Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “asteroid regolith”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Global Variations in Regolith Properties on Asteroid Vesta from Dawn's Low-Altitude Mapping Orbit

We investigate the depth, variability, and history of regolith on asteroid Vesta using data from the Dawn spacecraft. High-resolution (15-20 m pixel(sup -1)) Framing Cameraimages are used to assess the presence of morphologic indicators of a shallow regolith,including the presence of blocks in crater ejecta, spur-and-gully-type features in crater walls,and the retention of small (less than 300 m) impact craters. Such features reveal that the broad,regional heterogeneities observed on Vesta in terms of albedo and surface composition extend to the physical properties of the upper approx. 1 km of the surface. Regions of thin regolithare found within the Rheasilvia basin and at equatorial latitudes from approx. 0-90 deg. E and approx.260-360 deg. E. Craters in these areas that appear to excavate material from beneath the regolithhave more diogenitic (Rheasilvia, 090 deg. E) and cumulate eucrite (260-360 deg. E) compositions.A region of especially thick regolith, where depths generally exceed 1 km, is found from approx.100-240 deg. E and corresponds to heavily cratered, low-albedo surface with a basaltic eucritecomposition enriched in carbonaceous chondrite material. The presence of a thick regolithin this area supports the idea that this is an ancient terrain that has accumulated a larger component of exogenic debris. We find evidence for the gardening of crater ejecta towardmore howarditic compositions, consistent with regolith mixing being the dominant form of "weathering" on Vesta.

asteroid↗
NASA NTRS2018

Physical, Chemical, and Petrological Characteristics of Chondritic Materials and Their Relationships to Small Solar System Bodies: Chapter - 2

Chondrite materials with varying abundances of volatile-bearing phases are expected at the destinations for the asteroid sample-return missions Hayabusa2 and OSIRIS-REx. The targets of the missions are 162173 (1999 JU3) Ryugu and 101955 (1999 RQ36) Bennu. Spectroscopic analyses of these asteroids suggest that their surface materials are related to types 1 and 2 carbonaceous chondrites. Some studies suggest that the parent bodies of these chondrites may have also experienced some thermal and/or shock metamorphism. The physical properties of boulders at asteroid surfaces and fine particles in asteroid regoliths are consequences of the diverse processes that fragmented them, mobilized them, and redeposited them in unique accumulations. Sample-return missions are likely to encounter a broad range of carbonaceous chondrite (CC)-like materials, to which aqueous alteration, thermal, and shock metamorphism imparted changes affecting their sub-micron- to meter-scale physical properties. Consequently, implementation of scale-dependent analytical techniques to the study of the chemical, physical, and geotechnical characteristics of these CC-like materials is fundamental to safe mission operations, sample selection, and return. However, most of the available knowledge for informing and formulating expectations about regolith processes, products, and properties on carbonaceous small bodies comes from missions that studied anhydrous (e.g., Itokawa studied by Hayabusa) and/or much larger asteroids (e.g., Vesta studied by Dawn). No previous mission is likely directly relevant to small ice-free carbonaceous NEOs 162173 Ryugu or 101955 Bennu, although the Rosetta Spaceraft performed a flyby of the large asteroid Lutetia which has variously been classified as M and C type (Pätzold et al., 2011). Carbonaceous chondrites carry the best record of the history, distribution, and activity of water in the early solar system. Ordinary and Enstatite chondrites carry only partial records, but these are still critical to understanding the full story. We will describe the records of water-rock interactions on asteroids, as recorded in these meteorites, with particular emphasis on the timing, nature, settings, and fluid compositions. An integral part of this story is the rare, but fortunate, preservation of actual early solar system water as aqueous fluid inclusions.

