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At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Osmium Isotope Systematics of Ureilites

The Os-187/Os-188 for twenty-two ureilite whole rock samples, including monomict, augite-bearing, and polymict lithologies, were examined in order to constrain the provenance and subsequent magmatic processing of the ureilite parent body (or bodies). The Re/Os ratios of most ureilites show evidence for a recent disturbance, probably related to Re mobility during weathering, and no meaningful chronological information can be extracted from the present data set. The ureilite Os-187/Os-188 ratios span a range from 0.11739 to 0.13018, with an average of 0.1258+/-0.0023 (1(sigma)), similar to typical carbonaceous chondrites, and distinct from ordinary or enstatite chondrites. The similar mean of Os-187/Os-188 measured for the ureilites and carbonaceous chondrites suggests that the ureilite parent body probably formed within the same region of the solar nebula as carbonaceous chondrites. From the narrow range of the 187Os/188Os distribution in ureilite meteorites it is further concluded that Re was not significantly fractionated from Os during planetary differentiation and was not lost along with the missing ureilitic melt component. The lack of large Re/Os fractionations requires that Re/Os partitioning was controlled by a metal phase, and thus metal had to be stable throughout the interval of magmatic processing on the ureilite parent body.

Rankenburg, K.↗
NASA NTRS2011

Safety-Critical Partitioned Software Architecture: A Partitioned Software Architecture for Robotic

The flight software on virtually every mission currently managed by JPL has several major flaws that make it vulnerable to potentially fatal software defects. Many of these problems can be addressed by recently developed partitioned operating systems (OS). JPL has avoided adopting a partitioned operating system on its flight missions, primarily because doing so would require significant changes in flight software design, and the risks associated with changes of that magnitude cannot be accepted by an active flight project. The choice of a partitioned OS can have a dramatic effect on the overall system and software architecture, allowing for realization of benefits far beyond the concerns typically associated with the choice of OS. Specifically, we believe that a partitioned operating system, when coupled with an appropriate architecture, can provide a strong infrastructure for developing systems for which reusability, modifiability, testability, and reliability are essential qualities. By adopting a partitioned OS, projects can gain benefits throughout the entire development lifecycle, from requirements and design, all the way to implementation, testing, and operations.

(Avionics Application Standard Software Interface ↗
NASA NTRS2016

Mars Sample Thermal Control During Mars Ascent and Orbit

Although NASA has no official plans at this time for a mission to return samples from Mars, the Program Formulation Office of the Mars Exploration Program sponsors ongoing mission concept studies, systems analyses, and technology investments which explore different strategies for the potential return of samples from Mars, consistent with the charter of the program and stated priorities of the science community. Maintaining the thermal integrity of collected samples would be very important. In general, samples would be collected, sealed inside tubes, and left on the surface for later retrieval. They would then be inserted into an OS (Orbiting Sample), and carried to a Mars or Solar orbit via a MAV (Mars Ascent Vehicle). Subsequently, an Earth return vehicle would rendezvous with the OS and bring it back to Earth. During ascent from Mars, the OS could serve as the nose cone of the MAV and would be subjected to significant aerodynamic heating from the Martian atmosphere. Once the OS is released from the MAV, its external surface would be exposed to potentially several years of sunlight, eclipse, planetary IR, albedo, and space. The challenge is to ensure that these samples are kept at thermally moderate conditions to preserve their integrity in these widely different environments. Various thermal techniques have been investigated to achieve sample thermal control: use of thermal protection shields and surfaces (ablative and non-ablative) to protect them from adverse exposure to ascent heating, as well combinations of thermo-optical coatings during the orbital phase. The work described herein is part of this ongoing effort & will describe the key challenges related to the thermal control of the potential Mars samples during these phases and the corresponding schemes to overcome them.

Bhandari, Pradeep↗
NASA NTRS2020

Mantle-melt Partitioning of the Highly Siderophile Elements: New Results and Application to Mars

Trace elements and extant and extinct isotopic attributes in martian meteorites have been used to argue that Mars accreted quickly, differentiated into core and mantle, and established several mantle reservoirs, possibly within 10 Ma of T0. The partitioning of trace elements in the deep mantle has been relatively unstudied, despite the need for such knowledge in understanding magma ocean crystallization and the origin of depleted and enriched mantle reservoirs. The siderophile element composition of the martian mantle, and lithophile isotopic systems such as Sr, Hf, and Nd, are thought to record evidence for early metal-silicate equilibrium and deep magma ocean at an intermediate depth and pressure of 800 km or 14 GPa. We have carried out experiments across this pressure range to better understand the mineral/melt partitioning of a wide range of elements. These new data are used to evaluate differentiation models for Mars and to help interpret the available isotopic data. The relatively incompatible nature of Re compared to mildly compatible Os means that the crystallization of a deep magma ocean will lead to residual liquids with super chondritic Re/Os, and solids with sub-chondritic Re/Os. Such material available in the mantle could be the source of enriched isotopic reservoir that produced shergottites with + Os values. On the other hand, slightly sub-chondritic Re/Os ratios in the crystallizing solids would provide a reservoir that could produce - Os values. Melting of mixtures of these two enriched and depleted end members could explain the Nd-Os isotopic correlations and systematics of shergottites.

