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At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

High Resolution Nature Runs and the Big Data Challenge

NASA's Global Modeling and Assimilation Office at Goddard Space Flight Center is undertaking a series of very computationally intensive Nature Runs and a downscaled reanalysis. The nature runs use the GEOS-5 as an Atmospheric General Circulation Model (AGCM) while the reanalysis uses the GEOS-5 in Data Assimilation mode. This paper will present computational challenges from three runs, two of which are AGCM and one is downscaled reanalysis using the full DAS. The nature runs will be completed at two surface grid resolutions, 7 and 3 kilometers and 72 vertical levels. The 7 km run spanned 2 years (2005-2006) and produced 4 PB of data while the 3 km run will span one year and generate 4 BP of data. The downscaled reanalysis (MERRA-II Modern-Era Reanalysis for Research and Applications) will cover 15 years and generate 1 PB of data. Our efforts to address the big data challenges of climate science, we are moving toward a notion of Climate Analytics-as-a-Service (CAaaS), a specialization of the concept of business process-as-a-service that is an evolving extension of IaaS, PaaS, and SaaS enabled by cloud computing. In this presentation, we will describe two projects that demonstrate this shift. MERRA Analytic Services (MERRA/AS) is an example of cloud-enabled CAaaS. MERRA/AS enables MapReduce analytics over MERRA reanalysis data collection by bringing together the high-performance computing, scalable data management, and a domain-specific climate data services API. NASA's High-Performance Science Cloud (HPSC) is an example of the type of compute-storage fabric required to support CAaaS. The HPSC comprises a high speed Infinib and network, high performance file systems and object storage, and a virtual system environments specific for data intensive, science applications. These technologies are providing a new tier in the data and analytic services stack that helps connect earthbound, enterprise-level data and computational resources to new customers and new mobility-driven applications and modes of work. In our experience, CAaaS lowers the barriers and risk to organizational change, fosters innovation and experimentation, and provides the agility required to meet our customers' increasing and changing needs

big data analysis↗
NASA NTRS1960

Vacancy Relaxation in Cubic Crystals

The configuration of the atoms surrounding a vacancy in four face-centered cubic and three body-centered cubic metals has been computed, using a pairwise, central-force model in which the energy of interaction between two atoms was taken to have the form of a Morse function. Only radial relaxations were considered. The first and second nearest-neighbor relaxations for the face-centered systems were found to be: Pb (1.42,−0.43), Ni (2.14,−0.39), Cu(2.24,−0.40) and Ca (2.73,−0.41, expressed in percentages of normal distances. For the body-centered systems the relaxations out to the fourth nearest neighbors to the vacancy were: Fe (6.07,−2.12, −0.25, −), Ba (7.85, −2.70, 0.70, −0.33) and Na (10.80, −3.14, 3.43, −0.20). The positive signs indicate relaxation toward the vacancy and the negative signs indicate relaxation away from the vacancy. The energies of relaxation (eV) are: Pb (0.162), Ni (0.626), Cu (0.560), Ca (0.400), Fe (1.410), Ba (0.950) and Na (0.172).