Zolensky, Michael E.↗
NASA NTRS1978

Luna 24: 90-150 micrometer fraction - Implications for remote sampling of regolith

An analysis of the mineral grains and glasses found in the 90 to 150 micron fraction of the Luna 24 core sample is presented and implications for the automatic collection of planetary and asteroidal regoliths are discussed. Electron microprobe analysis for pyroxene, olivine, plagioclase, opaque minerals and glass in samples at various depths indicate that polymineralic grains have compositions similar to those of gabbroic and basaltic fragments from coarser samples, while monomineralic grains contain an additional population of Mg-rich olivines and pyroxene. Most of the glasses are found to be related to mare basalts or local regolith, with nonmare material represented by glasses of highland basalt and low K Fra Mauro composition. It is concluded that as regards mineralogy and petrology, a single grab sample would have been as useful and a series of grab samples on a long traverse would have been more useful than the Luna 24 core sample, with the fine sample being more informative than the coarse.

Papp, H. A.↗
NASA NTRS1976

Asteroids as meteorite parent-bodies - The astronomical perspective

A review of astronomical evidence suggests that asteroids are the parent-bodies for most meteorites. The surfaces of most asteroids are like carbonaceous chondrites while a significant minority are of stony-iron composition. Other meteorite types are recognized in the belt but are rare. The size distribution of stony-iron asteroids implies they are remnant cores of about 100 differentiated bodies subjected to collisional fragmentation by carbonaceous objects initially about 300 times more numerous than now. Incomplete evidence on parent-body collisions exists in data on Hirayama families, asteroid lightcurves, and the compositional homogeneity of individual asteroids. Modern-day asteroid regoliths are thin and cannot have been environments for formation of most brecciated, gas-rich meteorites; such meteorites formed during early accretion of the asteroids. A scenario for the origin and evolution of meteorite parent-bodies is presented which includes: (1) interruption of planet-formation by processes due to Jupiter; (2) substantial asteroidal collisions during the first 0.5 b.y.; and (3) formation of most meteorite types within the differentiated bodies.

Chapman, C. R.↗
NASA NTRS1987

A search for spectral alteration effects in chondritic gas-rich breccias

Several samples of gas-rich breccias were selected, including slabs of the Kapoeta howardite, the ordinary chondrites Dubrovnik, Cangas de Onis, and Dimmit. Numerous 0.8 to 2.5 micron reflection spectra of selected areas on sawed or broken surfaces were measured with the Planetary Geosciences Division spectrogoniometer. While these spectra are not directly comparable to those of powered samples, comparisons within the data set should reveal any spectral differences due to weathering. These results indicate that unknown regolith processes do not confer the ordinary-chondrite parent bodies with an altered layer exhibiting S-class spectral properties. This is consistent with recent interpretations of the new Q-class of asteroids as the ordinary-chondrite parent bodies. However, significant spectral effects do occur in asteroid regoliths: darkening and suppression of absorption bands in highly shocked material, as seen previously in the so-called black chondrites; and segregation of metal in large impact melt pools on chondritic asteroids, which may have achondritic spectra. Neither of these effects is likely to be significant in interpreting current integral-disk spectra, but should be searched for in spectral maps returned by future spacecraft.

Bell, J. F.↗
NASA NTRS1991

Three basaltic earth-approaching asteroids and the source of the basaltic meteorites

Diameters of 1.2, 1.0, and 3.4 km are respectively derived for the earth-approaching asteroids 1983 RD, 1980 PA, and 1985 DO2, whose spectra are virtually identical to that of the basaltic-surfaced large asteroid, Vesta. While probably not fragments of Vesta, the three asteroids may be fragments of one or more Vesta-like parent bodies; it is suggested that they may be fragments of the source body or bodies of the HED meteorites. While these asteroids' regoliths have significant insulating properties, they differ from that of the moon in that lunar-like glasses and agglutinates are largely absent. It is noted that asteroids of this kind may have impacted the earth without leaving the chemical signatures associated with the K-T boundary event.

