Search NASA⌕ Search

SEARCH · Search NASA

Results for “Planetary differentiation”

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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

The H2o Content of the Ureilite Parent Body

The fate of highly volatile elements (H, C, F, Cl and S) during planetary accretion and differentiation is debated. Recent analyses of water in non-carbonaceous chondrites (RC, OC, EC) and achondrites (angrites, eucrites) have been used to argue that inner solar system parent bodies accreted and retained their highly volatile element budgets from their primary feedstock without substantial loss during accretion, metamorphism and differentiation. An alternative model posits that differentiated inner solar system parent bodies (e.g., the angrite parent body, 4 Vesta, Earth) derived the majority of their water from a carbonaceous chondrite-like source, delivered during the final stages of accretion. In order to add new constraints to this debate, we have measured water in nominally anhydrous minerals, melt inclusions, and interstitial glass in ureilites, the largest group of primitive achondrites in the terrestrial meteorite collection. Primitive achondrites did not experience global melting and homogenization. Therefore, these meteorites capture part of the transition from chondritic to achondritic parent bodies, allowing us to constrain the fate of water during the earliest stages of differentiation. Our nano-scale secondary ion mass spectrometry (nanoSIMS) analyses allow us to assess the viability of ureilite-like material as a potential source of terrestrial water. Analyses of pigeonite in main group ureilites yield a range of 2.0 – 6.0 µg/g H2O, and analyses of high-Ca pyroxene and glass (glassy melt inclusions and interstitial glass) in the Almahata Sitta ureilitic trachyandesite yield ranges of 13 – 19 µg/g H2O and 44 – 216 µg/g H2O, respectively. Mass balance, incremental melting, and batch melting calculations yield a preferred ureilite parent body H2O content of 2 – 20 µg/g, similar to previous estimates of water in the eucrite parent body (4 Vesta), but lower than estimates of Earth’s water budget. With these data, we demonstrate that 1) the ureilite parent body is H2O-depleted relative to the Earth; 2) ureilite-like material is unlikely to be a primary source of H2O to the Earth; 3) C and H are not necessarily coupled elements during planetary accretion and thermal processing; and 4) accretion, heating, partial melting, and degassing of rocky planetesimals likely results in significant depletion of H2O.

Primitive achondrites↗
NASA NTRS1993

LEW88516 and SNC meteorites

We report on the isotopic composition of Pb and the concentration of Pb, U, and Th in a sample of LEW88516 (LEW). LEW was a 13-g stone recovered from Antarctica and was classified as a new member of the Shergottite group. This work was undertaken with the hope that LEW might yield new information to elucidate further the origin and evolution of Shergottites and other SNC meteorites. We have previously studied U-Th-Pb in other Shergottites, namely Shergotty, Zagami, EETA79001, and ALHA77005, as well as Nakhla. The results indicate that the initial leads of these Shergottites were well defined, were distinct from each other, and have high Pb-204/Pb-206 (from 0.0652 to 0.0739). These leads evolved in different reservoirs over most of solar system history in a low U-238/Pb-204(micro) is approximately equal to 5 environment. The U-Th-Pb isotopic systems are quite regular, which unambiguously indicates an event of U-Th-Pb fractionation at approximately 200 m.y. The details of the data arrays are complex. The young age is in general agreement with some of the ages obtained by other methods, but precise concordance between the different methods is not established. The new results on LEW are remarkably similar to those of ALHA77005 and support the other observations based on the mineralogy, petrology, and bulk composition. The clear distinction between the Shergottites and Nakhla is confirmed. We consider that the Shergottites and possibly all the SNC's were derived from an impact on the regolith of a differentiated terrestrial type planetary body (Mars?) with a high content of volatiles as compared to the earth.

Chen, J. H.↗
NASA NTRS1993

The Sm-Nd systematics of silicate inclusions in iron meteorites: Results from Caddo (IAB)

