The Galley Parallel File System

NASA Technical Reports Server (NTRS)

Nieuwejaar, Nils; Kotz, David

1996-01-01

Most current multiprocessor file systems are designed to use multiple disks in parallel, using the high aggregate bandwidth to meet the growing I/0 requirements of parallel scientific applications. Many multiprocessor file systems provide applications with a conventional Unix-like interface, allowing the application to access multiple disks transparently. This interface conceals the parallelism within the file system, increasing the ease of programmability, but making it difficult or impossible for sophisticated programmers and libraries to use knowledge about their I/O needs to exploit that parallelism. In addition to providing an insufficient interface, most current multiprocessor file systems are optimized for a different workload than they are being asked to support. We introduce Galley, a new parallel file system that is intended to efficiently support realistic scientific multiprocessor workloads. We discuss Galley's file structure and application interface, as well as the performance advantages offered by that interface.

Characterizing parallel file-access patterns on a large-scale multiprocessor

NASA Technical Reports Server (NTRS)

Purakayastha, A.; Ellis, Carla; Kotz, David; Nieuwejaar, Nils; Best, Michael L.

1995-01-01

High-performance parallel file systems are needed to satisfy tremendous I/O requirements of parallel scientific applications. The design of such high-performance parallel file systems depends on a comprehensive understanding of the expected workload, but so far there have been very few usage studies of multiprocessor file systems. This paper is part of the CHARISMA project, which intends to fill this void by measuring real file-system workloads on various production parallel machines. In particular, we present results from the CM-5 at the National Center for Supercomputing Applications. Our results are unique because we collect information about nearly every individual I/O request from the mix of jobs running on the machine. Analysis of the traces leads to various recommendations for parallel file-system design.

The asteroid-meteorite connection: Forging a new link to Vesta as the parent body of basaltic achondrite (HED) meteorites

NASA Technical Reports Server (NTRS)

Binzel, R. P.

1993-01-01

Asteroid 4 Vesta has been at the center of the debate over the identity of the howardite eucrite diogenite (HED) parent body since the early 1970s. Despite its unique (among the 500 largest asteroids) compositional match to HED meteorites, substantial dynamical difficulties in delivering fragments from Vesta to the Earth have precluded any conclusive HED parent body link. These dynamical difficulties arise because Vesta's orbital location is far from known resonances. Consequently, it has been argued as dynamically improbable that meteoroid-sized (1 km) fragments could be excavated from Vesta with sufficient velocities to reach the resonances. Through new astronomical observations, numerous small (4-7 km) asteroids between Vesta and the 3:1 resonance have been discovered to have eucrite and diogenite compositions. Based on similar orbital elements to Vesta, all of these new asteroids are likely large impact fragments excavated from Vesta. Their current orbits imply ejection velocities in excess of 700 m/sec. Smaller (1 km) fragments can therefore be expected to have been ejected with velocities greater than 1 km/sec, sufficient to reach the 3:1 and v6 resonances. Thus it now appears to be dynamically viable for Vesta to be linked as the HED parent body.

Dawn Orbit Determination Team: Modeling and Fitting of Optical Data at Vesta

NASA Technical Reports Server (NTRS)

Kennedy, Brian; Abrahamson, Matt; Ardito, Alessandro; Haw, Robert; Mastrodemos, Nicholas; Nandi, Sumita; Park, Ryan; Rush, Brian; Vaughan, Andrew

2013-01-01

The Dawn spacecraft was launched on September 27th, 2007. Its mission is to consecutively rendezvous with and observe the two largest bodies in the main asteroid belt, Vesta and Ceres. It has already completed over a year's worth of direct observations of Vesta (spanning from early 2011 through late 2012) and is currently on a cruise trajectory to Ceres, where it will begin scientific observations in mid-2015. Achieving this data collection required careful planning and execution from all Dawn operations teams. Dawn's Orbit Determination (OD) team was tasked with reconstruction of the as-flown trajectory as well as determination of the Vesta rotational rate, pole orientation and ephemeris, among other Vesta parameters. Improved knowledge of the Vesta pole orientation, specifically, was needed to target the final maneuvers that inserted Dawn into the first science orbit at Vesta. To solve for these parameters, the OD team used radiometric data from the Deep Space Network (DSN) along with optical data reduced from Dawn's Framing Camera (FC) images. This paper will de-scribe the initial determination of the Vesta ephemeris and pole using a combination of radiometric and optical data, and also the progress the OD team has made since then to further refine the knowledge of Vesta's body frame orientation and rate with these data.

Asteroid-Meteorite Links: The Vesta Conundrum(s)

NASA Technical Reports Server (NTRS)

Pieters, C. M.; Binzel, R.; Bogard, D.; Hiroi, T.; Mittlefehldt, D. W.; Nyquist, L.; Rivkin, A.; Takeda, H.

2006-01-01

Although a direct link between the HED meteorites and the asteroid 4 Vesta is generally acknowledged, several issues continue to be actively examined that tie Vesta to early processes in the solar system. Vesta is no longer the only basaltic asteroid in the Main belt. In addition to the Vestoids of the Vesta family, the small asteroid Magnya is basaltic but appears to be unrelated to Vesta. Similarly, diversity now identified in the collection of basaltic meteorites requires more than one basaltic parent body, consistent with the abundance of differentiated parent bodies implied by iron meteorites. The timing of the formation of the Vestoids (and presumably the large crater at the south pole of Vesta) is unresolved. Peaks in Ar-Ar dates of eucrites suggest this impact event could be related to a possible late heavy bombardment at least 3.5 Gyr ago. On the other hand, the optically fresh appearance of both Vesta and the Vestoids requires either a relatively recent resurfacing event or that their surfaces do not weather in the same manner thought to occur on other asteroids such as the ordinary chondrite parent body. Diversity across the surface of Vesta has been observed with HST and there are hints of compositional variations (possibly involving minor olivine) in near-infrared spectra.

Performance of the Galley Parallel File System

NASA Technical Reports Server (NTRS)

Nieuwejaar, Nils; Kotz, David

1996-01-01

As the input/output (I/O) needs of parallel scientific applications increase, file systems for multiprocessors are being designed to provide applications with parallel access to multiple disks. Many parallel file systems present applications with a conventional Unix-like interface that allows the application to access multiple disks transparently. This interface conceals the parallism within the file system, which increases the ease of programmability, but makes it difficult or impossible for sophisticated programmers and libraries to use knowledge about their I/O needs to exploit that parallelism. Furthermore, most current parallel file systems are optimized for a different workload than they are being asked to support. We introduce Galley, a new parallel file system that is intended to efficiently support realistic parallel workloads. Initial experiments, reported in this paper, indicate that Galley is capable of providing high-performance 1/O to applications the applications that rely on them. In Section 3 we describe that access data in patterns that have been observed to be common.

Storing files in a parallel computing system based on user-specified parser function

DOEpatents

Faibish, Sorin; Bent, John M; Tzelnic, Percy; Grider, Gary; Manzanares, Adam; Torres, Aaron

2014-10-21

Techniques are provided for storing files in a parallel computing system based on a user-specified parser function. A plurality of files generated by a distributed application in a parallel computing system are stored by obtaining a parser from the distributed application for processing the plurality of files prior to storage; and storing one or more of the plurality of files in one or more storage nodes of the parallel computing system based on the processing by the parser. The plurality of files comprise one or more of a plurality of complete files and a plurality of sub-files. The parser can optionally store only those files that satisfy one or more semantic requirements of the parser. The parser can also extract metadata from one or more of the files and the extracted metadata can be stored with one or more of the plurality of files and used for searching for files.

Methods and apparatus for capture and storage of semantic information with sub-files in a parallel computing system

DOEpatents

Faibish, Sorin; Bent, John M; Tzelnic, Percy; Grider, Gary; Torres, Aaron

2015-02-03

Techniques are provided for storing files in a parallel computing system using sub-files with semantically meaningful boundaries. A method is provided for storing at least one file generated by a distributed application in a parallel computing system. The file comprises one or more of a complete file and a plurality of sub-files. The method comprises the steps of obtaining a user specification of semantic information related to the file; providing the semantic information as a data structure description to a data formatting library write function; and storing the semantic information related to the file with one or more of the sub-files in one or more storage nodes of the parallel computing system. The semantic information provides a description of data in the file. The sub-files can be replicated based on semantically meaningful boundaries.

VizieR Online Data Catalog: Deep Herschel PACS point spread functions (Bocchio+, 2016)

NASA Astrophysics Data System (ADS)

Bocchio, M.; Bianchi, A.; Abergel, S.

2016-06-01

Herschel PACS dedicated PSF observations are scanmaps centred on various objects taken at 70 (blue channel), 100 (green channel) and 160 (red channel) um. The core of the PSF is best characterised observing faint objects (e.g. the asteroid Vesta), while the wings of the PSF can only be seen in observations of bright objects (e.g. Mars). Using a combination of images of bright and faint objects it is therefore possible to have a good characterisation of the PACS PSFs. (2 data files).

Origin of Dark Material on VESTA from DAWN FC Data: Remnant Carbonaceous Chondrite Impators

NASA Technical Reports Server (NTRS)

Reddy, V.; LeCorre, L.; Nathues, A.; Mittlefehldt, David W.; Cloutis, E. A.; OBrien, D. P.; Durda, D. D.; Bottke, W. F.; Buczkowski, D.; Scully, J. E. C.;

Revealing Shadows 1

NASA Image and Video Library

2012-07-23

These images from NASA Dawn spacecraft, located in Vesta Caparronia quadrangle, in Vesta northern hemisphere, demonstrate a special analytical technique, which results in shadowed areas of Vesta surface becoming illuminated.

Revealing Shadows 6

NASA Image and Video Library

2012-07-30

These images from NASA Dawn spacecraft, located in asteroid Vesta Caparronia quadrangle, in Vesta northern hemisphere, demonstrate a special analytical technique, which results in shadowed areas of Vesta surface becoming illuminated.

Revealing Shadows 3

NASA Image and Video Library

2012-07-25

These images from NASA Dawn spacecraft, located in asteroid Vesta Marcia quadrangle, in Vesta northern hemisphere, demonstrate a special analytical technique, which results in shadowed areas of Vesta surface becoming illuminated.

Revealing Shadows 2

NASA Image and Video Library

2012-07-24

These images from NASA Dawn spacecraft, located in asteroid Vesta Oppia quadrangle, in Vesta northern hemisphere, demonstrate a special analytical technique, which results in shadowed areas of Vesta surface becoming illuminated.

Revealing Shadows 7

NASA Image and Video Library

2012-07-31

These images from NASA Dawn spacecraft, located in asteroid VestaFloronia quadrangle, in Vesta northern hemisphere, demonstrate a special analytical technique, which results in shadowed areas of Vesta surface becoming illuminated.

Revealing Shadows 5

NASA Image and Video Library

2012-07-27

These images from NASA Dawn spacecraft, located in asteroid Vesta Floronia quadrangle, in Vesta northern hemisphere, demonstrate a special analytical technique, which results in shadowed areas of Vesta surface becoming illuminated.

Revealing Shadows 4

NASA Image and Video Library

2012-07-26

These images from NASA Dawn spacecraft, located in asteroid Vesta Marcia quadrangle, in Vesta northern hemisphere, demonstrate a special analytical technique, which results in shadowed areas of Vesta surface becoming illuminated.

Cooperative storage of shared files in a parallel computing system with dynamic block size

DOEpatents

Bent, John M.; Faibish, Sorin; Grider, Gary

2015-11-10

Improved techniques are provided for parallel writing of data to a shared object in a parallel computing system. A method is provided for storing data generated by a plurality of parallel processes to a shared object in a parallel computing system. The method is performed by at least one of the processes and comprises: dynamically determining a block size for storing the data; exchanging a determined amount of the data with at least one additional process to achieve a block of the data having the dynamically determined block size; and writing the block of the data having the dynamically determined block size to a file system. The determined block size comprises, e.g., a total amount of the data to be stored divided by the number of parallel processes. The file system comprises, for example, a log structured virtual parallel file system, such as a Parallel Log-Structured File System (PLFS).

Getting to Know Vesta

NASA Astrophysics Data System (ADS)

Martel, L. M. V.

2007-11-01

The howardite-eucrite-diogenite class of meteorites (called the HEDs) are rocks formed from basaltic magmas. What makes them special is that the HEDs have reflectance spectra in the visible and near-infrared that match spectra from asteroid 4 Vesta, implying Vesta is their parent body. We will soon have new data from Vesta from NASA's Dawn orbiting spacecraft, which carries a gamma ray and neutron detector, dubbed the GRaND instrument. GRaND will orbit asteroid 4 Vesta and dwarf planet Ceres and map the near-surface abundances of major and minor elements, and volatiles found in ices (in the case of Ceres) such as hydrogen, carbon, nitrogen, and oxygen. Tomohiro Usui and Harry Y. (Hap) McSween, Jr. (University of Tennessee) have proposed a way to interpret the upcoming GRaND data from Vesta based on well-analyzed samples of HED meteorites and a mixing model they devised that uses element ratios of the three expected rock types. In turn, the new data from Vesta may help scientists better understand the geologic context for HED meteorites.

RAMA: A file system for massively parallel computers

NASA Technical Reports Server (NTRS)

Miller, Ethan L.; Katz, Randy H.

1993-01-01

This paper describes a file system design for massively parallel computers which makes very efficient use of a few disks per processor. This overcomes the traditional I/O bottleneck of massively parallel machines by storing the data on disks within the high-speed interconnection network. In addition, the file system, called RAMA, requires little inter-node synchronization, removing another common bottleneck in parallel processor file systems. Support for a large tertiary storage system can easily be integrated in lo the file system; in fact, RAMA runs most efficiently when tertiary storage is used.

pcircle - A Suite of Scalable Parallel File System Tools

DOE Office of Scientific and Technical Information (OSTI.GOV)

WANG, FEIYI

2015-10-01

Most of the software related to file system are written for conventional local file system, they are serialized and can't take advantage of the benefit of a large scale parallel file system. "pcircle" software builds on top of ubiquitous MPI in cluster computing environment and "work-stealing" pattern to provide a scalable, high-performance suite of file system tools. In particular - it implemented parallel data copy and parallel data checksumming, with advanced features such as async progress report, checkpoint and restart, as well as integrity checking.

Early history of Vesta: implications for the surface morphology and composition

NASA Astrophysics Data System (ADS)

Turrini, D.; Coradini, A.; Formisano, M.; Carli, C.; Magni, G.

2011-12-01

The Dawn mission inserted into orbit around Vesta on 15 July 2011 and is presently gathering data on the morphology and the composition of the asteroid. In order to fully exploit the data that the Dawn mission is supplying to probe the ancient past of our Solar System, we need to be able to understand how the present state of Vesta is linked to its origin and its secular evolution. The spectral connection between Vesta and the Howardite-Eurcrite-Diogenite (HED) suite of meteorites suggests that Vesta formed very early in the history of the Solar System and differentiated on a Ma-long timescale due to the decay of short-lived radioactive nuclides (see Keil 2002 and references therein). Short after the differentiation process ended, Vesta started to cool down quickly, so that on a 10 Ma timescale its molten mantle would be topped by a thick solid layer (Formisano et al. 2011). Across the same timespan, Jupiter and the other giant planets would form in the outer Solar System and trigger a primordial phase of bombardment on the other already formed planetary bodies (Turrini et al. 2011, Coradini et al. 2011). Such primordial bombardment is expected to excavate the solid crust of Vesta and to cause local to regional effusive phenomena (Turrini et al. 2011). Moreover, due to the relatively high escape speed from Vesta, most of the excavated material would fall back on the asteroid as an ejecta blanket. Here we discuss the timescale of the formation and evolution of Vesta and the implications for the interpretation of the data that the Dawn mission is collecting while orbiting the asteroid. Bibliography 1. Coradini A., Turrini D., Federico C., Magni G. (2011). Vesta and Ceres: crossing the history of the Solar System. Space Science Reviews, DOI: 10.1007/s11214-011-9792-x. 2. Formisano M., Federico C., Coradini A. (2011). Vesta Thermal Models. EPSC-DPS Joint Meeting 2011, Nantes, France. 3. Keil K. (2002). Geological History of Asteroid 4 Vesta: The Smallest Terrestrial Planet. Asteroids III, Eds. W. F. Bottke Jr., A. Cellino, P. Paolicchi, and R. P. Binzel, University of Arizona Press, Tucson, 573-584. 4. Turrini D., Magni G., Coradini A. (2011). Probing the history of Solar System through the cratering records on Vesta and Ceres. Monthly Notices of the Royal Astronomical Society, DOI: 10.1111/j.1365-2966.2011.18316.x.

Geochemistry at 4 Vesta: Observations Using Fast Neutrons

NASA Technical Reports Server (NTRS)

Lawrence, David J.; Prettyman, Thomas H.; Feldman, William C.; Bazell, David; Mittlefehldt, David W.; Peplowski, Patrick N.; Reedy, Robert C.

2012-01-01

Dawn is currently in orbit around the asteroid 4 Vesta, and one of the major objectives of the mission is to probe the relationship of Vesta to the Howardite, Eucrite, and Diogenite (HED) meteorites. As Vesta is an example of a differentiated planetary embryo, Dawn will also provide fundamental information about planetary evolution in the early solar system [1]. To help accomplish this overall goal, the Dawn spacecraft carries the Gamma-Ray and Neutron Detector (GRaND). GRaND uses planetary gamma-ray and neutron spectroscopy to measure the surface elemental composition of Vesta and will provide information that is unique and complementary to that provided by the other Dawn instruments and investigations. Gamma-ray and neutron spectroscopy is a standard technique for measuring planetary compositions [2], having successfully made measurements at near-Earth asteroids, the Moon, Mars, Mercury and now Vesta. GRaND has made the first measurements of the neutron spectrum from any asteroid (previous asteroid measurements were only made with gamma-rays). Dawn has been collecting data at Vesta since July 2011. The prime data collection period for GRaND is the Low-Altitude Mapping Orbit (LAMO), which started on 12 December 2011 and will last through spring 2012. During LAMO, the Dawn spacecraft orbits at an average altitude of 210 km above the surface of Vesta, which allows good neutron and gamma-ray signals to be detected from Vesta. A description of the overall goals of GRaND and a summary of the initial findings are given elsewhere [3,4]. The subject of this study is to present the information that will be returned from GRaND using fast neutron measurements. Here, we discuss what fast neutrons can reveal about Vesta s surface composition, how such data can address Dawn science goals, and describe fast neutron measurements made in the early portion of the Vesta LAMO phase.

Occia Crater

NASA Image and Video Library

2012-05-10

This image from NASA Dawn spacecraft of asteroid Vesta shows Occia crater, located in Vesta Gegania quadrangle, in Vesta southern hemisphere. A distinctive butterfly pattern is seen consisting of two separate lobes of ejecta on the opposite sides.

Map of Hydrated Minerals on Vesta

NASA Image and Video Library

2012-09-26

This map from NASA Dawn mission indicates the presence of hydrated minerals on the giant asteroid Vesta about 30 degrees north latitude, in August 2011. At the time, it was winter in Vesta northern hemisphere.

Vesta Evolution from Surface Mineralogy: Mafic and Ultramafic Mineral Distribution

NASA Technical Reports Server (NTRS)

DeSanctis, M. C.; Ammannito, E.; Palomba, E.; Longobardo, A.; Mittlefehldt, D. W.; McSween, H. Y; Marchi, S.; Capria, M. T.; Capaccioni, F.; Frigeri, A.;

Model of Vesta

NASA Image and Video Library

2011-03-10

This image incorporates the best data on dimples and bulges of the protoplanet Vesta from ground-based telescopes and NASA Hubble Space Telescope. This model of Vesta uses scientists best guess to date of what the surface might look like.

The Vestal Cataclysm

NASA Technical Reports Server (NTRS)

Cohen, Barbara A.

2012-01-01

The currently operating Dawn mission shows asteroid 4 Vesta to be an extensively cratered body, with craters in a variety of morphologies and preservation states The crater size-frequency distribution for Vesta, modeled using the lunar chronology and scaled to impact frequencies modeled for Vesta, shows that both the north and south pole areas are ancient in age [1]. We have in our meteorite collection products from 4 Vesta in the form of the HED (howardite, eucrite, diogenite) meteorites. The HED parent body globally differentiated and fully crystallized by approx.4.56 Ga; subsequently, the eucrites were brecciated and heated by large impacts into the parent body surface, reflected in their disturbance ages [2, 3]. Dawn images have also shown that Vesta is covered with a well-developed regolith that is spectrally similar to howardite meteorites [4, 5]. Howardites are polymict regolith breccias made up mostly of clasts of eucrites and diogenites, but which also contain clasts formed by impact into the regolith. Impact-melt clast ages from howardites extend our knowledge of the impact history of Vesta, expanding on eucrite disturbance ages and helping give absolute age context to the observed crater-counts on Vesta.

Paradigms and Paradoxes: Dawn at Vesta

NASA Technical Reports Server (NTRS)

Raymond, C. A.; Russell, C. T.; Mittlefehldt, D. W.

2014-01-01

While confirming the popular paradigm of Vesta as the parent body of the HED meteorites, Dawn measurements have discovered many unexpected aspects of the vestan surface. First, an olivine layer was not found in the bottom of the large basin near the south pole of Vesta. In fact, while patches of olivine have been found in the north, it is rare on the surface. Secondly, while Vesta has little gravity and appears to have completely differentiated, it is not completely dry evidence for transient flows and pits resulting from devolatization have been found, implying a substantial amount of accessible water. Thirdly, transport of material to the surface of Vesta from elsewhere in the asteroid belt appears as dark material buried near the top of the crust to Vesta. This may have arrived in a single large impact and been spread around the surface and buried, later to be re-excavated. However, it is not certain that this is the only scenario possible for the source of this material. In short, Dawn's observations of Vesta have been both reassuring but unsettling at the same time.

Hydrogen Hotspots on Vesta

NASA Image and Video Library

2012-09-20

This image shows that NASA Dawn mission detected abundances of hydrogen in a wide swath around the equator of the giant asteroid Vesta. The hydrogen probably exists in the form of hydroxyl or water bound to minerals in Vesta surface.

Storing files in a parallel computing system using list-based index to identify replica files

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faibish, Sorin; Bent, John M.; Tzelnic, Percy

Improved techniques are provided for storing files in a parallel computing system using a list-based index to identify file replicas. A file and at least one replica of the file are stored in one or more storage nodes of the parallel computing system. An index for the file comprises at least one list comprising a pointer to a storage location of the file and a storage location of the at least one replica of the file. The file comprises one or more of a complete file and one or more sub-files. The index may also comprise a checksum value formore » one or more of the file and the replica(s) of the file. The checksum value can be evaluated to validate the file and/or the file replica(s). A query can be processed using the list.« less

Comparing Vesta Topography

NASA Image and Video Library

2013-09-27

These two images compare topographic maps of the giant asteroid Vesta as discerned by NASA Hubble Space Telescope top and as seen by NASA Dawn spacecraft bottom. Hubble has been in an orbit around Earth, while Dawn orbited Vesta from 2011 to 2012.

Lunar and Vesta Web Portals

NASA Astrophysics Data System (ADS)

Law, E.; JPL Luna Mapping; Modeling Project Team

2015-06-01

The Lunar Mapping and Modeling Project offers Lunar Mapping and Modeling Portal (http://lmmp.nasa.gov) and Vesta Trek Portal (http://vestatrek.jpl.nasa.gov) providing interactive visualization and analysis tools to enable users to access mapped Lunar and Vesta data products.

Vesta's Elemental Composition

NASA Technical Reports Server (NTRS)

Prettyman, T. H.; Beck, A. W.; Feldman, W. C.; Lawrence, D. J.; McCoy, T. J.; McSween, H. Y.; Mittlefehldt, D. W.; Peplowski, P. N.; Raymond, C. A.; Reedy, R. C.;

Bulk Composition of Vesta as Constrained by the Dawn Mission and the HED Meteorites

NASA Technical Reports Server (NTRS)

Toplis, M. J.; Mizzon, H.; Forni, O.; Monnereau, H.; Prettyman, T. H.; McSween, H. Y.; McCoy, T. J.; Mittlefehldt, D. W.; DeSactis, M. C.; Raymond, C. T.;

Simulated Vesta from the South Pole

NASA Image and Video Library

2011-03-10

This image shows the scientists best guess to date of what the surface of the protoplanet Vesta might look like from the south pole and incorporates the best data on dimples and bulges Vesta from ground-based telescopes and NASA Hubble Space Telescope.

VizieR Online Data Catalog: Line list for stellar chemical abundances (Bedell+, 2014)

NASA Astrophysics Data System (ADS)

Bedell, M.; Melendez, J.; Bean, J. L.; Ramirez, I.; Leite, P.; Asplund, M.

2017-05-01

The five solar spectra used in this analysis were obtained with very high resolution and signal-to-noise ratios (S/Ns) characteristic of data used in past stellar abundance analyses. Two spectra were taken with the Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) instrument (Donati 2003, Solar Polarization (ASP Conf. Ser. 307), ed. J. Trujillo-Bueno & J. Sanchez Almeida (San Francisco, CA: ASP), 41) at the 3.6 m Canada-France-Hawaii Telescope on the night of 2013 March 4. The asteroids Ceres and Vesta were each observed in "star only" mode at a spectral resolving power R=81000. The remaining three solar spectra were taken with the Magellan Inamori Kyocera Echelle (MIKE) spectrograph (Bernstein et al. 2003SPIE.4841.1694B) at the 6.5 m Magellan Clay telescope. The asteroid Vesta was observed twice and Iris was observed once during three separate observing runs spanning January to September of 2011. All observations were carried out in MIKE's standard setup with the 0.35 arcsec width slit, giving a spectral resolving power of R=83000 on the blue CCD and 65000 on the red CCD. (1 data file).

Chaotic Diffusion of the Vesta Family

NASA Astrophysics Data System (ADS)

Delisle, Jean-Baptiste; Laskar, J.

2012-10-01

The Vesta family is a known source of near-Earth asteroids (NEAs). Members of this family first slowly migrate in the main belt until they enter in the nu_6 or the 3:1 resonance with Jupiter. Their life time is then very short, and they often become NEAs before reaching hyperbolic orbits (Migliorini et al. 1997). The Yarkovsky effect is considered as the main explanation for the slow migration of Vesta family asteroids towards both resonances (Carruba et al. 2003). We numerically estimate the semi-major axis diffusion of Vesta family members induced by close encounters with 11 massive main-belt asteroids: (1) Ceres, (2) Pallas, (3) Juno, (4) Vesta, (7) Iris, (10) Hygiea, (15) Eunomia, (19) Fortuna, (324) Bamberga, (532) Herculina, (704) Interamnia. We find that most of the diffusion is due to Ceres and Vesta. We extrapolate our results to constrain the global effect of close encounters with all main-belt asteroids. We show that for asteroids whose diameter is larger than about 40 km, the diffusion due to close encounters dominate the Yarkovsky effect (Delisle & Laskar 2012). Since Vesta family members are all smaller than 8 km, we confirm that the main mechanism of its diffusion is the Yarkovsky effect. We also show by extrapolations on the closest distance of approach during encounters that 10 over the 13800 known Vesta family objects (Nesvorny, 2010) may have had an encounter with Vesta within one diameter over the age of the family. Such an event may have resulted in a semi-major axis jump of about 1 AU. Thus, even if the mean effect of close encounters is secondary compared to the Yarkovsky effect, they considerably affect some individual orbits. Ref: Delisle, J.-B., & Laskar, J.: 2012, Chaotic diffusion of the Vesta family induced by close encounters with massive asteroids, A&A, 540, A118

Large ejecta fragments from asteroids. [Abstract only

NASA Technical Reports Server (NTRS)

Asphaug, E.

1994-01-01

The asteroid 4 Vesta, with its unique basaltic crust, remains a key mystery of planetary evolution. A localized olivine feature suggests excavation of subcrustal material in a crater or impact basin comparable in size to the planetary radius (R(sub vesta) is approximately = 280 km). Furthermore, a 'clan' of small asteroids associated with Vesta (by spectral and orbital similarities) may be ejecta from this impact 151 and direct parents of the basaltic achondrites. To escape, these smaller (about 4-7 km) asteroids had to be ejected at speeds greater than the escape velocity, v(sub esc) is approximately = 350 m/s. This evidence that large fragments were ejected at high speed from Vesta has not been reconciled with the present understanding of impact physics. Analytical spallation models predict that an impactor capable of ejecting these 'chips off Vesta' would be almost the size of Vesta! Such an impact would lead to the catastrophic disruption of both bodies. A simpler analysis is outlined, based on comparison with cratering on Mars, and it is shown that Vesta could survive an impact capable of ejecting kilometer-scale fragments at sufficient speed. To what extent does Vesta survive the formation of such a large crater? This is best addressed using a hydrocode such as SALE 2D with centroidal gravity to predict velocities subsequent to impact. The fragmentation outcome and velocity subsequent to the impact described to demonstrate that Vesta survives without large-scale disassembly or overturning of the crust. Vesta and its clan represent a valuable dataset for testing fragmentation hydrocodes such as SALE 2D and SPH 3D at planetary scales. Resolution required to directly model spallation 'chips' on a body 100 times as large is now marginally possible on modern workstations. These boundaries are important in near-surface ejection processes and in large-scale disruption leading to asteroid families and stripped cores.

A Perfect View of Vesta: Creating Pointing Observations for the Dawn Spacecraft on Asteroid 4 Vesta

NASA Technical Reports Server (NTRS)

Hay, Katrina M.

2005-01-01

The Dawn spacecraft has a timely and clever assignment in store. It will take a close look at two intact survivors from the dawn of the solar system (asteroids 4 Vesta and 1 Ceres) to understand more about solar system origin and evolution. To optimize science return, Dawn must make carefully designed observations on approach and in survey orbit, high altitude mapping orbit, and low altitude mapping orbit at each body. In this report, observations outlined in the science plan are modeled using the science opportunity analyzer program for the Vesta encounter. Specifically, I encoded Dawn's flight rules into the program, modeled pointing profiles of the optical instruments (framing camera, visible infrared spectrometer) and mapped their fields of view onto Vesta's surface. Visualization of coverage will provide the science team with information necessary to assess feasibility of alternative observation plans. Dawn launches in summer 2006 and ends its journey in 2016. Instrument observations on Vesta in 2011 will supply detailed information about Vesta's surface and internal structure. These data will be used to analyze the formation and history of the protoplanet and, therefore, complete an important step in understanding the development of our solar system.

Nature of the "Orange" Material on Vesta From Dawn

NASA Technical Reports Server (NTRS)

LeCorre, L.; Reddy, V.; Schmedemann, N.; Becker, K. J.; OBrien, D. P.; Yamashita, N.; Peplowski, P. N.; Prettyman, T. H.; Li, J.-Y.; Coultis, E. A.;

Comparing Vesta's Surface Roughness to the Moon Using Bistatic Radar Observations by the Dawn Mission

NASA Astrophysics Data System (ADS)

Palmer, E. M.; Heggy, E.; Kofman, W. W.; Moghaddam, M.

2015-12-01

The first orbital bistatic radar (BSR) observations of a small body have been conducted opportunistically by NASA's Dawn spacecraft at Asteroid Vesta using the telecommunications antenna aboard Dawn to transmit and the Deep Space Network 70-meter antennas on Earth to receive. Dawn's high-gain communications antenna continuously transmitted right-hand circularly polarized radio waves (4-cm wavelength), and due to the opportunistic nature of the experiment, remained in a fixed orientation pointed toward Earth throughout each BSR observation. As a consequence, Dawn's transmitted radio waves scattered from Vesta's surface just before and after each occultation of the Dawn spacecraft behind Vesta, resulting in surface echoes at highly oblique incidence angles of greater than 85 degrees, and a small Doppler shift of ~2 Hz between the carrier signal and surface echoes from Vesta. We analyze the power and Doppler spreading of Vesta's surface echoes to assess surface roughness, and find that Vesta's area-normalized radar cross section ranges from -8 to -17 dB, which is notably much stronger than backscatter radar cross section values reported for the Moon's limbs (-20 to -35 dB). However, our measurements correspond to the forward scattering regime--such that at high incidence, radar waves are expected to scatter more weakly from a rough surface in the backscatter direction than that which is scattered forward. Using scattering models of rough surfaces observed at high incidence, we report on the relative roughness of Vesta's surface as compared to the Moon and icy Galilean satellites. Through this, we assess the dominant processes that have influenced Vesta's surface roughness at centimeter and decimeter scales, which are in turn applicable to assisting future landing, sampling and orbital missions of other small bodies.

Ultraviolet Spectroscopy of Asteroid(4) Vesta

NASA Technical Reports Server (NTRS)

Li, Jian-Yang; Bodewits, Dennis; Feaga, Lori M.; Landsman, Wayne; A'Hearn, Michael F.; Mutchler, Max J.; Russell, Christopher T.; McFadden, Lucy A.; Raymond, Carol A.

2011-01-01

We report a comprehensive review of the UV-visible spectrum and rotational lightcurve of Vesta combining new observations by Hubble Space Telescope and Swift with archival International Ultraviolet Explorer observations. The geometric albedos of Vesta from 220 nm to 953 nm arc derived by carefully comparing these observations from various instruments at different times and observing geometries. Vesta has a rotationally averaged geometric albedo of 0.09 at 250 nm, 0.14 at 300 nm, 0.26 at 373 nm, 0.38 at 673 nm, and 0.30 at 950 nm. The linear spectral slope in the ultraviolet displays a sharp minimum ncar sub-Earth longitude of 20deg, and maximum in the eastern hemisphere. This is completely consistent with the distribution of the spectral slope in the visible wavelength. The uncertainty of the measurement in the ultraviolet is approx.20%, and in the visible wavelengths better than 10%. The amplitude of Vesta's rotational lightcurves is approx.10% throughout the range of wavelengths we observed, but is smaller at 950 nm (approx.6%) ncar the 1-micron mafic band center. Contrary to earlier reports, we found no evidence for any difference between the phasing of the ultraviolet and visible/ncar-infrared lightcurves with respect to sub-Earth longitude. Vesta's average spectrum between 220 and 950 nm can well be described by measured reflectance spectra of fine particle howardite-like materials of basaltic achondrite meteorites. Combining this with the in-phase behavior of the ultraviolet, visible. and ncar-infrared lightcurves, and the spectral slopes with respect to the rotational phase, we conclude that there is no global ultraviolet/visible reversal on Vesta. Consequently, this implies lack of global space weathering on Vesta. Keyword,: Asteroid Vesta; Spectrophotometry; Spectroscopy; Ultraviolet observations; Hubble Space Telescope observations

Constraints on Vesta's elemental composition: Fast neutron measurements by Dawn's gamma ray and neutron detector

PubMed Central

Lawrence, David J; Peplowski, Patrick N; Prettyman, Thomas H; Feldman, William C; Bazell, David; Mittlefehldt, David W; Reedy, Robert C; Yamashita, Naoyuki

2013-01-01

Surface composition information from Vesta is reported using fast neutron data collected by the gamma ray and neutron detector on the Dawn spacecraft. After correcting for variations due to hydrogen, fast neutrons show a compositional dynamic range and spatial variability that is consistent with variations in average atomic mass from howardite, eucrite, and diogenite (HED) meteorites. These data provide additional compositional evidence that Vesta is the parent body to HED meteorites. A subset of fast neutron data having lower statistical precision show spatial variations that are consistent with a 400 ppm variability in hydrogen concentrations across Vesta and supports the idea that Vesta's hydrogen is due to long-term delivery of carbonaceous chondrite material. PMID:26074718

Dawn First Glimpse of Vesta -- Processed

NASA Image and Video Library

2011-05-11

This image, processed to show the true size of the giant asteroid Vesta, shows Vesta in front of a spectacular background of stars. It was obtained by the framing camera aboard NASA Dawn spacecraft on May 3, 2011, from a distance of about 750,000 miles.

Dawn Orbit Determination Team: Trajectory and Gravity Prediction Performance During Vesta Science Phases

NASA Technical Reports Server (NTRS)

Kennedy, Brian; Abrahamson, Matt; Ardito, Alessandro; Han, Dongsuk; Haw, Robert; Mastrodemos, Nicholas; Nandi, Sumita; Park, Ryan; Rush, Brian; Vaughan, Andrew

2013-01-01

The Dawn spacecraft was launched on September 27th, 2007. Its mission is to consecutively rendezvous with and observe the two largest bodies in the asteroid belt, Vesta and Ceres. It has already completed over a year's worth of direct observations of Vesta (spanning from early 2011 through late 2012) and is currently on a cruise trajectory to Ceres, where it will begin scientific observations in mid-2015. Achieving this data collection required careful planning and execution from all spacecraft teams. Dawn's Orbit Determination (OD) team was tasked with accurately predicting the trajectory of the Dawn spacecraft during the Vesta science phases, and also determining the parameters of Vesta to support future science orbit design. The future orbits included the upcoming science phase orbits as well as the transfer orbits between science phases. In all, five science phases were executed at Vesta, and this paper will describe some of the OD team contributions to the planning and execution of those phases.

Integration experiences and performance studies of A COTS parallel archive systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Hsing-bung; Scott, Cody; Grider, Bary

2010-01-01

Current and future Archive Storage Systems have been asked to (a) scale to very high bandwidths, (b) scale in metadata performance, (c) support policy-based hierarchical storage management capability, (d) scale in supporting changing needs of very large data sets, (e) support standard interface, and (f) utilize commercial-off-the-shelf(COTS) hardware. Parallel file systems have been asked to do the same thing but at one or more orders of magnitude faster in performance. Archive systems continue to move closer to file systems in their design due to the need for speed and bandwidth, especially metadata searching speeds such as more caching and lessmore » robust semantics. Currently the number of extreme highly scalable parallel archive solutions is very small especially those that will move a single large striped parallel disk file onto many tapes in parallel. We believe that a hybrid storage approach of using COTS components and innovative software technology can bring new capabilities into a production environment for the HPC community much faster than the approach of creating and maintaining a complete end-to-end unique parallel archive software solution. In this paper, we relay our experience of integrating a global parallel file system and a standard backup/archive product with a very small amount of additional code to provide a scalable, parallel archive. Our solution has a high degree of overlap with current parallel archive products including (a) doing parallel movement to/from tape for a single large parallel file, (b) hierarchical storage management, (c) ILM features, (d) high volume (non-single parallel file) archives for backup/archive/content management, and (e) leveraging all free file movement tools in Linux such as copy, move, ls, tar, etc. We have successfully applied our working COTS Parallel Archive System to the current world's first petaflop/s computing system, LANL's Roadrunner, and demonstrated its capability to address requirements of future archival storage systems.« less

Integration experiments and performance studies of a COTS parallel archive system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Hsing-bung; Scott, Cody; Grider, Gary

2010-06-16

Current and future Archive Storage Systems have been asked to (a) scale to very high bandwidths, (b) scale in metadata performance, (c) support policy-based hierarchical storage management capability, (d) scale in supporting changing needs of very large data sets, (e) support standard interface, and (f) utilize commercial-off-the-shelf (COTS) hardware. Parallel file systems have been asked to do the same thing but at one or more orders of magnitude faster in performance. Archive systems continue to move closer to file systems in their design due to the need for speed and bandwidth, especially metadata searching speeds such as more caching andmore » less robust semantics. Currently the number of extreme highly scalable parallel archive solutions is very small especially those that will move a single large striped parallel disk file onto many tapes in parallel. We believe that a hybrid storage approach of using COTS components and innovative software technology can bring new capabilities into a production environment for the HPC community much faster than the approach of creating and maintaining a complete end-to-end unique parallel archive software solution. In this paper, we relay our experience of integrating a global parallel file system and a standard backup/archive product with a very small amount of additional code to provide a scalable, parallel archive. Our solution has a high degree of overlap with current parallel archive products including (a) doing parallel movement to/from tape for a single large parallel file, (b) hierarchical storage management, (c) ILM features, (d) high volume (non-single parallel file) archives for backup/archive/content management, and (e) leveraging all free file movement tools in Linux such as copy, move, Is, tar, etc. We have successfully applied our working COTS Parallel Archive System to the current world's first petafiop/s computing system, LANL's Roadrunner machine, and demonstrated its capability to address requirements of future archival storage systems.« less

Does Vesta Have Moons?: Dawn's Search for Satellites

NASA Technical Reports Server (NTRS)

McFadden, L. A.; Sykes, M. V.; Tricarico, P.; Carsenty, U.; Gutierrez-Marques, P.; Jacobson, R. A.; Joy, S.; Keller, H. U.; Li, J.-Y.; McLean, B.;

Spectral characterization of V-type asteroids: are all the basaltic objects coming from Vesta?

NASA Astrophysics Data System (ADS)

Ieva, S.; Fulvio, D.; Dotto, E.; Lazzaro, D.; Perna, D.; Strazzulla, G.; Fulchignoni, M.