Cruikshank, D. P.↗
NASA NTRS1986

The spectral and physical properties of metal in meteorite assemblages - Implications of asteroid surface materials

One of the objectives of the present paper is related to a definition of the spectral contribution of the nickel-iron metal component in meteoritic assemblages. Another objective is the elucidation of the chemical, physical, and petrographic properties of the metal grains which affect the spectral signature in asteroid surface materials. It is pointed out that an improved understanding of the spectral and physical properties of metal in asteroid regoliths should permit an improved characterization of these objects, and, in particular, a better evaluation of the differentiated or undifferentiated nature of the S-type and M-type asteroids. Attention is given to the spectra of iron and nickel-iron metals, the spectral effects of metal in chondritic assemblages, the spectral reflectance of metal grains in ordinary chondrites, the nature of the surfaces of chondritic metal grains, the origin of coats on chondritic metal grains, and the fragmentation of metal on asteroid surfaces.

Gaffey, M. J.↗
NASA NTRS2016

Direct Determination of the Space Weathering Rates in Lunar Soils and Itokawa Regolith from Sample Analyses

Space weathering effects on airless bodies result largely from micrometeorite impacts and solar wind interactions. Decades of research have provided insights into space weathering processes and their effects, but a major unanswered question still remains: what is the rate at which these space weathering effects are acquired in lunar and asteroidal regolith materials? To determine the space weathering rate for the formation of rims on lunar anorthite grains, we combine the rim width and type with the exposure ages of the grains, as determined by the accumulation of solar flare particle tracks. From these analyses, we recently showed that space weathering effects in mature lunar soils (both vapor-deposited rims and solar wind amorphized rims) accumulate and attain steady state in 10(sup 6)-10(sup 7) y. Regolith grains from Itokawa also show evidence for space weathering effects, but in these samples, solar wind interactions appear to dominate over impactrelated effects such as vapor-deposition. While in our lunar work, we focused on anorthite, given its high abundance on the lunar surface, for the Itokawa grains, we focused on olivine. We previously studied 3 olivine grains from Itokawa and determined their solar flare track densities and described their solar wind damaged rims]. We also analyzed olivine grains from lunar soils, measured their track densities and rim widths, and used this data along with the Itokawa results to constrain the space weathering rate on Itokawa. We observe that olivine and anorthite have different responses to solar wind irradiation.

Keller, L. P.↗
NASA NTRS2018

Outer Solar System Material in Inner Solar System Regolith Breccias

There is excellent evidence that a dynamical instability in the early solar system led to gravitational interactions between the giant planets and trans-Neptunian objects (TNOs). Giant planetary migration triggered by the instability dispersed a disk of primordial TNOs and created a number of small body reservoirs (e.g. the Kuiper Belt, scattered disk, irregular satellites, and the Jupiter/Neptune Trojan populations). It also injected numerous bodies into the main asteroid belt, where modeling shows they can successfully reproduce the observed P and D-type asteroid populations. During the injection era and after implantation, some of these “main belt TNOs” would have collided with S-class asteroids. Some of this material may have survived as a component of asteroid regolith breccias. Thus, we have been searching for evidence of these impact events in the form of carbonaceous xenoliths in brecciated ordinary chondrites. These xenoliths would have experienced a wide range of impact velocities, and therefore we should expect to see everything between relatively unaltered material to completely shock-melted lithologies. This material might also be different from the carbonaceous chondrites that represent standard C-complex asteroids. A goal of this research is to define useful criteria for distinguishing between these two classes of materials, including O, Cr, N and C isotopes, petrographic characteristics, and chronology.

Zolensky, M.↗
NASA NTRS1992

S-asteroids 387 Aquitania and 980 Anacostia - Possible fragments of the breakup of a spinel-bearing parent body with CO3/CV3 affinities

Asteroids 387 Aquitania and 980 Anacostia are anomalous members of the S-class. Their reflectance spectra exhibit a strong broad absorption feature longwards of 1.5 micron and no significant feature near 1 micron. Their spectra indicate the presence of spinel, an aluminum-magnesium oxide mineral commonly present in inclusions in CV3 and CO3 meteorites. Spinel probably makes up only a small percentage of the surface assemblages of these asteroids, but its spectral effect may be enhanced by its presence in fine-grained white inclusions in immature asteroid regoliths. It is speculated that Aquitania and Anacostia represent material formed in the same nebular zone as the CV3 and CO3 chondrites but either: (A) at an earlier time in the nebula when such inclusions might have been a relatively larger fraction of the nebular grain population; or (B) in local regions where nebular processes (e.g., settling to the midplane) had concentrated such inclusions. The close similarity of two orbital elements (a, i) suggests that Aquitania and Anacostia may be members of a partially dispersed asteroid family produced by the early disruption of a spinel-bearing parent body.