The timing of events leading to the formation of silicate-rich and metal-rich regions in planetesimals remains an important problem in the study of planetary formation and differentiation in the early solar system. The IAB irons are especially important as they are considered to represent a magmatic differentiation series. Iron meteorites present a particular challenge for chronological studies, due to the relative paucity of phases serving as hosts for radioactive parent-daughter nuclides. Recent work using the Re-Os system, following on the pioneering work by Herr et al. and Luck and Allegre, appears promising, but investigators up to now have concentrated on whole rock isochrons. Silicate clasts enclosed within iron meteorites can provide information about the chronology and thermal history of irons. Extensive work on Rb-Sr, K-Ar, and I-Xe has been reported on silicate inclusions in iron meteorites. We report the initial results from our Sm-Nd study of an inclusion with the Caddo IAB iron, the first Sm-Nd isotopic study of a silicate clast embedded within an iron meteorite. Our results include measurements of the standard long-lived Sm-147/Nd-143 (tau = 152 AE) system, as well as the shorter-lived SM-146/Nd-142 (tau = 0.149 AE) system, which has been shown to be very useful in deciphering the history of the early solar system. The Caddo silicate clast was described by Palme et al., who kindly provided us with a major part of the inclusion. The inclusion is coarse-grained consisting predominantly of olivine, clinopyroxene, and plagioclase, with lesser amounts of orthopyroxene, Fe-Ni metal, sulfide, and phosphate. The relatively large grain size (up to 3 mm) and 120 degree grain boundaries suggest extensive metamorphism at high temperatures. Based on study of a thin section, there is evidence for metal invading along grain boundaries in some regions of the inclusion, suggesting that the Fe-Ni metal was molten when the silicate clast was incorporated. Metamorphic recrystallization may have occurred during this event.

Stewart, Brian W.↗
NASA NTRS1998

Isotopic, Chemical and Mineralogical Investigations of Extraterrestrial Materials

The principal aim of our work was to improve our understanding of the earliest evolutionary period of our solar system (i.e. the first tens of millions of years). We have studied its chronology by using short and long term chronometers (based on extinct and long lived radioactive nuclei), explored the bearing of short lived nuclei on planetary heating and differentiation, and the addition of 'exotic' nuclei to solar system matter to help constrain models of nucleosynthesis. Our basic tool is high precision Thermal Ionization Mass Spectrometry (TIMS). Over the years we have developed clean chemical separation procedures for many elements. The chemical elements most relevant to our investigations are Cr, Ni, Rb, Sr, Sm, Nd, Pb, and U, for which highly efficient measurement techniques by TIMS have been developed and have been in use in our laboratory for many years. We have explored the Mn-53 Cr-53 system (T (Mn-53) = 3.7 Ma) and have found it to be a powerful tool to obtain relative ages of meteorite formation and, more general, of early solar system processes with a time resolution of approx. 1 Ma. By measuring the Mn-Cr system in many meteorite types (chondrites, basaltic achondrites, angrites, pallasites, etc.) we have found that this condition is indeed met for most meteorite families.

Lugmair, Guenter W.↗
NASA NTRS2002

Pristine Igneous Rocks and the Genesis of Early Planetary Crusts

Our studies are highly interdisciplinary, but are focused on the processes and products of early planetary and asteroidal differentiation, especially the genesis of the ancient lunar crust. The compositional diversity that we explore is the residue of process diversity, which has strong relevance for comparative planetology.

Warren, Paul H.↗
NASA NTRS2011

Almahata Sitta and Brecciated Ureilites: Insights into the Heterogeneity of Asteroids and Implications for Sample Return

Analysis of samples returned to terrestrial laboratories enables more precise measurements and a wider range of techniques to be utilized than can be achieved with either remote sensing or rover instruments. Furthermore, returning samples to Earth allows them to be stored and re-examined with future technology. Following the success of the Hayabusa mission, returning samples from asteroids should be a high priority for understanding of early solar system evolution, planetary formation and differentiation. Meteorite falls provide us with materials and insight into asteroidal compositions. Almahata Sitta (AS) was the first meteorite fall from a tracked asteroid (2008 TC3) [1] providing a rare opportunity to compare direct geochemical observations with remote sensing data. Although AS is predominantly ureilitic, multiple chondritic fragments have been associated with this fall [2,3]. This is not unique, with chondritic fragments being found in many howardite samples (as described in a companion abstract [4]) and in brecciated ureilites, some of which are known to represent ureilitic regolith [5-7]. The heterogeneity of ureilite samples, which are thought to all originate from a single asteroidal ureilite parent body (UPB) [5], gives us information about both internal and external asteroidal variations. This has implications both for the planning of potential sample return missions and the interpretation of material returned to Earth. This abstract focuses on multiple fragments of two meteorites: Almahata Sitta (AS); and Dar al Gani (DaG) 1047 (a highly brecciated ureilite, likely representative of ureilite asteroidal regolith).