In the last twenty-five years several small basaltic V-type asteroids have been identified all around the main belt. Most of them are members of the Vesta dynamical family, but an increasingly large number appear to have no link with it. The question that arises is whether all these basaltic objects do indeed come from Vesta. In the light of the Dawn mission, who visited Vesta in 2011-2012, recent works were dedicated to the observation of several new V-type asteroids and their comparison with laboratory data (Fulvio et al., \\cite{Fulvio2015}), and to a statistical analysis of the spectroscopic and mineralogical properties of the largest sample of V-types ever collected (Ieva et al., \\cite{Ieva2015}, with the objective to highlight similarities and differences among objects belonging and not belonging to the Vesta dynamical family. Laboratory experiments support the idea that V-type NEAs spectral properties could be due to a balance of space weathering and rejuvenation processes triggered by close encounters with terrestrial planets. Statistical analysis shows that although most of the V-type asteroids in the inner main belt do have a surface composition compatible with Vesta family members, this seem not to be the case for V-types in the middle and outer main belt. For these Middle and Outer V-types (MOVs), their sizes, spectral parameters and location far away from the Vesta dynamical region point to a different origin than Vesta.

Improvement of AEP Predictions Using Diurnal CFD Modelling with Site-Specific Stability Weightings Provided from Mesoscale Simulation

NASA Astrophysics Data System (ADS)

Hristov, Y.; Oxley, G.; Žagar, M.

2014-06-01

The Bolund measurement campaign, performed by Danish Technical University (DTU) Wind Energy Department (also known as RISØ), provided significant insight into wind flow modeling over complex terrain. In the blind comparison study several modelling solutions were submitted with the vast majority being steady-state Computational Fluid Dynamics (CFD) approaches with two equation k-epsilon turbulence closure. This approach yielded the most accurate results, and was identified as the state-of-the-art tool for wind turbine generator (WTG) micro-siting. Based on the findings from Bolund, further comparison between CFD and field measurement data has been deemed essential in order to improve simulation accuracy for turbine load and long-term Annual Energy Production (AEP) estimations. Vestas Wind Systems A/S is a major WTG original equipment manufacturer (OEM) with an installed base of over 60GW in over 70 countries accounting for 19% of the global installed base. The Vestas Performance and Diagnostic Centre (VPDC) provides online live data to more than 47GW of these turbines allowing a comprehensive comparison between modelled and real-world energy production data. In previous studies, multiple sites have been simulated with a steady neutral CFD formulation for the atmospheric surface layer (ASL), and wind resource (RSF) files have been generated as a base for long-term AEP predictions showing significant improvement over predictions performed with the industry standard linear WAsP tool. In this study, further improvements to the wind resource file generation with CFD are examined using an unsteady diurnal cycle approach with a full atmospheric boundary layer (ABL) formulation, with the unique stratifications throughout the cycle weighted according to mesoscale simulated sectorwise stability frequencies.

The structure of the asteroid 4 Vesta as revealed by models of planet-scale collisions.

PubMed

Jutzi, M; Asphaug, E; Gillet, P; Barrat, J-A; Benz, W

2013-02-14

Asteroid 4 Vesta seems to be a major intact protoplanet, with a surface composition similar to that of the HED (howardite-eucrite-diogenite) meteorites. The southern hemisphere is dominated by a giant impact scar, but previous impact models have failed to reproduce the observed topography. The recent discovery that Vesta's southern hemisphere is dominated by two overlapping basins provides an opportunity to model Vesta's topography more accurately. Here we report three-dimensional simulations of Vesta's global evolution under two overlapping planet-scale collisions. We closely reproduce its observed shape, and provide maps of impact excavation and ejecta deposition. Spiral patterns observed in the younger basin Rheasilvia, about one billion years old, are attributed to Coriolis forces during crater collapse. Surface materials exposed in the north come from a depth of about 20 kilometres, according to our models, whereas materials exposed inside the southern double-excavation come from depths of about 60-100 kilometres. If Vesta began as a layered, completely differentiated protoplanet, then our model predicts large areas of pure diogenites and olivine-rich rocks. These are not seen, possibly implying that the outer 100 kilometres or so of Vesta is composed mainly of a basaltic crust (eucrites) with ultramafic intrusions (diogenites).

The structure of the asteroid 4 Vesta as revealed by models of planet-scale collisions

NASA Astrophysics Data System (ADS)

Jutzi, M.; Asphaug, E.; Gillet, P.; Barrat, J.-A.; Benz, W.

2013-02-01

Asteroid 4 Vesta seems to be a major intact protoplanet, with a surface composition similar to that of the HED (howardite-eucrite-diogenite) meteorites. The southern hemisphere is dominated by a giant impact scar, but previous impact models have failed to reproduce the observed topography. The recent discovery that Vesta's southern hemisphere is dominated by two overlapping basins provides an opportunity to model Vesta's topography more accurately. Here we report three-dimensional simulations of Vesta's global evolution under two overlapping planet-scale collisions. We closely reproduce its observed shape, and provide maps of impact excavation and ejecta deposition. Spiral patterns observed in the younger basin Rheasilvia, about one billion years old, are attributed to Coriolis forces during crater collapse. Surface materials exposed in the north come from a depth of about 20 kilometres, according to our models, whereas materials exposed inside the southern double-excavation come from depths of about 60-100 kilometres. If Vesta began as a layered, completely differentiated protoplanet, then our model predicts large areas of pure diogenites and olivine-rich rocks. These are not seen, possibly implying that the outer 100 kilometres or so of Vesta is composed mainly of a basaltic crust (eucrites) with ultramafic intrusions (diogenites).

Investigating the Origin of Bright Materials on Vesta: Synthesis, Conclusions, and Implications

NASA Technical Reports Server (NTRS)

Li, Jian-Yang; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Schroder, S. E.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.

2012-01-01

The Dawn spacecraft started orbiting the second largest asteroid (4) Vesta in August 2011, revealing the details of its surface at an unprecedented pixel scale as small as approx.70 m in Framing Camera (FC) clear and color filter images and approx.180 m in the Visible and Infrared Spectrometer (VIR) data in its first two science orbits, the Survey Orbit and the High Altitude Mapping Orbit (HAMO) [1]. The surface of Vesta displays the greatest diversity in terms of geology and mineralogy of all asteroids studied in detail [2, 3]. While the albedo of Vesta of approx.0.38 in the visible wavelengths [4, 5] is one of the highest among all asteroids, the surface of Vesta shows the largest variation of albedos found on a single asteroid, with geometric albedos ranging at least from approx.0.10 to approx.0.67 in HAMO images [5]. There are many distinctively bright and dark areas observed on Vesta, associated with various geological features and showing remarkably different forms. Here we report our initial attempt to understand the origin of the areas that are distinctively brighter than their surroundings. The dark materials on Vesta clearly are different in origin from bright materials and are reported in a companion paper [6].

Cratering on 4 Vesta - Comparison of Crater Retention Ages and Ar-Ar Ages of HED Meteorites.

NASA Astrophysics Data System (ADS)

Schmedemann, N.; Kneissl, T.; Michael, G.; Neukum, G.; Nathues, A.; Sierks, H.; Wagner, R.; Krohn, K.; Reddy, V.; Hiesinger, H.; Jaumann, R.; Raymond, C. A.; Russell, C. T.

2012-04-01

In July 2011 the Dawn spacecraft entered orbit around the Main Belt asteroid 4 Vesta utilizing three different instruments to map the asteroid [1]. The Main Belt is the source region of most impactors in the inner solar system [2]. We compare the obtained crater size-frequency distribution (CSFD) of Vesta with that of the Moon and other Main Belt asteroids such as 951 Gaspra, 243 Ida, and 21 Lutetia. We also compare our results of crater counting on Vesta with K/Ar-Ar reset ages of HED meteorites, which most likely originated from Vesta [3]. To properly compare the lunar CSFD with that of the asteroids we applied scaling laws [4] to account for various impact velocities, surface gravities as well as material properties between the investigated bodies. We found well defined lunar-like CSFDs of impact craters on all four asteroids. The CSFD of Vesta and Lutetia had to be constructed from several individual measurements following [5]. We were able to derive lunar-like chronologies for each asteroid utilizing intrinsic collision probabilities [6], lunar-like CSFDs and the ground truth-derived lunar chronology. Since the Moon and the Main Belt asteroids share the same main impactor source, it is straightforward to also assume a very similar time-dependent impact rate over the solar system history. Alternative chronologies, which are based on computer models of the LHB [7], result in surface ages >4.5 Ga, which are highly unlikely for Vesta. Our lunar-like chronology for Vesta is able to match three out of four peaks in age probabilities of HED meteorites [3]. We measured the age of the Rheasilvia basin with 3.70 +/-0.02 Ga, which coincides with a wide-spread resurfacing age on Vesta. An underlying older basin, partially obliterated by the Rheasilvia impact was formed 3.81 +/-0.05 Ga ago. Finally the large basins and craters >150 km in diameter and the densest cratered areas on Vesta indicate a global resurfacing event 4.00 +/-0.02 Ga ago. This represents the oldest age we can infer from Vesta by this technique. Acknowledgement: This work has been supported by the German Space Agency (DLR) on behalf of the Federal Ministry of Economics and Technology, grant 50 OW 1101.

Checkpoint-Restart in User Space

DOE Office of Scientific and Technical Information (OSTI.GOV)

CRUISE implements a user-space file system that stores data in main memory and transparently spills over to other storage, like local flash memory or the parallel file system, as needed. CRUISE also exposes file contents fo remote direct memory access, allowing external tools to copy files to the parallel file system in the background with reduced CPU interruption.

Vesta and the HED Meteorites: Comparison of Spectral Properties

NASA Technical Reports Server (NTRS)

Ammannito, E.; De Sanctis, M. C.; Fonte, S.; Magni, G.; Capaccioni, F.; Tosi, F.; Capria, M. T.; Blewett, D.; Combe, J. P.; Farina, M.;

A Study Regarding the Possibility of True Polar Wander on the Asteroid Vesta

NASA Astrophysics Data System (ADS)

Karimi, M.; Dombard, A. J.

2014-12-01

The asteroid 4 Vesta, with an average diameter of ~525 km, is the second most massive asteroid in the solar system. Most of our knowledge about this differentiated asteroid comes from the Howardite-Eucrite-Diogenite class of meteorites that originated from Vesta, images provided by Hubble Space Telescope, and data from the Dawn spacecraft that orbited Vesta from July 2011 to September 2012. Notably, these close-range data confirmed what Hubble images suggested: a highly oblate shape in which the equatorial radius is ~60 km greater than the polar radius, a shape consistent with Vesta's short rotational period of ~5.3 hr. These images also revealed the presence of two large impact craters near the asteroid's south pole. Rheasilvia, the younger and larger crater at ~500 km in diameter, is superimposed over Veneneia, ~400 km in diameter. The occurrence of two large impacts near a pole, which possesses a relatively small area (less than 30% of the surface), is highly improbable. Thus, we investigate the possibility of True Polar Wander. We hypothesize that the integrated mass deficit of these two basins applied a torque to the lithosphere to reorient the surface relative to the spin axis and thereby placing these basins near the pole. In order for this phenomenon to occur, however, the lithosphere needs to be pliable enough to allow relaxation of the ancient rotational bulge and concurrent development of the current bulge. We have previously explored whether the lithosphere of Vesta could support the large-scale (~20 vertical km) topography of the basins (short answer: it can). Here, we explore whether this lithosphere could also permit True Polar Wander. We use the Finite Element Method and a viscoelastic rheology to simulate the relaxation of an oblate Vesta under a range of plausible thermal scenarios consistent with Vesta's expected budget of long-lived radiogenic nuclides. Our results indicate that under reasonable thermal conditions, the relaxation of the rotational bulge of Vesta and subsequent True Polar Wander cannot happen. As unlikely as it may be, it seems that both large impacts occurred in the south polar region of Vesta.

Cloud object store for checkpoints of high performance computing applications using decoupling middleware

DOEpatents

Bent, John M.; Faibish, Sorin; Grider, Gary

2016-04-19

Cloud object storage is enabled for checkpoints of high performance computing applications using a middleware process. A plurality of files, such as checkpoint files, generated by a plurality of processes in a parallel computing system are stored by obtaining said plurality of files from said parallel computing system; converting said plurality of files to objects using a log structured file system middleware process; and providing said objects for storage in a cloud object storage system. The plurality of processes may run, for example, on a plurality of compute nodes. The log structured file system middleware process may be embodied, for example, as a Parallel Log-Structured File System (PLFS). The log structured file system middleware process optionally executes on a burst buffer node.

Storing files in a parallel computing system based on user or application specification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faibish, Sorin; Bent, John M.; Nick, Jeffrey M.

2016-03-29

Techniques are provided for storing files in a parallel computing system based on a user-specification. A plurality of files generated by a distributed application in a parallel computing system are stored by obtaining a specification from the distributed application indicating how the plurality of files should be stored; and storing one or more of the plurality of files in one or more storage nodes of a multi-tier storage system based on the specification. The plurality of files comprise a plurality of complete files and/or a plurality of sub-files. The specification can optionally be processed by a daemon executing on onemore » or more nodes in a multi-tier storage system. The specification indicates how the plurality of files should be stored, for example, identifying one or more storage nodes where the plurality of files should be stored.« less

Vesta Thermal Models

NASA Astrophysics Data System (ADS)

Formisano, M.; Federico, C.; Coradini, A.; Carli, C.; Turrini, D.

2011-12-01

Vesta is one of the largest Main Belt asteroid, considered the parent of the HED (Howardite - Eucrite - Diogenite) meteorites. Spectroscopic studies in fact show the presence of the 0.9 and 1.9 μm absorption bands for pyroxene in the spectra of Vesta that match those observed in the spectra of HED meteorites (see Gaffey, 1997, Surface Lihologic Heterogeneity of Asteroid 4 Vesta, Icarus, 127). The spectral connection between Vesta and the Howardite-Eurcrite-Diogenite (HED) suite of meteorites suggests that Vesta formed very early in the history of the Solar System and differentiated on a Ma-long timescale due to the decay of short-lived radioactive nuclides (see Keil K., 2002, Geological History of Asteroid 4 Vesta: The Smallest Terrestrial Planet. Asteroids III, and references therein). The importance of studying the thermal evolution of Vesta is therefore linked to the understanding of the processes of core and crust formation in planetary bodies so Vesta can be considered a good model for the primordial stages of the terrestrial planets. Our interest is mainly focused on the study of different energy sources, and how they contribute to differentiation and, more generally, to the thermal history of the body. We analyze not only the contribution of short-lived radionuclides, i.e. 26Al and 60Fe, but also the contribution of long-lived radionuclides, in particular 40K, 232Th, 235U and 238U, and that of accretional heating. The contribution of the long-lived radionuclides does not change the overall thermal history but it only slows down the cooling of the body. We have also observed that the effect of the accretional heating is limited if not negligible: in the most favourable scenarios its contribution only raise the starting temperature of the body but it is not sufficient to start the differentiation process. Vesta thermal and structural evolution is therefore characterized by the contribution of the short-lived radionuclides. The scenarios we considered differ in the time delay Δt. The time delay Δt is a parameter that takes into account not only the uncertainties due to the injection of 26Al in the Solar Nebula, but also the uncertainties linked to the time of the accretional process of Vesta. In all the scenarios we observe the differentiation of the body, i.e. the formation of a metallic core (mainly iron) and a silicatic crust of which we discuss the chemical and physical evolution, in particular by analyzing the link with the Jovian Early Bombardment phase ( D.Turrini, G.Magni, A.Coradini, 2011, Probing the history of Solar System through the cratering records on Vesta and Ceres, MNRAS, DOI: 10.1111/j.1365-2966.2011.18316.x). We also preliminarly discuss the heat released by the impacts during the Jovian Early Bombardment phase and their possible contribution to the thermal history of Vesta.

Dawn Arrives at Vesta: The Smallest Terrestrial Planet

NASA Astrophysics Data System (ADS)

Russell, C. T.; Raymond, C. A.; Coradini, A.; Nathues, A.; De Sanctis, M. C.; Prettyman, T. H.; Jaumann, R.; McSween, H. Y.; McCord, T. B.; Keller, H. U.; Rayman, M.

2011-12-01

The Dawn Mission is a revolutionary concept in planetary exploration. Within the cost cap of a low-cost Discovery mission, a spacecraft has been flown to the main asteroid belt and been put into orbit around its second most massive body, 4 Vesta. Vesta was clearly beginning its march to planet-hood when its accretion stopped, most probably by the formation of Jupiter. Dawn's exploration is enabled by an ion propulsion system that will not only allow Dawn to descend to 200 km altitude, but to leave Vesta, travel to and orbit 1 Ceres in 2015 and map this largest main belt asteroid, a dwarf planet. The initial images of the surface of Vesta have been astounding. They reveal the diverse geochemical processes driven by the internal heat of this 530 km diameter body and titanic forces that have battered Vesta for over 4.65 billion years. A large southern impact structure, troughs ringing the equator, striped craters, dark albedo features contrasting with very high albedo features and a richly colored surface distinguish this most unusual small world.

Thermal Analysis of Unusual Local-scale Features on the Surface of Vesta

NASA Technical Reports Server (NTRS)

Tosi, F.; Capria, M. T.; DeSanctis, M. C.; Capaccioni, F.; Palomba, E.; Zambon, F.; Ammannito, E.; Blewett, D. T.; Combe, J.-Ph.; Denevi, B. W.;

Search for Olivine Spectral Signatures on the Surface of Vesta

NASA Technical Reports Server (NTRS)

Palomba, E.; De Sanctis, M. C.; Ammannito, E.; Capaccioni, F.; Capria, M. T.; Farina, M.; Frigeri, A.; Longobardo, A.; Tosi, F.; Zambon, F.;

Ar-39 - Ar-40 Dating of Unusual Eucrite NWA-011: Is it from Vesta?

NASA Technical Reports Server (NTRS)

Bogard, D. D.; Garrison, D. H.

2004-01-01

Basaltic meteorite NWA-011 is similar to eucrites in many aspects, but its oxygen isotopic composition lies far off the oxygen fractionation line defined by eucrites. It was suggested that NWA011 may have derived from a different parent body from that of eucrites, which are thought to derive from the asteroid Vesta. Some other eucrites also show small anomalous oxygen compositions. This suggests that for all eucrites to derive from Vesta, it must be compositionally inhomogeneous. Some workers have speculated whether early, large impactors on Vesta might have contributed the anomalous oxygen.

Vesta Mineralogy after Dawn Global Observations

NASA Technical Reports Server (NTRS)

ChristinaDeSanctis, Maria; Ammannito, E.; Capaccioni, F.; Cparia, M. T.; Carraro, F.; Fonte, S.; Frigeri, A.; Longobardo, A.; Marchi, S.; Palomba, E.;

Modeling the early evolution of Vesta

NASA Astrophysics Data System (ADS)

Weisfeiler, Marie; Turcotte, Donald L.; Kellogg, Louise H.

2017-05-01

The early evolution of the asteroid Vesta has been extensively studied because of the availability of relevant data, especially important new studies of HED meteorites which originated from Vesta and the Dawn mission to Vesta in 2011-2012. These studies have concluded that an early melting episode led to the differentiation of Vesta into crust, mantle, and core. This melting episode is attributed to the decay of 26Al, which has a half-life of 7.17 × 105 yr. This heating produced a global magma ocean. Surface cooling of this magma ocean will produce a solid crust. In this paper, we propose a convective heat-transfer mechanism that effectively cools the asteroid when the degree of melting reaches about 50%. We propose that a cool solid surface crust, which is gravitationally unstable, will founder into the solid-liquid mix beneath and will very effectively transfer heat that prevents further melting of the interior. In this paper, we quantify this process. If Vesta had a very early formation, melting would commence at an age of about 1,30,000 yr, and solidification would occur at an age of about 10 Myr. If Vesta formed with a time delay greater than about 2 Myr, no melting would have occurred. An important result of our model is that the early melting episode is restricted to the first 10 Myr. This result is in good agreement with the radiometric ages of the HED meteorites.

A Thermal Model for the Differentiation of Asteroid 4 Vesta, Based on Radiogenic and Collisional Heating

NASA Astrophysics Data System (ADS)

Ghosh, Amitabha

A finite element code has been developed to study the thermal history of asteroid 4 Vesta. This is the first attempt to model the thermal history of a differentiated asteroid, from accretion through core and crust formation and subsequent cooling until geochemical closure is attained. Previous thermal models were simpler formulations aimed at explaining metamorphism and aqueous alteration in unmelted asteroids. The results of the simulation are consistent with chronological measurements of cumulate and noncumulate eucrites, meteorites belonging to the HED suite, believed to have been derived from 4 Vesta. The work solves major problems with the hypothesis of heating by decay of 26Al, an extinct radionuclide, believed to be a plausible heat source in the early solar system. The simulation draws a model chronology of Vesta and predicts the time interval of accretion at 2.85 Myrs, the absolute times (with respect to CAI formation) of core formation at 4.58 Myrs, crust formation at 6.58 Myrs and geochemical closure on Vesta at ~100 Myrs. It is concluded that neither collisional heating nor heating due to the radioactive decay of 60Fe caused any perceptible difference in the whole-body thermal history of Vesta. Further, the thermal model suggested that the olivine-rich spot observed on Vesta may not be excavated mantle material, but may be unmelted near-surface material that escaped the asteroid's differentiation history.

Paradigms and Paradoxes: Dawn at Vesta

NASA Astrophysics Data System (ADS)

Raymond, Carol; Russell, Christopher; Mittlefehldt, David

2014-05-01

While confirming the paradigm of Vesta as the parent body of the HED meteorites, measurements by Dawn have discovered many unexpected aspects of the vestan surface. First, an olivine layer was not found in the bottom of the large basin near the south pole of Vesta where excavation of the mantle was thought to have occurred. In fact, while patches of olivine have been found in the north, it is rare on the surface. Secondly, while Vesta has little gravity and appears to have completely differentiated, it is not completely dry. Morphological evidence from the walls and floors of some craters suggest transient fluid flows and pits formed by devolatization, implying a substantial amount of accessible water. The question is, did this water derive from internal or external sources? Thirdly, transport of material to the surface of Vesta from elsewhere in the asteroid belt appears as dark material buried near the top of the regolith of Vesta. This may have arrived in a single large impact and been spread around the surface and buried, later to be re-excavated. However, this is not the only scenario possible for the source of this material. Meteoritical evidence from howardites shows that debris from multiple types of impactors are present in the vestan regolith. In short, Dawn's observations of Vesta have been both reassuring but unsettling at the same time.

4 Vesta in Color: High Resolution Mapping from Dawn Framing Camera Images

NASA Technical Reports Server (NTRS)

Reddy, V.; LeCorre, L.; Nathues, A.; Sierks, H.; Christensen, U.; Hoffmann, M.; Schroeder, S. E.; Vincent, J. B.; McSween, H. Y.; Denevi, B. W.;

Tuning HDF5 subfiling performance on parallel file systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byna, Suren; Chaarawi, Mohamad; Koziol, Quincey

Subfiling is a technique used on parallel file systems to reduce locking and contention issues when multiple compute nodes interact with the same storage target node. Subfiling provides a compromise between the single shared file approach that instigates the lock contention problems on parallel file systems and having one file per process, which results in generating a massive and unmanageable number of files. In this paper, we evaluate and tune the performance of recently implemented subfiling feature in HDF5. In specific, we explain the implementation strategy of subfiling feature in HDF5, provide examples of using the feature, and evaluate andmore » tune parallel I/O performance of this feature with parallel file systems of the Cray XC40 system at NERSC (Cori) that include a burst buffer storage and a Lustre disk-based storage. We also evaluate I/O performance on the Cray XC30 system, Edison, at NERSC. Our results show performance benefits of 1.2X to 6X performance advantage with subfiling compared to writing a single shared HDF5 file. We present our exploration of configurations, such as the number of subfiles and the number of Lustre storage targets to storing files, as optimization parameters to obtain superior I/O performance. Based on this exploration, we discuss recommendations for achieving good I/O performance as well as limitations with using the subfiling feature.« less

Parallel file system with metadata distributed across partitioned key-value store c

DOEpatents

Bent, John M.; Faibish, Sorin; Grider, Gary; Torres, Aaron

2017-09-19

Improved techniques are provided for storing metadata associated with a plurality of sub-files associated with a single shared file in a parallel file system. The shared file is generated by a plurality of applications executing on a plurality of compute nodes. A compute node implements a Parallel Log Structured File System (PLFS) library to store at least one portion of the shared file generated by an application executing on the compute node and metadata for the at least one portion of the shared file on one or more object storage servers. The compute node is also configured to implement a partitioned data store for storing a partition of the metadata for the shared file, wherein the partitioned data store communicates with partitioned data stores on other compute nodes using a message passing interface. The partitioned data store can be implemented, for example, using Multidimensional Data Hashing Indexing Middleware (MDHIM).

78 FR 55057 - Authorization of Production Activity, Foreign-Trade Subzone 123E, Vestas Nacelles America, Inc...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-09

... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [B-47-2013] Authorization of Production Activity, Foreign-Trade Subzone 123E, Vestas Nacelles America, Inc., (Wind Turbines), Brighton, Denver, Pueblo, and Windsor, Colorado On May 3, 2013, Vestas Nacelles America, Inc., operator of Subzone 123E in Brighton, Denver, Pueblo, and Windsor, Colorado,...

Cloud object store for archive storage of high performance computing data using decoupling middleware

DOEpatents

Bent, John M.; Faibish, Sorin; Grider, Gary

2015-06-30

Cloud object storage is enabled for archived data, such as checkpoints and results, of high performance computing applications using a middleware process. A plurality of archived files, such as checkpoint files and results, generated by a plurality of processes in a parallel computing system are stored by obtaining the plurality of archived files from the parallel computing system; converting the plurality of archived files to objects using a log structured file system middleware process; and providing the objects for storage in a cloud object storage system. The plurality of processes may run, for example, on a plurality of compute nodes. The log structured file system middleware process may be embodied, for example, as a Parallel Log-Structured File System (PLFS). The log structured file system middleware process optionally executes on a burst buffer node.

The Dawn of Vesta Science

NASA Technical Reports Server (NTRS)

Garner, Charles E.; Rayman, Marc D.; Brophy, John R.; Mikes, Steven C.

2011-01-01

The Dawn mission is part of NASA's Discovery Program and has as its goal the scientific exploration of the two most massive main-belt asteroids, Vesta and Ceres. The Dawn spacecraft was launched from the Cape Canaveral Air Force Station on September 27, 2007 on a Delta-II 7925H-9.5 (Delta-II Heavy) rocket that placed the 1218-kg spacecraft onto an Earth-escape trajectory. On-board the spacecraft is an ion propulsion system (IPS) developed at the Jet Propulsion Laboratory which will provide a total ?V of 11.3 km/s for the heliocentric transfer to Vesta, orbit capture at Vesta, transfer between Vesta science orbits, departure and escape from Vesta, heliocentric transfer to Ceres, orbit capture at Ceres, and transfer between Ceres science orbits. Fullpower thrusting from December 2007 through October 2008 was used to successfully target a Mars gravity assist flyby in February 2009 that provided an additional ?V of 2.6 km/s. Deterministic thrusting for the heliocentric transfer to Vesta resumed in June 2009 and concluded with orbit capture at Vesta on July 16, 2011. An additional 210 hours of IPS thrusting was used to enter the first Vesta science orbit, called Survey orbit, on August 3, 2011 at an altitude of approximately 2,735 km. To date the IPS has been operated for 23,621 hours, consumed approximately 252 kg of xenon, and provided a delta-V of approximately 6.7 km/s. The IPS performance characteristics are very close to the expected performance based on analysis and testing performed pre-launch. The only significant issue in over the almost four years of IPS operations in flight was the temporary failure of a valve driver board in the Digital Control and Interface Unit-1 (DCIU-1), resulting in a loss of thrust of approximately 29 hours. Thrusting operations resumed after switching to DCIU-2, and power cycling conducted after orbit capture restored DCIU-1 to full functionality. After about three weeks of Survey orbit operations the IPS will be used to transfer the spacecraft to the other planned science orbit altitudes. After approximately one year of science operations the IPS will be used for escape from Vesta and then for thrusting to Ceres with a planned arrival date at Ceres in February 2015. This paper provides an overview of Dawn's mission objectives and the results of Dawn IPS mission operations through the start of science operations at Vesta.

The Atlases of Vesta derived from Dawn Framing Camera images

NASA Astrophysics Data System (ADS)

Roatsch, T.; Kersten, E.; Matz, K.; Preusker, F.; Scholten, F.; Jaumann, R.; Raymond, C. A.; Russell, C. T.

2013-12-01

The Dawn Framing Camera acquired during its two HAMO (High Altitude Mapping Orbit) phases in 2011 and 2012 about 6,000 clear filter images with a resolution of about 60 m/pixel. We combined these images in a global ortho-rectified mosaic of Vesta (60 m/pixel resolution). Only very small areas near the northern pole were still in darkness and are missing in the mosaic. The Dawn Framing Camera also acquired about 10,000 high-resolution clear filter images (about 20 m/pixel) of Vesta during its Low Altitude Mapping Orbit (LAMO). Unfortunately, the northern part of Vesta was still in darkness during this phase, good illumination (incidence angle < 70°) was only available for 66.8 % of the surface [1]. We used the LAMO images to calculate another global mosaic of Vesta, this time with 20 m/pixel resolution. Both global mosaics were used to produce atlases of Vesta: a HAMO atlas with 15 tiles at a scale of 1:500,000 and a LAMO atlas with 30 tiles at a scale between 1:200,000 and 1:225,180. The nomenclature used in these atlases is based on names and places historically associated with the Roman goddess Vesta, and is compliant with the rules of the IAU. 65 names for geological features were already approved by the IAU, 39 additional names are currently under review. Selected examples of both atlases will be shown in this presentation. Reference: [1]Roatsch, Th., etal., High-resolution Vesta Low Altitude Mapping Orbit Atlas derived from Dawn Framing Camera images. Planetary and Space Science (2013), http://dx.doi.org/10.1016/j.pss.2013.06.024i

Mass movement on Vesta at steep scarps and crater rims

NASA Astrophysics Data System (ADS)

Krohn, K.; Jaumann, R.; Otto, K.; Hoogenboom, T.; Wagner, R.; Buczkowski, D. L.; Garry, B.; Williams, D. A.; Yingst, R. A.; Scully, J.; De Sanctis, M. C.; Kneissl, T.; Schmedemann, N.; Kersten, E.; Stephan, K.; Matz, K.-D.; Pieters, C. M.; Preusker, F.; Roatsch, T.; Schenk, P.; Russell, C. T.; Raymond, C. A.

2014-12-01

The Quadrangles Av-11 and Av-12 on Vesta are located at the northern rim of the giant Rheasilvia south polar impact basin. The primary geologic units in Av-11 and Av-12 include material from the Rheasilvia impact basin formation, smooth material and different types of impact crater structures (such as bimodal craters, dark and bright crater ray material and dark ejecta material). Av-11 and Av-12 exhibit almost the full range of mass wasting features observed on Vesta, such as slump blocks, spur-and-gully morphologies and landslides within craters. Processes of collapse, slope instability and seismically triggered events force material to slump down crater walls or scarps and produce landslides or rotational slump blocks. The spur-and-gully morphology that is known to form on Mars is also observed on Vesta; however, on Vesta this morphology formed under dry conditions.

Mass Movement on Vesta at Steep Scarps and Crater Rims

NASA Technical Reports Server (NTRS)

Krohn, K.; Jaumann, R.; Otto, K.; Hoogenboom, T.; Wagner, R.; Buczkowski, D. L.; Garry, B.; Williams, D. A.; Yingst, R. A.; Scully, J.;

Dawn and the Vesta-HED Connection

NASA Technical Reports Server (NTRS)

McSween, H. Y.; Mittlefehldt, D. W.; Beck, A. W.; McCoy, T.; Marchi, S.; DeSanctis, M. C.; Ammannito, E.; Raymond, C. A.; Russell, C. T.

2012-01-01

Although it is difficult to explain exactly how eucrites and diogenites are related through simple magmatic processes, their shared oxygen isotopic compositions and the common occurrence of clasts of both lithologies in howardite breccias support derivation from a common parent body. For decades, HED meteorites have been linked to asteroid 4 Vesta, based on spectral similarities [1] and the discovery of a dynamical family (Vestoids) that provides a bridge between Vesta and nearby resonance escape hatches [2]. Although recently derived constraints on the rapidity of HED parent body differentiation, based on measurements of Al-26 in diogenites, have been used to argue against the Vesta-HED connection [3], new thermal evolution models [e.g., 4] appear to be heated and melted fast enough to account for this constraint. Data from the Dawn orbiter strengthen the Vesta - HED linkage and provide new insights into petrogenetic interpretations of these meteorites.

Rough-surface model for surface temperature calculations on Vesta

NASA Astrophysics Data System (ADS)

Palmer, E.; Sykes, M.

2014-07-01

We model observations by the Dawn Visual and Infrared spectrometer (VIR) [1] to reproduce the observed surface temperature of Vesta. The VIR instrument has collected over 3,700 spectral cubes of Vesta out to 5.1 microns. The observed surface temperature is derived by matching the irradiance near 5 microns with a grey body, the Planck function after removing a reflected-light component per previous procedures [2--5] with similar results. We noted that the observed surface temperatures are significantly hotter than what simple theoretical models would predict [2]. To better understand this, we used a high-resolution topographic model of Vesta [6] that provided exact phase, incidence, and emission angles for every VIR pixel. We assume an emissivity of 0.9, Bond albedo of between 0.16 and 0.22 [5], and a variety of thermal inertia values for a low-contrast, highly degraded, homogenous crater. We have created a ''rough-surface'' thermal model that takes into account how irregular grains create sub-pixel variations in the thermal spectrum and describe the effect it has on the observed surface temperatures of Vesta. We have applied this method to the VIR observations of Vesta, which produced a high level of agreement with the observed surface temperatures.

Dawn at Vesta: Characterizing a minor planet

NASA Astrophysics Data System (ADS)

Pieters, C.; Russell, C.; Raymond, C.; Dawn Team

2014-07-01

The Dawn spacecraft arrived at Vesta in July 2011, spent more than a year exploring the surface with orbital instruments, and is now on its way to Ceres to do the same [1]. Beginning the investigations at Vesta, we were in the unique position of having what we believed to be samples from the surface (the HED family of meteorites) to guide our planning of scientific exploration. We also had telescopic spectra of Vesta that linked it to the meteorites [2] and had spatially resolved images of Vesta from HST [3] that indicated variations exist across the surface, and that an enormous depression occurs at the south pole. Since the HED meteorites show evidence of early melting and differentiation, we expected an ancient evolved anhydrous surface, perhaps similar to that of the Moon complete with early magma ocean. Although the Moon has often been considered a small body 'end member' that can be used to study early terrestrial planet evolution, with the year-long exploration of Vesta by Dawn, we now have extensive information for an even smaller differentiated planetary body with which to compare and test models and paradigms. We now know that both bodies are heavily cratered and exhibit at least one enormous basin that models predict should have excavated (and possibly exposed) the mantle [4]. Nevertheless, although compositional diversity is found on both, evidence for mantle material has been illusive. These two airless differentiated silicate bodies are ancient and essentially (but not completely) anhydrous. Regionally coherent areas containing H as well as OH are identified across the surface of Vesta [5] but exhibit no apparent relation to OH recently detected on the Moon [6]. Instead, Vesta's hydrated areas are spatially correlated with low-albedo regions, suggesting an exogeneous source (such as delivery by and mixing with carbonaceous chondritic material) [5,7]. Vesta exhibits its own style of space weathering that transforms fresh craters into background soils, one that involves regolith mixing instead of accumulation of nano-phase opaque components on surface grains [8]. The apparent dearth of nano-phase opaque coatings on regolith grains is due to a combination of factors involving Vesta's location and specific surface composition. The result is a mineralogically rich surface exposed to Dawn's sensors [9], although substantially rearranged by impact processes. Major scientific insights will continue to emerge as calibration improves for the Dawn instruments that measure spectral properties of the surface.

An Iron-Rain Model for Core Formation on Asteroid 4 Vesta

NASA Technical Reports Server (NTRS)

Kiefer, Walter S.; Mittlefehldt, David W.

2016-01-01

Asteroid 4 Vesta is differentiated into a crust, mantle, and core, as demonstrated by studies of the eucrite and diogenite meteorites and by data from NASA's Dawn spacecraft. Most models for the differentiation and thermal evolution of Vesta assume that the metal phase completely melts within 20 degrees of the eutectic temperature, well before the onset of silicate melting. In such a model, core formation initially happens by Darcy flow, but this is an inefficient process for liquid metal and solid silicate. However, the likely chemical composition of Vesta, similar to H chondrites with perhaps some CM or CV chondrite, has 13-16 weight percent S. For such compositions, metal-sulfide melting will not be complete until a temperature of at least 1350 degrees Centigrade. The silicate solidus for Vesta's composition is between 1100 and 1150 degrees Centigrade, and thus metal and silicate melting must have substantially overlapped in time on Vesta. In this chemically and physically more likely view of Vesta's evolution, metal sulfide drops will sink by Stokes flow through the partially molten silicate magma ocean in a process that can be envisioned as "iron rain". Measurements of eucrites show that moderately siderophile elements such as Ni, Mo, and W reached chemical equilibrium between the metal and silicate phases, which is an important test for any Vesta differentiation model. The equilibration time is a function of the initial metal grain size, which we take to be 25-45 microns based on recent measurements of H6 chondrites. For these sizes and reasonable silicate magma viscosities, equilibration occurs after a fall distance of just a few meters through the magma ocean. Although metal drops may grow in size by merger with other drops, which increases their settling velocities and decreases the total core formation time, the short equilibration distance ensures that the moderately siderophile elements will reach chemical equilibrium between metal and silicate before metal drop merger becomes important. In this model, there must be at least 30 percent melting of the silicate phase when metal melting is complete, corresponding to a crust thickness of at least 30 kilometers on Vesta, consistent with Dawn gravity observations. Greater degrees of silicate melting and a correspondingly thicker crust are possible if Vesta accreted sufficiently rapidly.

Dynamic file-access characteristics of a production parallel scientific workload

NASA Technical Reports Server (NTRS)

Kotz, David; Nieuwejaar, Nils

1994-01-01

Multiprocessors have permitted astounding increases in computational performance, but many cannot meet the intense I/O requirements of some scientific applications. An important component of any solution to this I/O bottleneck is a parallel file system that can provide high-bandwidth access to tremendous amounts of data in parallel to hundreds or thousands of processors. Most successful systems are based on a solid understanding of the expected workload, but thus far there have been no comprehensive workload characterizations of multiprocessor file systems. This paper presents the results of a three week tracing study in which all file-related activity on a massively parallel computer was recorded. Our instrumentation differs from previous efforts in that it collects information about every I/O request and about the mix of jobs running in a production environment. We also present the results of a trace-driven caching simulation and recommendations for designers of multiprocessor file systems.

Speckle interferometry of asteroids. IV - Reconstructed images of 4 Vesta

NASA Technical Reports Server (NTRS)

Drummond, J.; Eckart, A.; Hege, E. K.

1988-01-01

The images of 4 Vesta obtained by means of speckle interferometric observations on November 16 and 17, 1983, support a 5-hr 20.5-min rotational period. The 4 Vesta visible light curve was approximately matched by the placing of circular 'spots' with 135-km diameter over the three dark and three bright features, followed by the assigning of albedos of 0 to the dark spots and 2 to the bright. The light curve is found to be primarily defined by albedo structure, rather than shape; this results in one maximum and one minimum/rotation, rather than the two of each that would be associated with 4 Vesta's triaxial ellipsoid morphology.

Spectroscopic Characterization of Mineralogy Across Vesta: Evidence of Different Lithologies

NASA Technical Reports Server (NTRS)

De Sanotis, M. C.; Ammannito, E.; Filacchione, G.; Capria, M. T.; Tosi, F.; Capaccioni, F.; Zambon, F.; Carraro, F.; Fonte, S.; Frigeri, A.;

Core Formation and Evolution of Asteroid 4 Vesta

NASA Technical Reports Server (NTRS)

Kiefer, Walter S.; Mittlefehldt, David W.

