Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Sm”

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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

Constraints on Martian Differentiation Processes from Rb-Sr and Sm-Nd Isotopic Analyses of the Basaltic Shergottite QUE 94201

Isotopic analyses of mineral, leachate, and whole rock fractions from the Martian shergottite meteorite QUE 94201 yield Rb-Sr and Sm-Nd crystallization ages of 327 +/- 12 and 327 +/- 19 Ma, respectively. These ages are concordant, although the isochrons are defined by different fractions within the meteorite. Comparison of isotope dilution Sm and Nd data for the various QUE 94201 fractions with in situ ion microprobe data for QUE 94201 minerals from the literature demonstrate the presence of a leachable crustal component in the meteorite. This component is likely to have been added to QUE 94201 by secondary alteration processes on Mars, and can affect the isochrons by selectively altering the isotopic systematics of the leachates and some of the mineral fractions. The absence of crustal recycling processes on Mars may preserve the geochemical evidence for early differentiation and the decoupling of the Rb-Sr and Sm-Nd isotopic systems, underscoring one of the fundamental differences between geologic processes on Mars and the Earth.

Borg, Lars E.↗
NASA NTRS2003

Using System Mass (SM), Equivalent Mass (EM), Equivalent System Mass (ESM) or Life Cycle Mass (LCM) in Advanced Life Support (ALS) Reporting

The Advanced Life Support (ALS) has used a single number, Equivalent System Mass (ESM), for both reporting progress and technology selection. ESM is the launch mass required to provide a space system. ESM indicates launch cost. ESM alone is inadequate for technology selection, which should include other metrics such as Technology Readiness Level (TRL) and Life Cycle Cost (LCC) and also consider perfom.arxe 2nd risk. ESM has proven difficult to implement as a reporting metric, partly because it includes non-mass technology selection factors. Since it will not be used exclusively for technology selection, a new reporting metric can be made easier to compute and explain. Systems design trades-off performance, cost, and risk, but a risk weighted cost/benefit metric would be too complex to report. Since life support has fixed requirements, different systems usually have roughly equal performance. Risk is important since failure can harm the crew, but it is difficult to treat simply. Cost is not easy to estimate, but preliminary space system cost estimates are usually based on mass, which is better estimated than cost. Amass-based cost estimate, similar to ESM, would be a good single reporting metric. The paper defines and compares four mass-based cost estimates, Equivalent Mass (EM), Equivalent System Mass (ESM), Life Cycle Mass (LCM), and System Mass (SM). EM is traditional in life support and includes mass, volume, power, cooling and logistics. ESM is the specifically defined ALS metric, which adds crew time and possibly other cost factors to EM. LCM is a new metric, a mass-based estimate of LCC measured in mass units. SM includes only the factors of EM that are originally measured in mass, the hardware and logistics mass. All four mass-based metrics usually give similar comparisons. SM is by far the simplest to compute and easiest to explain.

Jones, Harry↗
NASA NTRS2007

A Rb-Sr and Sm-Nd Isotope Geochronology and Trace Element Study of Lunar Meteorite LaPaz Icefield 02205

Rubidium-strontium and samarium-neodymium isotopes of lunar meteorite LaPaz Icefield (LAP) 02205 are consistent with derivation of the parent magma from a source region similar to that which produced the Apollo 12 low-Ti olivine basalts followed by mixing of the magma with small amounts (1 to 2 wt%) of trace element-enriched material similar to lunar KREEP-rich sample SaU 169. The crystallization age of LAP 02205 is most precisely dated by an internal Rb-Sr isochron of 2991+/-14 Ma, with an initial Sr-87/Sr-88 at the time of crystallization of 0.699836+/-0.000010. Leachable REE-rich phosphate phases of LAP 02205 do not plot on a Sm-Nd mineral isochron, indicating contamination or open system behavior of the phosphates. Excluding anomalous phases from the calculation of a Sm-Nd isochron yields a crystallization age of 2992+/-85 (initial Epsilon Nd-143 = +2.9+/-0.8) that is within error of the Rb-Sr age, and in agreement with other independent age determinations for LAP 02205 from Ar-Ar and U-Pb methods. The calculated Sm-147/Nd-144 source ratios for LAP 02205, various Apollo 12 and 15 basalts, and samples with strong affinities to KREEP (SaU 169, NWA 773, 15386) are uncorrelated with their crystallization ages. This finding does not support the involvement of a common KREEP component as a heat source for lunar melting events that occurred after crystallization of the lunar magma ocean.