Girifalco, L. A.↗
NASA NTRS2016

AR-40 AR-39 Age of an Impact-Melt Lithology in DHOFAR 961

The South Pole-Aitken (SPA) basin is the stratigraphically oldest identifiable lunar basin and is therefore one of the most important targets for absolute age-dating to help understand whether ancient lunar bombardment history smoothly declined or was punctuated by a cataclysm. The SPA basin also has another convenient property, a geochemically distinct interior, unobscured by extensive mare basalt fill. A case has been made for the possible origin of the Dhofar 961 lunar meteorite in the South Pole-Aitken (SPA) basin, based on comparing its composition with Lunar Prospector gamma-ray data for the interior of the SPA basin. Dhofar 961 contains several different impact-melt (IM) lithologies. Jolliff et al. described two classes of mafic impact-melt lithologies, one dominated by olivine (Lithology A) and the other by plagioclase (An 95-96.5) (Lithology B). Broad-beam analyses of these lithologies yielded (is) approximately 14.0 wt% FeO, 11.7 wt% MgO, and 15.4 wt% Al2O3. Lithologies A and B differ by approximately 2.5% Al2O3, 1.5% FeO and 1.5% MgO, consistent with the occurrence of olivine phenocrysts in A and plagioclase clasts in B. Both lithologies are considerably more mafic than the Apollo mafic impact-melt breccias, corresponding to olivine gabbronorite. Joy et al. used U-Pb dating to investigate phosphate fragments in the Dhofar 961 matrix and impact-melt clasts. Matrix phosphates have 4.34 to 4 Ga ages, consistent with ancient KREEP-driven magmatic episodes and Pre-Nectarian ((is) greater than 3.92 Ga). Phosphates found within Dhofar 961 crystalline impact melt breccia clasts range from 4.26 to 3.89 Ga, potentially recording events throughout the basin forming epoch of lunar history. The youngest reset ages in the Dhofar 961 sample represent an upper limit for the time of formation of the meteorite. Joy et al suggested this age represents the final impact that mixed and consolidated several generations of precursor rocks into the Dhofar meteorite group, although they note that further age dating of all the stones is required to test this hypothesis. We received a split of Dhofar 961 from R. Zeigler consisting of a large clast of IM Lithology B, with some light-colored, friable matrix clinging to the external margins of the impact-melt clast. This lithology was not present in the samples investigated by Joy et al. and thus does not have corresponding U-Pb ages on it. We created multiple subsplits of both the IM and matrix lithologies, each weighing several tens of micrograms. We conducted Ar-40 Ar-39 dating of this candidate SPA material by high-resolution step heating and comparing it with the regolith that surrounds it.

Lithology↗
NASA NTRS2018

Detrital Shocked Zircon Provides First Radiometric Age Constraint of <1472 Ma for the Santa Fe Impact Structure, New Mexico, USA

Impact structures are prone to erosion, burial and tectonic deformation. The Santa Fe impact structure in New Mexico contains shatter cones and shocked quartz, but is highly tectonized and eroded; estimates of the impact age (1200-300 Ma) and size (6-13 km) are poorly constrained. Here we report the first occurrence of shock-twinned zircon identified both in modern sediments and bedrock at the Santa Fe impact structure. Zircon {112} twin lamellae are considered diagnostic evidence of shock deformation and have been identified at several impact structures including Vredefort, Sudbury, Ries, Rock Elm, and in lunar impact breccia. A total of 6619 grains from fifteen sediment samples and two rock samples were surveyed; seven shocked grains were identified (7/6619 = 0.1%). One shocked zircon was identified in a biotite schist shatter cone. Five of seven shocked zircon grains were EBSD mapped; three were analyzed with multiple SIMS spots. EBSD mapping revealed {112} deformation twin lamellae in each of the five zircon grains. U-Pb geochronology for three of the shocked zircon grains yield crystallization ages from 1715+/-22 to 1472+/-35 Ma. LA-ICPMS U-Th-Pb analysis of detrital zircon grains from five samples yielded Paleoproterozoic (1800-1600 Ma) and Mesoproterozoic (1500-1300 Ma) ages. We reveal the first confirmed shocked zircon at the Santa Fe structure. Zircon is the third shocked mineral identified at this site, in addition to xenotime and quartz]; the {112} twin lamellae indicate that exposed bedrock may have experienced shock pressures up to ~20 GPa. The 1472+/-35 Ma age determined from a shock-twinned zircon is the first reliable maximum impact age constraint based on analysis of shocked material and extends the window for the Santa Fe impact event into the Mesoproterozoic.