2014-01-01

The howardites, eucrites, and diogenites (HEDs) are a suite of related meteorite types that formed by igneous and impact processes on the same parent body. Multiple lines of evidence, including infrared spectroscopy of the asteroid belt and the petrology and geochemistry of the HEDs, suggest that the asteroid 4 Vesta is the parent body for the HEDs. Observations by NASA's Dawn spacecraft mission strongly support the conclusion that the HEDs are from Vesta. The abundances of the moderately siderophile elements Ni, Co, Mo, W, and P in eucrites require that most or all of the metallic phase in Vesta segregated to form a core prior to eucrite solidification. These observations place important constraints on the mode and timescale of core formation on Vesta. Possible core formation mechanisms include porous flow, which potentially could occur prior to initiation of silicate melting, and metallic rain in a largely molten silicate magma ocean. Once the core forms, convection within the core could possible sustain a magnetic dynamo for a period of time. We consider each process in turn.

Types and Distribution of Bright Materials in 4 Vesta

NASA Technical Reports Server (NTRS)

Mittlefehldt, D. W.; Li, Jian-Yang; Pieters, C. M.; De Sanctis, M. C.; Schroder, S. E.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Yingst, R. A.

2012-01-01

A strong case can be made that Vesta is the parent asteroid of the howardite, eucrite and diogenite (HED) meteorites [1]. As such, we have over a century of detailed sample analysis experience to call upon when formulating hypotheses regarding plausible lithologic diversity on Vesta. It thus came as a surprise when Dawn s Framing Camera (FC) first revealed distinctly localized materials of exceptionally low and high albedos, often closely associated. To understand the nature and origin of these materials, and how they inform us of the geological evolution of Vesta, task forces began their study. An initial step of the scientific endeavor is to develop a descriptive, non-genetic classification of objects to use as a basis for developing hypotheses and observational campaigns. Here we present a catalog of the types of light-toned deposits and their distribution across Vesta. A companion abstract [2] discusses possible origins of bright materials and the constraints they suggest for vestan geology.

Nemesis I: Parallel Enhancements to ExodusII

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hennigan, Gary L.; John, Matthew S.; Shadid, John N.

2006-03-28

NEMESIS I is an enhancement to the EXODUS II finite element database model used to store and retrieve data for unstructured parallel finite element analyses. NEMESIS I adds data structures which facilitate the partitioning of a scalar (standard serial) EXODUS II file onto parallel disk systems found on many parallel computers. Since the NEMESIS I application programming interface (APl)can be used to append information to an existing EXODUS II files can be used on files which contain NEMESIS I information. The NEMESIS I information is written and read via C or C++ callable functions which compromise the NEMESIS I API.

Flexibility and Performance of Parallel File Systems

NASA Technical Reports Server (NTRS)

Kotz, David; Nieuwejaar, Nils

1996-01-01

As we gain experience with parallel file systems, it becomes increasingly clear that a single solution does not suit all applications. For example, it appears to be impossible to find a single appropriate interface, caching policy, file structure, or disk-management strategy. Furthermore, the proliferation of file-system interfaces and abstractions make applications difficult to port. We propose that the traditional functionality of parallel file systems be separated into two components: a fixed core that is standard on all platforms, encapsulating only primitive abstractions and interfaces, and a set of high-level libraries to provide a variety of abstractions and application-programmer interfaces (API's). We present our current and next-generation file systems as examples of this structure. Their features, such as a three-dimensional file structure, strided read and write interfaces, and I/O-node programs, are specifically designed with the flexibility and performance necessary to support a wide range of applications.

NASA Software Lets You Explore Mars, the Asteroid Vesta and the Moon

NASA Image and Video Library

2016-10-06

NASA wants you to use your web browser to explore Mars, the Moon and the asteroid Vesta! The three portals are some of NASA's planetary mapping and modeling web portals. It makes it easy for mission planners, scientists, students and the public to visualize details on the surface of Mars, the Moon and Vesta, as seen with a variety of instruments aboard a number of spacecraft.

The Dawn Topography Investigation

NASA Technical Reports Server (NTRS)

Raymond, C. A.; Jaumann, R.; Nathues, A.; Sierks, H.; Roatsch, T.; Preusker, E; Scholten, F.; Gaskell, R. W.; Jorda, L.; Keller, H.-U.;

Cosmic-Ray-Exposure Ages of Diogenites and the Collisional History of the HED Parent Body or Bodies

NASA Technical Reports Server (NTRS)

Welten, K. C.; Lindner, L.; vanderBorg, K.; Loeken, T.; Scherer, P.; Schultz, L.

1996-01-01

Cosmic-ray-exposure ages of meteorites provide information on the collisional history of their parent bodies and the delivery mechanism of meteorites to Earth. The exposure-age distributions of ordinary chondrites show distinct patterns for H, L, and LL types, consistent with their origin on different parent bodies. The exposure-age distributions of howardites, eucrites. and diogenites (HEDS) show a common pattern with major peaks at 22 Ma and 38 Ma This provides additional evidence for a common origin of the HED meteorites, possibly 4 Vesta, although orbital dynamics calculations showed that the delivery of meteorites from Vesta to Earth is difficult. However, the discovery of several kilometer-sized Vesta-like asteroids in the region between Vesta and the 3:1 resonance suggested that these seem more likely parent bodies of the HEDs than Vesta itself. This implies that the exposure-age clusters may represent samples of several parent bodies. Therefore, the near-absence of diogenites with ages <20 Ma might be of interest for the composition of these kilometer-sized fragments of Vesta. Here we present cosmic-ray-exposure ages of 20 diogenites, including 9 new meteorites. In addition, we calculate the probability for each peak to occur by chance, assuming a constant production rate of HED fragments.

Olivine on Vesta as exogenous contaminants brought by impacts: Constraints from modeling Vesta's collisional history and from impact simulations

NASA Astrophysics Data System (ADS)

Turrini, D.; Svetsov, V.; Consolmagno, G.; Sirono, S.; Pirani, S.

2016-12-01

The survival of asteroid Vesta during the violent early history of the Solar System is a pivotal constraint on theories of planetary formation. Particularly important from this perspective is the amount of olivine excavated from the vestan mantle by impacts, as this constrains both the interior structure of Vesta and the number of major impacts the asteroid suffered during its life. The NASA Dawn mission revealed that olivine is present on Vesta's surface in limited quantities, concentrated in small patches at a handful of sites not associated with the two large impact basins Rheasilvia and Veneneia. The first detections were interpreted as the result of the excavation of endogenous olivine, even if the depth at which the detected olivine originated was a matter of debate. Later works raised instead the possibility that the olivine had an exogenous origin, based on the geologic and spectral features of the deposits. In this work, we quantitatively explore the proposed scenario of a exogenous origin for the detected vestan olivine to investigate whether its presence on Vesta can be explained as a natural outcome of the collisional history of the asteroid over the last one or more billion years. To perform this study we took advantage of the impact contamination model previously developed to study the origin and amount of dark and hydrated materials observed by Dawn on Vesta, a model we updated by performing dedicated hydrocode impact simulations. We show that the exogenous delivery of olivine by the same impacts that shaped the vestan surface can offer a viable explanation for the currently identified olivine-rich sites without violating the constraint posed by the lack of global olivine signatures on Vesta. Our results indicate that no mantle excavation is in principle required to explain the observations of the Dawn mission and support the idea that the vestan crust could be thicker than indicated by simple geochemical models based on the Howardite-Eucrite-Diogenite family of meteorites.

The Regolith of 4 Vesta: Perspectives from Howardite Meteorites and Dawn Mission Observations

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.; Blewett, David T.; Denevi, Brett W.; DeSanctis, M. C.; Jaumann, Ralf; Keller, H. Uwe; Nathues, Andreas; Pieters, Carle M.; Raymond, C. A.; Zuber, Maria T.

2011-01-01

4 Vesta is the largest asteroid with a basaltic surface, the only surviving differentiated asteroid recording igneous processes from the earliest phase of solar system history. The Dawn spacecraft is in orbit about Vesta pursuing a campaign of high resolution imaging and visible and infrared spectrometry of the surface; compositional mapping by gamma-ray and neutron spectrometry will follow. Vesta is heavily cratered with a surface covered by impact debris, a regolith. One important goal of the Dawn mission is to develop an understanding of regolith processes that are affecting this surface debris. Regolith characteristics are a record of interaction with the environment (e.g., impactors, dust, solar wind, galactic cosmic-rays) and give evidence of surface processes (down-gravity movement, etc.). Regolith mineralogy and composition reflect the local bedrock, with influences from regional and global mixing. Understanding regolith processes will aid in determining the lithology of underlying crust. Vesta is most likely the parent asteroid of the howardite, eucrite and diogenite meteorites. Eucrites are intrusive and extrusive mafic rocks composed mostly of ferroan low-Ca clinopyroxene and calcic plagioclase, while diogenites are cumulate magnesian orthopyroxenites. Magmatism occurred within a few million years of the formation of the solar system and then ceased. Impacts into the igneous crust produced the howardites - polymict breccias composed of mineral and lithic debris derived mostly from eucrites and diogenites. Some howardites are true regolith breccias formed by lithification of extensively impact-gardened surface debris. However, howardites have a number of significant petrologic and compositional differences from mature lunar regolith breccias and soils reflecting the different environment around Vesta compared to that at 1 AU. The most significant differences are the higher impactor flux with a lower mean impact velocity and the lower gravity. As a result, regolith processes on Vesta differ in detail from those on the Moon. Laboratory study of howardites and orbital investigation of Vesta will allow for development of robust models of regolith formation on hand sample to multi-kilometer scales.

Spectral studies of asteroids 21 lutetia and 4 vesta as objects of space missions

NASA Astrophysics Data System (ADS)

Busarev, V. V.

2010-12-01

Asteroid 21 Lutetia is one of the objects of the Rosetta mission carried out by the European Space Agency (ESA). The Rosetta spacecraft launched in 2004 is to approach Lutetia in July 2010, and then it will be directed to the comet Churyumov-Gerasimenko. Asteroid 4 Vesta is planned to be investigated in 2011 from the Dawn spacecraft launched by the National Aeronautics and Space Administration (NASA) in 2007 (its second object is the largest asteroid, 1 Ceres). The observed characteristics of Lutetia and Vesta are different and even contradictory. In spite of the intense and versatile ground-based studies, the origin and evolution of these minor planets remain obscure or not completely clear. The types of Lutetia and Vesta (M and V, respectively) determined from their spectra correspond to the high-temperature mineralogy, which agrees with their albedo estimated from the Infrared Astronomical Satellite (IRAS) observations. However, according to the opinion of some researchers, Lutetia is of the C type, and, therefore, its mineralogy is of the lowtemperature type. In turn, hydrosilicate formations have been found in some places on the surface of Vesta. Our observations also testify that at some relative phases of rotation (RP), the reflectance spectra of Lutetia and Vesta demonstrate features confirming the presence of hydrosilicates in the surface material. However, this fact can be reconciled with the magmatic nature of Lutetia and Vesta if the hydrated material was delivered to their surfaces by falling primitive bodies. Such small bodies are probably present everywhere in the main asteroid belt and can be the relicts of silicate-icy planetesimals from Jupiter's formation zone or the fragments of primitive-type asteroids. When interpreting the reflectance spectra of Lutetia and Vesta, we discuss the spectral classification by Tholen (1984) from the standpoint of its general importance for the estimation of the mineralogical type of the asteroids and the study of their origin and evolution.

File-access characteristics of parallel scientific workloads

NASA Technical Reports Server (NTRS)

Nieuwejaar, Nils; Kotz, David; Purakayastha, Apratim; Best, Michael; Ellis, Carla Schlatter

1995-01-01

Phenomenal improvements in the computational performance of multiprocessors have not been matched by comparable gains in I/O system performance. This imbalance has resulted in I/O becoming a significant bottleneck for many scientific applications. One key to overcoming this bottleneck is improving the performance of parallel file systems. The design of a high-performance parallel file system requires a comprehensive understanding of the expected workload. Unfortunately, until recently, no general workload studies of parallel file systems have been conducted. The goal of the CHARISMA project was to remedy this problem by characterizing the behavior of several production workloads, on different machines, at the level of individual reads and writes. The first set of results from the CHARISMA project describe the workloads observed on an Intel iPSC/860 and a Thinking Machines CM-5. This paper is intended to compare and contrast these two workloads for an understanding of their essential similarities and differences, isolating common trends and platform-dependent variances. Using this comparison, we are able to gain more insight into the general principles that should guide parallel file-system design.

Modeling close encounters with massive asteroids: a Markovian approach. An application to the Vesta family

NASA Astrophysics Data System (ADS)

Carruba, V.; Roig, F.; Michtchenko, T. A.; Ferraz-Mello, S.; Nesvorný, D.

2007-04-01

Context: Nearly all members of the Vesta family cross the orbits of (4) Vesta, one of the most massive asteroids in the main belt, and some of them approach it closely. When mutual velocities during such close encounters are low, the trajectory of the small body can be gravitationally deflected, consequently changing its heliocentric orbital elements. While the effect of a single close encounter may be small, repeated close encounters may significantly change the proper element distribution of members of asteroid families. Aims: We develop a model of the long-term effect of close encounters with massive asteroids, so as to be able to predict how far former members of the Vesta family could have drifted away from the family. Methods: We first developed a new symplectic integrator that simulates both the effects of close encounters and the Yarkovsky effect. We analyzed the results of a simulation involving a fictitious Vesta family, and propagated the asteroid proper element distribution using the probability density function (pdf hereafter), i.e. the function that describes the probability of having an encounter that modifies a proper element x by Δx, for all the possible values of Δx. Given any asteroids' proper element distribution at time t, the distribution at time t+T may be predicted if the pdf is known (Bachelier 1900, Théorie de la spéculation; Hughes 1995, Random Walks and Random Environments, Vol. I). Results: We applied our new method to the problem of V-type asteroids outside the Vesta family (i.e., the 31 currently known asteroids in the inner asteroid belt that have the same spectral type of members as the Vesta family, but that are outside the limits of the dynamical family) and determined that at least ten objects have a significant diffusion probability over the minimum estimated age of the Vesta family of 1.2 Gyr (Carruba et al. 2005, A&A, 441, 819). These objects can therefore be explained in the framework of diffusion via repeated close encounters with (4) Vesta of asteroids originally closer to the parent body. Conclusions: We computed diffusion probabilities at the location of four of these asteroids for various initial conditions, parametrized by values of initial ejection velocity V_ej. Based on our results, we believe the Vesta family age is (1200 ± 700) Myr old, with an initial ejection velocity of (240 ± 60) m/s. Appendices are only available in electronic form at http://www.aanda.org

Characterizing parallel file-access patterns on a large-scale multiprocessor

NASA Technical Reports Server (NTRS)

Purakayastha, Apratim; Ellis, Carla Schlatter; Kotz, David; Nieuwejaar, Nils; Best, Michael

1994-01-01

Rapid increases in the computational speeds of multiprocessors have not been matched by corresponding performance enhancements in the I/O subsystem. To satisfy the large and growing I/O requirements of some parallel scientific applications, we need parallel file systems that can provide high-bandwidth and high-volume data transfer between the I/O subsystem and thousands of processors. Design of such high-performance parallel file systems depends on a thorough grasp of the expected workload. So far there have been no comprehensive usage studies of multiprocessor file systems. Our CHARISMA project intends to fill this void. The first results from our study involve an iPSC/860 at NASA Ames. This paper presents results from a different platform, the CM-5 at the National Center for Supercomputing Applications. The CHARISMA studies are unique because we collect information about every individual read and write request and about the entire mix of applications running on the machines. The results of our trace analysis lead to recommendations for parallel file system design. First the file system should support efficient concurrent access to many files, and I/O requests from many jobs under varying load conditions. Second, it must efficiently manage large files kept open for long periods. Third, it should expect to see small requests predominantly sequential access patterns, application-wide synchronous access, no concurrent file-sharing between jobs appreciable byte and block sharing between processes within jobs, and strong interprocess locality. Finally, the trace data suggest that node-level write caches and collective I/O request interfaces may be useful in certain environments.

Vesta in the Light of Dawn, But Without HEDS?

NASA Technical Reports Server (NTRS)

McSween, H. Y.; Mittlefehldt, D. W.

2014-01-01

The derivation of HEDs from Vesta is strongly supported by Dawn data [1], and these meterorites have made interpretations of Dawn spectra much more rigorous. Compared to the Moon, where samples became available after geologic mapping, the exploration of Vesta has been backwards. But what if HEDs had not been available or identified as vestan samples? What petrologic and geochemical predictions would have been possible using Dawn data, without the benefit of HEDs?

Reconstructed images of 4 Vesta.

NASA Astrophysics Data System (ADS)

Drummond, J.; Eckart, A.; Hege, E. K.

The first glimpses of an asteroid's surface have been obtained from images of 4 Vesta reconstructed from speckle interferometric observations made with Harvard's PAPA camera coupled to Steward Observatory's 2.3 m telescope. Vesta is found to have a "normal" triaxial ellipsoid shape of 566(±15)×532(±15)×466(±15) km. Its rotational pole lies within 4° of ecliptic long. 327°, lat. = +55°. Reconstructed images obtained with the power spectra and Knox-Thompson cross-spectra reveal dark and bright patterns, reminiscent of the Moon. Three bright and three dark areas are visible, and when combined with an inferred seventh bright region not visible during the rotational phases covered during the authors' run, lead to lightcurves that match Vesta's lightcurve history.

Dawn 2013-2015 Double-sided Mission Events Calendar

NASA Image and Video Library

2007-01-01

The mosaic of Visible and Infrared Spectrometer (VIR) data shows the location of the data acquired by VIR during the HAMO (high-altitude mapping orbit) phase of NASA's Dawn mission. VIR can image Vesta in a number of different wavelengths of light, ranging from the visible to the infrared part of the electromagnetic spectrum. This mosaic shows the images taken at a wavelength of 550 nanometers, which is in the visible part of the electromagnetic spectrum. During HAMO VIR obtained more than 4.6 million spectra of Vesta. It is clear from this image that the VIR observations are widely distributed across Vesta, which results in a global view of the spectral properties of Vesta's surface. http://photojournal.jpl.nasa.gov/catalog/PIA19368

Illumination Conditions at the Asteroid 4 Vesta: Implications for the Presence of Water Ice

NASA Technical Reports Server (NTRS)

Stubbs, Timothy J.; Wang, Yongli

2011-01-01

The mean illumination conditions and surface temperatures over one orbital period are calculated for the Asteroid 4 Vesta using a coarse digital elevation model produced from Hubble Space Telescope images. Even with the anticipated effects of finer-scale topography taken into account, it is unlikely that any significant permanently shadowed regions currently exist on Vesta due to its large axial tilt (approx. = 27deg). However, under present day conditions, it is predicted that about half of Vesta's surface has an average temperature of less than 145 K, which, based on previous thermal modeling of main belt asteroids, suggests that water ice could survive in the top few meters of the vestal regolith on billion-year timescales.

Visible Color and Photometry of Bright Materials on Vesta

NASA Technical Reports Server (NTRS)

Schroder, S. E.; Li, J. Y.; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.

2012-01-01

The Dawn Framing Camera (FC) collected images of the surface of Vesta at a pixel scale of 70 m in the High Altitude Mapping Orbit (HAMO) phase through its clear and seven color filters spanning from 430 nm to 980 nm. The surface of Vesta displays a large diversity in its brightness and colors, evidently related to the diverse geology [1] and mineralogy [2]. Here we report a detailed investigation of the visible colors and photometric properties of the apparently bright materials on Vesta in order to study their origin. The global distribution and the spectroscopy of bright materials are discussed in companion papers [3, 4], and the synthesis results about the origin of Vestan bright materials are reported in [5].

Mapping Vesta Equatorial Quadrangle V-8EDL: Various Craters and Giant Grooves

NASA Astrophysics Data System (ADS)

Le Corre, L.; Nathues, A.; Reddy, V.; Buczkowski, D.; Denevi, B. W.; Gaffey, M.; Williams, D. A.; Garry, W. B.; Yingst, R.; Jaumann, R.; Pieters, C. M.; Russell, C. T.; Raymond, C. A.

2011-12-01

NASA's Dawn spacecraft arrived at the asteroid 4Vesta on July 15, 2011, and is now collecting imaging, spectroscopic, and elemental abundance data during its one-year orbital mission. As part of the geological analysis of the surface, a series of 15 quadrangle maps are being produced based on Framing Camera images (FC: spatial resolution: ~65 m/pixel) along with Visible & Infrared Spectrometer data (VIR: spatial resolution: ~180 m/pixel) obtained during the High-Altitude Mapping Orbit (HAMO). This poster presentation concentrates on our geologic analysis and mapping of quadrangle V-8EDL located between -22 and 22 degrees latitude and 144 and 216 degrees East longitude. This quadrangle is dominated by old craters (without any ejecta visible in the clear and color bands), but one small recent crater can be seen with bright ejecta blanket and rays. The latter has some small, dark units outside and inside the crater rim that could be indicative of impact melt. This quadrangle also contains a set of giant linear grooves running almost parallel to the equator that might have formed subsequent to a big impact. We will use FC mosaics with clear images and false color composites as well as VIR spectroscopy data in order to constrain the geology and identify the nature of each unit present in this quadrangle.

V-type candidates and Vesta family asteroids in the Moving Objects VISTA (MOVIS) catalogue

NASA Astrophysics Data System (ADS)

Licandro, J.; Popescu, M.; Morate, D.; de León, J.

2017-04-01

Context. Basaltic asteroids (spectrally classified as V-types) are believed to be fragments of large differentiated bodies. The majority of them are found in the inner part of the asteroid belt, and are current or past members of the Vesta family. Recently, some V-type asteroids have been discovered far from the Vesta family supporting the hypothesis of the presence of multiple basaltic asteroids in the early solar system. The discovery of basaltic asteroids in the outer belt challenged the models of the radial extent and the variability of the temperature distribution in the early solar system. Aims: We aim to identify new basaltic V-type asteroids using near-infrared colors of 40 000 asteroids observed by the VHS-VISTA survey and compiled in the MOVIS-C catalogue. We also want to study their near-infrared colors and to study the near-infrared color distribution of the Vesta dynamical family. Methods: We performed a search in the MOVIS-C catalogue of all the asteroids with (Y-J) and (J-Ks) in the range (Y-J) ≥ 0.5 and (J-Ks) ≤ 0.3, associated with V-type asteroids, and studied their color distribution. We have also analyzed the near-infrared color distribution of 273 asteroid members of the Vesta family and compared them with the albedo and visible colors from WISE and SDSS data. We determined the fraction of V-type asteroids in the family. Results: We found 477 V-type candidates in MOVIS-C, 244 of them outside the Vesta dynamical family. We identified 19 V-type asteroids beyond the 3:1 mean motion resonance, 6 of them in the outer main belt, and 16 V-types in the inner main belt with proper inclination Ip ≤ 3.0°, well below the inclination of the Vesta family. We computed that 85% of the members of the Vesta dynamical family are V-type asteroids, and only 1-2% are primitive class asteroids and unlikely members of the family. Conclusions: This work almost doubles the sample of basaltic asteroid candidates in regions outside the Vesta family. Spectroscopic studies in the near-infrared and dynamical studies are needed to confirm their basaltic composition and to determine their origin.

Chemical Mapping of Vesta and Ceres

NASA Technical Reports Server (NTRS)

Prettyman, Thomas H.; Mittlefehldt, David W.; Yamashita, Naoyuki; McSween, Harry Y.; Feldman, William C.; Lawrence, David J.; Beck, Andrew W.; McCoy, Timothy J.; Toplis, Michael J.; Mizzon, Hugau;

Characterization of Mineralogy Across Vesta

NASA Technical Reports Server (NTRS)

De Sanctis, M. C.; Ammannito, E.; Capria, M. T.; Capaccioni, F.; Carraro, F.; Fonte, S.; Frigeri, A.; Magni, G.; Marchi, S.; Palomba, E.;

Neutron Absorption Measurements Constrain Eucrite-Diogenite Mixing in Vesta's Regolith

NASA Technical Reports Server (NTRS)

Prettyman, T. H.; Mittlefehldt, D. W.; Feldman, W. C.; Hendricks, J. S.; Lawrence, D. J.; Peplowski, P. N.; Toplis, M. J.; Yamashita, N.; Beck, A.; LeCorre, L.;

Petrologic constraints on the surface processes on asteroid 4 Vesta and on excavation depths of diogenite fragments

NASA Technical Reports Server (NTRS)

Grove, T. L.

1993-01-01

The eucrite-howardite-diogenite meteorite groups are though to be related by magmatic processes. Asteroid 4 Vesta has been proposed as the parent body for these basaltic achondrite meteorites. The similarity of the planetesimal's surface composition to eucrite and diogenite meteorites and the large size of the asteroid (r = 250 km) make it an attractive source, but its position in the asteroid belt far from the known resonances from which meteorites originate make a relation between Vesta and eucrite-howardite-giogenite group problematic. It has been proposed that diogenites are low-Ca pyroxene-rich cumulates that crystallized from a magnesian parent (identified in howardite breccias), and this crystallization process led to evolved eucrite derivative magmas. This eucrite-diogenite genetic relationship places constraints on the physical conditions under which crystallization occurred. Elevated pressure melting experiments on magnesian eucrite parent compositions show that the minimum pressure at which pyroxene crystallization could lead to the observed compositions of main series eucrites is 500 bars, equivalent to a depth of 135 km in a 4 Vesta-sized eucrite parent body. Therefore, the observation of diogenite on the surface of 4 Vesta requires a post-crystallization process that excavates diogenite cumulate from depth. The discovery of diogenite asteroidal fragments is consistent with an impact event on 4 Vesta that penetrated the deep interior of this planetesimal.

Snowman

NASA Image and Video Library

2011-10-27

This composite image is a simulated true color image of part of asteroid Vesta northern region, which contains the nowman craters. Images such as these greatly help the process of understanding Vesta geological history.

Differentiation of Asteroid 4 Vesta: Core Formation by Iron Rain in a Silicate Magma Ocean

NASA Technical Reports Server (NTRS)

Kiefer, Walter S.; Mittlefehldt, David W.

2017-01-01

Geochemical observations of the eucrite and diogenite meteorites, together with observations made by NASA's Dawn spacecraft while orbiting asteroid 4 Vesta, suggest that Vesta resembles H chondrites in bulk chemical composition, possible with about 25 percent of a CM-chondrite like composition added in. For this model, the core is 15 percent by mass (or 8 percent by volume) of the asteroid, with a composition of 73.7 percent by weight Fe, 16.0 percent by weight S, and 10.3 percent by weight Ni. The abundances of moderately siderophile elements (Ni, Co, Mo, W, and P) in eucrites require that essentially all of the metallic phase in Vesta segregated to form a core prior to eucrite solidification. The combination of the melting phase relationships for the silicate and metal phases, together with the moderately siderophile element concentrations together require that complete melting of the metal phase occurred (temperature is greater than1350 degrees Centigrade), along with substantial (greater than 40 percent) melting of the silicate material. Thus, core formation on Vesta occurs as iron rain sinking through a silicate magma ocean.

Modelling the Thermal History of Asteroid 4 Vesta

NASA Technical Reports Server (NTRS)

Solano, James M.; Kiefer, W. S.; Mittlefehldt, D. W.

2012-01-01

The asteroid 4 Vesta is widely thought to be the source of the HED (Howardite, Eucrite and Diogenite) meteorites, with this link supported by spectroscopic and dynamical studies. The availability of the HED meteorites for study and the new data being gained from the Dawn mission provides an excellent opportunity to investigate Vesta s history. In this study, modelling of Vesta has been undertaken to investigate its evolution from an unconsolidated chondritic body to a differentiated body with an iron core. In contrast to previous modelling, both heat and mass transfer are considered as coupled processes. This work draws on models of melt segregation in terrestrial environments to inform the evolution of Vesta into the differentiated body observed today. In order for a core to form in this body, a separation of the metallic iron from the silicates must take place. Temperatures in excess of the solidus temperatures for the Fe-FeS system and the silicates are therefore required. Thermal modelling has shown accretion before 2Myr leads to temperatures in excess of the silicate solidus.

Rocks from Vesta -- Part 1: Eucrites

NASA Image and Video Library

2011-12-02

These images are of HED howardite, eucrite and diogenite meteorites, a large group of meteorites believed to originate from asteroid Vesta, a hypothesis that is consistent with current Dawn observations.

The Violent Collisional History of Asteroid 4 Vesta

NASA Astrophysics Data System (ADS)

Marchi, S.; McSween, H. Y.; O'Brien, D. P.; Schenk, P.; De Sanctis, M. C.; Gaskell, R.; Jaumann, R.; Mottola, S.; Preusker, F.; Raymond, C. A.; Roatsch, T.; Russell, C. T.

2012-05-01

Vesta is a large differentiated rocky body in the main asteroid belt that accreted within the first few million years after the formation of the earliest solar system solids. The Dawn spacecraft extensively imaged Vesta’s surface, revealing a collision-dominated history. Results show that Vesta’s cratering record has a strong north-south dichotomy. Vesta’s northern heavily cratered terrains retain much of their earliest history. The southern hemisphere was reset, however, by two major collisions in more recent times. We estimate that the youngest of these impact structures, about 500 kilometers across, formed about 1 billion years ago, in agreement with estimates of Vesta asteroid family age based on dynamical and collisional constraints, supporting the notion that the Vesta asteroid family was formed during this event.

Rocks from Vesta -- Part 3: Diogenites

NASA Image and Video Library

2011-12-04

These images are of HED howardite, eucrite and diogenite meteorites are a large group of meteorites believed to originate from asteroid Vesta, a hypothesis that is consistent with current Dawn observations.

Rocks from Vesta -- Part 2: Howardites

NASA Image and Video Library

2011-12-03

These images are of HED howardite, eucrite and diogenite meteorites are a large group of meteorites believed to originate from asteroid Vesta, a hypothesis that is consistent with current Dawn observations.

The Faces of Vesta

NASA Image and Video Library

2010-10-08

NASA Hubble Space Telescope snapped these images of the asteroid Vesta in preparation for the Dawn spacecraft visit in 2011. The images show the difference in brightness and color on the asteroid surface.

Global Mineral Map of Vesta

NASA Image and Video Library

2012-05-10

This colorized map from NASA Dawn mission shows the distribution of minerals across the surface of the giant asteroid Vesta. It was made from spectra -- or data collected in different wavelengths of radiation.

Geologic Mapping of the Av-11 Pinaria Quadrangle of Asteroid 4 Vesta

NASA Astrophysics Data System (ADS)

Schenk, P.; Hoogenboom, T.; Williams, D.; Yingst, R. A.; Jaumann, R.; Gaskell, R.; Preusker, F.; Nathues, A.; Roatsch, T.

2012-04-01

As part of the Dawn's orbital mapping investigation of Vesta, the Science Team is conducting geologic mapping of the surface in the form of 15 quadrangle maps, including quadrangle Av-11 (Pinaria). The base map is a monochrome Framing Camera (FC) mosaic at ~70 m/pixel, supplemented by Digital Terrain Models (DTM) and FC color ratio images, both at ~250 m/pixel, slope and contour maps, and Visible and Infrared (VIR) hyperspectral images. Av-11 straddles the 45-degree longitude in the South Polar Region, and is dominated by the rim of the ~505 km south polar topographic feature, Rheasilvia. Sparsely cratered (relatively), Av-11 is dominated by a 20 km high rim scarp (Matronalia Rupes) and by arcuate ridges and troughs forming a radial to spiral pattern across the basin floor. Primary geologic features of Av-11 include the following. Ridge-and-groove terrain radiating arcuately from the central mound unit, interpreted to be structural disruption of the basin floor associated with basin formation. The largest crater in Av-11 is Pinaria (37 km). Mass wasting deposits are observed on its floor. Secondary crater chains and fields are also evident. Mass wasting observed along Rheasilvia rim scarp and in the largest craters indicates scarp failure is a significant process. Parallel fault scarps mark this deposit of slumped debris at the base of 20 km high Matronalia Rupes, which may have formed during or shortly after basin excavation. We interpret most of these deposits as slump material emplaced as a result of the effects of basin formation and collapse. Lobate materials are characterized by lineations and lobate scarps and interpreted as Rheasilvia ejecta deposit outside Rheasilvia rim (the smoothest terrain on Vesta), and are consistent with formation by ejecta. Partial burial of older craters near the edge of these deposits are also observed.

Vesta: A Geological Overview

NASA Astrophysics Data System (ADS)

Ralf, Jaumann; Russell, C. T.; Raymond, C. A.; Pieters, C. M.; Yingst, R. A.; Williams, D. A.; Buczkowski, D. L.; Schenk, P.; Denevi, B.; Krohn, K.; Stephan, K.; Roatsch, T.; Preusker, F.; Otto, K.; Mest, S. C.; Ammannito, E.; Blewett, D.; Carsenty, U.; DeSanctis, C. M.; Garry, W.; Hiesinger, H.; Keller, H. U.; Kersten, E.; Marchi, S.; Matz, K. D.; McCord, T. B.; McSween, H. Y.; Mottola, S.; Nathues, A.; Neukum, G.; O'Brien, D. P.; Schmedemann, N.; Scully, J. E. C.; Sykes, M. V.; Zuber, M. T.

2012-10-01

The Dawn spacecraft has collected over 28,000 images and a wealth of spectral data providing nearly complete coverage of Vesta’s surface with multiple views. These data enable analysis of Vesta’s diverse geology including impact craters of all sizes and unusual shapes, a variety of ejecta blankets, large troughs extending around the equatorial region, impact basins, enigmatic dark material, and considerable evidence for mass wasting and surface alteration features (1). Two large impact basins, Veneneia (400km) underlying the larger Rheasilvia basin (500km) dominate the south pole (1,2). Rheasilvia exhibits a huge central peak, with total relief of -22km to 19km, and steep scarps with mass wasting features. Vesta’s global tectonic patterns (two distinct sets of large troughs almost parallel to the equator) strongly correlate with the locations of the two south polar impact basins, and were likely created by their formation (1,3). Numerous unusual asymmetric impact craters and ejecta indicate the strong role of topographic slope in cratering processes on Vesta (1). Such very steep topographic slopes are near to the angle of repose; slope failures make resurfacing due to impacts and their associated gravitational slumping and seismic effects an important geologic process on Vesta (1). Outcrops in crater walls indicate reworked crustal material and impact melt in combination with clusters of pits that show thermal surface processes (4). Relatively dark material of still unknown origin is intermixed in the regolith layers and partially excavated by younger impacts yielding dark outcrops, rays and ejecta (1,5). Finally, Vesta’s surface is younger than expected (6). (1) Jaumann, et al., 2012, Science 336, 687-690; (2) Schenk et al., 2012, Science 336, 964-967; (3) Buczkowski, et al., 2012, GRL, submitted; (4) Denevi, et al., 2012, Science, submitted; (5) McCord, et al., 2012, Nature, submitted; (6) Marchi, et al., 2012, Science 336, 690-694.

Vesta Topography Map

NASA Image and Video Library

2013-07-08

This color-coded topography map from NASA Dawn mission shows the giant asteroid Vesta in an equirectangular projection at 32 pixels per degree, relative to an ellipsoid of 177 miles by 177 miles by 142 miles.

Application of blind source separation to gamma ray spectra acquired by GRaND around Vesta

NASA Astrophysics Data System (ADS)

Mizzon, H.; Toplis, M. J.; Forni, O.; Prettyman, T. H.; Raymond, C. A.; Russell, C. T.

2012-12-01

The bismuth germinate (BGO) scintillator is one of the sensors of the gamma ray and neutron detector (GRaND)1 on board the Dawn spacecraft, that has spent just over one year in orbit around the asteroid 4-Vesta. The BGO detector is excited by energetic gamma-rays produced by galactic cosmic rays (GCR) or energetic solar particles interacting either with Vesta and/or the Dawn spacecraft. In detail, during periods of quiet solar activity, gamma ray spectra produced by the scintillator can be considered as consisting of three signals: i) a contribution of gamma-rays from Vesta produced by GCR interactions at the asteroid's surface, ii) a contribution from the spacecraft excited by neutrons coming from Vesta, and iii) a contribution of the spacecraft excited by local interaction with galactic cosmic rays. While the first two contributions should be positive functions of the solid angle of Vesta in the field of view during acquisition, the last one should have a negative dependence because Vesta partly shields the spacecraft from GCR. This theoretical mix can be written formally as: S=aΩSV+bΩSSCNV+c(4π-Ω)SSCGCR (1) where S is the series of recorded spectra, Ω is the solid angle, SV is the contribution of gamma rays coming from Vesta, SSCNV is the contribution of gamma rays coming from the spacecraft excited by the neutron coming from Vesta and SSCGCR is the contribution of gamma rays coming from the spacecraft excited by GCR. A blind source separation method called independent component analysis enables separating additive subcomponents supposing the mutual statistical independence of the non-Gaussian source signals2. Applying this method to BGO spectra acquired during the first three months of the low-altitude measurement orbit (LAMO) reveals two main independent components. The first one is dominated by the positron electron annihilation peak and is positively correlated to the solid angle. The second is negatively correlated to the solid angle and displays peaks of elements present in the spacecraft, of energy in the range 1 to 3.5 MeV. At energy >3.5 MeV, the dominant independent component highlighted by this method has no significant peaks, suggesting that it is not influenced by Vesta itself which is known to have a strong signal associated with iron at 7.6 MeV. Our method therefore represents a first step in retrieving the contribution of the spacecraft that could be used in conjunction with the mixing equation (1) to determine the contribution from the planet itself. 1 : Prettyman, T. H., Mcsween, Jr., H. Y., Feldman, W. C., JUN 2010. Dawn's GRaND to map the chemical composition of asteroids Vesta and Ceres. Geochimica and Cosmochimica Acta 74 (12, 1), A832, Con- ference on Goldschmidt 2010 - Earth, Energy, and the Environment, Knoxville, TN, JUN 13-18, 2010. 2 : Hyvarinen, A., Oja, E., May-Jun 2000. Independent component analysis: algorithms and applications. Neural Networks 13 (4-5), 411-430.

Distribution of Vesta Dark Materials, Southern View

NASA Image and Video Library

2013-01-03

This map shows the distribution of dark materials throughout the southern hemisphere of the giant asteroid Vesta. The circles, diamonds, and stars show where the dark material appears in craters, spots and topographic highs.

Virtual Vesta

NASA Image and Video Library

2011-03-10

This image shows NASAS Dawn scientists best guess to date of what the surface of the protoplanet Vesta might look like; it incorporates the best data on dimples and bulges from ground-based telescopes and NASA Hubble Space Telescope.

KSC-07pd1384

NASA Image and Video Library

2007-06-06

KENNEDY SPACE CENTER, FLA. -- In Astrotech's Hazardous Processing Facility, a technician monitors the loading of xenon for the ion propulsion system in the Dawn spacecraft. Dawn's mission is to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. The Dawn spacecraft uses ion propulsion to get the additional velocity needed to reach Vesta once it leaves the Delta rocket. It also uses ion propulsion to spiral to lower altitudes on Vesta, to leave Vesta and cruise to Ceres and to spiral to a low-altitude orbit at Ceres. Ion propulsion makes efficient use of the onboard fuel by accelerating it to a velocity 10 times that of chemical rockets. Dawn is scheduled to launch July 7aboard a Delta II rocket from Launch Complex 17-B at Cape Canaveral Air Force Station. Photo credit: NASA/Kim Shiflett

KSC-07pd1386

NASA Image and Video Library

2007-06-06

KENNEDY SPACE CENTER, FLA. -- In Astrotech's Hazardous Processing Facility, a technician monitors the loading of xenon for the ion propulsion system in the Dawn spacecraft. Dawn's mission is to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. The Dawn spacecraft uses ion propulsion to get the additional velocity needed to reach Vesta once it leaves the Delta rocket. It also uses ion propulsion to spiral to lower altitudes on Vesta, to leave Vesta and cruise to Ceres and to spiral to a low-altitude orbit at Ceres. Ion propulsion makes efficient use of the onboard fuel by accelerating it to a velocity 10 times that of chemical rockets. Dawn is scheduled to launch July 7aboard a Delta II rocket from Launch Complex 17-B at Cape Canaveral Air Force Station. Photo credit: NASA/Kim Shiflett

KSC-07pd1387

NASA Image and Video Library

2007-06-06

KENNEDY SPACE CENTER, FLA. -- In Astrotech's Hazardous Processing Facility, technicians check data during the loading of xenon for the ion propulsion system in the Dawn spacecraft. Dawn's mission is to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. The Dawn spacecraft uses ion propulsion to get the additional velocity needed to reach Vesta once it leaves the Delta rocket. It also uses ion propulsion to spiral to lower altitudes on Vesta, to leave Vesta and cruise to Ceres and to spiral to a low-altitude orbit at Ceres. Ion propulsion makes efficient use of the onboard fuel by accelerating it to a velocity 10 times that of chemical rockets. Dawn is scheduled to launch July 7aboard a Delta II rocket from Launch Complex 17-B at Cape Canaveral Air Force Station. Photo credit: NASA/Kim Shiflett

KSC-07pd1388

NASA Image and Video Library

2007-06-07

KENNEDY SPACE CENTER, FLA. -- At Astrotech's Hazardous Processing Facility, technicians are loading the Dawn spacecraft with xenon gas for the ion propulsion system. Dawn's mission is to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. The Dawn spacecraft uses ion propulsion to get the additional velocity needed to reach Vesta once it leaves the Delta rocket. It also uses ion propulsion to spiral to lower altitudes on Vesta, to leave Vesta and cruise to Ceres and to spiral to a low-altitude orbit at Ceres. Ion propulsion makes efficient use of the onboard fuel by accelerating it to a velocity 10 times that of chemical rockets. Dawn is scheduled to launch July 7aboard a Delta II rocket from Launch Complex 17-B at Cape Canaveral Air Force Station. Photo credit: NASA/Jim Grossmann

KSC-07pd1385

NASA Image and Video Library

2007-06-06

KENNEDY SPACE CENTER, FLA. -- In Astrotech's Hazardous Processing Facility, technicians check data during the loading of xenon for the ion propulsion system in the Dawn spacecraft. Dawn's mission is to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. The Dawn spacecraft uses ion propulsion to get the additional velocity needed to reach Vesta once it leaves the Delta rocket. It also uses ion propulsion to spiral to lower altitudes on Vesta, to leave Vesta and cruise to Ceres and to spiral to a low-altitude orbit at Ceres. Ion propulsion makes efficient use of the onboard fuel by accelerating it to a velocity 10 times that of chemical rockets. Dawn is scheduled to launch July 7aboard a Delta II rocket from Launch Complex 17-B at Cape Canaveral Air Force Station. Photo credit: NASA/Kim Shiflett

Automated Spectral System for Terrain Classification, Mineralogy of Vesta from the Dawn Framing Cameras

NASA Astrophysics Data System (ADS)

Reddy, V.; Le Corre, L.; Nathues, A.; Hall, I.; Gutierrez-Marques, P.; Hoffmann, M.