Rankenburg, K.↗
NASA NTRS2008

Sm-Nd for Norite 78236 and Eucrite Y980318/433: Implications for Planetary and Solar System Processes

Here, we compare Sm-147-Nd-143 and Sm-146-Nd-142 data for lunar norite 78236 to those for approximately 4.54-4.56 Ga old cumulate eucrite Yamato 980318/433 and show that the norite data are compatible with its derivation from an isotopic reservoir similar to that from whence the eucrite pair came. Thus, lunar-like Sm-Nd isotopic systematics are not unique to the Earth-Moon system.

Nyquist, L. E.↗
NASA NTRS2009

Sm-Nd, Rb-Sr, and Mn-Cr Ages of Yamato 74013

Yamato 74013 is one of 29 paired diogenites having granoblastic textures. The Ar-39 - Ar-40 age of Y-74097 is approximately 1100 Ma. Rb-Sr and Sm-Nd analyses of Y-74013, -74037, -74097, and -74136 suggested that multiple young metamorphic events disturbed their isotopic systems. Masuda et al. reported that REE abundances were heterogeneous even within the same sample (Y-74010) for sample sizes less than approximately 2 g. Both they and Nyquist et al. reported data for some samples showing significant LREE enrichment. In addition to its granoblastic texture, Y-74013 is characterized by large, isolated clots of chromite up to 5 mm in diameter. Takeda et al. suggested that these diogenites originally represented a single or very small number of coarse orthopyroxene crystals that were recrystallized by shock processes. They further suggested that initial crystallization may have occurred very early within the deep crust of the HED parent body. Here we report the chronology of Y-74013 as recorded in chronometers based on long-lived Rb-87 and Sm-147, intermediate- lived Sm-146, and short-lived Mn-53.

Nyquist, L. E.↗
NASA NTRS2010

SM-ND Age and REE Systematics of Larkman Nunatek 06319: Closed System Fractional Crystallization of a Shergottite Magma

Sm-Nd isotopic data were collected on mineral separates and bulk rock powders of LAR 06319, yielding an age of 180+/-13 Ma (2(sigma)). This age is concordant with the Lu-Hf age (197+/-29 Ma, [1]) determined in conjunction with these data and the Sm-Nd age (190+/-26 Ma) of Shih et al., 2009 [2]. The Sm-Nd data form at statistically significant isochron (Fig. 1) that is controlled largely by leachate-residue pairs (samples with the R suffix are residues after leaching in cold 2N HCl for 10 minutes).

Shafer, J. T.↗
NASA NTRS2011

Sm-Nd and Ar-Ar Studies of DHO 908 and 489: Implications for Lunar Crustal History