Montalvo, Pedro E.↗
NASA NTRS2019

Volatile Element Depletion of the Moon – The Roles of Pre-Cursors, Post-Impact Disk Dynamics, and Core Formation

The compositional and isotopic similarity of Earth’s primitive upper mantle (PUM) and the Moon has bolstered the idea that the Moon was derived from the proto-Earth, but the Moon’s inventory of volatile lithophile elements – Na, K, Rb and Cs – are lower than in Earth’s PUM by a factor of 4 to 5. The abundances of fourteen other volatile elements exhibit siderophile behavior (volatile siderophile elements or VSE; P, As, Cu, Ag, Sb, Ga, Ge, Bi, Pb, Zn, Sn, Cd, In, and Tl) that could be used to evaluate whether the Moon was derived from the proto-Earth, and whether their depletion can be attributed to volatility or core formation. In this study, newly available core-mantle partitioning data are used, together with bulk Moon compositions, protolunar disk dynamics modelling to test the hypothesis that the Moon was derived from PUM-like material. At lunar core formation conditions, As, Sb, Ag, Ge, Bi, Sn are siderophile, whereas P, Cu, Ga, Pb, Zn, Cd, In and Tl are all weakly siderophile or lithophile. Most of the VSE can be explained by a combination of known processes – pre-cursor volatile depletion, melt-gas dynamics and equilibria in the protolunar disk, and core formation. Explaining this whole group of volatile elements may require a combination of mixing and separation of the newly formed Moon from remnant gas rich in the highest volatility VSEs. This large group of volatile elements informs a wide temperature range and offers a powerful test of melt-gas segregation mechanisms in the protolunar disk and lunar formation hypotheses.

Righter, K.↗
NASA NTRS2020

Shock Deformation in Zircon, a Comparison of Results from Shock-Reverberation and Single-Shock Experiments

The utility of the mineral zircon, ZrSiO4, as a shock-metamorphic geobarometer and geochronometer, has been steadily growing within the planetary science community. Zircon is an accessory phase found in many terrestrial rock types, lunar samples, lunar meteorites, martian meteorites and various other achondrites. Because zircon is refractory and has a high closure temperature for Pb diffusion, it has been used to determine the ages of some of the oldest material on Earth and elsewhere in the Solar System. Furthermore, major (O) and trace-element (REE, Ti, Hf) abundances and isotope compositions of zircon help characterize the petrogenetic environments and sources from which they crystallized. The response of zircon to impact-induced shock deformation is predominantly crystallographic, including dislocation creep and the formation of planar and sub-planar, low-angle grain boundaries; the formation of mechanical {112} twins; transformation to the high pressure polymorph reidite; the development of polycrystalline microtextures; and dissociation to the oxide constituents SiO2 and ZrO2. Shock microstructures can also variably affect the U- Pb isotope systematics of zircon and, in some instances, be used to constrain the impact age. While numerous studies have characterized shock deformation in zircon recovered from a variety of terrestrial impact craters and ejecta deposits and Apollo samples, experimental studies of shock deformation in zircon are limited to a handful of examples in the literature. In addition, the formation conditions (e.g., P, T) of various shock microstructures, such as planar-deformation bands, twins, and reidite lamellae, remain poorly con-strained. Furthermore, previous shocked-zircon experimental charges have not been analyzed using modern analytical equipment. This study will therefore under-take an new set of zircon shock experiments, which will then be microstructurally characterized using state-of-the-art instrumentation within the Astromaterials Research and Exploration Science Division (ARES), NASA Johnson Space Center.

Erickon, T. M.↗
NASA NTRS2021

TOI-2076 and TOI-1807: Two Young, Comoving Planetary Systems within 50 pc Identified by TESS that are Ideal Candidates for Further Follow Up