2011-10-01

The Dawn mission will rendezvous with asteroid (4) Vesta in July 2011. We have developed a set of equations for extracting mean pyroxene chemistry (Ferrosilite and Wollastonite) for classifying terrains on Vesta by using the Dawn Framing Camera (FC) multi-color bands. The Automated Spectral System (ASS) utilizes pseudo-Band I minima to estimate the mean pyroxene chemistry of diogenites, and basaltic eucrites. The mean pyroxene chemistries of cumulate eucrites, and howardites overlap each other on the pyroxene quadrilateral and hence are harder to distinguish. We expect our ASS to carry a bulk of the terrain classification and mineralogy workload utilizing these equations and complement the work of DawnKey (Le Corre et al., 2011, DPS/EPSC 2011). The system will also provide surface mineral chemistry layers that can be used for mapping Vesta's surface.

Thrust Direction Optimization: Satisfying Dawn's Attitude Agility Constraints

NASA Technical Reports Server (NTRS)

Whiffen, Gregory J.

2013-01-01

The science objective of NASA's Dawn Discovery mission is to explore the two largest members of the main asteroid belt, the giant asteroid Vesta and the dwarf planet Ceres. Dawn successfully completed its orbital mission at Vesta. The Dawn spacecraft has complex, difficult to quantify, and in some cases severe limitations on its attitude agility. The low-thrust transfers between science orbits at Vesta required very complex time varying thrust directions due to the strong and complex gravity and various science objectives. Traditional thrust design objectives (like minimum (Delta)V or minimum transfer time) often result in thrust direction time evolutions that can not be accommodated with the attitude control system available on Dawn. This paper presents several new optimal control objectives, collectively called thrust direction optimization that were developed and necessary to successfully navigate Dawn through all orbital transfers at Vesta.

Vesta's UV Lightcurve: Hemispheric Variation in Brightness and Spectral Reversal

NASA Technical Reports Server (NTRS)

Hendrix, Amanda R.; Vilas, Faith; Festou, Michael

2003-01-01

Spectra of asteroid 4 Vesta obtained in October 1990 with the International Ultraviolet Explorer are reanalyzed and reinterpreted. A large portion of the eastern hemisphere (based on the prime meridian definition of Thomas et al., 1997a) is darker at UV Wavelengths than much of the western hemisphere. The UV lightcurve is in contrast with the visible lightcurve, which shows that the eastern hemisphere is brighter than the western. These IUE spectra of Vesta thus may be evidence for the "spectral reversal." first seen on the Moon by Apollo 17. where the visibly brighter lunar highlands are darker than the maria at far-UV wavelengths. This effect was linked to space weathering when it was noted (Wagner et al., 1987) that the spectral reversal appears in the laboratory spectra of lunar soils but not powdered lunar rocks. We investigate Vesta's UV lightcurve and spectral reversal, and its possible connection with space weathering. The addition to grain coatings of small amounts of submicroscopic iron (SMFe) through vapor deposition causes drastic spectral changes at UV-visible wavelengths (Hapke, 2001). while the longer wavelength spectrum remains largely unaffected. Other laboratory results (e.g., Hiroi and Pieters, 1998) indicate that the UV-visible wavelength range is affected by simulated weathering processes in a manner similar to what is seen on Vesta. It is likely that Vesta has experienced relatively minor amounts of space weathering, as indicated by the spectral reversal, along with the subtle visible-near infrared weathering effects (e.g., Binzel et al., 1997).

In-Flight Operation of the Dawn Ion Propulsion System Through Survey Science Orbit at Ceres

NASA Technical Reports Server (NTRS)

Garner, Charles E.; Rayman, Marc D.

2015-01-01

The Dawn mission, part of NASA's Discovery Program, has as its goal the scientific exploration of the two most massive main-belt objects, Vesta and Ceres. The Dawn spacecraft was launched from the Cape Canaveral Air Force Station on September 27, 2007 on a Delta-II 7925H- 9.5 (Delta-II Heavy) rocket that placed the 1218-kg spacecraft onto an Earth-escape trajectory. On-board the spacecraft is an ion propulsion system (IPS) developed at the Jet Propulsion Laboratory which will provide a total delta V of 11 km/s for the heliocentric transfer to Vesta, orbit capture at Vesta, transfer between Vesta science orbits, departure and escape from Vesta, heliocentric transfer to Ceres, orbit capture at Ceres, and transfer between Ceres science orbits. Full-power thrusting from December 2007 through October 2008 was used to successfully target a Mars gravity assist flyby in February 2009 that provided an additional delta V of 2.6 km/s. Deterministic thrusting for the heliocentric transfer to Vesta resumed in June 2009 and concluded with orbit capture at Vesta on July 16, 2011. From July 2011 through September 2012 the IPS was used to transfer to all the different science orbits at Vesta and to escape from Vesta orbit. Cruise for a rendezvous with Ceres began in September 2012 and concluded with the start of the approach to Ceres phase on December 26, 2015, leading to orbit capture on March 6, 2015. Deterministic thrusting continued during approach to place the spacecraft in its first science orbit, called RC3, which was achieved on April 23, 2015. Following science operations at RC3 ion thrusting was resumed for twenty-five days leading to arrival to the next science orbit, called survey orbit, on June 3, 2015. The IPS will be used for all subsequent orbit transfers and trajectory correction maneuvers until completion of the primary mission in approximately June 2016. To date the IPS has been operated for over 46,774 hours, consumed approximately 393 kg of xenon, and provided a delta V of over 10.8 km/s to the spacecraft. The IPS performance characteristics are very close to the expected performance based on analysis and testing performed pre-launch. This paper provides an overview of Dawn's mission objectives and the results of Dawn IPS mission operations through arrival at the second science orbit at Ceres.

Evidence of Space Weathering Processes Across the Surface of Vesta

NASA Technical Reports Server (NTRS)

Pieters, Carle M.; Blewett, David T.; Gaffey, Michael; Mittlefehldt, David W.; CristinaDeSanctis, Maria; Reddy, Vishnu; Coradini, Angioletta; Nathues, Andreas; Denevi, Brett W.; Li, Jian-Yang;

Dawn Orbit Determination Team : Trajectory Modeling and Reconstruction Processes at Vesta

NASA Technical Reports Server (NTRS)

Abrahamson, Matt; Ardito, Alessandro; Han, Don; Haw, Robert; Kennedy, Brian; Mastrodemos, Nicholas; Nandi, Sumita; Park, Ryan; Rush, Brian; Vaughan, Andrew

2013-01-01

The NASA Dawn spacecraft was launched on September 27, 2007 on a mission to study the asteroid belt's two largest objects, Vesta and Ceres. It is the first deep space orbiting mission to demonstrate solar-electric ion propulsion, providing the necessary delta-V to enable capture and escape from two extraterrestrial bodies. At this time, Dawn has completed its science campaign at Vesta and is currently on its journey to Ceres, where it will arrive in mid-2015. The spacecraft spent over a year in orbit around Vesta from July 2011 through August 2012, capturing science data during four dedicated orbit phases. In order to maintain the reference orbits necessary for science and enable the transfers between those orbits, precise and timely orbit determination was required. The constraints associated with low-thrust ion propulsion coupled with the relatively unknown a priori gravity and rotation models for Vesta presented unique challenges for the Dawn orbit determination team. While [1] discusses the prediction performance of the orbit determination products, this paper discusses the dynamics models, filter configuration, and data processing implemented to deliver a rapid orbit determination capability to the Dawn project.

Dark Hill on Asteroid Vesta Movie

NASA Image and Video Library

2011-12-06

This still from a movie shows an image taken by NASA Dawn spacecraft layered on a digital terrain model of an unusual hill containing a dark-rayed impact crater and nearby dark deposit on asteroid Vesta.

Topography of Vesta Surface

NASA Image and Video Library

2011-08-26

This view of the topography of asteroid Vesta surface is composed of several images obtained with the framing camera on NASA Dawn spacecraft on August 6, 2011. The image mosaic is shown superimposed on a digital terrain model.

Geoscientific Mapping of Vesta by the Dawn Mission

NASA Technical Reports Server (NTRS)

Jaumann, R.; Pieters, C. M.; Neukum, G.; Mottola, S.; DeSanctis, M. C.; Russell, C. T.; Raymond, C. A.; McSween, H. Y.; Roatsch, T.; Nathues, A.;

Chemical Mixing Model and K-Th-Ti Systematics and HED Meteorites for the Dawn Mission

NASA Technical Reports Server (NTRS)

Usui, T.; McSween, H. Y., Jr.; Mittlefehldt, D. W.; Prettyman, T. H.

2009-01-01

The Dawn mission will explore 4 Vesta, a large differentiated asteroid believed to be the parent body of the howardite, eucrite and diogenite (HED) meteorite suite. The Dawn spacecraft carries a gamma-ray and neutron detector (GRaND), which will measure the abundances of selected elements on the surface of Vesta. This study provides ways to leverage the large geochemical database on HED meteorites as a tool for interpreting chemical analyses by GRaND of mapped units on the surface of Vesta.

Machine Learning Applied to Dawn/VIR data of Vesta in view of MERTIS/BepiColombo.

NASA Astrophysics Data System (ADS)

Helbert, J.; D'Amore, M.; Le Scaon, R.; Maturilli, A.; Palomba, E.; Longobardo, A.; Hiesinger, H.

2016-12-01

Remote sensing spectroscopy is one of the most commonly used technique in planetary science and for recent instruments producing huge amount of data, classic methods could fails to unlock the full scientific potential buried in the measurements. We explored several Machine Learning techniques: multi-step clustering method is developed, using an image segmentation method, a stream algorithm, and hierarchical clustering. The MErcury Radiometer and Thermal infrared Imaging Spectrometer (MERTIS) is part of the payload of the Mercury Planetary Orbiter spacecraft of the ESA-JAXA BepiColombo mission. MERTIS's scientific goals are to infer rock-forming minerals, to map surface composition, and to study surface temperature variations on Mercury. The NASA mission DAWN carry a suites of instruments aimed at understanding the two most massive objects in the main asteroid belt: Vesta and Ceres. DAWN has already successfully completed the exploration of Vesta in September 2012 and it is now in the last phase of the mission around Ceres. To cope with the stream of data that will be delivered by MERTIS, we developed an algorithm that could aggregate new data as they come in during the mission giving the scientist a guide for the most interesting and new discovery on Mercury. The DAWN/VESTA VIR data is a testbed for the algorithm. The algorithm identified the Olivine outcrops around two craters on Vesta's surface described in Ammannito et al., 2013. We furthermore mimic the data acquisition process as if the mission were dumping the data live. The algorithm provides insightful information on the novelty and classes int he data as they are collected. This will enhance MERTIS targeting and maximize its scientific return during BepiColombo mission at Mercury. E Ammannito et al. "Olivine in an unexpected location on Vesta/'s surface". In: Nature 504.7478 (2013), pp. 122-125.

Evidence for ground-ice occurrence on asteroid Vesta using Dawn bistatic radar observations

NASA Astrophysics Data System (ADS)

Palmer, E. M.; Heggy, E.; Kofman, W. W.

2017-12-01

From 2011 to 2012, the Dawn spacecraft orbited asteroid Vesta, the first of its two targets in the asteroid belt, and conducted the first bistatic radar (BSR) experiment at a small-body, during which Dawn's high-gain communications antenna is used to transmit radar waves that scatter from Vesta's surface toward Earth at high incidence angles just before and after occultation of the spacecraft behind the asteroid. Among the 14 observed mid-latitude forward-scatter reflections, the radar cross section ranges from 84 ± 8 km2 (near Saturnalia Fossae) to 3,588 ± 200 km2 (northwest of Caparronia crater), implying substantial spatial variation in centimeter- to decimeter-scale surface roughness. The compared distributions of surface roughness and subsurface hydrogen concentration [H]—measured using data from Dawn's BSR experiment and Gamma Ray and Neutron Spectrometer (GRaND), respectively—reveal the occurrence of heightened subsurface [H] with smoother terrains that cover tens of square kilometers. Furthermore, unlike on the Moon, we observe no correlation between surface roughness and surface ages on Vesta—whether the latter is derived from lunar or asteroid-flux chronology [Williams et al., 2014]—suggesting that cratering processes alone are insufficient to explain Vesta's surface texture at centimeter-to-decimeter scales. Dawn's BSR observations support the hypothesis of transient melting, runoff and recrystallization of potential ground-ice deposits, which are postulated to flow along fractures after an impact, and provide a mechanism for the smoothing of otherwise rough, fragmented impact ejecta. Potential ground-ice presence within Vesta's subsurface was first proposed by Scully et al. [2014], who identified geomorphological evidence for transient water flow along several of Vesta's crater walls using Dawn Framing Camera images. While airless, differentiated bodies such as Vesta and the Moon are thought to have depleted their initial volatile content during the process of differentiation, evidence to the contrary is continuing to change our understanding of the distribution and preservation of volatiles during planetary formation in the early solar system.

Vesta Surface at High Resolution: Dominated by Impact Craters

NASA Image and Video Library

2012-02-13

This image from NASA Dawn spacecraft shows a large number of craters, formed by collisions into the surface of asteroid Vesta. The relatively large circular depressions in this image are older, heavily degraded impact craters.

Small Scale Features at Vesta South Pole

NASA Image and Video Library

2011-10-01

This image from NASA Dawn spacecraft shows a raised mound material overlying the brighter material that makes up the floor of the south polar depression of asteroid Vesta. Many small scale craters are clear in this image.

Topography and Albedo Image of Grooved Terrain on Vesta

NASA Image and Video Library

2011-11-29

These images from NASA Dawn spacecraft show part of the grooved terrain in asteroid Vesta Pinaria quadrangle, which is in the southern hemisphere. Large-scale grooves and depressions can be seen running diagonally across the image.

KSC-07pd1389

NASA Image and Video Library

2007-06-07

KENNEDY SPACE CENTER, FLA. -- At Astrotech's Hazardous Processing Facility, technicians look at the connections for loading the Dawn spacecraft with xenon gas for the ion propulsion system. Dawn's mission is to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. The Dawn spacecraft uses ion propulsion to get the additional velocity needed to reach Vesta once it leaves the Delta rocket. It also uses ion propulsion to spiral to lower altitudes on Vesta, to leave Vesta and cruise to Ceres and to spiral to a low-altitude orbit at Ceres. Ion propulsion makes efficient use of the onboard fuel by accelerating it to a velocity 10 times that of chemical rockets. Dawn is scheduled to launch July 7aboard a Delta II rocket from Launch Complex 17-B at Cape Canaveral Air Force Station. Photo credit: NASA/Jim Grossmann

KSC-07pd1390

NASA Image and Video Library

2007-06-07

KENNEDY SPACE CENTER, FLA. -- At Astrotech's Hazardous Processing Facility, a technician checks the connections for loading the Dawn spacecraft with xenon gas for the ion propulsion system. Dawn's mission is to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. The Dawn spacecraft uses ion propulsion to get the additional velocity needed to reach Vesta once it leaves the Delta rocket. It also uses ion propulsion to spiral to lower altitudes on Vesta, to leave Vesta and cruise to Ceres and to spiral to a low-altitude orbit at Ceres. Ion propulsion makes efficient use of the onboard fuel by accelerating it to a velocity 10 times that of chemical rockets. Dawn is scheduled to launch July 7aboard a Delta II rocket from Launch Complex 17-B at Cape Canaveral Air Force Station. Photo credit: NASA/Jim Grossmann

Dawn's Exploration of Vesta

NASA Technical Reports Server (NTRS)

Rayman, Marc D.; Mase, Robert A.

2012-01-01

On 16 July 2011, after completing nearly four years of interplanetary flight, Dawn entered orbit around (4) Vesta, the second most massive body in the main asteroid belt. Dawn used solar electric propulsion to spiral to a series of six different orbits to accomplish its science campaign. Although the transfers to progressively lower orbits presented significant challenges, all were executed smoothly. During its nearly 14 months in orbit, Dawn spiraled down to 210 km above the surface and back up, before initiating the gradual departure to travel to dwarf planet (1) Ceres for a 2015 rendezvous. Dawn's exploration of Vesta has shown it to be geologically complex and fascinating, resembling terrestrial planets more than typical asteroids. Among the principal features is a 500-km diameter impact basin within which is the second tallest mountain known in the solar system. This paper presents Dawn's operations at Vesta and summarizes the principal findings.

Space Weathering on 4 Vesta: Processes and Products

NASA Technical Reports Server (NTRS)

Pieters, C. M.; Blewett, D. T.; Gaffey, M.; Mittlefehldt, D. W.; De Sanctis, M. C.; Reddy, V.; Nathues, A.; Denevi, B. W.; Li, J. Y.; McCord, T. B.;

Mapping Vesta: First Results from Dawn's Survey Orbit

NASA Technical Reports Server (NTRS)

Jaumann, R.; Yingst, A. R.; Pieters, C. M.; Russell, C. T.; Raymond, C. A.; Neukum, G.; Mottola, S.; Keller, H. U.; Nathues, A.; Sierks, H.;

Thrust Direction Optimization: Satisfying Dawn's Attitude Agility Constraints

NASA Technical Reports Server (NTRS)

Whiffen, Gregory J.

2013-01-01

The science objective of NASA's Dawn Discovery mission is to explore the giant asteroid Vesta and the dwarf planet Ceres, the two largest members of the main asteroid belt. Dawn successfully completed its orbital mission at Vesta. The Dawn spacecraft has complex, difficult to quantify, and in some cases severe limitations on its attitude agility. The low-thrust transfers between science orbits at Vesta required very complex time varying thrust directions due to the strong and complex gravity and various science objectives. Traditional low-thrust design objectives (like minimum change in velocity or minimum transfer time) often result in thrust direction time evolutions that cannot be accommodated with the attitude control system available on Dawn. This paper presents several new optimal control objectives, collectively called thrust direction optimization that were developed and turned out to be essential to the successful navigation of Dawn at Vesta.

Multiple Independent File Parallel I/O with HDF5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, M. C.

2016-07-13

The HDF5 library has supported the I/O requirements of HPC codes at Lawrence Livermore National Labs (LLNL) since the late 90’s. In particular, HDF5 used in the Multiple Independent File (MIF) parallel I/O paradigm has supported LLNL code’s scalable I/O requirements and has recently been gainfully used at scales as large as O(10 6) parallel tasks.

Storage of sparse files using parallel log-structured file system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bent, John M.; Faibish, Sorin; Grider, Gary

A sparse file is stored without holes by storing a data portion of the sparse file using a parallel log-structured file system; and generating an index entry for the data portion, the index entry comprising a logical offset, physical offset and length of the data portion. The holes can be restored to the sparse file upon a reading of the sparse file. The data portion can be stored at a logical end of the sparse file. Additional storage efficiency can optionally be achieved by (i) detecting a write pattern for a plurality of the data portions and generating a singlemore » patterned index entry for the plurality of the patterned data portions; and/or (ii) storing the patterned index entries for a plurality of the sparse files in a single directory, wherein each entry in the single directory comprises an identifier of a corresponding sparse file.« less

Neutron absorption constraints on the composition of 4 Vesta

USGS Publications Warehouse

Prettyman, Thomas H.; Mittlefehldt, David W.; Yamashita, Naoyuki; Beck, Andrew W.; Feldman, William C.; Hendricks, John S.; Lawrence, David J.; McCoy, Timothy J.; McSween, Harry Y.; Paplowski, Patrick N.; Reedy, Robert C.; Toplis, Michael J.; Le Corre, Lucille; Mizzon, Hugau; Reddy, Vishnu; Titus, Timothy N.; Raymond, Carol A.; Russell, Christopher T.

2013-01-01

Global maps of the macroscopic thermal neutron absorption cross section of Vesta's regolith by the Gamma Ray and Neutron Detector (GRaND) on board the NASA Dawn spacecraft provide constraints on the abundance and distribution of Fe, Ca, Al, Mg, and other rock-forming elements. From a circular, polar low-altitude mapping orbit, GRaND sampled the regolith to decimeter depths with a spatial resolution of about 300 km. At this spatial scale, the variation in neutron absorption is about seven times lower than that of the Moon. The observed variation is consistent with the range of absorption for howardite whole-rock compositions, which further supports the connection between Vesta and the howardite, eucrite, and diogenite meteorites. We find a strong correlation between neutron absorption and the percentage of eucritic materials in howardites and polymict breccias, which enables petrologic mapping of Vesta's surface. The distribution of basaltic eucrite and diogenite determined from neutron absorption measurements is qualitatively similar to that indicated by visible and near infrared spectroscopy. The Rheasilvia basin and ejecta blanket has relatively low absorption, consistent with Mg-rich orthopyroxene. Based on a combination of Fe and neutron absorption measurements, olivine-rich lithologies are not detected on the spatial scales sampled by GRaND. The sensitivity of GRaND to the presence of mantle material is described and implications for the absence of an olivine signature are discussed. High absorption values found in Vesta's “dark” hemisphere, where exogenic hydrogen has accumulated, indicate that this region is richer in basaltic eucrite, representative of Vesta's ancient upper crust.

Neutron absorption constraints on the composition of 4 Vesta

NASA Astrophysics Data System (ADS)

Prettyman, Thomas H.; Mittlefehldt, David W.; Yamashita, Naoyuki; Beck, Andrew W.; Feldman, William C.; Hendricks, John S.; Lawrence, David J.; McCoy, Timothy J.; McSween, Harry Y.; Peplowski, Patrick N.; Reedy, Robert C.; Toplis, Michael J.; Corre, Lucille; Mizzon, Hugau; Reddy, Vishnu; Titus, Timothy N.; Raymond, Carol A.; Russell, Christopher T.

2013-11-01

Global maps of the macroscopic thermal neutron absorption cross section of Vesta's regolith by the Gamma Ray and Neutron Detector (GRaND) on board the NASA Dawn spacecraft provide constraints on the abundance and distribution of Fe, Ca, Al, Mg, and other rock-forming elements. From a circular, polar low-altitude mapping orbit, GRaND sampled the regolith to decimeter depths with a spatial resolution of about 300 km. At this spatial scale, the variation in neutron absorption is about seven times lower than that of the Moon. The observed variation is consistent with the range of absorption for howardite whole-rock compositions, which further supports the connection between Vesta and the howardite, eucrite, and diogenite meteorites. We find a strong correlation between neutron absorption and the percentage of eucritic materials in howardites and polymict breccias, which enables petrologic mapping of Vesta's surface. The distribution of basaltic eucrite and diogenite determined from neutron absorption measurements is qualitatively similar to that indicated by visible and near infrared spectroscopy. The Rheasilvia basin and ejecta blanket has relatively low absorption, consistent with Mg-rich orthopyroxene. Based on a combination of Fe and neutron absorption measurements, olivine-rich lithologies are not detected on the spatial scales sampled by GRaND. The sensitivity of GRaND to the presence of mantle material is described and implications for the absence of an olivine signature are discussed. High absorption values found in Vesta's "dark" hemisphere, where exogenic hydrogen has accumulated, indicate that this region is richer in basaltic eucrite, representative of Vesta's ancient upper crust.

A Next-Generation Parallel File System Environment for the OLCF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dillow, David A; Fuller, Douglas; Gunasekaran, Raghul

2012-01-01

When deployed in 2008/2009 the Spider system at the Oak Ridge National Laboratory s Leadership Computing Facility (OLCF) was the world s largest scale Lustre parallel file system. Envisioned as a shared parallel file system capable of delivering both the bandwidth and capacity requirements of the OLCF s diverse computational environment, Spider has since become a blueprint for shared Lustre environments deployed worldwide. Designed to support the parallel I/O requirements of the Jaguar XT5 system and other smallerscale platforms at the OLCF, the upgrade to the Titan XK6 heterogeneous system will begin to push the limits of Spider s originalmore » design by mid 2013. With a doubling in total system memory and a 10x increase in FLOPS, Titan will require both higher bandwidth and larger total capacity. Our goal is to provide a 4x increase in total I/O bandwidth from over 240GB=sec today to 1TB=sec and a doubling in total capacity. While aggregate bandwidth and total capacity remain important capabilities, an equally important goal in our efforts is dramatically increasing metadata performance, currently the Achilles heel of parallel file systems at leadership. We present in this paper an analysis of our current I/O workloads, our operational experiences with the Spider parallel file systems, the high-level design of our Spider upgrade, and our efforts in developing benchmarks that synthesize our performance requirements based on our workload characterization studies.« less

Distributing an executable job load file to compute nodes in a parallel computer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gooding, Thomas M.

Distributing an executable job load file to compute nodes in a parallel computer, the parallel computer comprising a plurality of compute nodes, including: determining, by a compute node in the parallel computer, whether the compute node is participating in a job; determining, by the compute node in the parallel computer, whether a descendant compute node is participating in the job; responsive to determining that the compute node is participating in the job or that the descendant compute node is participating in the job, communicating, by the compute node to a parent compute node, an identification of a data communications linkmore » over which the compute node receives data from the parent compute node; constructing a class route for the job, wherein the class route identifies all compute nodes participating in the job; and broadcasting the executable load file for the job along the class route for the job.« less

Vesta Surface Comes into View

NASA Image and Video Library

2011-06-13

This image from the framing camera aboard NASA Dawn spacecraft shows surface details beginning to resolve as the spacecraft closes in on the giant asteroid Vesta on June 1, 2011, from a distance of about 300,000 miles 483,000 kilometers.

Crater Impacts on Vesta

NASA Image and Video Library

2012-05-10

This graphic shows the global distribution of craters that hit the giant asteroid Vesta, based on data from NASA Dawn mission. The yellow circles indicate craters of 2 miles or wider, with the size of the circles indicating the size of the crater.

Dark Areas in Cratered Terrain on Vesta

NASA Image and Video Library

2011-10-14

In this image from NASA Dawn spacecraft, a number of small dark areas, mostly clustered in the center and left of the image, are visible in asteroid Vesta cratered landscape. A lot of these dark patches are small impact craters.

Dawn Mission to Vesta and Ceres Lithograph

NASA Image and Video Library

2007-01-01

This artist's lithograph features general information, significant dates, and interesting facts on the backabout asteroid Vesta and dwarf planet Ceres and is part of the Mission Art series from NASA's Dawn mission. http://photojournal.jpl.nasa.gov/catalog/PIA19370

Vesta Partly Shadowed Northern Regions

NASA Image and Video Library

2012-06-01

This image from NASA Dawn spacecraft shows a part of asteroid Vesta surface reasonably far north into the northern hemisphere which appears washed out because it has been stretched to make features visible that would otherwise be too dark to see.

False-Color Image of an Impact Crater on Vesta

NASA Image and Video Library

2011-08-24

NASA Dawn spacecraft obtained this false-color image right of an impact crater in asteroid Vesta equatorial region with its framing camera on July 25, 2011. The view on the left is from the camera clear filter.

Fresh Impact Craters on Asteroid Vesta

NASA Image and Video Library

2011-12-06

This image combines two separate views of the giant asteroid Vesta obtained by NASA Dawn spacecraft. The fresh impact craters in this view are located in the south polar region, which has been partly covered by landslides from the adjacent crater.

Geologic Mapping of the Av-11 Pinaria Quadrangle of Asteroid 4 Vesta

NASA Astrophysics Data System (ADS)

Hoogenboom, T.; Schenk, P.; White, O. L.; Williams, D.; Heisinger, H.; Garry, W. B.; Yingst, R. A.; Buczkowski, D. L.; McCord, T. B.; Jaumann, R.; Pieters, C. M.; Gaskell, R. W.; Neukum, G.; Schmedemann, N.; Marchi, S.; Nathues, A.; Lecorre, L.; Roatsch, T.; Preusker, F.; de Sanctis, M. C.; Fillacchione, G.; Raymond, C. A.; Russell, C. T.

2012-03-01

Dawn entered orbit of the asteroid 4 Vesta in 7/2011, to characterize its geology, elemental and mineralogical composition, topography, shape, and internal structure. This abstract describes the results from mapping quadrangle Av-11.

Apparent Brightness and Topography Images of Sossia and Canuleia Craters

NASA Image and Video Library

2012-07-03

These images from NASA Dawn spacecraft are located in asteroid Vesta Urbinia quadrangle, in Vesta southern hemisphere. Rays of bright material surround Canuleia crater and rays of dark material extend from the top part of Sossia crater.

Topography of Troughs on Vesta

NASA Image and Video Library

2011-08-23

This view of the topography of asteroid Vesta surface is composed of several images obtained with the clear filter in the framing camera on NASA Dawn spacecraft on August 6, 2011. The image has a resolution of about 260 meters per pixel.

Laboratory spectroscopy of HED meteorites

NASA Astrophysics Data System (ADS)

Farina, M.; Coradini, A.; Carli, C.; Ammannito, E.; Consolmagno, G.; De sanctis, M.; Di Iorio, T.; Turrini, D.

2011-12-01

4 Vesta is one of the largest and the most massive asteroid in the Main Asteroid Belt. This asteroid possesses a basaltic surface and apparently formed and differentiated very early in the history of the solar system. There are strong evidences that indicate Vesta as the parent body of Howardites, Diogenites and Eucrites (HEDs). HED meteorites are a subgroup of achondrite meteorites and they are a suite of rocks that formed at high temperature and experienced igneous processing similar to the magmatic rocks found on Earth. The visible and near-infrared (VNIR) reflectance spectra of Vesta's surface show high similarity with the laboratory spectra of HED meteorites. Vesta and HEDs spectra have two crystal field absorption bands close to 0.9 μm and 1.9 μm indicative of the presence of ferrous iron in pyroxenes. The HEDs differ from each other primarily based on variation in pyroxene composition and the pyroxene-plagioclase ratio as well as rocks texture characteristics (e.g., size of crystals). These differences suggest that a combined VNIR spectra studies of Vesta and HED meteorites might reveal the different characteristics of the surface compositions and shed new light on the origin and the thermal history of Vesta. Moreover the link between Vesta and HEDs could provide a test bed to understand the short-lived radionuclide-driven differentiation of planetary bodies. Here we present preliminary result of a study of spectral characteristics of different HED samples, provided to us by the Vatican Observatory. Bidirectional reflectance spectra of slabs of meteorites are performed in the VNIR, between (0.35/2.50) μm, using a Fieldspec spectrometer mounted on a goniometer, in use at the SLAB (Spectroscopy laboratory, INAF, Rome). The spectra are acquired in standard conditions with an incidence angle i=30o and an emission angle e=0o, measuring a spot with a diameter of 5 mm. Different Howardite, Diogenite and Eucrite samples are "mapped" considering several spots on the surface of the slabs to define their spectral variability between samples representing the different types of HEDs and to describe the spectral heterogeneity for each samples. A preliminary comparison with mineralogical and petrographic characteristics has been done describing hand samples and their thin sections. These data will be incorporated in a spectral library that could be an useful tool for the interpretation of data acquired by the Dawn mission in orbit on Vesta.

Workshop on Evolution of Igneous Asteroids: Focus on Vesta and the HED Meteorites. Pt. 1

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W. (Editor); Papike, James J. (Editor)

1996-01-01

This volume contains abstracts of papers that have been accepted for presentation at the Workshop on Evolution of Igneous Asteroids: Focus on Vesta and the HED Meteorites, October 16-18, 1996, in Houston, Texas.

Dawn Orbit Determination Team: Trajectory Modeling and Reconstruction Processes at Vesta

NASA Technical Reports Server (NTRS)

Abrahamson, Matthew J.; Ardito, Alessandro; Han, Dongsuk; Haw, Robert; Kennedy, Brian; Mastrodemos, Nick; Nandi, Sumita; Park, Ryan; Rush, Brian; Vaughan, Andrew

2013-01-01

The Dawn spacecraft spent over a year in orbit around Vesta from July 2011 through August 2012. In order to maintain the designated science reference orbits and enable the transfers between those orbits, precise and timely orbit determination was required. Challenges included low-thrust ion propulsion modeling, estimation of relatively unknown Vesta gravity and rotation models, track-ing data limitations, incorporation of real-time telemetry into dynamics model updates, and rapid maneuver design cycles during transfers. This paper discusses the dynamics models, filter configuration, and data processing implemented to deliver a rapid orbit determination capability to the Dawn project.

The formation of jupiter, the jovian early bombardment and the delivery of water to the asteroid belt: the case of (4) vesta.

PubMed

Turrini, Diego; Svetsov, Vladimir

2014-01-28

The asteroid (4) Vesta, parent body of the Howardite-Eucrite-Diogenite meteorites, is one of the first bodies that formed, mostly from volatile-depleted material, in the Solar System. The Dawn mission recently provided evidence that hydrated material was delivered to Vesta, possibly in a continuous way, over the last 4 Ga, while the study of the eucritic meteorites revealed a few samples that crystallized in presence of water and volatile elements. The formation of Jupiter and probably its migration occurred in the period when eucrites crystallized, and triggered a phase of bombardment that caused icy planetesimals to cross the asteroid belt. In this work, we study the flux of icy planetesimals on Vesta during the Jovian Early Bombardment and, using hydrodynamic simulations, the outcome of their collisions with the asteroid. We explore how the migration of the giant planet would affect the delivery of water and volatile materials to the asteroid and we discuss our results in the context of the geophysical and collisional evolution of Vesta. In particular, we argue that the observational data are best reproduced if the bulk of the impactors was represented by 1-2 km wide planetesimals and if Jupiter underwent a limited (a fraction of au) displacement.

The Formation of Jupiter, the Jovian Early Bombardment and the Delivery of Water to the Asteroid Belt: The Case of (4) Vesta

PubMed Central

Turrini, Diego; Svetsov, Vladimir

2014-01-01

The asteroid (4) Vesta, parent body of the Howardite-Eucrite-Diogenite meteorites, is one of the first bodies that formed, mostly from volatile-depleted material, in the Solar System. The Dawn mission recently provided evidence that hydrated material was delivered to Vesta, possibly in a continuous way, over the last 4 Ga, while the study of the eucritic meteorites revealed a few samples that crystallized in presence of water and volatile elements. The formation of Jupiter and probably its migration occurred in the period when eucrites crystallized, and triggered a phase of bombardment that caused icy planetesimals to cross the asteroid belt. In this work, we study the flux of icy planetesimals on Vesta during the Jovian Early Bombardment and, using hydrodynamic simulations, the outcome of their collisions with the asteroid. We explore how the migration of the giant planet would affect the delivery of water and volatile materials to the asteroid and we discuss our results in the context of the geophysical and collisional evolution of Vesta. In particular, we argue that the observational data are best reproduced if the bulk of the impactors was represented by 1–2 km wide planetesimals and if Jupiter underwent a limited (a fraction of au) displacement. PMID:25370027

cljam: a library for handling DNA sequence alignment/map (SAM) with parallel processing.

PubMed

Takeuchi, Toshiki; Yamada, Atsuo; Aoki, Takashi; Nishimura, Kunihiro

2016-01-01

Next-generation sequencing can determine DNA bases and the results of sequence alignments are generally stored in files in the Sequence Alignment/Map (SAM) format and the compressed binary version (BAM) of it. SAMtools is a typical tool for dealing with files in the SAM/BAM format. SAMtools has various functions, including detection of variants, visualization of alignments, indexing, extraction of parts of the data and loci, and conversion of file formats. It is written in C and can execute fast. However, SAMtools requires an additional implementation to be used in parallel with, for example, OpenMP (Open Multi-Processing) libraries. For the accumulation of next-generation sequencing data, a simple parallelization program, which can support cloud and PC cluster environments, is required. We have developed cljam using the Clojure programming language, which simplifies parallel programming, to handle SAM/BAM data. Cljam can run in a Java runtime environment (e.g., Windows, Linux, Mac OS X) with Clojure. Cljam can process and analyze SAM/BAM files in parallel and at high speed. The execution time with cljam is almost the same as with SAMtools. The cljam code is written in Clojure and has fewer lines than other similar tools.

ATLAS software configuration and build tool optimisation

NASA Astrophysics Data System (ADS)

Rybkin, Grigory; Atlas Collaboration

2014-06-01

ATLAS software code base is over 6 million lines organised in about 2000 packages. It makes use of some 100 external software packages, is developed by more than 400 developers and used by more than 2500 physicists from over 200 universities and laboratories in 6 continents. To meet the challenge of configuration and building of this software, the Configuration Management Tool (CMT) is used. CMT expects each package to describe its build targets, build and environment setup parameters, dependencies on other packages in a text file called requirements, and each project (group of packages) to describe its policies and dependencies on other projects in a text project file. Based on the effective set of configuration parameters read from the requirements files of dependent packages and project files, CMT commands build the packages, generate the environment for their use, or query the packages. The main focus was on build time performance that was optimised within several approaches: reduction of the number of reads of requirements files that are now read once per package by a CMT build command that generates cached requirements files for subsequent CMT build commands; introduction of more fine-grained build parallelism at package task level, i.e., dependent applications and libraries are compiled in parallel; code optimisation of CMT commands used for build; introduction of package level build parallelism, i. e., parallelise the build of independent packages. By default, CMT launches NUMBER-OF-PROCESSORS build commands in parallel. The other focus was on CMT commands optimisation in general that made them approximately 2 times faster. CMT can generate a cached requirements file for the environment setup command, which is especially useful for deployment on distributed file systems like AFS or CERN VMFS. The use of parallelism, caching and code optimisation significantly-by several times-reduced software build time, environment setup time, increased the efficiency of multi-core computing resources utilisation, and considerably improved software developer and user experience.

High-Performance, Multi-Node File Copies and Checksums for Clustered File Systems

NASA Technical Reports Server (NTRS)

Kolano, Paul Z.; Ciotti, Robert B.

2012-01-01

Modern parallel file systems achieve high performance using a variety of techniques, such as striping files across multiple disks to increase aggregate I/O bandwidth and spreading disks across multiple servers to increase aggregate interconnect bandwidth. To achieve peak performance from such systems, it is typically necessary to utilize multiple concurrent readers/writers from multiple systems to overcome various singlesystem limitations, such as number of processors and network bandwidth. The standard cp and md5sum tools of GNU coreutils found on every modern Unix/Linux system, however, utilize a single execution thread on a single CPU core of a single system, and hence cannot take full advantage of the increased performance of clustered file systems. Mcp and msum are drop-in replacements for the standard cp and md5sum programs that utilize multiple types of parallelism and other optimizations to achieve maximum copy and checksum performance on clustered file systems. Multi-threading is used to ensure that nodes are kept as busy as possible. Read/write parallelism allows individual operations of a single copy to be overlapped using asynchronous I/O. Multinode cooperation allows different nodes to take part in the same copy/checksum. Split-file processing allows multiple threads to operate concurrently on the same file. Finally, hash trees allow inherently serial checksums to be performed in parallel. Mcp and msum provide significant performance improvements over standard cp and md5sum using multiple types of parallelism and other optimizations. The total speed-ups from all improvements are significant. Mcp improves cp performance over 27x, msum improves md5sum performance almost 19x, and the combination of mcp and msum improves verified copies via cp and md5sum by almost 22x. These improvements come in the form of drop-in replacements for cp and md5sum, so are easily used and are available for download as open source software at http://mutil.sourceforge.net.