It is widely assumed that ferroan anorthosites (FANs) formed as flotation cumulates on a global lunar magma ocean (LMO). A corollary is that all FANs are approximately contemporaneous and formed with the same initial Nd-143/Nd-144 ratio. Indeed, a whole rock isochron for selected FANs (and An93 anorthosite) yields an isochron age of 4.42 +/- 0.13 Ga and initial Nd-143/Nd-144, expressed in epsilon-units, of epsilon(sub Nd,CHUR) = 0.3+/-0.3 relative to the CHondritic Uniform Reservoir , or epsilon(sub Nd,HEDPB)=-0.6+/-0.3 relative to the HED Parent Body. These values are in good agreement with the age (T) = 4.47+/-0.07 Ga, and epsilon(sub Nd,HEDPB) =-0.6 +/- 0.5 for FAN 67075. We also have studied anorthositic clasts in the Dhofar 908 and 489 lunar highland meteorites containing clasts of magnesian anorthosites (MAN) with Mg# approximately 75. Because of their relatively high Mg#, magnesian anorthosites should have preceded most FANs in crystallization from the LMO if both are LMO products. Thus, it is important to determine whether the Nd-isotopic data of MAN and FAN are consistent with a co-magmatic origin. We previously reported Sm-Nd data for white clast Dho 908 WC. Mafic minerals in this clast were too small to be physically separated for an isochron. However, we estimated initial Nd-143/Nd-144 for the clast by combining its bulk ("whole rock") Sm-Nd data with an Ar-39-Ar-40 age of 4.42+/-.04 Ga. Here we report additional Sm-Nd data for bulk samples of Dho 908 and its pair Dho 489.

Nyquist, L. E.↗
NASA NTRS2011

Rb-Sr and Sm-Nd Study of Asuka 881394: Evidence of "Late" Metamorphism

The Asuka 881394 achondrite contains fossil Al-26 and Mn-53 [1,2,3] and has a Pb-207/Pb-206 age of 4566.5 plus or minus 0.2 Ma [3], the oldest for an achondrite. Preliminary results showed initial Sm-146/Sm-144 = (7.4 plus or minus 1.2) x 10(exp -3), indicative of an ancient age, but Rb-87 - Sr-87 and Sm-147 - Nd-143 ages of 4370 plus or minus 60 and 4490 plus or minus 20 Ma, resp. [1], were younger than expected from the presence of short-lived nuclides. We revisit the Rb-Sr and Sm-Nd chronology of A881394 in an attempt to establish whether late metamorphism led to inconsistency in its apparent ages.

Nyquist, L. E.↗
NASA NTRS2014

Sm-Nd and Rb-Sr Isotopic Systematics of a Heavily Shocked Martian Meteorite Tissint and Petrogenesis of Depleted Shergottites

Tissint is a very fresh Martian meteorite that fell near the town of Tissint in Morocco on July 18, 2011. It contains abundant olivine megacrysts (~23%) in a fine-grained matrix of pyroxene (~55%), maskelynitized plagioclase (~15%), opaques (~4%) and melt pockets (~3%) and is petrographically similar to lithologies A and C of picritic shergottite EETA 79001 [1,2]. The presence of 2 types of shock-induced glasses and all 7 high-pressure mineral phases that were ever found in melt pockets of Martian meteorites suggests it underwent an intensive shock metamorphism of ~25 GPa and ~2000 C localized in melt pockets [2]. Mineral textures suggest that olivines, pyroxenes and plagioclases probably did not experience such hightemperature. Earlier determinations of its age yielded 596+/-23 Ma [3] and 616+/-67 Ma [4], respectively, for the Sm-Nd system and 583+/-86 Ma for the Lu-Hf system [4], in agreement with the 575+/-18 Ma age of the oldest olivine-phyric depleted shergottite Dho 019 [5]. However, the exposure ages of Tissint (~1 Ma [1, 6, 7]) and Dho 019 (~20 Ma [8]) are very different requiring two separate ejection events. These previously determined Sm-Nd and Lu-Hf ages are older than the Ar-Ar maskelynite plateau age of 524+/-15 Ma [9], reversing the pattern usually observed for Martian meteorites. In order to clarify these age issues and place models for Tissint's petrogenesis on a firm basis, we present new Rb-Sr and Sm- Nd isotopic results for Tissint, and discuss (a) the shock effects on them and the Ar-Ar chronometer, (b) correlation of the determined ages with those of other depleted shergottites, and (c) the petrogenesis of depleted shergottites. Since the meteorite is a recent fall, terrestrial contamination is expected to be minimal, but, the strong shock metamorphism might be expected to compromise the equilibrium of the isotopic systems.