Burbine, Thomas H.↗
NASA NTRS1991

Infrared (2.08-14 micron) spectra of powered stony meteorites

Infrared biconical reflectance spectra of 60 powdered meteorite samples, representing 50 different stony meteorites, were measured as analogues of asteroidal regolith. Representative samples were measured in directional hemispherical reflectance to assure that Kirchhoff's Law can be used to predict relative emissivity from the reflectance spectra. These spectral data confirm that the O-H fundamental absorption band near 2.9 microns is an extremely sensitive indicator of incipient alteration, which often has taken place in powdered meteorite samples exposed only to water vapor in the air. Such non-carbonaceous samples typically contain less than 1 percent water by weight. Likewise, the C-H fundamental absorption bands near 3.4 and 3.5 microns are equally sensitive indicators of contamination with volatile hydrocarbons, which can also be absorbed from the air. The heavy, macromolecular hydrocarbons native to chondrites do not display such heavy bands, making detection of these bands in remote sensing of asteroids unlikely. Despite the spectral artifacts introduced by alteration and hydrocarbon contamination, powdered stony meteorites display a wide variety of real spectral features that can be used for their identification, including residual reststrahlen bands, absorption bands, and the Christiansen feature. Researchers found that the wavelengths of the peaks or troughs of each of these spectral features can be used independently to infer meteorite composition, but the best results are obtained when the entire spectral curve is used, or at least the portion of it encompassed by the 8 to 14 micron atmospheric window, in a digital search library.

Salisbury, J. W.↗
NASA NTRSDate not supplied

Contamination monitoring of the OSIRIS-REx ISO5 asteroid sample cleanroom

The OSIRIS-REx mission to asteroid Bennu successfully collected hundreds of grams of asteroid regolith in October 2020 [1]. The spacecraft departed Bennu in May 2021 for Earth return and will release the sample canister to be recovered in Utah in September 2023 [2]. Samples will be transported to the curation facility at NASA Johnson Space Center, where an ISO5 equivalent cleanroom has been designed in 2017 and completed in 2021. Aspects of the design and material selection for the cleanroom and its supporting facilities (air handling system, cleanroom floors and walls, filters, paints, etc.) were optimized to minimize effects of organic and inorganic contaminants and offgassing [3]. Since its completion, the lab has been carefully monitored to understand and establish a baseline with respect to multiple environmental aspects – measurement of particle counts, deploying Si wafer witness plates for organic and inorganic contaminants, deploying aluminum foils for a focus on organics with JSC in-house expertise, gas samples, and regular microbial and fungal measurements on selected surfaces and air samples in the cleanroom. This contribution will report on nearly one year of monitoring and highlight several specific aspects that have led to a better understanding of the new cleanroom environment.

carbonaceous asteroid↗
NASA NTRS1976

Spectrophotometry /0.33 to 1.07 microns/ of 433 Eros and compositional implications

The spectral reflectance (0.33-1.07 micrometers) for the asteroid 433 Eros was determined as a function of rotational phase during January 28-30, and February 15, 1975. Interpretation of absorption features suggests Eros is composed of an undifferentiated assemblage of moderate to high temperature minerals (iron, pyroxene, and olivine, but no carbon). H-type ordinary chondrites are such assemblages, but it would be premature to conclude that Eros is like an H chondrite meteorite in composition until a better understanding is reached of possible physical differences between laboratory powders and asteroid regoliths for metal-bearing assemblages. There are no large-scale major compositional variations on the different sides of Eros.