Chondritic models of 4 Vesta: Implications for geochemical and geophysical properties

NASA Astrophysics Data System (ADS)

Toplis, M. J.; Mizzon, H.; Monnereau, M.; Forni, O.; McSween, H. Y.; Mittlefehldt, D. W.; McCoy, T. J.; Prettyman, T. H.; De Sanctis, M. C.; Raymond, C. A.; Russell, C. T.

2013-11-01

Simple mass-balance and thermodynamic constraints are used to illustrate the potential geochemical and geophysical diversity of a fully differentiated Vesta-sized parent body with a eucrite crust (e.g., core size and density, crustal thickness). The results of this analysis are then combined with data from the howardite-eucrite-diogenite (HED) meteorites and the Dawn mission to constrain Vesta's bulk composition. Twelve chondritic compositions are considered, comprising seven carbonaceous, three ordinary, and two enstatite chondrite groups. Our analysis excludes CI and LL compositions as plausible Vesta analogs, as these are predicted to have a negative metal fraction. Second, the MELTS thermodynamic calculator is used to show that the enstatite chondrites, the CV, CK and L-groups cannot produce Juvinas-like liquids, and that even for the other groups, depletion in sodium is necessary to produce liquids of appropriate silica content. This conclusion is consistent with the documented volatile-poor nature of eucrites. Furthermore, carbonaceous chondrites are predicted to have a mantle too rich in olivine to produce typical howardites and to have Fe/Mn ratios generally well in excess of those of the HEDs. On the other hand, an Na-depleted H-chondrite bulk composition is capable of producing Juvinas-like liquids, has a mantle rich enough in pyroxene to produce abundant howardite/diogenite, and has a Fe/Mn ratio compatible with eucrites. In addition, its predicted bulk-silicate density is within 100 kg m-3 of solutions constrained by data of the Dawn mission. However, oxidation state and oxygen isotopes are not perfectly reproduced and it is deduced that bulk Vesta may contain approximately 25% of a CM-like component. Values for the bulk-silicate composition of Vesta and a preliminary phase diagram are proposed.

Tuning HDF5 for Lustre File Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Howison, Mark; Koziol, Quincey; Knaak, David

2010-09-24

HDF5 is a cross-platform parallel I/O library that is used by a wide variety of HPC applications for the flexibility of its hierarchical object-database representation of scientific data. We describe our recent work to optimize the performance of the HDF5 and MPI-IO libraries for the Lustre parallel file system. We selected three different HPC applications to represent the diverse range of I/O requirements, and measured their performance on three different systems to demonstrate the robustness of our optimizations across different file system configurations and to validate our optimization strategy. We demonstrate that the combined optimizations improve HDF5 parallel I/O performancemore » by up to 33 times in some cases running close to the achievable peak performance of the underlying file system and demonstrate scalable performance up to 40,960-way concurrency.« less

Thermal Implications of the Iron Rain Model for Core Formation on Asteroid 4 Vesta

NASA Astrophysics Data System (ADS)

Kiefer, W. S.

2018-05-01

The abundance of moderately siderophile elements on Vesta implies that core formation occurred by iron rain sinking through a silicate magma ocean. This requires an internal temperature of at least 1400–1475°C and very rapid accretion.

Surface texture of Vesta from optical polarimetry

NASA Technical Reports Server (NTRS)

Le Bertre, T.; Zellner, B.

1980-01-01

Polarimetric, photometric, and reflective spectroscopic properties of asteroid 4 Vesta are simulated in the laboratory by a preparation of eucrite Bereba consisting of a broad mixture of particle sizes (mainly greater than 50-micron) mixed and partially coated with particles of size 10 microns and less. Coarse grains are necessary for producing the same albedo and a very fine dust coating is necessary for producing the same polarization inversion angle as observed for Vesta. There are less small grains and fine dust in this sample than in lunar soils. Photometrically, if coating a sphere, this sample shows a constant brightness on the sunward half of the observed hemisphere, the brightness being given on the other half by the Minnaert reciprocity principle. With such a photometric behavior, the global geometric albedo and the sub-earth point geometric albedo differ by no more than 5%. The microscopic phase coefficient is 0.021 magnitude per degree for the sample; the larger value, 0.025, observed telescopically for Vesta, indicates that large-scale roughness is present on this asteroid.

The Grand Geochemistry of 4 Vesta: First Results

NASA Technical Reports Server (NTRS)

Prettyman, T. H.; Beck, A.; Feldman, W. C.; Forni, O.; Joy, S. P.; Lawrence, D. J.; McCoy T. J.; McFadden, L. A.; McSween, H. Y.; Mittlefehldt, D. W.;

Geochemical Mapping of 4 Vesta Begins

NASA Technical Reports Server (NTRS)

Prettyman, Thomas H.; Feldman, William C.; Forni, Olivier; Joy, Steven P.; Lawrence, David J.; LeCorre, Lucille; Mafi, Joseph N.; McCord, Thomas B.; McCoy, Timothy J.; McSween, Harry Y.;

Speckle interferometry of asteroids

NASA Technical Reports Server (NTRS)

Drummond, Jack D.; Hege, E. Keith

1989-01-01

Steward Observatory's two-dimensional power spectrum signature analysis of speckle interferometry observations is summarized. Results for six asteroids are presented. The poles and triaxial ellipsoid dimensions of 4 Vesta, 433 Eros, 511 Davida, and 532 Herculina have been previously reported. New results for 2 Pallas and 29 Amphitrite are given, as well as further results for Vesta. Image reconstruction is ultimately required to minimize biasing effects of asteroid surface features on the simpler power spectrum analysis. Preliminary imaging results have been achieved for Vesta and Eros, and images for these two are displayed. Speckle interferometry and radiometry diameters are compared, and diameters from the two occultations of Pallas are addressed.

Anaglyph Image of the Mountain-Central Complex in Vesta South Polar Region

NASA Image and Video Library

2011-10-11

The broad morphology of asteroid Vesta mountain/central complex is clear in this image from NASA Dawn spacecraft; it is a roughly circular topographic mound, which is approximately 200km in diameter and has approximately 20km of relief from its base.

Vesta Surface in 3-D: A Big Mountain at the Asteroid South Pole

NASA Image and Video Library

2011-09-16

When NASA Dawn spacecraft sent the first images of the giant asteroid Vesta to the ground, scientists were fascinated by an enormous mound inside a big circular depression at the south pole. You need 3D glasses to view this image.

Modeling of Giant Impact into a Differentiated Asteroid and Implications for the Large-Scale Troughs on Vesta

NASA Astrophysics Data System (ADS)

Buczkowski, D.; Iyer, K.; Raymond, C. A.; Wyrick, D. Y.; Kahn, E.; Nathues, A.; Gaskell, R. W.; Roatsch, T.; Preusker, F.; Russell, C. T.

2012-12-01

Linear structures have been identified in a concentric orientation around impact craters on several asteroids (e.g. Ida [1], Eros [2], Lutetia [3]) and their formation tied to the impact event [1,2]. Images of Vesta taken by the Dawn spacecraft reveal large-scale linear structural features in a similar orientation around the Rheasilvia and Veneneia basins [4]. However, the dimensions and shape of these features suggest that they are graben similar to those observed on terrestrial planets, not fractures or grooves such as are found on Ida, Eros and Lutetia [5]. Although the fault plane analysis [4] implies that impact may have been responsible for triggering the formation of these features as on the smaller asteroids, we suggest the significantly different morphology implies that some other component must also have been involved in their development. It has been established that Vesta is a differentiated body with a core [6]. This differentiated interior could be a factor in the troughs' resemblance to planetary faults rather than asteroidal fractures, as it is predicted that the stresses resultant from impact would be amplified and reoriented compared to a similar impact on an undifferentiated body. Preliminary CTH hydrocode [7] models of a 530 km sphere composed of a basalt analog with a 220 km iron core [6] show that the impact of a 50 km object results in different patterns of tensile stress and pressure compared to an undifferentiated sphere of the same material and diameter. While these first-order models have yet to fully mimic the observations we've made on Vesta, they do demonstrate that the density contrast in Vesta's differentiated interior affects the stresses resulting from the Rheasilivia and Veneneia impacts. It is this impedance mismatch that we suggest is responsible for the development of Vesta's planet-like troughs. Thus, future identification of planetary-style tectonic features on small solar system bodies may then imply a differentiated interior like Vesta's. The authors gratefully acknowledge the support of the Dawn Instrument, Operations, and Science Teams. This work was funded by the Dawn at Vesta Participating Science Program. [1] Asphaug et al. 1996, Icarus, 120, 158-184. [2] Buczkowski et al. 2008, Icarus, 193, 39-52. [3] Thomas et al. 2011, Planet. Space Sci., doi:10.1016/j.pss.2011.10.003. [4] Jaumann et al. 2012, Science 336, 687-690. [5] Buczkowski et al. 2012, GRL, submitted. [6] Russell et al. 2012, Science 336, 684-686. [7] McGlaun et al. 1990, Int. J. Impact Eng., 10(1-40), 351-360.

Asteroid 4 Vesta: A Fully Differentiated Dwarf Planet

NASA Technical Reports Server (NTRS)

Mittlefehldt, David

2014-01-01

One conclusion derived from the study of meteorites is that some of them - most irons, stony irons, some achondrites - hail from asteroids that were heated to the point where metallic cores and basaltic crusts were formed. Telescopic observations show that there remains only one large asteroid with a basaltic crust, 4 Vesta; present day mean radius 263 km. The largest clan of achondrites, the howardite, eucrite and diogenite (HED) meteorites, represent the crust of their parent asteroid. Diogenites are cumulate harzburgites and orthopyroxenites from the lower crust whilst eucrites are cumulate gabbros, diabases and basalts from the upper crust. Howardites are impact-engendered breccias of diogenites and eucrites. A strong case can be made that HEDs are derived from Vesta. The NASA Dawn spacecraft orbited Vesta for 14 months returning data allowing geological, mineralogical, compositional and geophysical interpretations of Vesta's surface and structure. Combined with geochemical and petrological observations of HED meteorites, differentiation models for Vesta can be developed. Proto-Vesta probably consisted of primitive chondritic materials. Compositional evidence, primarily from basaltic eucrites, indicates that Vesta was melted to high degree (>=50%) which facilitated homogenization of the silicate phase and separation of immiscible Fe,Ni metal plus Fe sulphide into a core. Geophysical models based on Dawn data support a core of 110 km radius. The silicate melt vigorously convected and initially followed a path of equilibrium crystallization forming a harzburgitic mantle, possibly overlying a dunitic restite. Once the fraction of crystals was sufficient to cause convective lockup, the remaining melt collected between the mantle and the cool thermal boundary layer. This melt undergoes fractional crystallization to form a dominantly orthopyroxenite (diogenite) lower crust. The initial thermal boundary layer of primitive chondritic material is gradually replaced by a mafic crust through impact disruption and foundering. The quenched mafic crust thickens over time through magma extrusion/intrusion. Melt from the residual magma ocean intrudes and penetrates the mafic crust forming cumulate eucrite plutons, and dikes, sills and flows of basaltic eucrite composition. The post-differentiation vestan structure is thus not too dissimilar from that of terrestrial planets: (i) a metallic core; (ii) an ultramafic mantle comprised of a lower dunitic layer (if melting was substantially <100%) and an upper cumulate harzburgitic layer; (iii) a lower crust of harzburgitic and orthopyroxenitic cumulates; and (iv) an upper mafic crust of basalts and diabases (melt compositions) with cumulate gabbro intrusions. Impacts have excavated to the lower crust and delivered howardites, eucrites and diogenites to Earth, but there is yet no evidence demonstrating excavation of the vestan mantlle.

Differentiation and magmatic activity in Vesta evidenced by 26Al-26Mg dating in eucrites and diogenites

NASA Astrophysics Data System (ADS)

Hublet, G.; Debaille, V.; Wimpenny, J.; Yin, Q.-Z.

2017-12-01

The 26Al-26Mg short-lived chronometer has been widely used for dating ancient objects in studying the early Solar System. Here, we use this chronometer to investigate and refine the geological history of the asteroid 4-Vesta. Ten meteorites widely believed to come from Vesta (4 basaltic eucrites, 3 cumulate eucrites and 3 diogenites) and the unique achondrite Asuka 881394 were selected for this study. All samples were analyzed for their δ26Mg∗ and 27Al/24Mg ratios, in order to construct both whole rock and model whole rock isochrons. Mineral separation was performed on 8 of the HED's in order to obtain internal isochrons. While whole rock Al-Mg analyses of HED's plot on a regression that could be interpreted as a vestan planetary isochron, internal mineral isochrons indicate a more complex history. Crystallization ages obtained from internal 26Al-26Mg systematic in basaltic eucrites show that Vesta's upper crust was formed during a short period of magmatic activity at 2.66-0.58+1.39 million years (Ma) after Calcium-Aluminum inclusions (after CAI). We also suggest that impact metamorphism and subsequent age resetting could have taken place at the surface of Vesta while 26Al was still extant. Cumulate eucrites crystallized progressively from 5.48-0.60+1.56 to >7.25 Ma after CAI. Model ages obtained for both basaltic and cumulate eucrites are similar and suggest that the timing of differentiation of a common eucrite source from a chondritic body can be modeled at 2.88-0.12+0.14 Ma after CAI, i.e. contemporaneously from the onset of the basaltic eucritic crust. Based on their cumulate texture, we suggest cumulate eucrites were likely formed deeper in the crust of Vesta. Diogenites have a more complicated history and their 26Al-26Mg systematics show that they likely formed after the complete decay of 26Al and thus are younger than eucrites. This refined chronology for eucrites and diogenites is consistent with a short magma ocean stage on 4-Vesta from which the basaltic eucrites rapidly crystallized. In order to explain the younger age and the complex history of diogenites, we postulate that a second episode of magmatism was possibly triggered by a mantle overturn. We bring a refined chronology of the geological history of Vesta that shows that the asteroid has known a more-complex differentiation than previously thought.

The Discovery and Analysis of a New Type of Wolf-Rayet Star

NASA Astrophysics Data System (ADS)

Nowinski, Matt Clarke

A massive impact event on (4) Vesta is believed to have created the Vesta family of asteroids (Asphaug, 1997). The rotational characteristics of the Vesta family provide important clues about this event, including its timing, the make-up of the resulting debris, the subsequent migration of members of the family into Earth-crossing orbits, and the deposition of the Howardite-Eucrite-Diogenite meteorites on the Earth's surface. This study conducted lightcurve measurements of ten Vp-type asteroids, drawn from an asteroid taxonomy defined by Carvano et al. (2010) and based on the Sloan Digital Sky Survey (SDSS) Moving Object Catalogue (MOC4). These measurements identified a range of asteroid rotation periods from approximately 2.5 to 9.5 hours, as well as a potential synchronous binary system, (15121) 2000 EN14. The lightcurve results were combined with those of other V/Vp-type asteroids available in LightCurve Database (LCDB; Warner et al., 2009), and matched with both WISE diameter/albedo (J. Masiero et al., 2011) and near-infrared spectroscopic (Hardersen et al., 2014-2018) data. This integrated approach identified a set of Vesta family asteroids with relatively fast spin rates, nearly spherical shapes, and loose aggregate compositions. These findings, combined with the non-Maxwellian shape of this population's spin rate distribution, highlighted the importance of thermal Yarkovsky-YORP effects on the evolution of the Vesta family.

Volatile Concentrations and H-Isotope Composition of Unequilibrated Eucrites

NASA Technical Reports Server (NTRS)

Sarafian, Adam R.; Nielsen, Sune G.; Marschall, Horst R.; Gaetani, Glenn A.; Hauri, Erik H.; Righter, Kevin; Berger, Eve L.

2017-01-01

Eucrites are among the oldest and best studied asteroidal basalts (1). They represent magmatism that occurred on their parent asteroid, likely 4-Vesta, starting at 4563 Ma and continuing for approx. 30 Myr. Two hypotheses are debated for the genesis of eucrites, a magma ocean model (2), and a mantle partial melting model. In general, volatiles (H, C, F, Cl) have been ignored for eucrites and 4-Vesta, but solubility of wt% levels of H2O are possible at Vestan interior PT conditions. Targeted measurements on samples could aid our understanding considerably. Recent studies have found evidence of volatile elements in eucrites, but quantifying the abundance of volatiles remains problematic (6). Volatile elements have a disproportionately large effect on melt properties and phase stability, relative to their low abundance. The source of volatile elements can be elucidated by examining the hydrogen isotope ratio (D/H), as different H reservoirs have drastically different H isotope compositions. Recent studies of apatite in eucrites have shown that the D/H of 4-Vesta matches that of Earth and carbonaceous chondrites, however, the D/H of apatites may not represent the D/H of a primitive 4-Vesta melt due to the possibility of degassing prior to the crystallization of apatite. Therefore, the D/H of early crystallizing phases must be measured to determine if the D/H of 4-Vesta is equal to that of the Earth and carbonaceous chondrites.

Reevaluating Surface Composition of Asteroid (4) Vesta by Comparing HED Spectral Data with Dawn Framing Camera (FC) Observations

NASA Astrophysics Data System (ADS)

Giebner, T.; Jaumann, R.; Schröder, S.

2016-08-01

This master's thesis project tries to reevaluate previous findings on asteroid (4) Vesta's surface composition by using DAWN FC Filter image ratios in a new way in order to identify HED (howardite, eucrite, diogenite) lithologies on the surface.

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Parallel checksumming of data chunks of a shared data object using a log-structured file system

DOEpatents

Bent, John M.; Faibish, Sorin; Grider, Gary

2016-09-06

Checksum values are generated and used to verify the data integrity. A client executing in a parallel computing system stores a data chunk to a shared data object on a storage node in the parallel computing system. The client determines a checksum value for the data chunk; and provides the checksum value with the data chunk to the storage node that stores the shared object. The data chunk can be stored on the storage node with the corresponding checksum value as part of the shared object. The storage node may be part of a Parallel Log-Structured File System (PLFS), and the client may comprise, for example, a Log-Structured File System client on a compute node or burst buffer. The checksum value can be evaluated when the data chunk is read from the storage node to verify the integrity of the data that is read.

Analysis of Temperature Maps of Selected Dawn Data Over the Surface of Vesta

NASA Technical Reports Server (NTRS)

Tosi, F.; Capria, M. T.; DeSanctis, M. C.; Palomba, E.; Grassi, D.; Capaccioni, F.; Ammannito, E.; Combe, J.-Ph.; Sunshine, J. M.; McCord, T. B.;

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Forward orbital evolution of the Vesta Family with and without the Yarkovsky effect

NASA Astrophysics Data System (ADS)

Wlodarczyk, Ireneusz; Leliwa-Kopystynski, Jacek

2018-02-01

Vesta family members (VFMs), totally 17164, were selected by means of hierarchical clustering method (HCM) from the data base containing 393347 synthetic proper elements of numbered asteroids from the ASTDyS Catalogue (2015) updated in May 5, 2015. Keplerian elements from the Lowell Catalogue (2015) were used for studying orbital evolution of all 17164 VFMs in the time interval 1 Gy forward. Two cases were considered: evolution pass without the Yarkovsky effect (YN) and evolution pass with it (YY). It has been found that swarm of asteroids disperses about 28 times more efficient for the case YY than in the case YN. Efficiency of dispersion was studied versus semiaxis of asteroids relative to Vesta (smaller or larger than semiaxis of Vesta) as well as versus the sizes of asteroids. Weak relationships between size and efficiency of dispersion on YE have been found for the both cases YN and YY. The loss of number of the asteroids from VF weakly depends on their sizes. The total lost by number as well by mass is about 10% per 1 Gy.

Core Formation on Asteroid 4 Vesta: Iron Rain in a Silicate Magma Ocean

NASA Technical Reports Server (NTRS)

Kiefer, Walter S.; Mittlefehldt, David W.

2017-01-01

Geochemical observations of the eucrite and diogenite meteorites, together with observations made by NASA's Dawn spacecraft, suggest that Vesta resembles H chondrites in bulk chemical composition, possibly with about 25% of a CM-chondrite like composition added in. For this model, the core is 15% by mass (or 8 volume %) of the asteroid. The abundances of moderately siderophile elements (Ni, Co, Mo, W, and P) in eucrites require that essentially all of the metallic phase in Vesta segregated to form a core prior to eucrite solidification. Melting in the Fe-Ni-S system begins at a cotectic temperature of 940 deg. C. Only about 40% of the total metal phase, or 3-4 volume % of Vesta, melts prior to the onset of silicate melting. Liquid iron in solid silicate initially forms isolated pockets of melt; connected melt channels, which are necessary if the metal is to segregate from the silicate, are only possible when the metal phase exceeds about 5 volume %. Thus, metal segregation to form a core does not occur prior to the onset of silicate melting.

Comparison of Observed Surface Temperatures of 4 Vesta to the KRC Thermal Model

NASA Technical Reports Server (NTRS)

Titus, T. N.; Becker, K. J.; Anderson, J. A.; Capria, M. T.; Tosi, F.; DeSanctis, M. C.; Palomba, E.; Grassi, D.; Capaccioni, F.; Ammannito, E.;

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchi, S.; Lazzarin, M.; Magrin, S.

The majority of basaltic asteroids are found in the inner main belt, although a few have also been observed in the outer main belt and near-Earth space. These asteroids-referred to as V-types-have surface compositions that resemble that of the 530 km sized asteroid Vesta. Besides the compositional similarity, dynamical evidence also links many V-type asteroids to Vesta. Moreover, Vesta is one of the few asteroids to have been identified as source of specific classes of meteorites, the howardite, eucrite, and diogenite achondrites (HEDs). Despite the general consensus on the outlined scenario, several questions remain unresolved. In particular, it is notmore » clear if the observed spectral diversity among Vesta, V-types, and HEDs is due to space weathering, as is thought to be the case for S-type asteroids. In this Letter, SDSS photometry is used to address the question of whether the spectral diversity among candidate V-types and HEDs can be explained by space weathering. We show that visible spectral slopes of V-types are systematically redder with respect to HEDs, in a similar way to what is found for ordinary chondrite meteorites and S-types. On the assumption that space weathering is responsible for the slope mismatch, we estimated an upper limit for the reddening timescale of about 0.5 Ga. Nevertheless, the observed slope mismatch between HEDs and V-types poses several puzzles to understanding its origin. The implication of our findings is also discussed in light of the Dawn mission to Vesta.« less

NASA's Dawn Mission to Asteroid 4 Vesta

NASA Technical Reports Server (NTRS)

McFadden, Lucyann A.

2011-01-01

NASA's Dawn Mission to asteroid 4 Vesta is part of a 13-year robotic space project designed to reveal the nature of two of the largest asteroids in the Main Asteroid Belt of our Solar System. Ceres and Vesta are two complementary terrestrial protoplanets whose accretion was probably terminated by the formation of Jupiter. They provide a bridge in our understanding between the rocky bodies of the inner solar system and the icy bodies of the outer solar system. Ceres appears to be undifferentiated Vesta has experienced significant heating and likely differentiation. Both formed very early in history of the solar system and while suffering many impacts have remained intact, thereby retaining a record of events and processes from the time of planet formation. Detailed study of the geophysics and geochemistry of these two bodies provides critical benchmarks for early solar system conditions and processes that shaped its subsequent evolution. Dawn provides the missing context for both primitive and evolved meteoritic data, thus playing a central role in understanding terrestrial planet formation and the evolution of the asteroid belt. Dawn is to he launched in 2006 arriving at Vesta in 20l0 and Ceres in 2014, stopping at each to make 11 months of orbital measurements. The spacecraft uses solar electric propulsion, both in cruise and in orbit, to make most efficient use of its xenon propellant. The spacecraft carries a framing camera, visible and infrared mapping spectrometer, gamma ray/neutron magnetometer, and radio science.

Dielectric properties of Asteroid Vesta's surface as constrained by Dawn VIR observations

NASA Astrophysics Data System (ADS)

Palmer, Elizabeth M.; Heggy, Essam; Capria, Maria T.; Tosi, Federico

2015-12-01

Earth and orbital-based radar observations of asteroids provide a unique opportunity to characterize surface roughness and the dielectric properties of their surfaces, as well as potentially explore some of their shallow subsurface physical properties. If the dielectric and topographic properties of asteroid's surfaces are defined, one can constrain their surface textural characteristics as well as potential subsurface volatile enrichment using the observed radar backscatter. To achieve this objective, we establish the first dielectric model of asteroid Vesta for the case of a dry, volatile-poor regolith-employing an analogy to the dielectric properties of lunar soil, and adjusted for the surface densities and temperatures deduced from Dawn's Visible and InfraRed mapping spectrometer (VIR). Our model suggests that the real part of the dielectric constant at the surface of Vesta is relatively constant, ranging from 2.3 to 2.5 from the night- to day-side of Vesta, while the loss tangent shows slight variation as a function of diurnal temperature, ranging from 6 × 10-3 to 8 × 10-3. We estimate the surface porosity to be ∼55% in the upper meter of the regolith, as derived from VIR observations. This is ∼12% higher than previous estimation of porosity derived from previous Earth-based X- and S-band radar observation. We suggest that the radar backscattering properties of asteroid Vesta will be mainly driven by the changes in surface roughness rather than potential dielectric variations in the upper regolith in the X- and S-band.

Geologic History of Asteroid 4 Vesta

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.

2014-01-01

Some types of meteorites - most irons, stony irons, some achondrites - hail from asteroids that were heated to the point where magmatism occurred within a very few million years of the formation of the earliest solids in the solar system. The largest clan of achondrites, the howardite, eucrite and diogenite (HED) meteorites, represent the crust of their parent asteroid]. Diogenites are cumulate harzburgites and orthopyroxenites from the lower crust whilst eucrites are basalts, diabases and cumulate gabbros from the upper crust. Howardites are impact-engendered breccias mostly of diogenites and eucrites. There remains only one large asteroid with a basaltic crust, 4 Vesta, which is thought to be the source of the HED clan. Differentiation models for Vesta are based on HED compositions. Proto-Vesta consisted of chondritic materials containing Al-26, a potent, short-lived heat source. Inferences from compositional data are that Vesta was melted to high degree (=50%) allowing homogenization of the silicate phase and separation of a metallic core. Convection of the silicate magma ocean allowed equilibrium crystallization, forming a harzburgitic mantle. After convective lockup occurred, melt collected between the mantle and the cool thermal boundary layer and underwent fractional crystallization forming an orthopyroxene-rich (diogenite) lower crust. The initial thermal boundary layer of chondritic material was replaced by a mafic upper crust through impact disruption and foundering. The mafic crust thickened over time as additional residual magma intrudes and penetrates the mafic crust forming plutons, dikes, sills and flows of cumulate and basaltic eucrite composition. This magmatic history may have taken only 2-3 Myr. This magma ocean scenario is at odds with a model of heat and magma transport that indicates that small degrees of melt would be rapidly expelled from source regions, precluding development of a magma ocean. Constraints from radiogenic Mg-26 distibutions suggest that the parent asteroid of HEDs was much smaller than Vesta. Thus, first-order questions regarding asteroid differentiation remain.

Vesta and Ceres as Seen by Dawn

NASA Astrophysics Data System (ADS)

Russell, C. T.; Nathues, A.; De Sanctis, M. C.; Prettyman, T. H.; Konopliv, A. S.; Park, R. S.; Jaumann, R.; McSween, H. Y., Jr.; Raymond, C. A.; Pieters, C. M.; McCord, T. B.; Marchi, S.; Schenk, P.; Buczkowski, D.

2015-12-01

Ceres and Vesta are the most massive bodies in the main asteroid belt. They have witnessed 4.6 Ga of solar system history. Dawn's objective is to interview these two witnesses. These bodies are relatively simple protoplanets, with a modest amount of thermal evolution and geochemical alteration. They are our best archetypes of the early building blocks of the terrestrial planets. In particular siderophile elements in the Earth's core were probably first segregated in Vesta-like bodies, and its water was likely first condensed in Ceres-like bodies. Vesta has provided copious meteorites for geochemical analysis. This knowledge was used to infer the constitution of the parent body. Dawn verified that Vesta was consistent with being that body, confirming the geochemical inferences from these samples on the formation and evolution of the solar system. Ceres has not revealed itself with a meteoritic record nor an asteroid family. While the surface is scarred with craters, it is probable that the ejecta from the crater-forming events created little competent material from the icy crust and any such ejected material that reached Earth might have disintegrated upon entry into the Earth's atmosphere. Ceres' surface differs greatly from Vesta's. Plastic or fluidized mass wasting is apparent as are many irregularly shaped craters, including many polygonal crater forms. There are many central-pit craters possibly caused by volatilization of the crust in the center of the impact. There are many central-peak craters but are these due to rebound or pingo-like formation processes? Bright spots, possibly salt deposits, dot the landscape, evidence of fluvial processes beneath the crust. Observations of the largest region of bright spots may suggest sublimation from the surface of the bright area, consistent with Herschel water vapor observations. Ceres is not only the most massive body in the asteroid belt but also possibly the most active occupant of the main belt.

Automation and Process Improvement Enables a Small Team to Operate a Low Thrust Mission in Orbit Around the Asteroid Vesta

NASA Technical Reports Server (NTRS)

Weise, Timothy M

2012-01-01

NASA's Dawn mission to the asteroid Vesta and dwarf planet Ceres launched September 27, 2007 and arrived at Vesta in July of 2011. This mission uses ion propulsion to achieve the necessary delta-V to reach and maneuver at Vesta and Ceres. This paper will show how the evolution of ground system automation and process improvement allowed a relatively small engineering team to transition from cruise operations to asteroid operations while maintaining robust processes. The cruise to Vesta phase lasted almost 4 years and consisted of activities that were built with software tools, but each tool was open loop and required engineers to review the output to ensure consistency. Additionally, this same time period was characterized by the evolution from manually retrieved and reviewed data products to automatically generated data products and data value checking. Furthermore, the team originally took about three to four weeks to design and build about four weeks of spacecraft activities, with spacecraft contacts only once a week. Operations around the asteroid Vesta increased the tempo dramatically by transitioning from one contact a week to three or four contacts a week, to fourteen contacts a week (every 12 hours). This was accompanied by a similar increase in activity complexity as well as very fast turn around activity design and build cycles. The design process became more automated and the tools became closed loop, allowing the team to build more activities without sacrificing rigor. Additionally, these activities were dependent on the results of flight system performance, so more automation was added to analyze the flight data and provide results in a timely fashion to feed the design cycle. All of this automation and process improvement enabled up the engineers to focus on other aspects of spacecraft operations, including spacecraft health monitoring and anomaly resolution.

Adding Data Management Services to Parallel File Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandt, Scott

2015-03-04

The objective of this project, called DAMASC for “Data Management in Scientific Computing”, is to coalesce data management with parallel file system management to present a declarative interface to scientists for managing, querying, and analyzing extremely large data sets efficiently and predictably. Managing extremely large data sets is a key challenge of exascale computing. The overhead, energy, and cost of moving massive volumes of data demand designs where computation is close to storage. In current architectures, compute/analysis clusters access data in a physically separate parallel file system and largely leave it scientist to reduce data movement. Over the past decadesmore » the high-end computing community has adopted middleware with multiple layers of abstractions and specialized file formats such as NetCDF-4 and HDF5. These abstractions provide a limited set of high-level data processing functions, but have inherent functionality and performance limitations: middleware that provides access to the highly structured contents of scientific data files stored in the (unstructured) file systems can only optimize to the extent that file system interfaces permit; the highly structured formats of these files often impedes native file system performance optimizations. We are developing Damasc, an enhanced high-performance file system with native rich data management services. Damasc will enable efficient queries and updates over files stored in their native byte-stream format while retaining the inherent performance of file system data storage via declarative queries and updates over views of underlying files. Damasc has four key benefits for the development of data-intensive scientific code: (1) applications can use important data-management services, such as declarative queries, views, and provenance tracking, that are currently available only within database systems; (2) the use of these services becomes easier, as they are provided within a familiar file-based ecosystem; (3) common optimizations, e.g., indexing and caching, are readily supported across several file formats, avoiding effort duplication; and (4) performance improves significantly, as data processing is integrated more tightly with data storage. Our key contributions are: SciHadoop which explores changes to MapReduce assumption by taking advantage of semantics of structured data while preserving MapReduce’s failure and resource management; DataMods which extends common abstractions of parallel file systems so they become programmable such that they can be extended to natively support a variety of data models and can be hooked into emerging distributed runtimes such as Stanford’s Legion; and Miso which combines Hadoop and relational data warehousing to minimize time to insight, taking into account the overhead of ingesting data into data warehousing.« less

Vesta's north pole quadrangle Av-1 (Albana): Geologic map and the nature of the south polar basin antipodes

NASA Astrophysics Data System (ADS)

Blewett, David T.; Buczkowski, Debra L.; Ruesch, Ottaviano; Scully, Jennifer E.; O'Brien, David P.; Gaskell, Robert; Roatsch, Thomas; Bowling, Timothy J.; Ermakov, Anton; Hiesinger, Harald; Williams, David A.; Raymond, Carol A.; Russell, Christopher T.

2014-12-01

As part of systematic global mapping of Vesta using data returned by the Dawn spacecraft, we have produced a geologic map of the north pole quadrangle, Av-1 Albana. Extensive seasonal shadows were present in the north polar region at the time of the Dawn observations, limiting the ability to map morphological features and employ color or spectral data for determination of composition. The major recognizable units present include ancient cratered highlands and younger crater-related units (undivided ejecta, and mass-wasting material on crater floors). The antipode of Vesta's large southern impact basins, Rheasilvia and Veneneia, lie within or near the Av-1 quadrangle. Therefore it is of particular interest to search for evidence of features of the kind that are found at basin antipodes on other planetary bodies. Albedo markings known as lunar swirls are correlated with basin antipodes and the presence of crustal magnetic anomalies on the Moon, but lighting conditions preclude recognition of such albedo features in images of the antipode of Vesta's Rheasilvia basin. “Hilly and lineated terrain,” found at the antipodes of large basins on the Moon and Mercury, is not present at the Rheasilvia or Veneneia antipodes. We have identified small-scale linear depressions that may be related to increased fracturing in the Rheasilvia and Veneneia antipodal areas, consistent with impact-induced stresses (Buczkowski, D. et al. [2012b]. Analysis of the large scale troughs on Vesta and correlation to a model of giant impact into a differentiated asteroid. Geol. Soc. of America Annual Meeting. Abstract 152-4; Bowling, T.J. et al. [2013]. J. Geophys. Res. - Planets, 118. http://dx.doi.org/10.1002/jgre.20123). The general high elevation of much of the north polar region could, in part, be a result of uplift caused by the Rheasilvia basin-forming impact, as predicted by numerical modeling (Bowling, T.J. et al. [2013]. J. Geophys. Res. - Planets, 118. http://dx.doi.org/10.1002/jgre.20123). However, stratigraphic and crater size-frequency distribution analysis indicate that the elevated terrain predates the two southern basins and hence is likely a remnant of the ancient vestan crust. The lack of large-scale morphological features at the basin antipodes can be attributed to weakened antipodal constructive interference of seismic waves caused by an oblique impact or by Vesta's non-spherical shape, or by attenuation of seismic waves because of the physical properties of Vesta's interior. A first-order analysis of the Dawn global digital elevation model for Vesta indicates that areas of permanent shadow are unlikely to be present in the vicinity of the north pole.

Mineralogical Mapping of Quadrangle Av-2 (belicia) and Av-3 (caparronia) on 4 Vesta.

NASA Astrophysics Data System (ADS)

Stephan, K.; Frigeri, A.; Barucci, M. A.; Sunshine, J.; Jaumann, R.; Palomba, E.; Blewett, D. T.; Yingst, A.; Marchi, S.; De Sanctis, C. M.; Matz, K.-D.; Roatsch, Th.; Preusker, F.; Le Corre, L.; Reddy, V.; Russell, C. T.; Raymond, C. A.

2012-04-01

Since the arrival of the Dawn spacecraft at 4 Vesta on July 16, 2011 the Visible and InfraRed Imaging Spectrometer (VIR) has acquired hyperspectral images of Vesta's surface, which enable to characterize Vesta's mineralogical composition in the wavelength range from 0.25 to 5.1µm. As part of the analysis of Vesta's surface composition the science team is preparing a series of 15 quadrangle maps showing the results derived from the spectroscopic analysis of the VIR and FC color data. We present preliminary results of the spectroscopic analysis achieved for the quadrangles Av-2 (Belicia) and Av-3 (Caparronia), which show Vesta's surface between 21°N - 66° N°, 0° - 90°E and 90° - 180° E, respectively. These results are based on the analysis of the combination of the visible albedo, spectral parameters including the position, depth of the pyroxene absorptions, as well as color ratio composites using the VIR channels centering at 749nm/438nm (Red), 749nm/917nm (Green) and 438nm/749nm (Blue). Vesta's rotation axis, however, is tilted ~29° with respect to its orbital plane. Since Dawn arrived during northern winter, portions of Vesta north of ~45° N are dominated by extended shadows or have not yet been imaged due to permanent night. Thus, limited FC color or VIR hyperspectral data have been available for the quadrangles Av-2 and Av-3. The illuminated parts are dominated by a heavily-cratered northern terrain with ancient troughs and grooves and named after the prominent relatively large impact craters Belicia (~37°N/48°E) and Caparronia (~36°N/167°E). Numerous impact craters of different size, morphology, and state of surface degradation are apparent. Most spectral variations are strongly affected by the extreme illumination conditions, making the analysis of albedo variations and spectral signatures rather difficult. Their interpretation thus remains. Nevertheless, VIR spectra show clear evidence of Vesta's surface composition similar to those of HED (howardite, eucrite and diogenite) meteorites. The prominent pyroxene absorptions near 0.9 and 1.9µm show different band depths and band centers, which are associated with the presence and abundance of the mafic minerals as well as grain size. Within the quadrangles Av-2 and Av3, band centers appear to shift slightly to shorter wavelength from W to E following the trend of the equatorial region. A similar trend can be observed with respect to the depth of the pyroxene absorptions with the absorption deepening eastward. Locally, bright material associated with strong pyroxene absorptions is observed on crater walls of a few relatively large impact craters with pronounced topography. Either these impact craters are relatively young or fresh material became exposed due mass wasting processes. The effects of photometry for under these illumination conditions are being assessed. The authors gratefully acknowledge the support of the Dawn Instrument, Operations, and Science Teams. This work is supported by NASA through the Dawn project and the German Space Agency (DLR).

Calibration pipeline for VIR data

NASA Astrophysics Data System (ADS)

Carraro, F.; Fonte, S.; Coradini, A.; Filacchione, G.; de Sanctis, M. C.; Ammannito, E.; Capria, M. T.; Cartacci, M.; Noschese, R.; Tosi, F.; Capaccioni, F.

2011-10-01

During the second quarter of 2011 VIR-MS (VIS and IR Mapping Spectrometer) [1] aboard Dawn mission [2] has approached Vesta in order to start a long period of acquisitions that will end at the beginning of 2012. Data acquired by each instrument always require a calibration process in order to remove all the instrument effects that could affect the scientific evaluations and analysis. VIR-MS instrument team has realized a calibration pipeline which has the goal of producing calibrated (1b level) data starting from the raw (1a level) ones. The other goal of the tool has been the check of the goodness of acquired data by means of the evaluation of a series of minimum requisites of each data file, such as the percentage of the saturated pixels, the presence of spikes or the mean S/N ratio of each qube.

Life and dynamic capacity modeling for aircraft transmissions

NASA Technical Reports Server (NTRS)

Savage, Michael

1991-01-01

A computer program to simulate the dynamic capacity and life of parallel shaft aircraft transmissions is presented. Five basic configurations can be analyzed: single mesh, compound, parallel, reverted, and single plane reductions. In execution, the program prompts the user for the data file prefix name, takes input from a ASCII file, and writes its output to a second ASCII file with the same prefix name. The input data file includes the transmission configuration, the input shaft torque and speed, and descriptions of the transmission geometry and the component gears and bearings. The program output file describes the transmission, its components, their capabilities, locations, and loads. It also lists the dynamic capability, ninety percent reliability, and mean life of each component and the transmission as a system. Here, the program, its input and output files, and the theory behind the operation of the program are described.

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The Dawn Gravity Investigation at Vesta and Ceres

NASA Technical Reports Server (NTRS)

Konopliv, A. S.; Asmar, S.W.; Bills, B. G.; Mastrodemos, N.; Park, R. S.; Raymond, C. A.; Smith, D. E.; Zuber, M. T.