Shih, C.-Y.↗
NASA NTRS2018

Soil Moisture Active Passive (SMAP) Mission Level 4 Surface and Root Zone Soil Moisture (L4_SM) Product Specification Document

This is the Product Specification Document (PSD) for Level 4 Surface and Root Zone Soil Moisture (L4_SM) data for the Science Data System (SDS) of the Soil Moisture Active Passive (SMAP) project. The L4_SM data product provides estimates of land surface conditions based on the assimilation of SMAP observations into a customized version of the NASA Goddard Earth Observing System, Version 5 (GEOS-5) land data assimilation system (LDAS). This document applies to any standard L4_SM data product generated by the SMAP Project.

Soil Moisture↗
DOE OSTI2020

Materials Data on Sm(PRu)2 by Materials Project

Sm(RuP)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sm2+ is bonded in a distorted body-centered cubic geometry to eight equivalent P3- atoms. All Sm–P bond lengths are 3.14 Å. Ru2+ is bonded to four equivalent P3- atoms to form a mixture of edge and corner-sharing RuP4 tetrahedra. All Ru–P bond lengths are 2.36 Å. P3- is bonded in a 9-coordinate geometry to four equivalent Sm2+, four equivalent Ru2+, and one P3- atom. The P–P bond length is 2.51 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(SiAu)2 by Materials Project

Sm(AuSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sm2+ is bonded in a 8-coordinate geometry to eight equivalent Au1- atoms. All Sm–Au bond lengths are 3.36 Å. Au1- is bonded to four equivalent Sm2+ and four equivalent Si atoms to form a mixture of distorted corner, edge, and face-sharing AuSm4Si4 tetrahedra. All Au–Si bond lengths are 2.58 Å. Si is bonded in a 5-coordinate geometry to four equivalent Au1- and one Si atom. The Si–Si bond length is 2.33 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(Ni2P)2 by Materials Project

SmNi4P2 crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. there are two inequivalent Sm2+ sites. In the first Sm2+ site, Sm2+ is bonded in a 6-coordinate geometry to six P3- atoms. There are a spread of Sm–P bond distances ranging from 2.89–2.94 Å. In the second Sm2+ site, Sm2+ is bonded to six P3- atoms to form SmP6 octahedra that share corners with six equivalent NiP4 tetrahedra, edges with two equivalent SmP6 octahedra, and edges with four equivalent NiP4 tetrahedra. There are two shorter (2.86 Å) and four longer (2.91 Å) Sm–P bond lengths. There are six inequivalent Ni1+ sites. In the first Ni1+ site, Ni1+ is bonded in a trigonal non-coplanar geometry to three P3- atoms. There are one shorter (2.18 Å) and two longer (2.27 Å) Ni–P bond lengths. In the second Ni1+ site, Ni1+ is bonded in a bent 120 degrees geometry to two P3- atoms. There are one shorter (2.25 Å) and one longer (2.31 Å) Ni–P bond lengths. In the third Ni1+ site, Ni1+ is bonded in a water-like geometry to two equivalent P3- atoms. Both Ni–P bond lengths are 2.30 Å. In the fourth Ni1+ site, Ni1+ is bonded to four P3- atoms to form NiP4 tetrahedra that share corners with three equivalent SmP6 octahedra, corners with three NiP4 tetrahedra, and edges with two equivalent NiP4 tetrahedra. The corner-sharing octahedra tilt angles range from 42–58°. There are a spread of Ni–P bond distances ranging from 2.22–2.38 Å. In the fifth Ni1+ site, Ni1+ is bonded to four P3- atoms to form NiP4 tetrahedra that share corners with three NiP4 tetrahedra, edges with two equivalent SmP6 octahedra, and edges with two equivalent NiP4 tetrahedra. There are a spread of Ni–P bond distances ranging from 2.30–2.48 Å. In the sixth Ni1+ site, Ni1+ is bonded in a trigonal planar geometry to three P3- atoms. There are two shorter (2.27 Å) and one longer (2.38 Å) Ni–P bond lengths. There are three inequivalent P3- sites. In the first P3- site, P3- is bonded in a 9-coordinate geometry to two equivalent Sm2+ and seven Ni1+ atoms. In the second P3- site, P3- is bonded in a 9-coordinate geometry to three Sm2+ and six Ni1+ atoms. In the third P3- site, P3- is bonded in a 9-coordinate geometry to four Sm2+ and five Ni1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(DyS2)2 by Materials Project