We report the discovery of two planetary systems around comoving stars: TOI-2076 (TIC 27491137) and TOI-1807 (TIC 180695581). TOI-2076 is a nearby (41.9 pc) multiplanetary system orbiting a young (204 ± 50 Myr), bright (K = 7.115 in TIC v8.1) start. TOI-1807 hosts a single transiting planet and is similarly nearby (42.58 pc), similarly young (180 ± 40 Myr ), and bright. Both targets exhibit significant, periodic variability due to starspots, characteristic of their young ages. Using photometric data collected by TESS we identify three transiting planets around TOI-2076 with radii of Rb = 3.3 ± 0.04 R⊕, Rc = 4.4 ± 0.05 R⊕, and Rd = 4.1 ± 0.07 R⊕. Planet TOI-2076b has a period of Pb = 10.356 days. For both TOI-2076c and d, TESS observed only two transits, separated by a 2 yr interval in which no data were collected, preventing a unique period determination. A range of long periods (<17 days) are consistent with the data. We identify a short-period planet around TOI-1807 with a radius of Rb = 1.8 ± 0.04 R⊕ and a period of Pb = 0.549 days. Their close proximity, and bright, cool host stars, and young ages make these planets excellent candidates for follow up. TOI-1807b is one of the best-known small (R < 2 ${R}_{\oplus }$) planets for characterization via eclipse spectroscopy and phase curves with JWST. TOI-1807b is the youngest ultra-short-period planet discovered to date, providing valuable constraints on formation timescales of short-period planets. Given the rarity of young planets, particularly in multiple-planet systems, these planets present an unprecedented opportunity to study and compare exoplanet formation, and young planet atmospheres, at a crucial transition age for formation theory.

Christina Hedges↗
NASA NTRSDate not supplied

Hybrid pulse-burst / cross-correlation DGV for high-speed flow measurements at 100 kHz

Hybrid pulse-burst Doppler global velocimetry (PB-DGV)/pulse-burst, cross-correlation DGV (PB-CC-DGV) was demonstrated for the first time in the NASA Langley 4-foot Supersonic Unitary Plan Wind Tunnel, allowing simultaneous acquisition of mean and instantaneous high-repetition-rate velocity fields. The technique was used to make planar velocity measurements across an oblique shockwave generated by a large splitter plate set at a -2° angle of attack in a Mach 2.4 flow. Sequences of more than 100 consecutive instantaneous velocity images were obtained at a rate of 100 kHz. Velocity fields from both aspects of the hybrid measurement indicated errors less than 1-percent of anticipated velocities. Likewise, all assessments of measurement precision were approximately 1.6-percent of the local velocities. Additional demonstrations in different flowfields including a subsonic axi-symmetric jet and a supersonic Mars reentry vehicle model further illustrate the utility of the new hybrid method.

laser↗
NASA NTRSDate not supplied

NASA EOSDIS 20 Years of Data Usage and User Assessment in Support of Open Science Initiative

NASA EOS Data and Information System (EOSDIS) has been distributing data to world-wide users free with open access. Since the launch of NASA’s Terra satellite in 1999, more than 10,000 distinct EOS data products have been archived and distributed by NASA-funded Earth Science data centers encompassed by the EOSDIS. As of September 30, 2022, more than 90 PB of data archived by EOSDIS have been made available to public users and during FY 2023 over 60 PB have been distributed to public users worldwide. Over these twenty and more years, it has shown significant increase in the distribution of various data products. This has been possible due to free and open access of the data thereby a step towards open science initiative. The purposes of this study are 1) to perform a comprehensive investigation of the archive and distribution patterns of EOSDIS data products for last 20 years, 2) to identify and characterize the global user community for those data, 3) analyze the increased demand for data products, 4) evaluate distribution of higher level products because those are the ones most frequently used in the studies of natural disasters by public users (those data requestors not involved directly in the production or validation of the data products.) and contribute globally to the advance scientific understanding of the Earth-Atmosphere Systems. Funded by the Earth Science Data and Information System (ESDIS) Project, the ESDIS Metrics System (EMS) collects archive, distribution, and user information from EOSDIS data centers. The information (comprising all data products including heritage datasets going back to the 1990s) is stored in a relational database from which it can be analyzed in many ways. We present several metrics analyses that include data distribution patterns for all, as well as the most frequently requested data products; and user characterizations by country, domain, and Earth Science discipline (e.g., Land, Ocean, Cryosphere) of the requested products. Due to the enormous quantity of data handled by EOSDIS data centers and requirements of future data systems to archive increasing amounts of Earth Science data from future and current Earth Science missions effectively, the results of this study can provide insight on how the user communities have accessed the data and provide guidance for open science initiative.