2011-01-01

The objective of the Dawn gravity investigation is to use high precision X-band Doppler tracking and landmark tracking from optical images to measure the gravity fields of Vesta and Ceres to a half-wavelength surface resolution better than 90-km and 300-km, respectively. Depending on the Doppler tracking assumptions, the gravity field will be determined to somewhere between harmonic degrees 15 and 25 for Vesta and about degree 10 for Ceres. The gravity fields together with shape models determined from Dawn's framing camera constrain models of the interior from the core to the crust. The gravity field is determined jointly with the spin pole location. The second degree harmonics together with assumptions on obliquity or hydrostatic equilibrium may determine the moments of inertia.

Rethinking key–value store for parallel I/O optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kougkas, Anthony; Eslami, Hassan; Sun, Xian-He

2015-01-26

Key-value stores are being widely used as the storage system for large-scale internet services and cloud storage systems. However, they are rarely used in HPC systems, where parallel file systems are the dominant storage solution. In this study, we examine the architecture differences and performance characteristics of parallel file systems and key-value stores. We propose using key-value stores to optimize overall Input/Output (I/O) performance, especially for workloads that parallel file systems cannot handle well, such as the cases with intense data synchronization or heavy metadata operations. We conducted experiments with several synthetic benchmarks, an I/O benchmark, and a real application.more » We modeled the performance of these two systems using collected data from our experiments, and we provide a predictive method to identify which system offers better I/O performance given a specific workload. The results show that we can optimize the I/O performance in HPC systems by utilizing key-value stores.« less

Data Partitioning and Load Balancing in Parallel Disk Systems

NASA Technical Reports Server (NTRS)

Scheuermann, Peter; Weikum, Gerhard; Zabback, Peter

1997-01-01

Parallel disk systems provide opportunities for exploiting I/O parallelism in two possible waves, namely via inter-request and intra-request parallelism. In this paper we discuss the main issues in performance tuning of such systems, namely striping and load balancing, and show their relationship to response time and throughput. We outline the main components of an intelligent, self-reliant file system that aims to optimize striping by taking into account the requirements of the applications and performs load balancing by judicious file allocation and dynamic redistributions of the data when access patterns change. Our system uses simple but effective heuristics that incur only little overhead. We present performance experiments based on synthetic workloads and real-life traces.

Multispectral Light Curves of Vesta

NASA Astrophysics Data System (ADS)

Jaumann, R.; Nathues, A.; Mottola, S.; Hoffmann, H.

1996-01-01

In order to characterize its compositional heterogeneity we have carried out time-resolved CCD spectrophotometry of 4 Vesta during its last apparition in 1996. The observations have been performed from the European Southern Observatory (La Silla, Chile), with the DLR CCD camera attached at the Bochum 24" telescope using a set of five interference filters covering the spectral range 0.45-0.95 pm. In order to obtain the high photometric accuracy necessary to reveal subtle color variations, we have performed on-chip differential photometry against a field star, which allows effective correction for short-term atmospheric extinction fluctuations. The observations were therefore carefully planned and scheduled for one night when 4 Vesta was passing close to a bright star (SAO 140637). Measurements in each filter were automatically cycled over about 5 hr, in order to fully cover an asteroid's rotational period. Only the small portion of the CCD actually containing 4 Vesta and the comparison star was read out, which allowed us to have a very fast duty cycle of about 90 s. A GO-type star (BS 5779) located less than 2 degrees from the Vesta field was acquired during its passage at meridian, in order to provide reflectance calibration. The resulting dataset of approximately 1000 frames was preprocessed using bias frames and twilight sky flat fields, while photometry was computed by using ASTPHOT, a synthetic aperture program developed at DLR. Extinction correction was derived directly by dividing the flux of the asteroid by the on-field comparison star, while higher-order, differential extinction coefficients were neglected due to the comparatively narrow bandwidth of the filters used.

The Geology of the Marcia Quadrangle of Asteroid 4Vesta: An Integrated Mapping Study Using Dawn Spacecraft Data

NASA Technical Reports Server (NTRS)

Williams, David A.; Denevi, B. W.; Mittlefehldt, D. W.; Mest, S. C.; Schenk, P. M.; Jaumann, R.; DeSanctis, M. C.; Buczkowski, D. L.; Ammannito, E.; Prettyman, T. H.;

[PVFS 2000: An operational parallel file system for Beowulf

NASA Technical Reports Server (NTRS)

Ligon, Walt

2004-01-01

The approach has been to develop Parallel Virtual File System version 2 (PVFS2) , retaining the basic philosophy of the original file system but completely rewriting the code. It shows the architecture of the server and client components. BMI - BMI is the network abstraction layer. It is designed with a common driver and modules for each protocol supported. The interface is non-blocking, and provides mechanisms for optimizations including pinning user buffers. Currently TCP/IP and GM(Myrinet) modules have been implemented. Trove -Trove is the storage abstraction layer. It provides for storing both data spaces and name/value pairs. Trove can also be implemented using different underlying storage mechanisms including native files, raw disk partitions, SQL and other databases. The current implementation uses native files for data spaces and Berkeley db for name/value pairs.

Speckle interferometry of asteroids

NASA Technical Reports Server (NTRS)

Drummond, Jack

1988-01-01

By studying the image two-dimensional power spectra or autocorrelations projected by an asteroid as it rotates, it is possible to locate its rotational pole and derive its three axes dimensions through speckle interferometry under certain assumptions of uniform, geometric scattering, and triaxial ellipsoid shape. However, in cases where images can be reconstructed, the need for making the assumptions is obviated. Furthermore, the ultimate goal for speckle interferometry of image reconstruction will lead to mapping albedo features (if they exist) as impact areas or geological units. The first glimpses of the surface of an asteroid were obtained from images of 4 Vesta reconstructed from speckle interferometric observations. These images reveal that Vesta is quite Moon-like in having large hemispheric-scale albedo features. All of its lightcurves can be produced from a simple model developed from the images. Although undoubtedly more intricate than the model, Vesta's lightcurves can be matched by a model with three dark and four bright spots. The dark areas so dominate one hemisphere that a lightcurve minimum occurs when the maximum cross-section area is visible. The triaxial ellipsoid shape derived for Vesta is not consistent with the notion that the asteroid has an equilibrium shape in spite of its having apparently been differentiated.

Geochemistry of Vesta and Ceres: In-flight calibration of Dawn

NASA Astrophysics Data System (ADS)

Prettyman, T. H.; Feldman, W. C.; McSween, H. Y.

2009-04-01

The purpose of the Dawn mission is to investigate processes that contributed to the formation and early evolution of solid bodies in the solar system by exploring Vesta and Ceres, which are the two largest bodies in the main astreroid belt. Because they were formed at different heliocentric distances, Vesta and Ceres incorporated different amounts of water and other volatiles, which strongly influenced their thermal evolution. Vesta, which is thought to be the source of the basaltic, Howardite, Eucrite, and Diogenite (HED) meteorites, is dry and underwent igneous differentiation. In contrast, low-temperature, aqueous processing must have played an important role in the evolution of Ceres, which is rich in water and other volatiles, and may still contain subsurface liquid water. By exploring both Vesta and Ceres, the gradient in the composition of the solar nebula and role of water in planetary evolution can be investigated. The Dawn payload includes redundant framing cameras (FC), a visible and infrared spectrometer (VIR), and a gamma ray and neutron detector (GRaND), which, along with radio science, will measure surface geomorphology, composition, and mineralogy, and provide constraints on the internal structure of Vesta and Ceres. For both Vesta and Ceres, global mapping data will be acquired from circular polar orbits. In low altitude orbits, GRaND will map the elemental composition of Vesta and Ceres to depths less than one meter, including major rock forming elements and light elements (such as H, C, and N), which are the primary constituents of ices. GRaND consists of 21 radiation sensors, which measure the spectrum of neutrons and gamma rays originating from interactions between galactic cosmic rays and the material constituents of the asteroids and, separately, backgrounds from spacecraft materials. GRaND uses a bismuth germanate (BGO) scintillator for gamma ray spectroscopy, which has high efficiency, enabling the measurement of gamma rays up to 10 MeV, including capture gamma rays from Fe and Ti. Below 3 MeV, the BGO sensor works in combination with a 16-element array of CdZnTe semiconductors, which have relatively high resolution, enabling accurate measurement of the densely populated, low energy region of the gamma ray spectrum, which contains gamma rays from radioactive decay (K, Th, and U) and from nuclear reactions (for example, with Mg, Si, and H). Thermal, epithermal, and fast neutrons are measured using a combination of boron-loaded plastic and lithium-loaded glass scintillators. At Vesta, gamma ray and neutron spectroscopy will be used to determine geochemical trends that can be compared with HED data. For example, a scatter plot of the average atomic mass (determined from fast neutrons) and magnesium number can be used to tell the difference between diogenite and eucrite compositions, which are HED end-members. Correlations with MgO (for example, with FeO or SiO2) also strongly differentiate between diogenite and eucrite, and, in combination with optical spectroscopy, can be used to determine whether an olivine-rich mantle is exposed in Vesta's large south polar crater. At Ceres, neutron spectroscopy can be used to determine water abundance and layering (for example, ice may be present in the shallow subsurface at high latitudes), which will provide constraints on recharge and loss mechanisms (for example, emplacement via water volcanism vs. gradual replenishment from a subsurface acquifer). In addition, nuclear spectroscopy can be used to determine the possible presence of CO2 and NH3 ices on the surface of Ceres as well as the composition of non-icy materials, including the hydration state and composition of surface minerals. GRaND was calibrated in the laboratory prior to delivery to the spacecraft. In addition, the response of the instrument to the space radiation environment was measured during Earth-Mars cruise, which followed launch in September of 2007. Because the data were acquired when the energetic particle flux was minimal, the measurements are ideal for determining the background from galactic cosmic rays under conditions that would be ideal for science data acquisition at Vesta and Ceres. In February of 2009, the spacecraft will fly by Mars. At closest approach, the spacecraft will be within 500 km of Mars, providing GRaND with a strong source of planetary neutrons and gamma rays, which will be used to cross-calibrate GRaND against elemental abundance data acquired by the Mars Odyssey Gamma Ray Spectrometer instrument suite. Here, we describe the instrument response model and its application to the analysis of the space radiation background during cruise and cross-calibration against Odyssey data at Mars. The model is applied to determine the expected performance of GRaND at Vesta and Ceres.

KNBD: A Remote Kernel Block Server for Linux

NASA Technical Reports Server (NTRS)

Becker, Jeff

1999-01-01

I am developing a prototype of a Linux remote disk block server whose purpose is to serve as a lower level component of a parallel file system. Parallel file systems are an important component of high performance supercomputers and clusters. Although supercomputer vendors such as SGI and IBM have their own custom solutions, there has been a void and hence a demand for such a system on Beowulf-type PC Clusters. Recently, the Parallel Virtual File System (PVFS) project at Clemson University has begun to address this need (1). Although their system provides much of the functionality of (and indeed was inspired by) the equivalent file systems in the commercial supercomputer market, their system is all in user-space. Migrating their 10 services to the kernel could provide a performance boost, by obviating the need for expensive system calls. Thanks to Pavel Machek, the Linux kernel has provided the network block device (2) with kernels 2.1.101 and later. You can configure this block device to redirect reads and writes to a remote machine's disk. This can be used as a building block for constructing a striped file system across several nodes.

In-Flight Operation of the Dawn Ion Propulsion System: Status at One Year from the Vesta Rendezvous

NASA Technical Reports Server (NTRS)

Garner, Charles E.; Rayman, Marc D.

2010-01-01

The Dawn mission, part of NASA's Discovery Program, has as its goal the scientific exploration of the two most massive main-belt asteroids, Vesta and Ceres. The Dawn spacecraft was launched from Cape Canaveral Air Force Station on September 27, 2007 on a Delta-II 7925H-9.5 (Delta-II Heavy) rocket that placed the 1218 kg spacecraft into an Earth-escape trajectory. On-board the spacecraft is an ion propulsion system (IPS) developed at the Jet Propulsion Laboratory which will provide most of the delta V needed for heliocentric transfer to Vesta, orbit capture at Vesta, transfer among Vesta science orbits, departure and escape from Vesta, heliocentric transfer to Ceres, orbit capture at Ceres, and transfer among Ceres science orbits. The Dawn ion thruster [I thought we only called it a thruster. Both terms are used in the paper, but I think a replacement of every occurrence of "engine" with "thruster" would be clearer.] design is based on the design validated on NASA's Deep Space 1 (DS1) mission. However, because of the very substantial (11 km/s) delta V requirements for this mission Dawn requires two engines to complete its mission objectives. The power processor units (PPU), digital control and interface units (DCIU) slice boards and the xenon control assembly (XCA) are derivatives of the components used on DS1. The DCIUs and thrust gimbal assemblies (TGA) were developed at the Jet Propulsion Laboratory. The spacecraft was provided by Orbital Sciences Corporation, Sterling, Virginia, and the mission is managed by and operated from the Jet Propulsion Laboratory. Dawn partnered with Germany, Italy and Los Alamos National Laboratory for the science instruments. The mission is led by the principal investigator, Dr. Christopher Russell, from the University of California, Los Angeles. The first 80 days after launch were dedicated to the initial checkout of the spacecraft followed by cruise to Mars. Cruise thrusting leading to a Mars gravity assist began on December 17, 2007 and was successfully concluded as planned on October 31, 2008. During this time period the Dawn IPS was operated mostly at full power for approximately 6500 hours, consumed 71.7 kg of xenon and delivered approximately 1.8 km/s of delta V to the spacecraft. The thrusting to Mars was followed by a coasting period of approximately 3.5 months that included a Mars flyby in February of 2009. The Mars flyby provided a gravity assist (MGA) for a plane change and approximately 1 km/s of heliocentric energy increase and is the only part of the mission following launch in which a needed velocity change is not accomplished by the IPS. During the coast period IPS was operated for a trajectory correction maneuver and for engineering tests but was not operated for primary propulsion. Closest approach to Mars occurred as planned on February 17, 2009 and was followed by another coasting period of just under 4 months in duration. During this last coasting phase IPS was operated only for routine maintenance activities and for system engineering tests. Deterministic thrusting for heliocentric transfer to Vesta resumed on June 8, 2009. Since resumption of cruise to Vesta IPS has been operated at throttled power levels, most of the time at full power, and with a duty cycle of approximately 93%, leading to an arrival at Vesta in July of 2011 and arrival at Ceres in February 2015. This paper provides an overview of Dawn's mission objectives and the results of Dawn IPS mission operations through one year from the spacecraft's rendezvous with Vesta.

Dawn Maps the Surface Composition of Vesta

NASA Technical Reports Server (NTRS)

Prettyman, T.; Palmer, E.; Reedy, R.; Sykes, M.; Yingst, R.; McSween, H.; DeSanctis, M. C.; Capaccinoni, F.; Capria, M. T.; Filacchione, G.;

A Howardite-Eucrite-Diogenite (HED) Meteorite Compendium: Summarizing Samples of ASteroid 4 Vesta in Preparation for the Dawn Mission

NASA Technical Reports Server (NTRS)

Garber, J. M.; Righter, K.

2011-01-01

The Howardite-Eucrite-Diogenite (HED) suite of achondritic meteorites, thought to originate from asteroid 4 Vesta, has recently been summarized into a meteorite compendium. This compendium will serve as a guide for researchers interested in further analysis of HEDs, and we expect that interest in these samples will greatly increase with the planned arrival of the Dawn Mission at Vesta in August 2011. The focus of this abstract/poster is to (1) introduce and describe HED samples from both historical falls and Antarctic finds, and (2) provide information on unique HED samples available for study from the Antarctic Meteorite Collection at JSC, including the vesicular eucrite PCA91007, the olivine diogenite EETA79002, and the paired ALH polymict eucrites.

Dawn: Testing Paradigms by Exploring Dichotomies

NASA Astrophysics Data System (ADS)

Russell, C. T.; Schmidt, B. E.; Wise, J.; Ristvey, J.; Raymond, C. A.

2010-12-01

NASA’s Dawn mission represents a series of “firsts” for major NASA missions. Dawn is the first major NASA science mission to use ion propulsion engines, allowing Dawn to be the first mission to orbit one target and then leave its gravity well to explore a second destination. Dawn is the first science mission to the main asteroid belt, reaching protoplanet Vesta in summer 2011, and will be the first mission to reach a “dwarf planet” when it arrives at Ceres in 2015. By targeting both Vesta and Ceres, Dawn explores two intriguing dichotomies in the solar system, that of the dry rocky planets and the wet icy bodies (Fire and Ice) and the dichotomy between planets and asteroids. Is there a clear dividing line here? Vesta, the second most massive asteroid, is a protoplanet: a round, mostly intact asteroid that bears more resemblance to a planet than to smaller asteroids. Vesta is also the likely parent body of the HED meteorites that richly populate Earth’s meteorite collections. It is possible to hold a piece of Vesta in your hands. From the HED meteorites, scientists have learned the Vesta is one of few differentiated asteroids. And from its spectrum, rich in basaltic minerals, it is known to be much like a mini-version of Earth’s Moon and Mercury. Vesta’s surface once was home to floods of lava not unlike those found still today on the Earth. Vesta is very similar to a terrestrial planet. Ceres is the giant of the asteroid belt with a hydrostatic shape that earns it a dwarf planet classification. Like its larger cousins, Ceres’ round shape suggests that the body may be differentiated, but due to its low density, Ceres’ interior is more like an icy moon of Jupiter. Beneath a relatively thin clay veneer probably lies an ice-rich mantle and rocky core, and even possibly a liquid ocean. With such enticing questions posed for Vesta and Ceres, Dawn will enable scientists and the public alike to explore how planets were born, how fire and ice have shaped the solar system, and have a chance to push the boundaries of our own classification system. Dawn’s set of instrumentation, with cameras, a visible and infrared spectrometer, a gamma ray and neutron detector and radio science, will produce a wealth of information about two previously unexplored, diverse and yet somehow familiar worlds. Communication of the lessons learned by Dawn from the scientists to the public has and will occur over a range of interfaces, including a series of online activities such as Find a Meteorite, Clickworkers and a simulation of an ion engine. Other activities include Dawn “Science of the Day” archives, fun family activities and games as well as classroom materials and outreach events. Since the two bodies are the brightest sources in the main belt, an integral part of Dawn’s journey has been the integration of amateur and “backyard” astronomers. All these activities allow us to share the science with the public. Dawn arrives at Vesta in the middle of the Year of the Solar System in July 2011 and will depart for Ceres as the YSS ends.

In-Flight Operation of the Dawn Ion Propulsion System Through Start of the Vesta Cruise Phase

NASA Technical Reports Server (NTRS)

Garner, Charles E.; Rayman, Marc D.; Brophy, John R.

2009-01-01

The Dawn mission, part of NASA's Discovery Program, has as its goal the scientific exploration of the two most massive main-belt asteroids, Vesta and Ceres. The Dawn spacecraft was launched from Cape Canaveral Air Force Station on September 27, 2007 on a Delta-II 7925H-9.5 (Delta-II Heavy) rocket that placed the 1218 kg spacecraft into an Earth-escape trajectory. On-board the spacecraft is an ion propulsion system (IPS) which will provide most of the delta V needed for heliocentric transfer to Vesta, orbit capture at Vesta, transfer to Vesta science orbits, departure and escape from Vesta, heliocentric transfer to Ceres, orbit capture at Ceres, and transfer to Ceres science orbits. The Dawn ion design is based on the design validated on NASA's Deep Space 1 (DS1) mission. However, because of the very substantial (11 km/s) delta V requirements for this mission Dawn requires two engines to complete its mission objectives. The power processor units (PPU), digital control and interface units (DCIU) slice boards and the xenon control assembly (XCA) are derivatives of the components used on DS1. The DCIUs and thrust gimbal assemblies (TGA) were developed at the Jet Propulsion Laboratory. The spacecraft was provided by Orbital Sciences Corporation, Sterling, Virginia, and the mission is managed by and operated from the Jet Propulsion Laboratory. Dawn partnered with Germany, Italy and Los Alamos National Laboratory for the science instruments. The mission is led by the principal investigator, Dr. Christopher Russell, from the University of California, Los Angeles. The first 80 days after launch were dedicated to the initial checkout of the spacecraft followed by cruise to Mars. Cruise thrusting leading to a Mars gravity assist began on December 17, 2007 and was successfully concluded as planned on October 31, 2008. During this time period the Dawn IPS was operated mostly at full power for approximately 6500 hours, consumed 71.7 kg of xenon and delivered approximately 1.8 km/s of delta V to the spacecraft. The thrusting to Mars was followed by a coasting period of approximately 3.5 months that included a Mars flyby in February of 2009. The Mars flyby provided a gravity assist (MGA) for a plane change and approximately 1 km/s of heliocentric energy increase and is the only part of the mission following launch in which a needed velocity change is not accomplished by the IPS. During the coast period IPS was operated for a trajectory correction maneuver and for engineering tests but was not operated for primary propulsion. Closest approach to Mars occurred as planned on February 17, 2009 and was followed by another coasting period of just under 4 months in duration. During this last coasting phase IPS was operated only for routine maintenance activities and for system engineering tests. Deterministic thrusting for heliocentric transfer to Vesta resumed on June 8, 2009. IPS will be operated for over two years at throttled power levels leading to arrival at Vesta in September of 2011 and arrival at Ceres in February 2015. This paper provides an overview of Dawn's mission objectives and the results of Dawn IPS mission operations through the start of deterministic thrusting to Vesta.

Analyses from Near (Meteorites) and Far (Spacecraft): Complementary Approaches to Planetary Geochemistry

NASA Astrophysics Data System (ADS)

McSween, H. Y.

2013-12-01

Spacecraft missions have transformed planets from astronomical objects into geologic worlds, but geochemical remote sensing has limits. Considerably greater geologic insights are possible for a few bodies to which we can confidently assign meteorite samples. Mars and asteroid 4 Vesta demonstrate the advances provided by coupling spacecraft remote sensing data and laboratory analyses of meteorites. Martian meteorites sample at least 7 as-yet unidentified sites but are strongly biased towards young crystallization ages compared to Martian surface ages. Geochemical comparison with generally older rocks analyzed by Mars rovers APXS reveals evolutionary differences [1] that might be explained by water or redox state. Trace elements and radiogenic isotopes, readily measured in Martian meteorites but not yet possible by remote sensing, constrain the planet's volatile inventory, the chronology of magmatism, and the compositions of mantle source regions and the bulk planet [2]. The origin and geochemical cycling of water that orbiters indicate once sculpted Mars' geomorphology and now resides in the Martian subsurface is revealed by measurements of stable isotopes and of apatite OH in meteorites. Although sedimentary rocks are nearly absent from the Martian meteorite collection, determining the processes that produced the regolith and the nature and source of organic matter on Mars are facilitated by comparing rover analyses of soils with meteorite data. In a similar way, analyses of Vesta by the Dawn orbiting spacecraft [3] are leveraged by laboratory analyses of the howardite, eucrite, diogenite (HED) meteorites [4]. Visible/near-infrared spectra of HEDs provide the calibration necessary for lithologic mapping of Vesta's surface, revealing an ancient eucrite crust, diogenite excavated from a huge crater, and a pervasive regolith of howardite. Gamma-ray and neutron data from Vesta are similarly interpreted by comparison with meteorite elemental abundances. The unexpected discovery of hydrogen in low-albedo regions on Vesta is explained by incorporation of carbonaceous chondrite impactor debris, as seen in clasts within howardites. An estimate of Vesta's bulk composition based on HEDs is consistent with the measured bulk density and the calculated mass of the core. The meteorites provide information on igneous and impact chronology and constrain models for Vesta's magmatic differentiation, which can be tested with spacecraft remote sensing observations. Meteorite analyses are limited by lack of geologic context, and spacecraft data are hampered by incomplete geochemical measurements, but taken together they offer great synergy. Mars and Vesta (and, of course, the Moon) illustrate that planets, large and small, can be rigorously deciphered by geochemical analyses, from near and far. [1] McSween, H. Y. et al. (2009) Science, 324, 736-739, [2] McSween, H. Y. and McLennan, S. M. (2013) Treatise in Geochemistry, 2nd ed., in press, [3] Russell C. T., et al. (2012) Science, 336, 684-686, [4] McSween, H. Y. et al. (2012) Space Sci. Rev., 163-174.

Meteoritical Implications of the Vesta Asteroid Family

NASA Astrophysics Data System (ADS)

Bell, J. F.

1993-07-01

The discovery of a large dynamical family of basaltic asteroids associated with Vesta and extending to the 3:1 Jupiter resonance [1] provides firm evidence at last that Vesta is the actual parent body of the basaltic achondrite meteorites [2]. This discovery raises several interesting questions. The Vesta family demonstrates that objects as large as ~10km can be ejected from large asteroids at velocities up to 500 m/sec, which is adequate to deliver material to a strong resonance from almost anywhere in the asteroid belt. However, most other asteroid families show a much smaller range of ejection velocities and a more symmetrical distribution of the fragments in orbital element space. These families probably come from complete disruption of parent bodies, which would therefore appear to be the dominant process. Meteoritical evidence is also relevant. There are at least six large dunite (A-class) asteroids, only one of which is providing brachinites to the Earth. Even more striking, the Nysa asteroid family is predominantly composed of the mysterious F-class asteroids, which have no meteorite analog at all. The evidence suggests that the Vesta event is atypical and that there is considerable bias in meteorite delivery. The family is extended in a but narrowly confined in e and i. Curiously, Vesta is not at one end but in the middle. The very narrow sunward leg of the family contains a rare pure-olivine (Class A) asteroid among the many eucrites (Class V) and diogenites (Class J), while in the more diffuse anti-sunward leg no olivine objects have yet been found. This mineral distribution mimics the mineral map of Vesta derived from telescopic spectroscopy [3], in which a small olivine spot is semi-antipodal to a large diogenite patch. This suggests that the sunward leg is direct ejecta from a large crater, while the anti-sunward leg (and the populartion of HEDs reaching Earth) is composed of crustal fragments spalled off by focused shock waves. This mechanism is well-known from lab experiments [4] and probably causes the jumbled terrain antipodal to impact basins on the Moon and Mercury. Finally, it is now clear that the association between the HED clan and the pallasites is coincidental. We may expect many more such false genetic links between meteorite classes as more oxygen isotope data is obtained. References: [1] Binzel R. P. and Xu S. (1993) Science, 260, 186- 191. [2] Gaffey M. J. (1993) Science, 260, 167-168. [3] Gaffey M. J. (1983) LPS XIV, 231-232. [4] Horz F. and Schaal R. B. (1981) Icarus, 46, 337-353.

New infrared telescopic observation of Vesta

NASA Astrophysics Data System (ADS)

Palomba, E.; D'Aversa, E.; Sato, T.; Longobardo, A.; Aoki, S.; Sindoni, G.; Oliva, F.

2017-09-01

In this work we present new telescopic observations of the Vesta asteroid made at the Subaru Telescope by using the COMICS IR spectrometer. We were able to obtain 5 different observations in 5 day, at two different epochs. The obtained spectra do not exhibit Reststrahlen bands and show only weak features attributable to the Christiansen peak and to the transparency feature compatible with a fine grain size regolith.

Imaging Asteroid 4 Vesta Using the Framing Camera

NASA Technical Reports Server (NTRS)

Keller, H. Uwe; Nathues, Andreas; Coradini, Angioletta; Jaumann, Ralf; Jorda, Laurent; Li, Jian-Yang; Mittlefehldt, David W.; Mottola, Stefano; Raymond, C. A.; Schroeder, Stefan E.

2011-01-01

The Framing Camera (FC) onboard the Dawn spacecraft serves a dual purpose. Next to its central role as a prime science instrument it is also used for the complex navigation of the ion drive spacecraft. The CCD detector with 1024 by 1024 pixels provides the stability for a multiyear mission and its high requirements of photometric accuracy over the wavelength band from 400 to 1000 nm covered by 7 band-pass filters. Vesta will be observed from 3 orbit stages with image scales of 227, 63, and 17 m/px, respectively. The mapping of Vesta s surface with medium resolution will be only completed during the exit phase when the north pole will be illuminated. A detailed pointing strategy will cover the surface at least twice at similar phase angles to provide stereo views for reconstruction of the topography. During approach the phase function of Vesta was determined over a range of angles not accessible from earth. This is the first step in deriving the photometric function of the surface. Combining the topography based on stereo tie points with the photometry in an iterative procedure will disclose details of the surface morphology at considerably smaller scales than the pixel scale. The 7 color filters are well positioned to provide information on the spectral slope in the visible, the depth of the strong pyroxene absorption band, and their variability over the surface. Cross calibration with the VIR spectrometer that extends into the near IR will provide detailed maps of Vesta s surface mineralogy and physical properties. Georeferencing all these observation will result in a coherent and unique data set. During Dawn s approach and capture FC has already demonstrated its performance. The strong variation observed by the Hubble Space Telescope can now be correlated with surface units and features. We will report on results obtained from images taken during survey mode covering the whole illuminated surface. Vesta is a planet-like differentiated body, but its surface gravity and escape velocity are comparable to those of other asteroids and hence much smaller than those of the inner planets or

Extending the Lunar Mapping and Modeling Portal - New Capabilities and New Worlds

NASA Astrophysics Data System (ADS)

Day, B. H.; Law, E.; Arevalo, E.; Bui, B.; Chang, G.; Dodge, K.; Kim, R. M.; Malhotra, S.; Sadaqathullah, S.

2015-12-01

NASA's Lunar Mapping and Modeling Portal (LMMP) provides a web-based Portal and a suite of interactive visualization and analysis tools to enable mission planners, lunar scientists, and engineers to access mapped lunar data products from past and current lunar missions (http://lmmp.nasa.gov). During the past year, the capabilities and data served by LMMP have been significantly expanded. New interfaces are providing improved ways to access and visualize data. Many of the recent enhancements to LMMP have been specifically in response to the requirements of NASA's proposed Resource Prospector lunar rover, and as such, provide an excellent example of the application of LMMP to mission planning. At the request of NASA's Science Mission Directorate, LMMP's technology and capabilities are now being extended to additional planetary bodies. New portals for Vesta and Mars are the first of these new products to be released. On March 31, 2015, the LMMP team released Vesta Trek (http://vestatrek.jpl.nasa.gov), a web-based application applying LMMP technology to visualizations of the asteroid Vesta. Data gathered from multiple instruments aboard Dawn have been compiled into Vesta Trek's user-friendly set of tools, enabling users to study the asteroid's features. With an initial release on July 1, 2015, Mars Trek replicates the functionality of Vesta Trek for the surface of Mars. While the entire surface of Mars is covered, higher levels of resolution and greater numbers of data products are provided for special areas of interest. Early releases focus on past, current, and future robotic sites of operation. Future releases will add many new data products and analysis tools as Mars Trek has been selected for use in site selection for the Mars 2020 rover and in identifying potential human landing sites on Mars. Other destinations will follow soon. The user community is invited to provide suggestions and requests as the development team continues to expand the capabilities of LMMP, its related products, and the range of data and tools that they provide. This presentation will provide an overview of LMMP, Vesta Trek, and Mars Trek, demonstrate their uses and capabilities, highlight new features, and preview coming enhancements.

To See a World in a Grain of Sand: Insights into Solar System Formation and Evolution from Isotopic Analyses of Planetary Materials

NASA Astrophysics Data System (ADS)

Wadhwa, M.

2016-12-01

The last few decades have seen revolutionary advances in the planetary sciences through remote observations (by spacecraft and Earth-based observatories) of many Solar System destinations and, in more recent years, even exoplanets around other stars. In parallel with this, ground-breaking developments in analytical capabilities and access to a greater variety of Solar System materials (through systematic and sustained meteorite collection programs as well as sample return missions) have led to significant insights that are complementary to those from remote observations and measurements. I will discuss two examples where the combination of remote observations and sample analyses has the potential to provide a more holistic picture of Solar System formation and evolution: 1) High-precision analyses of radiogenic isotopes in primitive and differentiated meteoritic materials, which are yielding a detailed high-resolution chronology of the first 10 million years of Solar System history. Such investigations are providing the chronological framework for the formation and evolution of small bodies (including comets, asteroids and Kuiper Belt Objects) in our Solar System that are the targets of recent spacecraft missions such as NASA's Dawn and New Horizons missions and ESA's Rosetta mission. 2) In-situ analyses of hydrogen isotope compositions and H2O abundances in meteorites from Mars and Vesta, which are giving constraints on the inventory and source of water and other volatiles in these planetary bodies. These studies are providing insights complementary to those about Mars from NASA's Mars Science Laboratory and Mars Atmosphere and Volatile Evolution (MAVEN) missions, and about Vesta from NASA's Dawn mission.

Experimental Analysis of File Transfer Rates over Wide-Area Dedicated Connections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, Nageswara S.; Liu, Qiang; Sen, Satyabrata

2016-12-01

File transfers over dedicated connections, supported by large parallel file systems, have become increasingly important in high-performance computing and big data workflows. It remains a challenge to achieve peak rates for such transfers due to the complexities of file I/O, host, and network transport subsystems, and equally importantly, their interactions. We present extensive measurements of disk-to-disk file transfers using Lustre and XFS file systems mounted on multi-core servers over a suite of 10 Gbps emulated connections with 0-366 ms round trip times. Our results indicate that large buffer sizes and many parallel flows do not always guarantee high transfer rates.more » Furthermore, large variations in the measured rates necessitate repeated measurements to ensure confidence in inferences based on them. We propose a new method to efficiently identify the optimal joint file I/O and network transport parameters using a small number of measurements. We show that for XFS and Lustre with direct I/O, this method identifies configurations achieving 97% of the peak transfer rate while probing only 12% of the parameter space.« less

Thermopyhsical conditions for the onset of a core dynamo in Vesta

NASA Astrophysics Data System (ADS)

Formisano, Michelangelo; Federico, Costanzo; De Angelis, Simone; De Sanctis, Maria Cristina; Magni, Gianfranco

2016-04-01

Recently, a study on the magnetization of the eucrite meteorite Allan Hills A81001 [1] has suggested the possibility that, in its primordial history, Vesta had an active core dynamo. The magnetic field associated could have preserved Vesta from the space-weathering. In this work, using a parametrized thermal convection method, we verified the thermophysical conditions for the onset of a core dynamo. The starting point is a post-differentiated structure [2,3,4], made of a metallic core, silicate mantle and rocky crust. We explored four different fully differentiated configurations of Vesta [5], characterized by different chondritic composition, with the constraints on the core size and density provided by [6]. We also explored three different scaling laws for the core velocity (mixing-length theory, MAC and an intermediate case). Core and mantle have both a temperature-dependent viscosity, which is the parameter that largely influences the magnetic Reynolds number and the dynamo duration. Our results suggest that Vesta had an active dynamo, whose duration lies in the range 150-500 Myr and the more appropriate scaling law for the core velocity is that given by the mixing-length theory. The maximum strength of the primordial core magnetic field is compatible with the estimations provided by [1]. [1] Fu, R. et al, 2012, Science 338, 238 [2] Ghosh, A. and McSween, H.Y., 1998, Icarus, 134, 187 [3] Formisano, M. et al., 2013, Meteoritics and Planetary Science, 48, 2316 [4] Neumann, W., et al., 2014, Earth and Planetary Science Letters, 395, 267 [5] Toplis, M.J., et al., 2013, Meteoritics and Planetary Science, 48, 2300 [6] Ermakov, A.I., et al.2014, Icarus, 240, 146

Vesta in the Light of Dawn: A Nuanced Confirmation of Expectations

NASA Astrophysics Data System (ADS)

Russell, C. T.

The ion-engine propelled Discovery-class mission Dawn was launched on its near decade-long odyssey to explore the two most massive asteroids in the main belt, 4 Vesta and 1 Ceres, in September 2007. Based on its mass and volume, its basaltic crust, and the chemistry of the associated HED meteorites, Vesta was expected to consist of a completely differentiated dry silicate body with an iron core in contrast to Ceres, whose much smaller density implied a much wetter body, perhaps with liquid water beneath the crust. Upon entering vestan orbit in July 2001, Dawn discovered that indeed the surface resembled the HED meteorites and the gravity data were consistent with a differentiated body with a 110-km radius core. The large southern basin seen from HST was studied and found to consist of two ancient impact basins with associated planetary rings of graben-like fossae. The water that had been hinted at in reflectance spectra observed by terrestrial telescopes was seen more broadly over the surface as was hydrogen detected with the GRaND gamma ray and neutron spectrometer. Moreover, some craters showed evidence for both running and standing water: gullies in the crater walls and pits in the crater floors. Furthermore, the expected exposure of olivine in the southern basin was not found. The presence of water, even if only transient, on the surface of Vesta, and the apparent lack of an olivine mantle were unexpected results. While these observations do not negate the earlier work based on the HED meteorites, they do add important new insight into the conditions under which Vesta formed and evolved.

Prefetching in file systems for MIMD multiprocessors

NASA Technical Reports Server (NTRS)

Kotz, David F.; Ellis, Carla Schlatter

1990-01-01

The question of whether prefetching blocks on the file into the block cache can effectively reduce overall execution time of a parallel computation, even under favorable assumptions, is considered. Experiments have been conducted with an interleaved file system testbed on the Butterfly Plus multiprocessor. Results of these experiments suggest that (1) the hit ratio, the accepted measure in traditional caching studies, may not be an adequate measure of performance when the workload consists of parallel computations and parallel file access patterns, (2) caching with prefetching can significantly improve the hit ratio and the average time to perform an I/O (input/output) operation, and (3) an improvement in overall execution time has been observed in most cases. In spite of these gains, prefetching sometimes results in increased execution times (a negative result, given the optimistic nature of the study). The authors explore why it is not trivial to translate savings on individual I/O requests into consistently better overall performance and identify the key problems that need to be addressed in order to improve the potential of prefetching techniques in the environment.

The Scalable Checkpoint/Restart Library

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moody, A.

The Scalable Checkpoint/Restart (SCR) library provides an interface that codes may use to worite our and read in application-level checkpoints in a scalable fashion. In the current implementation, checkpoint files are cached in local storage (hard disk or RAM disk) on the compute nodes. This technique provides scalable aggregate bandwidth and uses storage resources that are fully dedicated to the job. This approach addresses the two common drawbacks of checkpointing a large-scale application to a shared parallel file system, namely, limited bandwidth and file system contention. In fact, on current platforms, SCR scales linearly with the number of compute nodes.more » It has been benchmarked as high as 720GB/s on 1094 nodes of Atlas, which is nearly two orders of magnitude faster thanthe parallel file system.« less

Toward Millions of File System IOPS on Low-Cost, Commodity Hardware

PubMed Central

Zheng, Da; Burns, Randal; Szalay, Alexander S.

2013-01-01

We describe a storage system that removes I/O bottlenecks to achieve more than one million IOPS based on a user-space file abstraction for arrays of commodity SSDs. The file abstraction refactors I/O scheduling and placement for extreme parallelism and non-uniform memory and I/O. The system includes a set-associative, parallel page cache in the user space. We redesign page caching to eliminate CPU overhead and lock-contention in non-uniform memory architecture machines. We evaluate our design on a 32 core NUMA machine with four, eight-core processors. Experiments show that our design delivers 1.23 million 512-byte read IOPS. The page cache realizes the scalable IOPS of Linux asynchronous I/O (AIO) and increases user-perceived I/O performance linearly with cache hit rates. The parallel, set-associative cache matches the cache hit rates of the global Linux page cache under real workloads. PMID:24402052

Toward Millions of File System IOPS on Low-Cost, Commodity Hardware.

PubMed

Zheng, Da; Burns, Randal; Szalay, Alexander S

2013-01-01

We describe a storage system that removes I/O bottlenecks to achieve more than one million IOPS based on a user-space file abstraction for arrays of commodity SSDs. The file abstraction refactors I/O scheduling and placement for extreme parallelism and non-uniform memory and I/O. The system includes a set-associative, parallel page cache in the user space. We redesign page caching to eliminate CPU overhead and lock-contention in non-uniform memory architecture machines. We evaluate our design on a 32 core NUMA machine with four, eight-core processors. Experiments show that our design delivers 1.23 million 512-byte read IOPS. The page cache realizes the scalable IOPS of Linux asynchronous I/O (AIO) and increases user-perceived I/O performance linearly with cache hit rates. The parallel, set-associative cache matches the cache hit rates of the global Linux page cache under real workloads.

Mineralogy of Inverted Pigeonite and Plagioclase in Cumulate Eucrites Y-980433 and Y-980318 with Reference to Early Crust Formation of the Vesta-Like Body

NASA Technical Reports Server (NTRS)

Takeda, H.; Ohtake, M.; Hiroi, T.; Nyquist, L. E.; Shih, C.-Y.; Yamaguchi, A.; Nagaoka, H.