Sm(DyS2)2 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Dy3+ is bonded to eight equivalent S2- atoms to form distorted DyS8 hexagonal bipyramids that share corners with four equivalent DyS8 hexagonal bipyramids, corners with four equivalent SmS8 hexagonal bipyramids, edges with four equivalent DyS8 hexagonal bipyramids, faces with four equivalent DyS8 hexagonal bipyramids, and faces with four equivalent SmS8 hexagonal bipyramids. There are a spread of Dy–S bond distances ranging from 2.77–3.01 Å. Sm2+ is bonded to eight equivalent S2- atoms to form distorted SmS8 hexagonal bipyramids that share corners with eight equivalent DyS8 hexagonal bipyramids, edges with four equivalent SmS8 hexagonal bipyramids, and faces with eight equivalent DyS8 hexagonal bipyramids. There are four shorter (2.83 Å) and four longer (3.00 Å) Sm–S bond lengths. S2- is bonded to four equivalent Dy3+ and two equivalent Sm2+ atoms to form a mixture of distorted edge, face, and corner-sharing SSm2Dy4 octahedra. The corner-sharing octahedra tilt angles range from 17–50°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(SbTe2)2 by Materials Project

Sm(SbTe2)2 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Sm2+ is bonded in a 8-coordinate geometry to eight equivalent Te2- atoms. There are four shorter (3.20 Å) and four longer (3.50 Å) Sm–Te bond lengths. Sb3+ is bonded to six equivalent Te2- atoms to form a mixture of corner and edge-sharing SbTe6 pentagonal pyramids. There are a spread of Sb–Te bond distances ranging from 3.02–3.29 Å. Te2- is bonded in a 5-coordinate geometry to two equivalent Sm2+ and three equivalent Sb3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(BiTe2)2 by Materials Project

Sm(BiTe2)2 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Sm2+ is bonded to eight equivalent Te2- atoms to form distorted edge-sharing SmTe8 hexagonal bipyramids. There are four shorter (3.19 Å) and four longer (3.47 Å) Sm–Te bond lengths. Bi3+ is bonded in a 6-coordinate geometry to six equivalent Te2- atoms. There are a spread of Bi–Te bond distances ranging from 3.17–3.30 Å. Te2- is bonded in a 5-coordinate geometry to two equivalent Sm2+ and three equivalent Bi3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(SiRh)2 by Materials Project

Sm(RhSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sm2+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Sm–Si bond lengths are 3.15 Å. Rh3+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing RhSi4 tetrahedra. All Rh–Si bond lengths are 2.42 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Sm2+, four equivalent Rh3+, and one Si4- atom. The Si–Si bond length is 2.49 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(SiNi)2 by Materials Project

Sm(NiSi)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sm3+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Sm–Si bond lengths are 3.10 Å. Ni+2.50+ is bonded to four equivalent Si4- atoms to form a mixture of corner and edge-sharing NiSi4 tetrahedra. All Ni–Si bond lengths are 2.32 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Sm3+, four equivalent Ni+2.50+, and one Si4- atom. The Si–Si bond length is 2.47 Å.

36 MATERIALS SCIENCE↗