Lalit Wanchoo↗
NASA NTRSDate not supplied

Phosphate (U-Th)/He Thermochronology of Apollo 14 Melt Breccia 14311

Our ability to confidently characterize the impact history of the inner solar system is limited by discrepancies in radiometric dates and age interpretations for lunar rocks, impact melts, and recovered meteorites. It is therefore important to explore different thermally sensitive radiometric systems to unravel the timing and extent of the long term impact flux. Low-temperature thermochronology of lunar samples has the potential to provide more complementary geochronological datasets and further test dynamical models related to the evolution of the inner solar system (e.g., [1]). (U-Th)/He dating is based on the production of 4He atoms by radioactive alpha decay of U and Th (and to a lesser extent, Sm) in a crystal and the thermally activated volumetric diffusion of those 4He nuclides. At high temperatures, the crystal is an open system from which 4He can escape; at lower temperatures, 4He may be retained. This retention temperature depends on factors such as crystal structure and volume fraction of radiation damage in the crystal (e.g., [2, 3]), but is significantly lower for phosphate minerals compared to the diffusion of the radiogenic daughter products in other widely used chronometric systems (e.g., ~75°C in terrestrial apatite (U-Th)/He vs. ~500°C in apatite U-Th-Pb vs. ~900°C in zircon U-Th-Pb chronometry). Phosphate (U-Th)/He dating has been used to decipher peak temperatures and cooling rates related to terrestrial impact events (e.g., [4]). Pairing a low-temperature thermochronometer with higher-temperature approaches (i.e., a combined 207Pb-206Pb and (U-Th)/He approach), can therefore resolve multiple impact ages within a given sample or even grain. However, despite its potential, phosphate (U-Th)/He dating has not been reported on any lunar samples. Here we present the first lunar phosphate (U-Th)/He thermochronology on an Apollo 14 impact melt-breccia.

C A Diaz↗
NASA NTRS2024

Combining Multi-Faceted Laboratory Studies of 74001-2 and Regional Remote Sensing to Address How Pyroclastic Eruptions Record and Affect the Lunar Volatile Budget

Basaltic magmatism is an efficient process for bringing volatiles from a planetary interior to its surface, with the possibility of generation of a transient lunar atmosphere as abundant volcanic materials de-gassed. However, pyroclastic deposits are locations where trapped gases may be studied [e.g., 2,3]. Volatile-rich pyroclastic deposits occur over a wide surface area of the Moon, indicating that the transport of volatiles and associated pyroclastic materials from the Moon’s mantle to the surface was a wide-spread phenomenon. Numerous studies analyzing remotely sensed data and using empirical modeling have demonstrated that various stages of pyroclastic eruptions significantly influence gas release patterns, morphology, and mineralogy of the deposit. Many observations based on mare basalts and pyroclastic deposits have identified potential histories of gas release [e.g., 2-10] and their influence on volatiles and their stable isotopes [e.g., 11-13]. The best representation of these pyroclastic deposits in the sample collection is core sample 74001-74002 that was collected during the Apollo 17 mission to the Taurus-Littrow Valley (TLV). The double drive tube penetrated a part of a regional-scale pyroclastic deposit and sampled approximately 68.1 cm of that deposit in the TLV. Remnants of this and other pyroclastic depos-its are represented throughout and beyond the TLV [e.g., 14-16]. The stratigraphy of this core has been investigated and defined by numerous studies. The CASA Moon SSERVI research team is conducting a multi-faceted analytical study of this deposit. Data generated from revisiting the stratigraphy of 74001-74002 will be used to place stable isotopes (H, B, Cl, S, Zn, Cu, Rb, Ga, Pb), Ar-Ar and U-Pb chronology, geochemistry, nanometer-scale observations of mineral surfaces, orbital observations, and experiments and modeling within a stratigraphic, eruptive, and geologic context. It is important to place these data into such a context. For example, recent S isotope measurements reported by Dottin et al. show differences within this core that may be related to either changes in source or eruptive process over the course of the eruption (vs. multiple eruptions). A fuller understanding of the stratigraphy is fundamental to resolving this interpretation. This comprehensive approach can only be achieved within the context of a program such as SSERVI. In addition, imaging produced in this project will be incorporated into a citizen scientist program to further identify many of the textural features of this double drive tube.

