile structures in lunar environments is advantageous as it allows the postponement of maintenance and repair actions, thereby conserving scarce resources for more urgent tasks. Moreover, the financial analysis demonstrated that lunar habitats with higher ductile capacities result in larger net present values, offering a higher return on the initial investment.

Arsalan Majlesi↗
NASA NTRS1967

Zodiacal dust and deep-sea sediments.

Zodiacal dust explained by radioactive Al 26 deposited in marine sediments and brought by micrometeorites exposed to solar protons

ZODIACAL DUST CLOUD↗
NASA NTRS1961

Radiation Observations with Satellite 1958 Alpha Explorer I

On 1 February 1958 at 0348 U.T. earth satellite 1958 Alpha (Explorer I) was launched from Cape Canaveral. This satellite contained a Geiger Muller tube for the measurement of the flux of energetic charged particles, and detectors for determining the micrometeorite flux and satellite temperature (see Figure 1), The high power transmitter and its associated instrumentation operated until partial exhaustion of the transmitter batteries on 12 February 1958. The transmitter reappeared briefly on 24 February, The low power system operated properly until about 0700 U,T, on 16 March, at which time the batteries powering the G.M. tube circuits became exhausted. During the operating time a large amount of data was recorded by a network of seventeen receiving stations. A sampling of early recordings was reduced and analyzed as they arrived from the receiving stations. These data, in conjunction with data from the first few orbits of 1958 Gamma (Explorer III), resulted in the announcement on 1 May 1958 of the region of high intensity radiation surrounding the earth (Van Allen, 1958), The detailed, complete reduction of the 1958 Alpha data has now been completed, This paper is a tabulation of all the data received from this satellite. It consists primarily of two parts. The first part is the master recording log on which are listed all recordings of the satellite signals obtained by the receiving station network. The actual data tabulation is contained in part two.

RADIATION↗
NASA NTRS1971

Distribution of Apollo 15 lunar samples: News release

More than 2200 Apollo 15 samples and polished thin sections weighing a total of about three kilograms will be distributed to 201 principal investigators for study during the next year. The scientific investigations will provide detailed information on the samples' mineralogy, petrology, chemistry, age, and history and on the effects of micrometeorite impacts, solar radiation, and cosmic ray bombardment. Preliminary examination of samples show the Apollo 15 material to be of three types: dark colored iron-rich basalts associated with mare and rille formation; a few basalts enriched in feldspar collected near the Apennine front; and light colored fragmental rocks or breccias consisting of soil-like materials which were cemented together or of rock fragments which were welded together by partial remelting.

Dick, L.↗
NASA NTRS1972

HEOS-A2: Press kit

The characteristics of the HEOS-A2 satellite and its assigned mission are discussed. The spacecraft carries seven experiments to investigate the strength and direction of the magnetic fields encountered, the energy distribution of protons and electrons, the nature of the solar winds, detection of micrometeorites, and low frequency solar observations. The highly elliptical polar orbit required for this mission will have an apogee of 38 earth radii. The lifetime of the satellite is expected to be one year minimum.

Allaway, H. G.↗
NASA NTRS1972

Interplanetary cosmic dust flux

Pioneer 8 and 9 measured cosmic dust flux rate data are in agreement with astronomy theory, zodiacal light measurements, and ground-based observations, but differ markedly from the high flux rates deduced from earlier in situ measurements. As many as seven orders-of-magnitude separate the small particle end of the high and low flux curves. It was concluded that the data from the multicoincidence cosmic dust sensors have not only measured very low flux for micrometeorites, which is in keeping with astronomy theory, but have also shown how a high flux theory may be based on faulty data.

Berg, O. E.↗
NASA NTRS1972

Preliminary examination of Surveyor 3 components for impact phenomena

Two pieces of the Surveyor 3 spacecraft recovered during the Apollo 12 mission were examined for secondary lunar ejecta and micrometeorite impacts. One piece was section E of the aluminum strut; the other was the nickel-coated beryllium television camera mirror.

Hallgren, D. S.↗
NASA NTRS1972

Surface studies on Surveyor 3 tubing sections

Sections C and E of the unpainted, polished aluminum tubing from the strut of the radar altimeter and Doppler velocity sensor were examined in a transmission electron microscope for micrometeorite damage and ion bombardment. Both sections were contaminated and eroded on one side; it is suggested that these conditions were caused by sandblasting by lunar dust and retrorocket plume contamination during Surveyor 3 landing. Microcraters of different configurations were found on the bright sides of the tubes. Several degrees of violence were involved in the formation of the craters, and the particle size could be responsible for some differences. All micropits found were on the bright areas and data indicate 0.2 hypervelocity impact/sq cm and 2/sq cm for other types of craters. The greatest degree of damage resulted from particle impact and was limited to a maximum depth of 2 microns.

Buvinger, E. A.↗