2011-01-01

On July 16, the Dawn spacecraft became the first probe to enter orbit around asteroid 4 Vesta and will study the asteroid for a year before departing for Ceres. The Vesta-HED link is directly tied to the observed and inferred mineralogy of the asteroid and the mineralogy of the meteorites [1]. Pieters et al. [2] reported reflectance spectra of the Yamato- (Y-)980318 cumulate eucrite as a part of their study on the Asteroid-Meteorite Links in connection with the Dawn Mission. Pyroxenes and calcic plagioclase are the dominant minerals present in HED meteorites and provide multiple clues about how the parent body evolved [1]. The differentiation trends of HED meteorites are much simpler than those of the lunar crust

Secular resonances with Ceres and Vesta

NASA Astrophysics Data System (ADS)

Tsirvoulis, Georgios; Novaković, Bojan

2016-12-01

In this work we explore dynamical perturbations induced by the massive asteroids Ceres and Vesta on main-belt asteroids through secular resonances. First we determine the location of the linear secular resonances with Ceres and Vesta in the main belt, using a purely numerical technique. Then we use a set of numerical simulations of fictitious asteroids to investigate the importance of these secular resonances in the orbital evolution of main-belt asteroids. We found, evaluating the magnitude of the perturbations in the proper elements of the test particles, that in some cases the strength of these secular resonances is comparable to that of known non-linear secular resonances with the giant planets. Finally we explore the asteroid families that are crossed by the secular resonances we studied, and identified several cases where the latter seem to play an important role in their post-impact evolution.

Development of the Large-Scale Statistical Analysis System of Satellites Observations Data with Grid Datafarm Architecture

NASA Astrophysics Data System (ADS)

Yamamoto, K.; Murata, K.; Kimura, E.; Honda, R.

2006-12-01

In the Solar-Terrestrial Physics (STP) field, the amount of satellite observation data has been increasing every year. It is necessary to solve the following three problems to achieve large-scale statistical analyses of plenty of data. (i) More CPU power and larger memory and disk size are required. However, total powers of personal computers are not enough to analyze such amount of data. Super-computers provide a high performance CPU and rich memory area, but they are usually separated from the Internet or connected only for the purpose of programming or data file transfer. (ii) Most of the observation data files are managed at distributed data sites over the Internet. Users have to know where the data files are located. (iii) Since no common data format in the STP field is available now, users have to prepare reading program for each data by themselves. To overcome the problems (i) and (ii), we constructed a parallel and distributed data analysis environment based on the Gfarm reference implementation of the Grid Datafarm architecture. The Gfarm shares both computational resources and perform parallel distributed processings. In addition, the Gfarm provides the Gfarm filesystem which can be as virtual directory tree among nodes. The Gfarm environment is composed of three parts; a metadata server to manage distributed files information, filesystem nodes to provide computational resources and a client to throw a job into metadata server and manages data processing schedulings. In the present study, both data files and data processes are parallelized on the Gfarm with 6 file system nodes: CPU clock frequency of each node is Pentium V 1GHz, 256MB memory and40GB disk. To evaluate performances of the present Gfarm system, we scanned plenty of data files, the size of which is about 300MB for each, in three processing methods: sequential processing in one node, sequential processing by each node and parallel processing by each node. As a result, in comparison between the number of files and the elapsed time, parallel and distributed processing shorten the elapsed time to 1/5 than sequential processing. On the other hand, sequential processing times were shortened in another experiment, whose file size is smaller than 100KB. In this case, the elapsed time to scan one file is within one second. It implies that disk swap took place in case of parallel processing by each node. We note that the operation became unstable when the number of the files exceeded 1000. To overcome the problem (iii), we developed an original data class. This class supports our reading of data files with various data formats since it converts them into an original data format since it defines schemata for every type of data and encapsulates the structure of data files. In addition, since this class provides a function of time re-sampling, users can easily convert multiple data (array) with different time resolution into the same time resolution array. Finally, using the Gfarm, we achieved a high performance environment for large-scale statistical data analyses. It should be noted that the present method is effective only when one data file size is large enough. At present, we are restructuring the new Gfarm environment with 8 nodes: CPU is Athlon 64 x2 Dual Core 2GHz, 2GB memory and 1.2TB disk (using RAID0) for each node. Our original class is to be implemented on the new Gfarm environment. In the present talk, we show the latest results with applying the present system for data analyses with huge number of satellite observation data files.

FT-IR and µ-IR characterization of HED meteorites in relation to infrared spectra of Vesta-like asteroids

NASA Astrophysics Data System (ADS)

Ferrari, M.; Dirri, F.; Palomba, E.; Stefani, S.; Longobardo, A.; Rotundi, A.

2017-09-01

We present the results of the FT-IR and µ-IR study of three Howardite-Eucrite-Diogenite meteorites (HEDs) compared to the spectroscopic data collected by VIR onboard Dawn spacecraft. The origin of this group of achondrites is thought to be linked to the asteroid 4 Vesta, hypothesis lately reinforced by the data provided by the Dawn mission.

Cosmic Ray Exposure Ages, Ar-Ar Ages, and the Origin and History of Eucrites

NASA Technical Reports Server (NTRS)

Wakefield, Kelli; Bogard, Donald; Garrison, Daniel

2004-01-01

HED meteorites likely formed at different depths on the large asteroid 4-Vesta, but passed through Vesta-derived, km-sized intermediary bodies (Vestoids), before arriving at Earth. Most eucrites and diogenites (and all howardites) are brecciated, and impact heating disturbed or reset the K-Ar ages (and some Rb-Sr ages) of most eucrites in the time period of approx. 3.4 - 4.1 Gyr ago. Some basaltic eucrites and most cumulate eucrites, however, are not brecciated. We recently showed that the Ar-39 - Ar-40 ages for several of these eucrites tightly cluster about a value of 4.48 +/- 0.02 Gyr, and we argue that this time likely represents a single large impact event on Vesta, which ejected these objects from depth and quenched their temperatures. A different parent body has been suggested for cumulate eucrites, although the Ar-Ar ages argue for a common parent. Similarities in the cosmic-ray (space) exposure ages for basaltic eucrites and diogenites also have been used to infer a common parent body for some HEDs. Here we present CRE ages of several cumulate and unbrecciated basaltic (UB) eucrites and compare these with CRE ages of other HEDs. This comparison also has some interesting implications for the relative locations of various HED types on Vesta and/or the Vestoids.

How to characterize terrains on 4 Vesta using Dawn Framing Camera color bands?

NASA Astrophysics Data System (ADS)

Le Corre, Lucille; Reddy, Vishnu; Nathues, Andreas; Cloutis, Edward A.

2011-12-01

We present methods for terrain classification on 4 Vesta using Dawn Framing Camera (FC) color information derived from laboratory spectra of HED meteorites and other Vesta-related assemblages. Color and spectral parameters have been derived using publicly available spectra of these analog materials to identify the best criteria for distinguishing various terrains. We list the relevant parameters for identifying eucrites, diogenites, mesosiderites, pallasites, clinopyroxenes and olivine + orthopyroxene mixtures using Dawn FC color cubes. Pseudo Band I minima derived by fitting a low order polynomial to the color data are found to be useful for extracting the pyroxene chemistry. Our investigation suggests a good correlation (R2 = 0.88) between laboratory measured ferrosilite (Fs) pyroxene chemistry vs. those from pseudo Band I minima using equations from Burbine et al. (Burbine, T.H., Buchanan, P.C., Dolkar, T., Binzel, R.P. [2009]. Planetary Science 44, 1331-1341). The pyroxene chemistry information is a complementary terrain classification capability beside the color ratios. We also investigated the effects of exogenous material (i.e., CM2 carbonaceous chondrites) on the spectra of HEDs using laboratory mixtures of these materials. Our results are the basis for an automated software pipeline that will allow us to classify terrains on 4 Vesta efficiently.

Mesosiderites on Vesta: A Hyperspectral VIS-NIR Investigation

NASA Technical Reports Server (NTRS)

Palomba, E.; Longobardo, A.; DeSanctis, M. C.; Mittlefehldt, D. W.; Ammannito, E.; Capaccioni, F.; Capria, M. T.; Frigeri, A.; Tosi, F.; Zambon, F.;

Lessons Learned in Deploying the World s Largest Scale Lustre File System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dillow, David A; Fuller, Douglas; Wang, Feiyi

2010-01-01

The Spider system at the Oak Ridge National Laboratory's Leadership Computing Facility (OLCF) is the world's largest scale Lustre parallel file system. Envisioned as a shared parallel file system capable of delivering both the bandwidth and capacity requirements of the OLCF's diverse computational environment, the project had a number of ambitious goals. To support the workloads of the OLCF's diverse computational platforms, the aggregate performance and storage capacity of Spider exceed that of our previously deployed systems by a factor of 6x - 240 GB/sec, and 17x - 10 Petabytes, respectively. Furthermore, Spider supports over 26,000 clients concurrently accessing themore » file system, which exceeds our previously deployed systems by nearly 4x. In addition to these scalability challenges, moving to a center-wide shared file system required dramatically improved resiliency and fault-tolerance mechanisms. This paper details our efforts in designing, deploying, and operating Spider. Through a phased approach of research and development, prototyping, deployment, and transition to operations, this work has resulted in a number of insights into large-scale parallel file system architectures, from both the design and the operational perspectives. We present in this paper our solutions to issues such as network congestion, performance baselining and evaluation, file system journaling overheads, and high availability in a system with tens of thousands of components. We also discuss areas of continued challenges, such as stressed metadata performance and the need for file system quality of service alongside with our efforts to address them. Finally, operational aspects of managing a system of this scale are discussed along with real-world data and observations.« less

GWM-VI: groundwater management with parallel processing for multiple MODFLOW versions

USGS Publications Warehouse

Banta, Edward R.; Ahlfeld, David P.

2013-01-01

Groundwater Management–Version Independent (GWM–VI) is a new version of the Groundwater Management Process of MODFLOW. The Groundwater Management Process couples groundwater-flow simulation with a capability to optimize stresses on the simulated aquifer based on an objective function and constraints imposed on stresses and aquifer state. GWM–VI extends prior versions of Groundwater Management in two significant ways—(1) it can be used with any version of MODFLOW that meets certain requirements on input and output, and (2) it is structured to allow parallel processing of the repeated runs of the MODFLOW model that are required to solve the optimization problem. GWM–VI uses the same input structure for files that describe the management problem as that used by prior versions of Groundwater Management. GWM–VI requires only minor changes to the input files used by the MODFLOW model. GWM–VI uses the Joint Universal Parameter IdenTification and Evaluation of Reliability Application Programming Interface (JUPITER-API) to implement both version independence and parallel processing. GWM–VI communicates with the MODFLOW model by manipulating certain input files and interpreting results from the MODFLOW listing file and binary output files. Nearly all capabilities of prior versions of Groundwater Management are available in GWM–VI. GWM–VI has been tested with MODFLOW-2005, MODFLOW-NWT (a Newton formulation for MODFLOW-2005), MF2005-FMP2 (the Farm Process for MODFLOW-2005), SEAWAT, and CFP (Conduit Flow Process for MODFLOW-2005). This report provides sample problems that demonstrate a range of applications of GWM–VI and the directory structure and input information required to use the parallel-processing capability.

17 CFR 12.24 - Parallel proceedings.

Code of Federal Regulations, 2010 CFR

2010-04-01

...) Definition. For purposes of this section, a parallel proceeding shall include: (1) An arbitration proceeding... the receivership includes the resolution of claims made by customers; or (3) A petition filed under... any of the foregoing with knowledge of a parallel proceeding shall promptly notify the Commission, by...

An Approach Using Parallel Architecture to Storage DICOM Images in Distributed File System

NASA Astrophysics Data System (ADS)

Soares, Tiago S.; Prado, Thiago C.; Dantas, M. A. R.; de Macedo, Douglas D. J.; Bauer, Michael A.

2012-02-01

Telemedicine is a very important area in medical field that is expanding daily motivated by many researchers interested in improving medical applications. In Brazil was started in 2005, in the State of Santa Catarina has a developed server called the CyclopsDCMServer, which the purpose to embrace the HDF for the manipulation of medical images (DICOM) using a distributed file system. Since then, many researches were initiated in order to seek better performance. Our approach for this server represents an additional parallel implementation in I/O operations since HDF version 5 has an essential feature for our work which supports parallel I/O, based upon the MPI paradigm. Early experiments using four parallel nodes, provide good performance when compare to the serial HDF implemented in the CyclopsDCMServer.

MPI-IO: A Parallel File I/O Interface for MPI Version 0.3

NASA Technical Reports Server (NTRS)

Corbett, Peter; Feitelson, Dror; Hsu, Yarsun; Prost, Jean-Pierre; Snir, Marc; Fineberg, Sam; Nitzberg, Bill; Traversat, Bernard; Wong, Parkson

1995-01-01

Thanks to MPI [9], writing portable message passing parallel programs is almost a reality. One of the remaining problems is file I/0. Although parallel file systems support similar interfaces, the lack of a standard makes developing a truly portable program impossible. Further, the closest thing to a standard, the UNIX file interface, is ill-suited to parallel computing. Working together, IBM Research and NASA Ames have drafted MPI-I0, a proposal to address the portable parallel I/0 problem. In a nutshell, this proposal is based on the idea that I/0 can be modeled as message passing: writing to a file is like sending a message, and reading from a file is like receiving a message. MPI-IO intends to leverage the relatively wide acceptance of the MPI interface in order to create a similar I/0 interface. The above approach can be materialized in different ways. The current proposal represents the result of extensive discussions (and arguments), but is by no means finished. Many changes can be expected as additional participants join the effort to define an interface for portable I/0. This document is organized as follows. The remainder of this section includes a discussion of some issues that have shaped the style of the interface. Section 2 presents an overview of MPI-IO as it is currently defined. It specifies what the interface currently supports and states what would need to be added to the current proposal to make the interface more complete and robust. The next seven sections contain the interface definition itself. Section 3 presents definitions and conventions. Section 4 contains functions for file control, most notably open. Section 5 includes functions for independent I/O, both blocking and nonblocking. Section 6 includes functions for collective I/O, both blocking and nonblocking. Section 7 presents functions to support system-maintained file pointers, and shared file pointers. Section 8 presents constructors that can be used to define useful filetypes (the role of filetypes is explained in Section 2 below). Section 9 presents how the error handling mechanism of MPI is supported by the MPI-IO interface. All this is followed by a set of appendices, which contain information about issues that have not been totally resolved yet, and about design considerations. The reader can find there the motivation behind some of our design choices. More information on this would definitely be welcome and will be included in a further release of this document. The first appendix contains a description of MPI-I0's 'hints' structure which is used when opening a file. Appendix B is a discussion of various issues in the support for file pointers. Appendix C explains what we mean in talking about atomic access. Appendix D provides detailed examples of filetype constructors, and Appendix E contains a collection of arguments for and against various design decisions.

The Impact History of Vesta: New Views from the Dawn Mission

NASA Technical Reports Server (NTRS)

OBrien, D. P.; Marchi, S.; Schenk, P.; Mittlefehldt, D. W.; Jaumann, R.; Ammannito, E.; Buczkowski, D. L.; DeSanctis, M. C.; Filacchione, G.; Gaskell, R.;

Global Surface Thermal Inertia Derived from Dawn VIR Observations

NASA Astrophysics Data System (ADS)

Titus, T. N.; Becker, K. J.; Anderson, J.; Capria, M.; Tosi, F.; Prettyman, T. H.; De Sanctis, M. C.; Palomba, E.; Grassi, D.; Capaccioni, F.; Ammannito, E.; Combe, J.; McCord, T. B.; Li, J. Y.; Russell, C. T.; Raymond, C. A.

2012-12-01

Comparisons of surface temperatures, derived from Dawn [1] Visible and Infrared Mapping Spectrometer (VIR-MS) [2] observations , to thermal models suggest that Vesta generally has a low-thermal-inertia surface, between 25 and 35 J m^-2 K^-1 s^-½, consistent with a thick layer of fine-grain material [3]. Temperatures were calculated using a Bayesian approach to nonlinear inversion as described by Tosi et al. [4]. In order to compare observed temperatures of Vesta to model calculations, several geometric and photometric parameters must be known or estimated. These include local mean solar time, latitude, local slope, bond bolometric albedo, and the effective emissivity at 5μm. Local time, latitude, and local slope are calculated using the USGS ISIS software system [5]. We employ a multi-layered thermal-diffusion model called 'KRC' [6], which has been used extensively in the study of Martian thermophysical properties. This thermal model is easily modified for use with Vesta by replacing the Martian ephemeris input with the Vesta ephemeris and disabling the atmosphere. This model calculates surface temperatures throughout an entire Vesta year for specific sets of slope, azimuth, latitude and elevation, and a range of albedo and thermal-inertia values. The ranges of albedo and thermal inertia values create temperature indices that are closely matched to the dates and times observed by VIR. Based on observed temperatures and best-fit KRC thermal models, estimates of the annual mean surface temperatures were found to range from 176 K - 188 K for flat zenith-facing equatorial surfaces, but these temperatures can drop as low as 112 K for polar-facing slopes at mid-latitudes. [7] In this work, we will compare observed temperatures of the surface of Vesta (using data acquired by Dawn VIR-MS [2] during the approach, survey, high-altitude mapping and departure phases) to model temperature results using the KRC thermal model [5]. Where possible, temperature observations from multiple times of day or seasons will be used to better constrain the thermal inertia. The authors gratefully acknowledge the support of the Dawn Instrument, Operations, and Science Teams. This work was funded by the Dawn at Vesta Participating Science Program. [1] C.T. Russell et al. (2004) P&SS, 52, 465-489. [2] M.C. De Sanctis et al. (2011) SSRv 163, 329. [3] M.T. Capria et al. (2012) LPSC XLIII #1863 [4] F. Tosi et al. (2012) LPSC XLIII #1886. [5] J. Anderson et al. (2011) AGU Fall Meeting, #U31A-0009. [6] H.H. Kieffer H., et al. (1977) JGR, 82, 4249-4291. [7] Titus et al. (2012) EPSC, #800.

nem_spread Ver. 5.10

DOE Office of Scientific and Technical Information (OSTI.GOV)

HENNIGAN, GARY; SHADID, JOHN; SJAARDEMA, GREGORY

2009-06-08

Nem_spread reads it's input command file (default name nem_spread.inp), takes the named ExodusII geometry definition and spreads out the geometry (and optionally results) contained in that file out to a parallel disk system. The decomposition is taken from a scalar Nemesis load balance file generated by the companion utility nem_slice.

More chips off of Asteroid (4) Vesta: Characterization of eight Vestoids and their HED meteorite analogs

NASA Astrophysics Data System (ADS)

Hardersen, Paul S.; Reddy, Vishnu; Roberts, Rachel; Mainzer, Amy

2014-11-01

Vestoids are generally considered to be fragments from Asteroid (4) Vesta that were ejected by past collisions that document Vesta's collisional history. Dynamical Vestoids are defined by their spatial proximity with Vesta (Zappala, V., Bendjoya, Ph., Cellino, A., Farinella, P., Froeschle', C. [1995]. Icarus 116, 291-314; Nesvorny, D. [2012]. Nesvorny HCM Asteroid Families V2.0. EAR-A-VARGBDET-5-NESVORNYFAM-V2.0. NASA Planetary Data System.). Taxonomic Vestoids are defined as V-type asteroids that have a photometric, visible-wavelength spectral, or other observational relationship with Vesta (Tholen, D.J., 1984. Asteroid Taxonomy from Cluster Analysis of Photometry. Ph.D. Thesis, University of Arizona, Tucson; Bus, S.J., Binzel, R.P. [2002]. Icarus 158, 106-145; Carvano, J., Hasselmann, P.H., Lazzaro, D., Mothe'-Diniz, T. [2010]. Astron. Astrophys. 510, A43). We define 'genetic Vestoids' as V-type asteroids that are probable fragments ejected from (4) Vesta based on the supporting combination of dynamical, near-infrared (NIR) spectral, and taxonomic evidence. NIR reflectance spectroscopy is one of the primary ground-based techniques to constrain an asteroid's major surface mineralogy (Burns, R.G. [1993a]. Mineralogical Applications of Crystal Field Theory. Cambridge University Press, Cambridge, UK, 551 p). Despite the reasonable likelihood that many dynamical and taxonomic Vestoids likely originate from Vesta, ambiguity exists concerning the fraction of these populations that are from Vesta as compared to the fraction of asteroids that might not be related to Vesta. Currently, one of the most robust techniques to identify the genetic Vestoid population is through NIR reflectance spectroscopy from ∼0.7 to 2.5 μm. The derivation of spectral band parameters, and the comparison of those band parameters with those from representative samples from the Howardite-Eucrite-Diogenite (HED) meteorite types, allows a direct comparison of their primary mineralogies. Establishing tighter constraints on the genetic Vestoid population will better inform mass estimates for the current population of probable Vestoids, will provide more accurate orbital information of Vestoid migration through time that will assist dynamical models, and will constrain the overall current abundance of basaltic material in the main asteroid belt (Moskovitz, N.A., Jedicke, R., Gaidos, E., Willman, M., Nesvorny, D., Fevig, R. [2008]. Icarus 198, 77-90). This work reports high-quality NIR spectra, and their respective interpretations, for eight Vp-type asteroids, as defined by Carvano et al. (Carvano, J., Hasselmann, P.H., Lazzaro, D., Mothe'-Diniz, T. [2010]. Astron. Astrophys. 510, A43), that were observed at the NASA Infrared Telescope Facility on January 14, 2013 UT. They include: (3867) Shiretoko, (5235) Jean-Loup, (5560) Amytis, (6331) 1992 FZ1, (6976) Kanatsu, (17469) 1991 BT, (29796) 1999 CW77, and (30872) 1992 EM17. All eight asteroids exhibit the broad ∼0.9- and ∼1.9-μm mineral absorption features indicative of pyroxene on each asteroid's surface. Data reduction and analysis via multiple techniques produced consistent results for the derived spectral absorption band centers and average pyroxene surface chemistries for all eight asteroids (Reddy, V., Sanchez, J.A., Nathues, A., Moskovitz, N.A., Li, J.-Y, Cloutis, E.A., Archer, K., Tucker, R.A., Gaffey, M.J., Mann, P.J., Sierks, H., Schade, U. [2012c]. Icarus 217, 153-168; Lindsay, S.S., Emery, J.P., Marchis, F., Enriquez, J., Assafin, M. [2013]. A spectroscopic and mineralogic study of multiple asteroid systems. American Astronomical Society, DPS Meeting #45, #112.04; Lindsay, S.S., Marchis, F., Emery, J.P., Enriquez, J.E., Assafin, M. [2014]. Icarus, submitted for publication; Gaffey, M.J., Cloutis, E.A., Kelley, M.K., Reed, K.L. [2002]. Mineralogy of asteroids. In: Bottke Jr., W.F., Cellino, A., Paolicchi, P., Binzel, R.P. (Eds.), Asteroids III. The University of Arizona Press, Tucson, pp. 183-204; Burbine, T.H., Buchanan, P.C., Dolkar, T., Binzel, R.P. [2009]. Met. Planet. Sci. 44, 1331-1341.). (3867) Shiretoko is most consistent with the eucrite meteorites while the remaining seven asteroids are most consistent with the howardite meteorites. The existing evidence suggests that all eight of these Vp-type asteroids are genetic Vestoids that probably originated from Vesta's surface.

Dawn Mission: A Journey in Space and Time

NASA Technical Reports Server (NTRS)

Russell, C. T.; Coradini, A.; DeSanctis, M. C.; Feldman, W. C.; Jaumann, R.; Konopliv, A. S.; McCord, T. B.; McFadden, L. A.; McSween, H. Y.; Mottola, S.

2003-01-01

By successively orbiting both 4 Vesta and 1 Ceres the Dawn mission directly addresses the longstanding goals of NASA and the planetary community to understand the origin and evolution of the solar system by obtaining geophysical and geochemical data on diverse main belt asteroids. Ceres and Vesta are two complementary terrestrial protoplanets (one apparently "wet" and one "dry"), whose accretion was terminated by the formation of Jupiter. Ceres is little changed since it formed in the early solar system, while Vesta has experienced significant heating and differentiation. Both have remained intact over the age of the solar system, thereby retaining a record of events and processes from the time of planet formation. Detailed study of the geophysics and geochemistry of these two bodies provides critical benchmarks for the early solar system conditions and processes that shaped its subsequent evolution. Dawn provides the missing context for both primitive and evolved meteoritic data, thus playing a central role in understanding terrestrial planet formation and the evolution of the asteroid belt. Dawn is to be launched in May 2006 arriving at Vesta in 2010 and Ceres in 2014, stopping at each to make 11 months of orbital measurements. The spacecraft uses solar electric propulsion both in cruise and in orbit to make most efficient use of its xenon propellant. The spacecraft carries a framing camera, visible and infrared mapping spectrometer, gamma ray/neutron spectrometer, a laser altimeter, magnetometer, and radio science.

High performance data transfer

NASA Astrophysics Data System (ADS)

Cottrell, R.; Fang, C.; Hanushevsky, A.; Kreuger, W.; Yang, W.

2017-10-01

The exponentially increasing need for high speed data transfer is driven by big data, and cloud computing together with the needs of data intensive science, High Performance Computing (HPC), defense, the oil and gas industry etc. We report on the Zettar ZX software. This has been developed since 2013 to meet these growing needs by providing high performance data transfer and encryption in a scalable, balanced, easy to deploy and use way while minimizing power and space utilization. In collaboration with several commercial vendors, Proofs of Concept (PoC) consisting of clusters have been put together using off-the- shelf components to test the ZX scalability and ability to balance services using multiple cores, and links. The PoCs are based on SSD flash storage that is managed by a parallel file system. Each cluster occupies 4 rack units. Using the PoCs, between clusters we have achieved almost 200Gbps memory to memory over two 100Gbps links, and 70Gbps parallel file to parallel file with encryption over a 5000 mile 100Gbps link.

75 FR 40815 - PJM Interconnection, L.L.C.; Notice of Filing

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-14

... Interconnection, L.L.C.; Notice of Filing July 7, 2010. Take notice that on July 1, 2010, PJM Interconnection, L.L.C. (PJM) filed revised sheets to Schedule 1 of the Amended and Restated Operating Agreement of PJM Interconnection, L.L.C. (Operating Agreement) and the parallel provisions of Attachment K--Appendix of the PJM...

In-Flight Operation of the Dawn Ion Propulsion System - The First Nine Months

NASA Technical Reports Server (NTRS)

Garner, Charles E.; Brophy, John R.; Mikes, Steven C.; Raymond, Marc D.

2008-01-01

The Dawn mission, part of NASA's Discovery Program, has as its goal the scientific exploration of the two most massive main-belt asteroids, Vesta and Ceres. The Dawn spacecraft was launched from Cape Canaveral Air Force Station on September 27, 2007 on a Delta-II 7925H-9.5 (Delta-II Heavy) rocket that placed the 1218 kg spacecraft into an Earth-escape trajectory. On-board the spacecraft is an ion propulsion system (IPS) which will provide most of the delta-V needed for heliocentric transfer to Vesta, orbit capture at Vesta, transfer to Vesta science orbits, departure and escape from Vesta, heliocentric transfer to Ceres, orbit capture at Ceres, and transfer to Ceres science orbits. The Dawn ion engine design is based on the design validated on NASA's Deep Space 1 mission. However, because of the very substantial (11 km/s) delta-V requirements for this mission Dawn requires two engines to complete its mission objectives. The power processor units (PPU), digital control and interface units (DCIU) slice boards and the xenon control assembly (XCA) are also based on the DS1 design. The DCIUs and thrust gimbal assemblies (TGA) were developed at the Jet Propulsion Laboratory. The spacecraft was provided by Orbital Sciences Corporation, Sterling, Virginia, and the mission is managed by and operated from the Jet Propulsion Laboratory. Dawn partnered with Germany, Italy and Los Alamos National Laboratory for the science instruments. The mission is led by the principal investigator, Dr. Christopher Russell, from the University of California, Los Angeles. The first 80 days after launch were dedicated to the initial checkout of the spacecraft prior to the initiation of long-term thrusting for the heliocentric transfer to Vesta. The IPS hardware, consisting of three ion thrusters and TGAs, two PPUs and DCIUs, xenon feed system, and spacecraft control software, was investigated extensively. Thrust measurements, roll torque measurements, pointing capabilities, control characteristics, and thermal behavior of the spacecraft and IPS were carefully evaluated. The Dawn IPS fully met all its initial checkout performance objectives. Deterministic thrusting for cruise began on December 17, 2007. Over the subsequent approximately 330 days the IPS will be operated virtually continuously at full power thrusting (approximately 91 mN) leading to a Mars flyby in February 2009. The encounter with Mars provides a gravity assist for a plane change and is the only source of post-launch delta-V apart from the IPS. Following the Mars gravity assist IPS will be operated for approximately one year at full power and for 1.3 years at throttled power levels leading to rendezvous with Vesta in August of 2011. Following nine months of orbital operations with IPS providing the propulsion needed for orbit capture, science orbit transfer and orbit maintenance and Vesta escape, Dawn will transit to Ceres with an expected arrival date of February 2015. As of June 16, 2008 the ion thrusters on Dawn have operated for close to 3,846 hours and have delivered nearly 1 km/s of delta-V to the spacecraft. Dawn IPS operation has been almost flawless during the initial checkout and six months of cruise. This paper provides an overview of Dawn's mission objectives, mission and system design, and the results of the post-launch Dawn IPS mission operations through June 2008

Dawn's Gamma Ray and Neutron Detector

NASA Astrophysics Data System (ADS)

Prettyman, Thomas H.; Feldman, William C.; McSween, Harry Y.; Dingler, Robert D.; Enemark, Donald C.; Patrick, Douglas E.; Storms, Steven A.; Hendricks, John S.; Morgenthaler, Jeffery P.; Pitman, Karly M.; Reedy, Robert C.

2011-12-01

The NASA Dawn Mission will determine the surface composition of 4 Vesta and 1 Ceres, providing constraints on their formation and thermal evolution. The payload includes a Gamma Ray and Neutron Detector (GRaND), which will map the surface elemental composition at regional spatial scales. Target elements include the constituents of silicate and oxide minerals, ices, and the products of volcanic exhalation and aqueous alteration. At Vesta, GRaND will map the mixing ratio of end-members of the howardite, diogenite, and eucrite (HED) meteorites, determine relative proportions of plagioclase and mafic minerals, and search for compositions not well sampled by the meteorite collection. The large south polar impact basin may provide an opportunity to determine the composition of Vesta’s mantle and lower crust. At Ceres, GRaND will provide chemical information needed to test different models of Ceres’ origin and thermal and aqueous evolution. GRaND is also sensitive to hydrogen layering and can determine the equivalent H2O/OH content of near-surface hydrous minerals as well as the depth and water abundance of an ice table, which may provide information about the state of water in the interior of Ceres. Here, we document the design and performance of GRaND with sufficient detail to interpret flight data archived in the Planetary Data System, including two new sensor designs: an array of CdZnTe semiconductors for gamma ray spectroscopy, and a loaded-plastic phosphor sandwich for neutron spectroscopy. An overview of operations and a description of data acquired from launch up to Vesta approach is provided, including annealing of the CdZnTe sensors to remove radiation damage accrued during cruise. The instrument is calibrated using data acquired on the ground and in flight during a close flyby of Mars. Results of Mars flyby show that GRaND has ample sensitivity to meet science objectives at Vesta and Ceres. Strategies for data analysis are described and prospective results for Vesta are presented for different operational scenarios and compositional models.

Predictive wind turbine simulation with an adaptive lattice Boltzmann method for moving boundaries

NASA Astrophysics Data System (ADS)

Deiterding, Ralf; Wood, Stephen L.

2016-09-01

Operating horizontal axis wind turbines create large-scale turbulent wake structures that affect the power output of downwind turbines considerably. The computational prediction of this phenomenon is challenging as efficient low dissipation schemes are necessary that represent the vorticity production by the moving structures accurately and that are able to transport wakes without significant artificial decay over distances of several rotor diameters. We have developed a parallel adaptive lattice Boltzmann method for large eddy simulation of turbulent weakly compressible flows with embedded moving structures that considers these requirements rather naturally and enables first principle simulations of wake-turbine interaction phenomena at reasonable computational costs. The paper describes the employed computational techniques and presents validation simulations for the Mexnext benchmark experiments as well as simulations of the wake propagation in the Scaled Wind Farm Technology (SWIFT) array consisting of three Vestas V27 turbines in triangular arrangement.

Diogenite-like Features in the Spitzer IRS (5-35 micrometers) Spectrum of 956 ELISA

NASA Technical Reports Server (NTRS)

Lim, Lucy F.; Emery, Joshua P.; Moskovitz, Nicholas A.

2009-01-01

We report preliminary results from the Spitzer Infrared Spectrograph (IRS) observations of the V-type asteroid 956 Elisa. Elisa was observed as part of a campaign to measure the 5.2-38 micron spectra of small basaltic asteroids with the Spitzer IRS. Targets include members of the dynamical family of the unique large differentiated asteroid 4 Vesta ("Vesroids"), several outer-main-belt basaltic asteroids whose orbits exclude them from originating on 4 Vesta, and the basaltic near-Earth asteroid 4055 Magellan.

Dawn : a mission in developement for exploration of main belt asteroids Vesta and Ceres

NASA Technical Reports Server (NTRS)

Rayman, Marc D.; Fraschetti, Thomas C.; Russell, Christopher T.; Raymond, Carol A.

2004-01-01

Dawn is in development for a 2006 launch on a mission to explore main belt asteroids in order to yield insights into important questions about the formation and evolution of the solar system. Its objective is to acquire detailed data from orbit around two complementary bodies, Vesta and Ceres, the two most massive asteroids. The project relies on extensive heritage from other deep-space and Earth-orbiting missions, thus permitting the ambitious objectives to be accomplished with an affordable budget.

Operating CFDP in the Interplanetary Internet

NASA Technical Reports Server (NTRS)

Burleigh, S.

2002-01-01

This paper examines the design elements of CCSDS File Delivery Protocol and Interplanetary Internet technologies that will simplify their integration and discusses the resulting new capabilities, such as efficient transmission of large files via multiple relay satellites operating in parallel.

Mineralogical and Geochemical Analysis of Howardite DaG 779: understanding geological evolution of asteroid (4) Vesta

NASA Astrophysics Data System (ADS)

Marcel Müller, Christian; Mengel, Kurt; Singh Thangjam, Guneshwar; Weckwerth, Gerd

2016-04-01

The HED meteorites, a clan of stony achondrites, are believed to originate from asteroid (4) Vesta (e.g. Mittlefehldt et al. (2015)). Recent evolution models (e.g. Toplis et al. (2013)) and observations from Dawn spacecraft data (e.g., Prettyman et al. (2013)) indicate that diogenites form the lower crust and uppermost mantle of (4) Vesta. Deep seated material excavated by large impacts such as the Rheasilvia- and Veneneiaforming event should be present in howardites. We analysed a slice of howardite DaG 779 which had been recovered from the Libyan Desert in 1999 and was briefly described by Grossmann (2000). The data presented here include electron microprobe, bulk-rock XRD and XRF as well as trace element analysis by ICP-MS and INA. The petrographic results confirm earlier observations that DaG 779 is polymict and mainly contains diogenite and eucrite clasts. Mass balance calculations using bulk-rock and microprobe major element data reveal a modal mineralogy of 77% orthopyroxene, 8% plagioclase, 7% clinopyroxene and 2% spinels, the rest being olivine, SiO2-phases, sulphides, and native Fe(Ni). When compared with the element compilation recently reported by Mittlefehldt (2015) the 39 trace element analysed here (including REE and PGE) confirm that this howardite is clearly dominated by diogenite. Beside the modal petrographic information, a number of more detailed observations obtained from microprobe investigations reveal fresh and recrystallized glasses, troilite-orthopyroxene symplectites from a mixed silicate-sulphide melt giving rise to graphic intergrowths as well as vermicular and reticular FeS in highly disrupted clasts. While the origin of the FeS in these clasts is not clear yet, its particular shape and distribution indicates that this mineral has been (partially) molten and recrystallized from a sulphide melt. The silicate minerals around these FeS occurrences are recrystallized but there is no indication for a partial silicate melt. Further metasomatic reactions were observed between clinopyroxene (pigeonite) and a sulphide-bearing agent, according to the principal reaction Pigeonite (Fe-rich) + S2 ↔ FeS + Augit (Mg-rich) + SiO2. This type of metasomatism (Zhang et al. (2013)) is not well understood yet. References: Grossman, J. N. (2000): The Meteoritical Bulletin, No. 84, 2000 August. Meteoritics & Planetary Science, 35: A119-A225. doi: 10.1111/j.1945-5100.2000.tb01797.x. Toplis, M.J. et al. (2013): Chondritic models of 4 Vesta: Implications for geochemical and geophysical properties. Meteoritics & Planetary Science, 48: 2300-2315. doi: 10.1111/maps.12195. Zhang, A. et al. (2013): Record of S-rich vapors on asteroid 4 Vesta: Sulfurization in the Northwest Africa 2339 eucrite. Geochim. Cosmochim. Acta 109, 1-13. Mittlefehldt, D.W., (2015): Asteroid (4) Vesta: I. The howardite-eucrite-diogenite (HED) clan of meteorites. Chemie Erde-Geochem. 75, 2, 155-183. Prettyman, T.H. et al. (2013): Neutron absorption constraints on the composition of 4 Vesta. Meteoritics & Planetary Science 48:2211-2236.

Trace elements record complex histories in diogenites

NASA Astrophysics Data System (ADS)

Balta, J. B.; Beck, A. W.; McSween, H. Y.

2012-12-01

Diogenite meteorites are cumulate rocks composed mostly of orthopyroxene and chemically linked to eucrites (basaltic) and howardites (brecciated mixtures of diogenites and eucrites). Together, they represent the largest single family of achondrite meteorites delivered to Earth, and have been spectrally linked to the asteroid 4 Vesta, the largest remaining basaltic protoplanet. However, this spectral link is non-unique as many basaltic asteroids likely formed and were destroyed in the early solar system. Recent work suggested that Vesta may be an unlikely parent body for the diogenites based on correlations between trace elements and short-lived isotope decay products, which would be unlikely to survive on a body as large as Vesta due to its long cooling history [1]. Recent analyses of terrestrial and martian olivines have demonstrated that trace element spatial distributions can preserve evidence of their crystallization history even when major elements have been homogenized [2]. We have mapped minor elements including Cr, Al, and Ti in seemingly homogeneous diogenite orthopyroxenes and found a variety of previously unobserved textures. The pyroxenes in one sample (GRA 98108) are seemingly large grains of variable shapes and sizes, but the trace elements reveal internal grain boundaries between roughly-equal sized original subgrains, with equilibrated metamorphic triple junctions between them and trace element depletions at the boundaries. These trends suggest extraction of trace elements by a magma along those relict grain boundaries during a reheating event. Two other samples show evidence of fracturing and annealing, with trace element mobility within grains. One sample appears to have remained a closed system during annealing (MET 01084), while the other has interacted with a fluid or magma to move elements along annealed cracks (LEW 88679). These relict features establish that the history of diogenite pyroxenes is more complex than their homogeneous major element compositions imply. Many trace element analyses are performed using either bulk rock techniques or spot analyses, and these maps suggest those types of analyses likely sample variable trace element abundances even within otherwise homogeneous grains, rendering their results difficult to interpret. Consequently, the correlation discussed previously between trace elements and short lived isotopes has likely been impacted by post-magmatic alteration and cannot solely be used to argue that HED's cannot be derived from Vesta. Furthermore, these maps strengthen the HED-Vesta link by suggesting that the diogenites underwent an extended history of cooling, reheating, partial melting, impact fragmentation, fluid/melt migration, and finally re-annealing. These complicated steps are particularly noteworthy as the pyroxene cumulate layer on the asteroid Vesta should lie beneath the eucritic crust, implying that early impacts were able to penetrate that crust and affect the diogenite layers early in Vesta's history, most likely while the asteroid was still hot enough to allow for annealing and regrowth of fractured grains. [1] Schiller et al. (2011) [2] Milman-Barris et al. (2008)

Reflectance properties and hydrated material distribution on Vesta: Global investigation of variations and their relationship using improved calibration of Dawn VIR mapping spectrometer

NASA Astrophysics Data System (ADS)

Combe, Jean-Philippe; Ammannito, Eleonora; Tosi, Federico; De Sanctis, Maria Cristina; McCord, Thomas B.; Raymond, Carol A.; Russell, Christopher T.