SSERVI↗
NASA NTRS2024

Evidence for a ~1 Ga Hypervelocity Impact Event Found in Northwest Greenland

There are likely many undiscovered impact structures on Earth, but several challenges prevent their detection, including possible concealment beneath large ice sheets. In recent years, geophysical, geochemical, and microphysical evidence has mounted for a ca. 58 Ma impact structure under the Hiawatha Glacier, northwest Greenland. Here, we report evidence for a second, much older hypervelocity impact event in this region, recorded in an impact melt rock sample collected from a glaciofluvial deposit in Inglefield Land. Secondary ion mass spectrometry U-Pb analyses of shock metamorphosed zircon grains yielded a previously unrecorded, Proterozoic best estimate impact age of 1039 ± 16 Ma (mean square of weighted deviates = 2.9). Based on Archean−Proterozoic target rock U-Pb ages obtained from unshocked zircon grains and the location of the melt rock sample along the ice margin, we suggest this sample was derived from a hypervelocity impact structure farther inland, concealed by the Greenland Ice Sheet. This study demonstrates the ability to uncover new impact events in some of the most inaccessible areas on Earth and the possibility of sampling multiple impact structures from one location when examining ex situ material. Our results have implications for current and future Martian and lunar returned samples that demonstrably bear complex impact histories.

William R. Hyde↗
NASA NTRS2023

4.46 Ga Zircons Anchor Chronology of Lunar Magma Ocean

The crystallisation ages of lunar samples provide critical constraints on the minimum formation age of the Moon and its early evolution. Zircon crystals from Apollo 17 lunar impact melt breccia 72255 preserve ancient domains with a concordant average uranium-lead radiometric date of 4460 ± 31 Ma (Zhang et al., 2021), the oldest lunar zircon yet reported. To assess the possible mobility of radiogenic lead in zircon, which may lead to redistribution and clustering of Pb atoms that may cause a U-Pb age bias (Valley et al., 2014), we investigated a zircon grain from Zhang et al. (2021) by atom probe tomography (APT). The atomic spatial resolution analysis of individual mineral grains demonstrates the absence of nanoscale clustering of lead, which supports a 4.46 Ga ancient formation age for lunar zircon in sample 72255. This age pushes back the age of the first preserved lunar crust by ∼40 Myr and provides a minimum formation age for the Moon within 110 Myr after the formation of the solar system.

atom probe tomography↗
NASA NTRS2020

Precise Radiometric Age Establishes Yarrabubba, Western Australia, as Earth's Oldest Recognised Meteorite Impact Structure

The ~70 km-diameter Yarrabubba impact structure in Western Australia is regarded as among Earth’s oldest, but has hitherto lacked precise age constraints. Here we present U-Pb ages for impact21 driven shock recrystallised accessory minerals. Shock-recrystallised monazite yields a precise impact age of 2229 ± 5 Ma, coeval with shock-reset zircon. This result establishes Yarrabubba as the oldest recognized meteorite impact structure on Earth, extending the terrestrial cratering record back >200 million years. The age of Yarrabubba coincides, within uncertainty, with temporal constraint for the youngest Palaeoproterozoic glacial deposits, the Rietfontein diamictite in South Africa. Numerical impact simulations indicate that a 70 km-diameter crater into a continental glacier could release between 8.7x1013 to 5.0x1015 kg of H2O vapour instantaneously into the atmosphere. These results provide new estimates of impact-produced H2O vapour abundances for models investigating termination of the Paleoproterozoic glaciations, and highlight the possible role of impact cratering in modifying Earth’s climate.

Impact cratering↗
NASA NTRS1968

Arc spectrum of lead.

Photographic IR arc emission spectrum of Pb analyzed from measurements with electrodeless discharge tubes, discussing spectral lines and atomic energy levels

Andrew, K. L.↗