K Righter↗
NASA NTRS2018

An Orbiting Sample Capture and Orientation System Architecture for Potential Mars Sample Return

An orbiting sample capture and orientation system architecture for a Rendezvous and Orbiting Sample Capture System (ROCS) concept was developed to enable spacecraft based, in-orbit capture, orientation, and transfer of a Mars sample container into a containment vessel as part of a potential Mars Sample Return (MSR) campaign. An analysis of the system functions, requirements, interactions, and constraints was performed. A trade study was carried out on relevant technologies, and a set of evaluation criteria was developed to help determine the most feasible concepts for implementation. The Mars Capture and Re-orientation for the potential Next Mars Orbiter (MACARONE) concept is proposed as a promising system architecture for the ROCS Capture and Orient Module (COM). The concept uses a sliding trap door for Orbiting Sample (OS) capture, a Motorized Cups Mechanism for OS orientation, and a 2 DOF Turret Arm with a paddle for transferring the OS into a containment vessel. This approach facilitates modularity, development flexibility, test-ability in a 1G environment, analyze-ability without the need to simulate or test for 0G contact dynamics, ability to encapsulate potential dust surrounding the OS, and ability to be ejected to reduce the probability of Earth exposure to non-sterilized Mars material.

Lalla, Karan↗
DOE OSTI2020

Materials Data on UB2Os3 by Materials Project

UOs3B2 crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. U6+ is bonded to twelve Os2- atoms to form UOs12 cuboctahedra that share corners with twelve equivalent UOs12 cuboctahedra, edges with six equivalent UOs12 cuboctahedra, edges with twelve equivalent BOs6 pentagonal pyramids, faces with two equivalent UOs12 cuboctahedra, and faces with six equivalent BOs6 pentagonal pyramids. There are four shorter (3.15 Å) and eight longer (3.16 Å) U–Os bond lengths. There are two inequivalent Os2- sites. In the first Os2- site, Os2- is bonded in a distorted square co-planar geometry to four equivalent U6+ and four equivalent B atoms. All Os–B bond lengths are 2.19 Å. In the second Os2- site, Os2- is bonded in a distorted square co-planar geometry to four equivalent U6+ and four equivalent B atoms. All Os–B bond lengths are 2.19 Å. B is bonded to six Os2- atoms to form distorted BOs6 pentagonal pyramids that share corners with six equivalent BOs6 pentagonal pyramids, edges with six equivalent UOs12 cuboctahedra, edges with three equivalent BOs6 pentagonal pyramids, faces with three equivalent UOs12 cuboctahedra, and faces with two equivalent BOs6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UOs2 by Materials Project

UOs2 is Cubic Laves structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. U4+ is bonded in a 12-coordinate geometry to twelve equivalent Os2- atoms. All U–Os bond lengths are 3.12 Å. Os2- is bonded to six equivalent U4+ and six equivalent Os2- atoms to form a mixture of face, edge, and corner-sharing OsU6Os6 cuboctahedra. All Os–Os bond lengths are 2.66 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfOs by Materials Project

OsHf is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Hf is bonded in a body-centered cubic geometry to eight equivalent Os atoms. All Hf–Os bond lengths are 2.82 Å. Os is bonded in a body-centered cubic geometry to eight equivalent Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NpOs2 by Materials Project

NpOs2 is Cubic Laves structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Np4+ is bonded in a 12-coordinate geometry to twelve equivalent Os2- atoms. All Np–Os bond lengths are 3.10 Å. Os2- is bonded to six equivalent Np4+ and six equivalent Os2- atoms to form a mixture of face, edge, and corner-sharing OsNp6Os6 cuboctahedra. All Os–Os bond lengths are 2.65 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Si3Os2 by Materials Project