Pieters, C.↗
NASA NTRS1981

Advances in planetary geology

Three dissertations are provided covering (1) the stochastic evolution of asteroidal regoliths and the origin of brecciated and gas-rich meteorites; (2) ridge systems on Mars; and (3) the morphology and evolution of Ganymede and Callisto.

Woronow, A.↗
NASA NTRS1982

Space environment and lunar surface processes, 2

The top few millimeters of a surface exposed to space represents a physically and chemically active zone with properties different from those of a surface in the environment of a planetary atmosphere. To meet the need or a quantitative synthesis of the various processes contributing to the evolution of surfaces of the Moon, Mercury, the asteroids, and similar bodies, (exposure to solar wind, solar flare particles, galactic cosmic rays, heating from solar radiation, and meteoroid bombardment), the MESS 2 computer program was developed. This program differs from earlier work in that the surface processes are broken down as a function of size scale and treated in three dimensions with good resolution on each scale. The results obtained apply to the development of soil near the surface and is based on lunar conditions. Parameters can be adjusted to describe asteroid regoliths and other space-related bodies.

Comstock, G. M.↗
NASA NTRS1983

Radar investigation of asteroids

For 80 Sappho, 356 Liguria, 694 Ekard, and 2340 Hathor, data were taken simultaneously in the same sense of circular polarization as transmitted (SC) as well as in the opposite (OC) sense. Graphs show the average OC and SC radar echo power spectra soothed to a resolution of EFB Hz and plotted against Doppler frequency. Radar observations of the peculiar object 2201 Oljato reveal an unusual set of echo power spectra. The albedo and polarization ratio remain fairly constant but the bandwidths range from approximately 0.8 Hz to 1.4 Hz and the spectral shapes vary dramatically. Echo characteristics within any one date's approximately 2.5-hr observation period do not fluctuate very much. Laboratory measurements of the radar frequency electrical properties of particulate metal-plus-silicate mixtures can be combined with radar albedo estimates to constrain the bulk density and metal weight, fraction in a hypothetical asteroid regolith having the same particle size distribution as lab samples.

Ostro, S. J.↗
NASA NTRS1989

Application of photometric models to asteroids

The way an asteroid or other atmosphereless solar system body varies in brightness in response to changing illumination and viewing geometry depends in a very complicated way on the physical and optical properties of its surface and on its overall shape. This paper summarizes the formulation and application of recent photometric models by Hapke (1981, 1984, 1986) and by Lumme and Bowell (1981). In both models, the brightness of a rough and porous surface is parameterized in terms of the optical properties of individual particles, by shadowing between particles, and by the way in which light is scattered among collections of particles. Both models succeed in their goal of fitting the observed photometric behavior of a wide variety of bodies, but neither has led to a very complete understanding of the properties of asteroid regoliths, primarily because, in most cases, the parameters in the present models cannot be adequately constrained by observations of integral brightness alone over a restricted range of phase angles.

Bowell, Edward↗
NASA NTRS1992

Asteroid exploration and utilization

The Earth is nearing depletion of its natural resources at a time when human beings are rapidly expanding the frontiers of space. The resources possessed by asteroids have enormous potential for aiding and enhancing human space exploration as well as life on Earth. Project STONER (Systematic Transfer of Near Earth Resources) is based on mining an asteroid and transporting raw materials back to Earth. The asteroid explorer/sample return mission is designed in the context of both scenarios and is the first phase of a long range plan for humans to utilize asteroid resources. Project STONER is divided into two parts: asteroid selection and explorer spacecraft design. The spacecraft design team is responsible for the selection and integration of the subsystems: GNC, communications, automation, propulsion, power, structures, thermal systems, scientific instruments, and mechanisms used on the surface to retrieve and store asteroid regolith. The sample return mission scenario consists of eight primary phases that are critical to the mission.

Radovich, Brian M.↗