Ross, A. J.↗
NASA NTRS2021

The Search for Lunar Mantle Rocks Exposed on the Surface of the Moon

The lunar surface is ancient and well-preserved, recording Solar System history and planetary evolution processes. Ancient basin-scale impacts excavated lunar mantle rocks, which are still expected to be present on the surface. Sampling these rocks would provide insight into fundamental planetary processes, including differentiation and magmatic evolution. There is contention among lunar scientists as to what lithologies make up the upper lunar mantle, and where they may have been exposed on the surface. We review dynamical models of lunar differentiation in the context of recent experiments and spacecraft data, assessing candidate lithologies, their distribution, and implications for lunar evolution.

Geochemistry↗
NASA NTRS2002

A Ground-Based Profiling Differential Absorption LIDAR System for Measuring CO2 in the Planetary Boundary Layer

Ground-based LIDAR observations can potentially provide continuous profiles of CO2 through the planetary boundary layer and into the free troposphere. We will present initial atmospheric measurements from a prototype system that is based on components developed by the telecommunications industry. Preliminary measurements and instrument performance calculations indicate that an optimized differential absorption LIDAR (DIAL) system will be capable of providing continuous hourly averaged profiles with 250m vertical resolution and better than 1 ppm precision at 1 km. Precision increases (decreases) at lower (higher) altitudes and is directly proportional to altitude resolution and acquisition time. Thus, precision can be improved if temporal or vertical resolution is sacrificed. Our approach measures absorption by CO2 of pulsed laser light at 1.6 microns backscattered from atmospheric aerosols. Aerosol concentrations in the planetary boundary layer are relatively high and are expected to provide adequate signal returns for the desired resolution. The long-term goal of the project is to develop a rugged, autonomous system using only commercially available components that can be replicated inexpensively for deployment in a monitoring network.

Andrews, Arlyn E.↗
NASA NTRS1992

Evidence for a high temperature differentiation in a molten earth: A preliminary appraisal

If the earth were molten during its later stages of accretion as indicated by the present understanding of planetary accretion process, the differentiation that led to the formation of the core and mantle must have occurred at high temperatures in the range of 3000-5000 K because of the effect of pressure on the temperature of melting in the interior of the earth. This calls into question the use of low-temperature laboratory measurements of partition coefficients of trace elements to make inferences about earth accretion and differentiation. The low temperature partition coefficients cannot be directly applied to high temperature fractionations because partition coefficients refer to an equilibrium specific to a temperature for a given reaction, and must change in some proportion to exp 1/RT. There are no laboratory data on partition coefficients at the high temperatures relevant to differentiation in the interior of the earth, and an attempt to estimate high temperature distribution coefficients of siderophile elements was made by considering the chemical potential of a given element at equilibrium and how this potential changes with temperature, under some specific assumptions.

Murthy, V. Rama↗
NASA NTRS1991

Variations in magmatic processes among igneous asteroids

Six asteroid classes (types V, E, A, R, M, S) are composed primarily of differentiated assemblages produced by igneous processes within their parent planetesimals. These are identified by surface materials which deviate from a chondritic composition to a degree that require igneous chemical fractionation processes. There are large variations among these igneous asteroids in the peak temperatures attained, in the efficiency of magmatic phase separation, and in the depth within the original parent body exposed at the present surface. These variations provide important constraints on the nature of asteroidal heating events, on the differentiation processes within small planetary bodies, and on the disruption of those parent bodies. Variations due to depth within the parent body and due to degree of magmatic differentiation are detailed.

Gaffey, M. J.↗
NASA NTRS1985

Laboratory studies of atomic collision processes of importance in planetary atmospheres

A series of differential cross sections for angular scattering and charge transfer was measured. These studies employ position-sensitive detectors (PSD's) to collect collision products scattered over a wide range of angles; and the research program includes investigation of differential cross sections for total angular scattering, charge transfer, stripping, and other collisions. All of these processes can be studied with the same basic apparatus, but minor modifications in the equipment details and in the data acquisition programs and techniques are required for each individual experiment.

Stebbings, R. F.↗
NASA NTRSDate not supplied

Location, location: deciphering the significance of in-situ hydrogen analyses of Martian meteorite phases