Os2Si3 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. there are three inequivalent Os2- sites. In the first Os2- site, Os2- is bonded in a 7-coordinate geometry to seven Si+1.33+ atoms. There are a spread of Os–Si bond distances ranging from 2.39–2.54 Å. In the second Os2- site, Os2- is bonded to six Si+1.33+ atoms to form distorted edge-sharing OsSi6 octahedra. There are a spread of Os–Si bond distances ranging from 2.36–2.49 Å. In the third Os2- site, Os2- is bonded in a 8-coordinate geometry to eight Si+1.33+ atoms. There are a spread of Os–Si bond distances ranging from 2.41–2.81 Å. There are three inequivalent Si+1.33+ sites. In the first Si+1.33+ site, Si+1.33+ is bonded in a 4-coordinate geometry to four Os2- atoms. In the second Si+1.33+ site, Si+1.33+ is bonded in a 5-coordinate geometry to five Os2- atoms. In the third Si+1.33+ site, Si+1.33+ is bonded in a distorted pentagonal planar geometry to five Os2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Si3Os2 by Materials Project

Os2Si3 crystallizes in the tetragonal P-4c2 space group. The structure is three-dimensional. there are three inequivalent Os2- sites. In the first Os2- site, Os2- is bonded in a 8-coordinate geometry to eight Si+1.33+ atoms. There are four shorter (2.46 Å) and four longer (2.61 Å) Os–Si bond lengths. In the second Os2- site, Os2- is bonded in a 6-coordinate geometry to six Si+1.33+ atoms. There are four shorter (2.33 Å) and two longer (2.65 Å) Os–Si bond lengths. In the third Os2- site, Os2- is bonded in a 6-coordinate geometry to eight Si+1.33+ atoms. There are a spread of Os–Si bond distances ranging from 2.37–2.89 Å. There are two inequivalent Si+1.33+ sites. In the first Si+1.33+ site, Si+1.33+ is bonded in a distorted pentagonal planar geometry to five Os2- atoms. In the second Si+1.33+ site, Si+1.33+ is bonded in a 5-coordinate geometry to five Os2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ThOs2 by Materials Project

ThOs2 is Cubic Laves structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Th4+ is bonded in a 12-coordinate geometry to twelve equivalent Os2- atoms. All Th–Os bond lengths are 3.21 Å. Os2- is bonded to six equivalent Th4+ and six equivalent Os2- atoms to form a mixture of corner, edge, and face-sharing OsTh6Os6 cuboctahedra. All Os–Os bond lengths are 2.73 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb3Os by Materials Project

Nb3Os crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. Nb is bonded in a 6-coordinate geometry to two equivalent Nb and four equivalent Os atoms. Both Nb–Nb bond lengths are 2.59 Å. All Nb–Os bond lengths are 2.90 Å. Os is bonded to twelve equivalent Nb atoms to form a mixture of face and edge-sharing OsNb12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sn15Os3O14 by Materials Project

Os3Sn15O14 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are three inequivalent Os2- sites. In the first Os2- site, Os2- is bonded to six Sn+2.27+ atoms to form OsSn6 octahedra that share corners with four OsSn6 octahedra and corners with four OSn4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of Os–Sn bond distances ranging from 2.60–2.65 Å. In the second Os2- site, Os2- is bonded to six Sn+2.27+ atoms to form OsSn6 octahedra that share corners with two equivalent OsSn6 octahedra and corners with seven OSn4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of Os–Sn bond distances ranging from 2.57–2.63 Å. In the third Os2- site, Os2- is bonded to six Sn+2.27+ atoms to form OsSn6 octahedra that share corners with two equivalent OsSn6 octahedra, corners with six OSn4 tetrahedra, and an edgeedge with one OSn4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of Os–Sn bond distances ranging from 2.60–2.67 Å. There are eleven inequivalent Sn+2.27+ sites. In the first Sn+2.27+ site, Sn+2.27+ is bonded in a 4-coordinate geometry to two Os2- and two O2- atoms. There are one shorter (2.15 Å) and one longer (2.35 Å) Sn–O bond lengths. In the second Sn+2.27+ site, Sn+2.27+ is bonded in a 5-coordinate geometry to one Os2- and four O2- atoms. There are a spread of Sn–O bond distances ranging from 2.09–2.35 Å. In the third Sn+2.27+ site, Sn+2.27+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are one shorter (2.10 Å) and two longer (2.12 Å) Sn–O bond lengths. In the fourth Sn+2.27+ site, Sn+2.27+ is bonded in a 4-coordinate geometry to two Os2- and two O2- atoms. There are one shorter (2.19 Å) and one longer (2.39 Å) Sn–O bond lengths. In the fifth Sn+2.27+ site, Sn+2.27+ is bonded in a 5-coordinate geometry to one Os2- and four O2- atoms. There are a spread of Sn–O bond distances ranging from 2.15–2.34 Å. In the sixth Sn+2.27+ site, Sn+2.27+ is bonded in a 3-coordinate geometry to one Os2- and three O2- atoms. There are two shorter (2.13 Å) and one longer (2.18 Å) Sn–O bond lengths. In the seventh Sn+2.27+ site, Sn+2.27+ is bonded in a 5-coordinate geometry to one Os2- and four O2- atoms. There are a spread of Sn–O bond distances ranging from 2.10–2.35 Å. In the eighth Sn+2.27+ site, Sn+2.27+ is bonded in a 5-coordinate geometry to one Os2- and four O2- atoms. There are a spread of Sn–O bond distances ranging from 2.10–2.30 Å. In the ninth Sn+2.27+ site, Sn+2.27+ is bonded in a 5-coordinate geometry to one Os2- and four O2- atoms. There are a spread of Sn–O bond distances ranging from 2.11–2.28 Å. In the tenth Sn+2.27+ site, Sn+2.27+ is bonded in a 4-coordinate geometry to one Os2- and three O2- atoms. There are one shorter (2.09 Å) and two longer (2.11 Å) Sn–O bond lengths. In the eleventh Sn+2.27+ site, Sn+2.27+ is bonded in a 4-coordinate geometry to one Os2- and three O2- atoms. There are two shorter (2.06 Å) and one longer (2.11 Å) Sn–O bond lengths. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded to four Sn+2.27+ atoms to form distorted OSn4 tetrahedra that share corners with four OsSn6 octahedra and corners with three OSn4 tetrahedra. The corner-sharing octahedra tilt angles range from 61–64°. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Sn+2.27+ atoms. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Sn+2.27+ atoms. In the fourth O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Sn+2.27+ atoms. In the fifth O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Sn+2.27+ atoms. In the sixth O2- site, O2- is bonded to four Sn+2.27+ atoms to form distorted OSn4 tetrahedra that share corners with four OsSn6 octahedra and an edgeedge with one OsSn6 octahedra. The corner-sharing octahedra tilt angles range from 50–70°. In the seventh O2- site, O2- is bonded to four Sn+2.27+ atoms to form distorted OSn4 tetrahedra that share corners with three OsSn6 octahedra and corners with five OSn4 tetrahedra. The corner-sharing octahedra tilt angles range from 64–68°. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to four Sn+2.27+ atoms. In the ninth O2- site, O2- is bonded to four Sn+2.27+ atoms to form distorted OSn4 tetrahedra that share corners with three OsSn6 octahedra and corners with five OSn4 tetrahedra. The corner-sharing octahedra tilt angles range from 64–65°. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Sn+2.27+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuOs2 by Materials Project

PuOs2 is Cubic Laves structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Pu4+ is bonded in a 12-coordinate geometry to twelve equivalent Os2- atoms. All Pu–Os bond lengths are 3.09 Å. Os2- is bonded to six equivalent Pu4+ and six equivalent Os2- atoms to form a mixture of edge, face, and corner-sharing OsPu6Os6 cuboctahedra. All Os–Os bond lengths are 2.64 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd(Sb3Os)4 by Materials Project

NdOs4Sb12 is Skutterudite-derived structured and crystallizes in the cubic Im-3 space group. The structure is three-dimensional and consists of two neodymium molecules and one OsSb3 framework. In the OsSb3 framework, Os+0.75- is bonded to six equivalent Sb atoms to form corner-sharing OsSb6 octahedra. The corner-sharing octahedral tilt angles are 55°. All Os–Sb bond lengths are 2.65 Å. Sb is bonded in a 2-coordinate geometry to two equivalent Os+0.75- and two equivalent Sb atoms. There are one shorter (2.95 Å) and one longer (3.04 Å) Sb–Sb bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr3Os by Materials Project

Cr3Os crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. Cr is bonded in a 6-coordinate geometry to two equivalent Cr and four equivalent Os atoms. Both Cr–Cr bond lengths are 2.32 Å. All Cr–Os bond lengths are 2.60 Å. Os is bonded to twelve equivalent Cr atoms to form a mixture of edge and face-sharing OsCr12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(Sb3Os)4 by Materials Project

PrOs4Sb12 is Skutterudite-derived structured and crystallizes in the cubic Im-3 space group. The structure is three-dimensional and consists of two praseodymium molecules and one OsSb3 framework. In the OsSb3 framework, Os+0.75- is bonded to six equivalent Sb atoms to form corner-sharing OsSb6 octahedra. The corner-sharing octahedral tilt angles are 55°. All Os–Sb bond lengths are 2.65 Å. Sb is bonded in a 2-coordinate geometry to two equivalent Os+0.75- and two equivalent Sb atoms. There are one shorter (2.96 Å) and one longer (3.02 Å) Sb–Sb bond lengths.

36 MATERIALS SCIENCE↗