Understanding how inner planets acquired their volatiles such as hydrogen (H) is fundamental to constrain models of solar system formation [e.g. 1]. One avenue of estimating the H content and isotopic characteristics of differentiated planets is to analyze the samples we have from them as meteorites. Ideally, the H content and isotopic characteristic of the mantle sources of these igneous rocks should give insight into the volatile origin of each planetary body. The mantle H signatures can be estimated from that of the parent melt, which in turn may be derived from that of the first crystallized phases. However, we will illustrate the processes that can modify the H content and D/H ratios of pyroxene, olivine and feldspar in selected Martian meteorites relative to those of their mantle sources, with two key protocols for SIMS analysis. The first key is to put each analysis in textural context ("location, location"). In particular, of prime importance is whether an analysis is done at the center or the edge of a mineral grain, close or far from a shock disturbed area, and in a mineral crystallized at the beginning or late in the differentiation sequence. Accompanying the H analyses done by SIMS with major and trace element data at the same analysis locations allows to constrain the history of crystallization, cooling, alteration and shock of the meteorite. For example, volcanic degassing can be evidenced by decreasing water contents and increasing D/H ratios from core to edge of nakhlite pyroxenes [2]. Traverses of H analyses in pyroxene and maskelynite in shergottite LAR 06319 provide examples of H contents and D/H ratios modified during degassing following shock [3]. The second key is to assess if the area analyzed by SIMS has shock generated damage of the mineral structure, as will be shown in pyroxene and olivine from shergottite RBT 04262. Olivine in shergottites have too high water contents to be explained with an igneous origin and their D/H ratios are more consistent with terrestrial alteration, as observed before [4]. A review of all these processes shows how careful one has to be prior to using H measurements in meteorites to infer the origin and amount of water in differentiated planetary interiors.

A.H. Peslier↗
NASA NTRS2006

A Lidar for Making Range Resolved CO2 Measurements within the Planetary Boundary Layer

A ground based differential absorption lidar is under development at NASA's Goddard Space Flight Center to make range resolved measurements of CO2 within the planetary boundary layer. This is a direct detection lidar designed for both photon counting and analog use. Technology being developed for this instrument will be discussed including efforts in fiber lasers, optical parametric amplifiers and both InGaAs and HgCdTe solid-state detectors. The capabilities of this system are investigated and preliminary results presented.

Burris, John↗
NASA NTRS1997

Phase Equilibrium Investigations of Planetary Materials

This grant provided funds to carry out experimental studies designed to illuminate the conditions of melting and chemical differentiation that has occurred in planetary interiors. Studies focused on the conditions of mare basalt generation in the moon's interior and on processes that led to core formation in the Shergottite Parent Body (Mars). Studies also examined physical processes that could lead to the segregation of metal-rich sulfide melts in an olivine-rich solid matrix. The major results of each paper are discussed below and copies of the papers are attached as Appendix I.

Grove, T. L.↗
NASA NTRS1985

The problem of the Earth's CO2 content and the iron core

The near absence of metallic iron and the presence of magnetite and FeS in the C-1 chondrites imply that metallic iron was a minor phase present during the accretion process that formed the C-1 chondrites. If the C-1 chondrites provided the bulk of the initial planetary growth materials, the carbon reduction model is favored. The above estimates suggest that some 1240 to 227 times as much CO2 may have been produced during the formation of the core than can be accounted for in the crust and mantle. This discrepancy taken to the extreme suggests either that: (1) the Earth has lost more than 99 percent of its initial CO2 during early differentiation (this is highly unlikely) or: (2) the Earth has acquired some 90 percent of its present mass by the accretion of debris from previously reduced and differentiated but subsequently disrupted planetary bodies whereby the associated CO2 would not be captured, or: (3) the C-1 chondrites represent only a trivial fraction of the initial accretion materials present in the nebular cloud or: (4) condensed iron and anhydrous silicate phases were preferentially accreted during the initial formation of the planetary bodies.

Devore, G. W.↗
NASA NTRS1979

Stellar occultation studies of the solar system

The paper covers the principles, observational procedures, and results relating to occultations of stars by solar system bodies other than the moon. Physical processes involved in occultations are presented including (1) extinction by ring material, (2) differential refraction by a planetary atmosphere, (3) extinction by a planetary atmosphere, and (4) Fresnel diffraction by sharp edges. It is noted that from a sufficient number of immersion and emersion timings of a stellar occultation, the radius and ellipticity of the occulting body can be accurately determined. From an occultation by a planet having an atmosphere, temperature, pressure, and number density profiles can be obtained along with information about the composition of the atmosphere and the extinction.

Elliot, J. L.↗
NASA NTRS1982

The gravitational interaction between inclined, elliptical rings

An expression for the potential for two elliptical, inclined rings is derived from a model in which the gravitational torque between two wide rings or within a ring of finite width can prevent differential precession caused by planetary oblateness. The model was proposed to explain the observed eccentricity and width variations of the Uranian epsilon ring. The stationary solutions and stability of this system are examined.

Yoder, C. F.↗