2015-10-01

Vesta's surface albedo variations and hydrated material content share similar spatial distribution. This observation is consistent with carbonaceous chondrite meteorites as a likely source material for dark surface units observed by the Dawn spacecraft, as presented by numerous publications. While these deposits have been studied extensively by analysis of data from the Framing Camera (FC) and the Visible and Infrared Spectrometer (VIR), we performed a new analysis based on an improved calibration of VIR. First we identified instrument and calibration artifacts, and we therefore developed corrections of the VIR flat field and response function. Then we developed a photometric correction for Vesta based on the lunar model by Shkuratov et al. (Shkuratov, Yu.G. et al. [1999]. Icarus 141, 132-155. http://dx.doi.org/10.1006/icar.1999.6154), and a semi-analytical inversion of the photometric parameters. This photometric model combines minimization of the scattering effects due to the topography (a disk function) and variations of multiple-scattering with phase angle (the phase function) caused by microscopic physical properties of the regolith. The improved calibration and photometric correction enable more accurate analysis of the spectral properties of Vesta's surface material, especially the reflectance at 1.4 μm and the 2.8 μm hydroxyl absorption band depth. We produced global and quadrangle maps that are used as a common dataset for this Icarus special issue on Vesta's surface composition. The joint interpretation of both the 1.4 μm reflectance and the 2.8 μm absorption band depth reveals unusual spectral properties for a number of impact craters and ejecta compared to the rest of Vesta. An area including the Bellicia, Arruntia and Pomponia craters, where olivine might be present, has relatively high reflectance and a strong hydroxyl absorption band. Another area in the vicinity of Capparonia crater has a high content of hydrated materials, although with moderate reflectance and typical pyroxene-rich composition. Ejecta blankets west of Oppia crater have a spectral behavior similar to Capparonia, except for the wider and more complex shape of the hydroxyl absorption band. On the other hand, some low-hydrated areas associated to crater floors and ejecta have higher reflectance and steeper spectral slope than most low-hydrated terrains Vesta. A broad lane that extends from Rheasilvia rim at Matronalia Rupes to the northern regions hosts little to no hydrated materials and exhibits a moderate spectral slope, similar to Rheasilvia's basin floor. These properties reinforce the hypothesis that the lane is composed of ejecta from Rheasilvia, as indicated by the distribution of pyroxene compositions by previous results from Dawn. A few small and fresh craters exhibit an association between low-reflectance, little to no hydrated materials and a strong positive spectral slope, suggesting optical effects by opaque coatings, as opposed to carbonaceous chondrite deposits, and possible coarser grains.

The Bombardment History of 4 Vesta as Told by Sample Geochronology

NASA Technical Reports Server (NTRS)

Cohen, B. A.

2014-01-01

The Dawn mission showed asteroid 4 Vesta to be an extensively cratered body, ancient in age, with craters in a variety of morphologies and preservation states [1-3]. Tying Vesta's relative crater ages to an absolute impact history can be accomplished through investigations of the HED (howardite, eucrite, diogenite) meteorites. Eucrites are crustal basalts and gabbros, diogenites are mostly orthopyroxenites representing lower crust or upper mantle materials, and howardites are mixed breccias containing both lithologies. Eucrite 53Mn-53Cr systematics show that the HED parent body globally differentiated by 4.56 Ga and fully crystallized soon afterwards [4]. Much later, many eucrites were brecciated and heated by large impacts into the parent body surface. Disturbance ages in eucrites show that multiple large impacts occurred within 1 Gyr after crystallization, showing a history that largely resembles that of the Moon [5-7]. Dawn images also showed that Vesta is covered with a well-developed regolith that is spectrally similar to howardite meteorites [8]. Howardites are polymict regolith breccias made up mostly of clasts of eucrites and diogenites, but which also contain clasts formed by melting of the regolith by relatively large, energetic impact events. Impact-melt clast ages from howardites extend our knowledge of the impact history of Vesta, expanding on eucrite disturbance ages and helping give absolute age context to the observed crater-counts produced using Dawn data. The distribution of 40Ar-39Ar ages of impact-melt clasts in howardites shows that they formed within the time period 3.3-3.8 Ga [9]. These, and other impact-melted HED materials, have distinct age and compositional characteristics that suggest they formed in discrete impact events. In order to create these crystalline impact-melt products on the surface of Vesta, the impacts during this time period must have had velocities much higher than 5 km/s, the main belt average [10]. This is inconsistent with formation by a normal distribution of impact velocities and points instead to a unique period where high-velocity collisions were more frequent than currently observed. Until now, impact-reset ages in the HED meteorites have been be interpreted under the umbrella of the canonical lunar cataclysm where an increase in the absolute number of bombarding objects is responsible for creating larger absolute amounts of impact-affected and impact-melted rocks, statistically increasing their chances of being found on Earth and dated. However, the distribution of age among the howardite impact-melt clasts may not necessarily result from an increased number of impacts, but rather result from impacts of higher velocity. The changeover from a typical main belt velocity profile to this regime of increased velocity population at Vesta occurs contemporaneously with a similar transition at the Moon, indicating that howardite impact-melt clast ages reinforce the notion of a dynamically unusual episode of bombardment in the inner solar system beginning at around 4.0 Ga.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gooding, Thomas M.

Distributing an executable job load file to compute nodes in a parallel computer, the parallel computer comprising a plurality of compute nodes, including: determining, by a compute node in the parallel computer, whether the compute node is participating in a job; determining, by the compute node in the parallel computer, whether a descendant compute node is participating in the job; responsive to determining that the compute node is participating in the job or that the descendant compute node is participating in the job, communicating, by the compute node to a parent compute node, an identification of a data communications linkmore » over which the compute node receives data from the parent compute node; constructing a class route for the job, wherein the class route identifies all compute nodes participating in the job; and broadcasting the executable load file for the job along the class route for the job.« less

Parallel compression of data chunks of a shared data object using a log-structured file system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bent, John M.; Faibish, Sorin; Grider, Gary

2016-10-25

Techniques are provided for parallel compression of data chunks being written to a shared object. A client executing on a compute node or a burst buffer node in a parallel computing system stores a data chunk generated by the parallel computing system to a shared data object on a storage node by compressing the data chunk; and providing the data compressed data chunk to the storage node that stores the shared object. The client and storage node may employ Log-Structured File techniques. The compressed data chunk can be de-compressed by the client when the data chunk is read. A storagemore » node stores a data chunk as part of a shared object by receiving a compressed version of the data chunk from a compute node; and storing the compressed version of the data chunk to the shared data object on the storage node.« less

Collectively loading programs in a multiple program multiple data environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aho, Michael E.; Attinella, John E.; Gooding, Thomas M.

Techniques are disclosed for loading programs efficiently in a parallel computing system. In one embodiment, nodes of the parallel computing system receive a load description file which indicates, for each program of a multiple program multiple data (MPMD) job, nodes which are to load the program. The nodes determine, using collective operations, a total number of programs to load and a number of programs to load in parallel. The nodes further generate a class route for each program to be loaded in parallel, where the class route generated for a particular program includes only those nodes on which the programmore » needs to be loaded. For each class route, a node is selected using a collective operation to be a load leader which accesses a file system to load the program associated with a class route and broadcasts the program via the class route to other nodes which require the program.« less

Parallel File System I/O Performance Testing On LANL Clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiens, Isaac Christian; Green, Jennifer Kathleen

2016-08-18

These are slides from a presentation on parallel file system I/O performance testing on LANL clusters. I/O is a known bottleneck for HPC applications. Performance optimization of I/O is often required. This summer project entailed integrating IOR under Pavilion and automating the results analysis. The slides cover the following topics: scope of the work, tools utilized, IOR-Pavilion test workflow, build script, IOR parameters, how parameters are passed to IOR, *run_ior: functionality, Python IOR-Output Parser, Splunk data format, Splunk dashboard and features, and future work.

Vesta and Ceres

NASA Astrophysics Data System (ADS)

Righter, Kevin

2018-04-01

Asteroids 1 Ceres and 4 Vesta are the two largest asteroids in the asteroid belt, with mean diameters of 946 km and 525 km, respectively. Ceres was reclassified as a dwarf planet by the IAU (International Astronomical Union) as a result of their new dwarf planet definition, which is a body that (a) orbits the sun, (b) has enough mass to assume a nearly round shape, (c) has not cleared the neighborhood around its orbit, and (d) is not a moon. Our understanding of these two bodies has been revolutionized in the last decade by the success of the Dawn mission that visited both bodies. Vesta is an example of a small body that has been heated substantially, and differentiated into a metallic core, silicate mantle, and basaltic crust. Ceres is a volatile-rich rocky body that did not experience significant heating and therefore has only partially differentiated. These two contrasting bodies have been instrumental in learning how inner solar system material formed and evolved.

Dielectric and thermal modeling of Vesta's surface

NASA Astrophysics Data System (ADS)

Palmer, E. M.; Heggy, E.; Capria, M. T.; Tosi, F.; Russell, C. T.

2013-09-01

We generate a dielectric model for the surface of Vesta from thermal observations by Dawn's Visible and Infrared (VIR) mapping spectrometer. After retrieving surface temperatures from VIR data, we model thermal inertia, and derive a theoretical temperature map of Vesta's surface at a given UTC. To calculate the real part of the dielectric constant (ɛ') and the loss tangent (tg δ) we use the dielectric properties of basaltic lunar regolith as a first-order analog, assuming surface density and composition consistent with fine basaltic lunar dust. First results indicate that for the majority of the surface, ɛ' ranges from 2.0 to 2.1 from the night to day side respectively, and tg δ ranges from 1.05E-2 to 1.40E-2. While these regions are consistent with a basaltic, desiccated ~55% porous surface, we also find anomalies in the thermal inertia that may correspond to a variation in local surface density relative to the global average, and a consequent variation in the local dielectric properties.

DOE Office of Scientific and Technical Information (OSTI.GOV)

SmartImport.py is a Python source-code file that implements a replacement for the standard Python module importer. The code is derived from knee.py, a file in the standard Python diestribution , and adds functionality to improve the performance of Python module imports in massively parallel contexts.

Global variations in regolith properties on asteroid Vesta from Dawn's low-altitude mapping orbit

NASA Astrophysics Data System (ADS)

Denevi, Brett W.; Beck, Andrew W.; Coman, Ecaterina I.; Thomson, Bradley J.; Ammannito, Eleonora; Blewett, David T.; Sunshine, Jessica M.; de Sanctis, Maria Cristina; Li, Jian-Yang; Marchi, Simone; Mittlefehldt, David W.; Petro, Noah E.; Raymond, Carol A.; Russell, Christopher T.

2016-12-01

We investigate the depth, variability, and history of regolith on asteroid Vesta using data from the Dawn spacecraft. High-resolution (15-20 m pixel-1) Framing Camera images 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 (<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 1 km of the surface. Regions of thin regolith are found within the Rheasilvia basin and at equatorial latitudes from 0-90°E and 260-360°E. Craters in these areas that appear to excavate material from beneath the regolith have more diogenitic (Rheasilvia, 0-90°E) and cumulate eucrite (260-360°E) compositions. A region of especially thick regolith, where depths generally exceed 1 km, is found from 100-240°E and corresponds to heavily cratered, low-albedo surface with a basaltic eucrite composition enriched in carbonaceous chondrite material. The presence of a thick regolith in 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 toward more howarditic compositions, consistent with regolith mixing being the dominant form of "weathering" on Vesta.

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

NASA Technical Reports Server (NTRS)

Denevi, Brett W.; Beck, Andrew W.; Coman, Ecaterina; Thomson, Bradley J.; Ammannito, Eleonora; Blewett, David T.; Sunshine, Jessica M.; De Sanctis, Maria Cristina; Li, Jian-Yang; Marchi, Simone;

The Unique Geomorphology and Physical Properties of the Vestalia Terra Plateau

NASA Technical Reports Server (NTRS)

Buczkowski, D.L.; Wyrick, D.Y.; Toplis, M.; Yingst, R. A.; Williams, D. A.; Garry, W. B.; Mest, S.; Kneissl, T.; Scully, J. E. C.; Nathues, A.;

VESTOIDS, PART II: THE BASALTIC NATURE AND HED METEORITE ANALOGS FOR EIGHT V{sub p}-TYPE ASTEROIDS AND THEIR ASSOCIATIONS WITH (4) VESTA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hardersen, Paul S.; Reddy, Vishnu; Roberts, Rachel, E-mail: Hardersen@space.edu

Improving the constraints on the abundance of basaltic asteroids in the main asteroid belt is necessary for better understanding the thermal and collisional environment in the early solar system, for more rigorously identifying the genetic family for (4) Vesta, for determining the effectiveness of Yarkovsky/YORP in dispersing asteroid families, and for better quantifying the population of basaltic asteroids in the outer main belt (a > 2.5 AU) that is likely unrelated to (4) Vesta. Near-infrared (NIR) spectral observations in this work were obtained for the V{sub p}-type asteroids (2011) Veteraniya, (5875) Kuga, (8149) Ruff, (9147) Kourakuen, (9553) Colas, (15237) 1988 RL{sub 6},more » (31414) Rotaryusa, and (32940) 1995 UW{sub 4} during 2014 August/September utilizing the SpeX spectrograph at the NASA Infrared Telescope Facility, Mauna Kea, Hawaii. Spectral band parameter (band centers, band area ratios) and mineralogical analysis (pyroxene chemistry) for each average asteroid NIR reflectance spectrum suggest a howardite–eucrite–diogenite meteorite analog for each asteroid. (5875) Kuga is most closely associated with the eucrite meteorites, (31414) Rotaryusa is most closely associated with the diogenites, and the remaining other six asteroids are most closely associated with the howardite meteorites. Along with their orbital locations in the inner main belt and in the vicinity of (4) Vesta, the existing evidence suggests that these eight V{sub p}-type asteroids are also likely Vestoids.« less

Colors and Photometry of Bright Materials on Vesta as Seen by the Dawn Framing Camera

NASA Technical Reports Server (NTRS)

Schroeder, S. E.; Li, J.-Y.; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.;

File-System Workload on a Scientific Multiprocessor

NASA Technical Reports Server (NTRS)

Kotz, David; Nieuwejaar, Nils

1995-01-01

Many scientific applications have intense computational and I/O requirements. Although multiprocessors have permitted astounding increases in computational performance, the formidable I/O needs of these applications cannot be met by current multiprocessors a their I/O subsystems. To prevent I/O subsystems from forever bottlenecking multiprocessors and limiting the range of feasible applications, new I/O subsystems must be designed. The successful design of computer systems (both hardware and software) depends on a thorough understanding of their intended use. A system designer optimizes the policies and mechanisms for the cases expected to most common in the user's workload. In the case of multiprocessor file systems, however, designers have been forced to build file systems based only on speculation about how they would be used, extrapolating from file-system characterizations of general-purpose workloads on uniprocessor and distributed systems or scientific workloads on vector supercomputers (see sidebar on related work). To help these system designers, in June 1993 we began the Charisma Project, so named because the project sought to characterize 1/0 in scientific multiprocessor applications from a variety of production parallel computing platforms and sites. The Charisma project is unique in recording individual read and write requests-in live, multiprogramming, parallel workloads (rather than from selected or nonparallel applications). In this article, we present the first results from the project: a characterization of the file-system workload an iPSC/860 multiprocessor running production, parallel scientific applications at NASA's Ames Research Center.

Climate Prediction Center - Reanalysis: Atmospheric Data

Science.gov Websites

files; i.e., wgrib for GRIB-2 files wgrib2mv,wgrib2ms parallel processing with wgrib2 grb1to2.pl perl US government, DOC, NWS, NCEP or CPC. All spelling errors are property of the finder. comments

77 FR 26542 - Black Mountain Hydro, LLC; Notice of Preliminary Permit Application Accepted for Filing and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-04

... the powerhouse to Sierra Pacific Power's Fort Churchill generating station, parallel to an existing... powerhouse to the PDCI and then parallel to the PDCI to the Fort Churchill generating station; and (9...

Development of a Distributed Parallel Computing Framework to Facilitate Regional/Global Gridded Crop Modeling with Various Scenarios

NASA Astrophysics Data System (ADS)

Jang, W.; Engda, T. A.; Neff, J. C.; Herrick, J.

2017-12-01

Many crop models are increasingly used to evaluate crop yields at regional and global scales. However, implementation of these models across large areas using fine-scale grids is limited by computational time requirements. In order to facilitate global gridded crop modeling with various scenarios (i.e., different crop, management schedule, fertilizer, and irrigation) using the Environmental Policy Integrated Climate (EPIC) model, we developed a distributed parallel computing framework in Python. Our local desktop with 14 cores (28 threads) was used to test the distributed parallel computing framework in Iringa, Tanzania which has 406,839 grid cells. High-resolution soil data, SoilGrids (250 x 250 m), and climate data, AgMERRA (0.25 x 0.25 deg) were also used as input data for the gridded EPIC model. The framework includes a master file for parallel computing, input database, input data formatters, EPIC model execution, and output analyzers. Through the master file for parallel computing, the user-defined number of threads of CPU divides the EPIC simulation into jobs. Then, Using EPIC input data formatters, the raw database is formatted for EPIC input data and the formatted data moves into EPIC simulation jobs. Then, 28 EPIC jobs run simultaneously and only interesting results files are parsed and moved into output analyzers. We applied various scenarios with seven different slopes and twenty-four fertilizer ranges. Parallelized input generators create different scenarios as a list for distributed parallel computing. After all simulations are completed, parallelized output analyzers are used to analyze all outputs according to the different scenarios. This saves significant computing time and resources, making it possible to conduct gridded modeling at regional to global scales with high-resolution data. For example, serial processing for the Iringa test case would require 113 hours, while using the framework developed in this study requires only approximately 6 hours, a nearly 95% reduction in computing time.

Schnek: A C++ library for the development of parallel simulation codes on regular grids

NASA Astrophysics Data System (ADS)

Schmitz, Holger

2018-05-01

A large number of algorithms across the field of computational physics are formulated on grids with a regular topology. We present Schnek, a library that enables fast development of parallel simulations on regular grids. Schnek contains a number of easy-to-use modules that greatly reduce the amount of administrative code for large-scale simulation codes. The library provides an interface for reading simulation setup files with a hierarchical structure. The structure of the setup file is translated into a hierarchy of simulation modules that the developer can specify. The reader parses and evaluates mathematical expressions and initialises variables or grid data. This enables developers to write modular and flexible simulation codes with minimal effort. Regular grids of arbitrary dimension are defined as well as mechanisms for defining physical domain sizes, grid staggering, and ghost cells on these grids. Ghost cells can be exchanged between neighbouring processes using MPI with a simple interface. The grid data can easily be written into HDF5 files using serial or parallel I/O.

Progress of IRSN R&D on ITER Safety Assessment

NASA Astrophysics Data System (ADS)

Van Dorsselaere, J. P.; Perrault, D.; Barrachin, M.; Bentaib, A.; Gensdarmes, F.; Haeck, W.; Pouvreau, S.; Salat, E.; Seropian, C.; Vendel, J.

2012-08-01

The French "Institut de Radioprotection et de Sûreté Nucléaire" (IRSN), in support to the French "Autorité de Sûreté Nucléaire", is analysing the safety of ITER fusion installation on the basis of the ITER operator's safety file. IRSN set up a multi-year R&D program in 2007 to support this safety assessment process. Priority has been given to four technical issues and the main outcomes of the work done in 2010 and 2011 are summarized in this paper: for simulation of accident scenarios in the vacuum vessel, adaptation of the ASTEC system code; for risk of explosion of gas-dust mixtures in the vacuum vessel, adaptation of the TONUS-CFD code for gas distribution, development of DUST code for dust transport, and preparation of IRSN experiments on gas inerting, dust mobilization, and hydrogen-dust mixtures explosion; for evaluation of the efficiency of the detritiation systems, thermo-chemical calculations of tritium speciation during transport in the gas phase and preparation of future experiments to evaluate the most influent factors on detritiation; for material neutron activation, adaptation of the VESTA Monte Carlo depletion code. The first results of these tasks have been used in 2011 for the analysis of the ITER safety file. In the near future, this R&D global programme may be reoriented to account for the feedback of the latter analysis or for new knowledge.

Cloud parallel processing of tandem mass spectrometry based proteomics data.

PubMed

Mohammed, Yassene; Mostovenko, Ekaterina; Henneman, Alex A; Marissen, Rob J; Deelder, André M; Palmblad, Magnus

2012-10-05

Data analysis in mass spectrometry based proteomics struggles to keep pace with the advances in instrumentation and the increasing rate of data acquisition. Analyzing this data involves multiple steps requiring diverse software, using different algorithms and data formats. Speed and performance of the mass spectral search engines are continuously improving, although not necessarily as needed to face the challenges of acquired big data. Improving and parallelizing the search algorithms is one possibility; data decomposition presents another, simpler strategy for introducing parallelism. We describe a general method for parallelizing identification of tandem mass spectra using data decomposition that keeps the search engine intact and wraps the parallelization around it. We introduce two algorithms for decomposing mzXML files and recomposing resulting pepXML files. This makes the approach applicable to different search engines, including those relying on sequence databases and those searching spectral libraries. We use cloud computing to deliver the computational power and scientific workflow engines to interface and automate the different processing steps. We show how to leverage these technologies to achieve faster data analysis in proteomics and present three scientific workflows for parallel database as well as spectral library search using our data decomposition programs, X!Tandem and SpectraST.

New Parallel computing framework for radiation transport codes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostin, M.A.; /Michigan State U., NSCL; Mokhov, N.V.

A new parallel computing framework has been developed to use with general-purpose radiation transport codes. The framework was implemented as a C++ module that uses MPI for message passing. The module is significantly independent of radiation transport codes it can be used with, and is connected to the codes by means of a number of interface functions. The framework was integrated with the MARS15 code, and an effort is under way to deploy it in PHITS. Besides the parallel computing functionality, the framework offers a checkpoint facility that allows restarting calculations with a saved checkpoint file. The checkpoint facility canmore » be used in single process calculations as well as in the parallel regime. Several checkpoint files can be merged into one thus combining results of several calculations. The framework also corrects some of the known problems with the scheduling and load balancing found in the original implementations of the parallel computing functionality in MARS15 and PHITS. The framework can be used efficiently on homogeneous systems and networks of workstations, where the interference from the other users is possible.« less

Pits and Gullies on Vesta: Potential Insights from Terrestrial Analogs

NASA Astrophysics Data System (ADS)

Sears, D. W.; Tornabene, L. L.; Osinski, G. R.; Hughes, S. S.; Heldmann, J. L.

2013-12-01

Arguably the most surprising discovery of the Dawn mission during its observations of Vesta were the pitted terrain [1,2], low albedo regions [3,4], and hydrogen abundances [5,6]. The presence of pitted terrain at the floors of craters on Vesta has been ascribed to the release of volatiles during impact, following the discovery of similar features on Mars where they are interpreted as volatile-rich impact melt deposits [7]. The numerous dark regions and the H abundance have been ascribed to the presence of infall material resembling CM chondrites. CM chondrite clasts are relatively common in brecciated meteorites [8], including the HED meteorites that are presumed to have come from Vesta (or Vesta fragments) [9,10], and contain up to about 10 vol% water [11]. On the walls of craters associated with the pitted terrain in craters, but also observed outside craters, are features resembling gullies [12,13]. The nature of these features, the amount of fluids required, and - especially - the relationship between the pits and gully-like features is unclear. Pit-like structures are commonly observed at terrestrial impact craters (hydrothermal pipes, [14]) and in volcanic fields (phreatic craters, [15]) in which water was present during the active phases of these processes. They are usually well-studied and offer a range of 'ground truths' which might help us understand the features on Vesta. The number, morphology, and locations of the features provide temporal information on their histories. The number, size and distribution of boulders around the features, provides information on energetics and water content. We expect such structures to be present in water-bearing C and X asteroids, where the water in endogenous, and S asteroids where, like Vesta, the water is exogenous. Such features, if present, were generally obscured by regolith on Eros [16], but a search in regolith-poor areas might be worthwhile. In summary, we suggest that new insights into volatile behavior on near-Earth asteroids, with its relevance to geological evolution, astrobiology, and space resources, will be possible through the study of terrestrial analogs. [1] Denevi et al 2012. Science 338, 246-249. [2] Boyce et al 2012. Icarus 221 262-275. [3] McCord et al., 2012. Nature 491, 83-86. [4] Reddy et al 2012. Icarus 221 544-559. [5] De Sanctis et al. 2012. Science 336, 697-700. [6] Prettyman et al 2012. Science 338, 242-246. [7] Tornabene et al (2012). Icarus 220, 348-368. [8] Wilkening et al 1973. Geochim. Cosmochim. Acta 37, 1985-1989. [9] McCord et al 1970. Science 168, 1445-1447. [10] Drake 2001. Meteorit. Planet. Sci. 36, 501-513. [11] Wiik 1969. Commun. Phys. Math. 34 135-145 [12] Scully et al 2012. AGU Meeting, 2012, December 3-7th. [13] Scully et al 2013. 44th LPSC paper #1578. [14] Kirsimäe and Osinski 2013. Chapter 6 in 'Impact Cratering: Processes and Products' eds Osinski and Pierazzo, Blackwell. [15] Hughes et al 1999. Pages 143-168 in 'Guidebook to the Geology of Eastern Idaho' eds Hughes and Thackray, Idaho Museum of Natural History. [16] Robinson et al 2001. Meteorit. Planet. Sci. 37, 1651-1684.

Polygonal Impact Craters on selected Minor Bodies: Rhea, Dione, Tethys, Ceres, and Vesta

NASA Astrophysics Data System (ADS)

Neidhart, Tanja; Leitner, Johannes; Firneis, Maria

2017-04-01

A polygonal impact crater (PIC) is a crater that does not have a full circular shape in plane view but consists of straight crater rim segments. PICs are common on all objects in our solar system that show a cratered surface. Previous studies showed that PICs make up about 10-25% of craters on Mercury, Venus, Mars, and the Moon [1, 2, 3, 4]. Although there have been several studies on PICs on the terrestrial planets, and the Moon there are only very few investigations on PICs on minor bodies, even though there exist surface maps of Rhea, Tethys, Dione, Ceres, and Vesta that have an appropriate resolution. The aim of this study is to get more information about the abundance and characteristics of PICs on these objects. We analysed all approved craters on Rhea, Dione, Tethys, Ceres, and Vesta using images provided by the IAU/NASA/USGS Planetary Database [5]. For the classification of PICs the definition by [2] was used which states that a crater is polygonal if it consists of at least two straight crater rim segments having a discernable angle. In total 417 impact craters were examined and 227 of them were classified as polygonal. On Rhea about 48% of the approved craters are PICs, on Dione 59%, on Tethys 34%, on Ceres 74%, and on Vesta 56%. The comparison with studies on PICs on terrestrial planets, and the Moon conducted by [1, 2, 3, 4] showed that the percentage of PICs found in this study is much higher. Most of the PICs have two or three straight rim segments and only few PICs are hexagonal or pentagonal. The mean angle between the straight rims yields 121° for Rhea, 124° for Dione, 123° for Tethys, 133° for Ceres, and 134° for Vesta. These angles are well in accordance to an average angle of 112° on Mercury [1]. Also the size distribution of PICs is in accordance to results by [4] who proved that PICs seem to favor small to middle size diameters. The largest diameters of non-polygonal craters on Vesta range from 0.6 km to 450 km while the diameters of PICs only range from 3.1 km to 53.2 km [5]. The study proves that a large number of polygonal impact craters on Rhea, Dione, Tethys, Ceres, and Vesta exist but it is still unclear why the fraction of PICs on these bodies is much higher than for terrestrial planets and the Moon. One possible solution could be the different composition of the surfaces of these bodies in comparison to the terrestrial planets but for definite answers to this question further understanding of the formation process of PICs, which is still unclear, is necessary. References: [1] Weihs G. T. et al. (2015) Planet. Space Sci., 111, 77-82. [2] Aittola M. et al. (2010) Icarus, 205, 356-363. [3] Öhman et al. (2008) Meteoritics & Planet. Sci., 43, 1605-1628. [4] Öhman et al. (2010) Geol. Soc. Spec. Pap., 465, 51-65. [5] IAU/NASA/USGS Planetary Database. (2016), http://planetarynames.wr.usgs.gov/.

Optimizing Input/Output Using Adaptive File System Policies

NASA Technical Reports Server (NTRS)

Madhyastha, Tara M.; Elford, Christopher L.; Reed, Daniel A.

1996-01-01

Parallel input/output characterization studies and experiments with flexible resource management algorithms indicate that adaptivity is crucial to file system performance. In this paper we propose an automatic technique for selecting and refining file system policies based on application access patterns and execution environment. An automatic classification framework allows the file system to select appropriate caching and pre-fetching policies, while performance sensors provide feedback used to tune policy parameters for specific system environments. To illustrate the potential performance improvements possible using adaptive file system policies, we present results from experiments involving classification-based and performance-based steering.

Extending the Lunar Mapping and Modeling Portal - New Capabilities and New Worlds

NASA Astrophysics Data System (ADS)

Day, Brian; Law, Emily

2015-11-01

NASA’s Lunar Mapping and Modeling Portal (LMMP) provides a web-based Portal and a suite of interactive visualization and analysis tools to enable mission planners, lunar scientists, and engineers to access mapped lunar data products from past and current lunar missions (http://lmmp.nasa.gov). During the past year, the capabilities and data served by LMMP have been significantly expanded. New interfaces are providing improved ways to access and visualize data. Many of the recent enhancements to LMMP have been specifically in response to the requirements of NASA's proposed Resource Prospector lunar rover, and as such, provide an excellent example of the application of LMMP to mission planning.At the request of NASA’s Science Mission Directorate, LMMP’s technology and capabilities are now being extended to additional planetary bodies. New portals for Vesta and Mars are the first of these new products to be released.On March 31, 2015, the LMMP team released Vesta Trek (http://vestatrek.jpl.nasa.gov), a web-based application applying LMMP technology to visualize the asteroid Vesta. Data gathered from multiple instruments aboard Dawn have been compiled into Vesta Trek’s user-friendly set of tools, enabling users to study the asteroid’s features.Released on July 1, 2015, Mars Trek replicates the functionality of Vesta Trek for the surface of Mars. While the entire surface of Mars is covered, higher levels of resolution and greater numbers of data products are provided for special areas of interest. Early releases focus on past, current, and future robotic sites of operation. Future releases will add many new data products and analysis tools as Mars Trek has been selected for use in site selection for the Mars 2020 rover and in identifying potential human landing sites on Mars.Other destinations will follow soon. The Solar Sytem Exploration Research Virtual Institute, which manages the project, invites the user community to provide suggestions and requests as the development team continues to expand the capabilities of these portals.This presentation will provide an overview of all three portals, demonstrate their uses and capabilities, highlight new features, and preview coming enhancements.

Vesta and Ceres by the light of Dawn

NASA Astrophysics Data System (ADS)

Russell, Christopher T.

2015-11-01

Ceres and Vesta are the most massive bodies in the main asteroid belt. They both appear to be intact protoplanets whose growth may have been drastically altered by the concomitant formation of Jupiter.. These two bodies have witnessed 4.6 Ga of solar system history, much, but not all, of which has been recorded in their surfaces. Dawn’s objective is to interview these two witnesses to learn as much as possible about the early epoch. These bodies are protoplanets, our best archetypes of the early building blocks of the terrestrial planets. In particular, siderophile elements in the Earth’s core were probably first segregated in Vesta-like bodies, and its water was likely first condensed in Ceres-like bodies.Many of the basaltic achondrites originated from a common parent body. Dawn verified that Vesta was consistent with that parent body. hence strengthening geochemical inferences from these samples on the formation and evolution of the solar system and supporting hypotheses for their delivery from Vesta to Earth. Ceres has not revealed itself with a meteoritic record. While the surface is scarred with craters, it is probable that the ejecta from the crater-forming event created little competent material from the icy crust and any such ejected projectiles that reached Earth might have disintegrated upon entry into the Earth’s atmosphere.Ceres’ surface differs greatly from Vesta’s. Plastic or fluidized mass wasting is apparent, as are many irregularly shaped craters, including many polygonal crater forms. There are many central-pit craters possibly caused by volatilization of the crust in the center of the impact. There are also many central-peak craters, which were made by rebound or pingo-like formation processes. Bright deposits dot the landscape, which are possibly salt-rich, suggesting fluvial activity beneath the crust. Observations of the brightest spots on Ceres could suggest sublimation from the surface of the bright area, which may be water vapor driven, as Herschel observations suggest. Ceres is not only the most massive body in the asteroid belt but also possibly the most active.

Divergent Geophysical Evolution of Vesta and Ceres

NASA Astrophysics Data System (ADS)

Raymond, C. A.; Ermakov, A.; Castillo, J. C.; Fu, R. R.; McSween, H. Y., Jr.; McCord, T. B.; Park, R. S.; Russell, C. T.; De Sanctis, M. C.; Jaumann, R.; Konopliv, A. S.

2017-12-01

The Dawn mission explored two massive protoplanets in the main asteroid belt, Vesta and Ceres, that are fossils from the earliest epoch of solar system formation. Dawn's data provide evidence that these bodies formed very early, within the first few million years after CAIs, yet they followed divergent evolutionary paths. Vesta formed <1.5 Myr after CAIs of volatile-depleted chondritic material. Dawn confirmed the HED-based prediction that Vesta melted, forming at least a partial magma ocean, that yielded a large iron core. Gravity and spectral data support a complex magmatic evolution, resulting in a compositionally stratified mantle, with olivine sequestered in the deep mantle, and eruption of evolved melts. Such complexity can explain the apparent distinct magmatic reservoirs implied by trace elements in the HED clan. Discovery of hydrated material on Vesta's surface implies that volatile delivery to the inner solar system was an important process. Thus, while the basic HED paradigm was confirmed, we learned that differentiation on a small planet is more complex than envisioned. Dwarf planet Ceres was known to be water-rich before Dawn arrived. However, contrary to the expected ice-rich, viscously-relaxed smooth surface resulting from physical differentiation and freezing of an ancient subsurface ocean, its surface has many craters, implying a mechanically strong thick crust. The lack of large craters and Ceres' gravitationally-relaxed shape at long wavelengths implies that a strong crust overlies a weaker deep interior. The globally homogeneous distribution of minerals across the surface indicates that Ceres' interior experienced pervasive alteration. Topography and morphology of the surface reveals smoother, apparently resurfaced areas, generally at lower elevation, and rougher areas with greater relief. Local morphology such as crater floor deposits, isolated mountains, and enigmatic bright areas indicate recently active processes on Ceres, likely driven by brine cryovolcanism. Causes of the divergent evolution of these bodies include their accretionary environment, timing of accretion and size. Acknowledgements: Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration.

Technology Performance Report: Duke Energy Notrees Wind Storage Demonstration Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wehner, Jeff; Mohler, David; Gibson, Stuart

2015-11-01

Duke Energy Renewables owns and operates the Notrees Wind Farm in west Texas’s Ector and Winkler counties. The wind farm, which was commissioned in April 2009, has a total capacity of 152.6 MW generated by 55 Vestas V82 turbines, one Vestas 1-V90 experimental turbine, and 40 GE 1.5-MW turbines. The Vestas V82 turbines have a generating capacity of 1.65 MW each, the Vestas V90 turbine has a generating capacity of 1.86 MW, and the GE turbines have a generating capacity of 1.5 MW each. The objective of the Notrees Wind Storage Demonstration Project is to validate that energy storage increasesmore » the value and practical application of intermittent wind generation and is commercially viable at utility scale. The project incorporates both new and existing technologies and techniques to evaluate the performance and potential of wind energy storage. In addition, it could serve as a model for others to adopt and replicate. Wind power resources are expected to play a significant part in reducing greenhouse gas emissions from electric power generation by 2030. However, the large variability and intermittent nature of wind presents a barrier to integrating it within electric markets, particularly when competing against conventional generation that is more reliable. In addition, wind power production often peaks at night or other times when demand and electricity prices are lowest. Energy storage systems can overcome those barriers and enable wind to become a valuable asset and equal competitor to conventional fossil fuel generation.« less

New Views of Diverse Worlds

NASA Astrophysics Data System (ADS)

Blewett, D.

2012-08-01

Spacecraft exploration is in the process of revolutionizing our knowledge of the airless rocky bodies in the inner Solar System. Mercury has long been viewed as a planetary "end-member", but NASA's MESSENGER spacecraft, which flew past the innermost planet three times in 2008-09 and entered orbit in March of 2011, is finding that Mercury is even stranger than we thought. Mercury is weird in essentially all its characteristics: interior structure, surface composition, geology, topography, magnetic field, exosphere, and interaction with the space environment. Closer to home, a flotilla of international probes have targeted the Moon in the past few years. Giving lie to the "been there, done that" attitude held by many toward the Moon, the new missions are making many new discoveries and reminding us that there is much we don't know about our nearest planetary neighbor, and that rich opportunities for exploration are waiting nearby. Finally, I'll present findings from NASA's Dawn spacecraft, which will begin its orbital mission around the asteroid Vesta in mid-July 2011. Vesta is sometimes called "the smallest terrestrial planet" because it has separated into a crust, mantle, and core, and experienced a protracted geological evolution. Vesta is probably the source of a common class of meteorites, so we have abundant samples that help to inform our interpretation of the data to be obtained by Dawn. Mercury, the Moon, and Vesta are worlds who share some characteristics, but have taken radically different evolutionary paths. They provide insight into the most fundamental geological processes that likely affect all rocky planets - around our Sun or beyond.

Next Generation Parallelization Systems for Processing and Control of PDS Image Node Assets

NASA Astrophysics Data System (ADS)

Verma, R.

2017-06-01

We present next-generation parallelization tools to help Planetary Data System (PDS) Imaging Node (IMG) better monitor, process, and control changes to nearly 650 million file assets and over a dozen machines on which they are referenced or stored.

An approach to enhance pnetCDF performance in environmental modeling applications

EPA Science Inventory

Data intensive simulations are often limited by their I/O (input/output) performance, and "novel" techniques need to be developed in order to overcome this limitation. The software package pnetCDF (parallel network Common Data Form), which works with parallel file syste...

Vestas Pinaria Region: Original Basaltic Achondrite Material Derived from Mixing Upper and Lower Crust

NASA Technical Reports Server (NTRS)

Mcfadden, L. A.; Combe, Jean-Philippe; Ammannito, Eleonora; Frigeri, Alessandro; Stephan, Katrin; Longobardo, Andrea; Palomba, Ernesto; Tosi, Federico; Zambon, Francesca; Krohn, Katrin;

Preliminary Iron Distribution on Vesta

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.; Mittlefehldt, David W.

2013-01-01

The distribution of iron on the surface of the asteroid Vesta was investigated using Dawn's Gamma Ray and Neutron Detector (GRaND) [1,2]. Iron varies predictably with rock type for the howardite, eucrite, and diogenite (HED) meteorites, thought to be representative of Vesta. The abundance of Fe in howardites ranges from about 12 to 15 wt.%. Basaltic eucrites have the highest abundance, whereas, lower crustal and upper mantle materials (cumulate eucrites and diogenites) have the lowest, and howardites are intermediate [3]. We have completed a mapping study of 7.6 MeV gamma rays produced by neutron capture by Fe as measured by the bismuth germanate (BGO) detector of GRaND [1]. The procedures to determine Fe counting rates are presented in detail here, along with a preliminary distribution map, constituting the necessary initial step to quantification of Fe abundances. We find that the global distribution of Fe counting rates is generally consistent with independent mineralogical and compositional inferences obtained by other instruments on Dawn such as measurements of pyroxene absorption bands by the Visual and Infrared Spectrometer (VIR) [4] and Framing Camera (FC) [5] and neutron absorption measurements by GRaND [6].

Subsurface failure in spherical bodies. A formation scenario for linear troughs on Vesta’s surface

DOE PAGES

Stickle, Angela M.; Schultz, P. H.; Crawford, D. A.

2014-10-13

Many asteroids in the Solar System exhibit unusual, linear features on their surface. The Dawn mission recently observed two sets of linear features on the surface of the asteroid 4 Vesta. Geologic observations indicate that these features are related to the two large impact basins at the south pole of Vesta, though no specific mechanism of origin has been determined. Furthermore, the orientation of the features is offset from the center of the basins. Experimental and numerical results reveal that the offset angle is a natural consequence of oblique impacts into a spherical target. We demonstrate that a set ofmore » shear planes develops in the subsurface of the body opposite to the point of first contact. Moreover, these subsurface failure zones then propagate to the surface under combined tensile-shear stress fields after the impact to create sets of approximately linear faults on the surface. Comparison between the orientation of damage structures in the laboratory and failure regions within Vesta can be used to constrain impact parameters (e.g., the approximate impact point and likely impact trajectory).« less

Using the Parallel Computing Toolbox with MATLAB on the Peregrine System |

Science.gov Websites

parallel pool took %g seconds.\\n', toc) % "single program multiple data" spmd fprintf('Worker %d says Hello World!\\n', labindex) end delete(gcp); % close the parallel pool exit To run the script on a compute node, create the file helloWorld.sub: #!/bin/bash #PBS -l walltime=05:00 #PBS -l nodes=1 #PBS -N

Graphical Representation of Parallel Algorithmic Processes

DTIC Science & Technology

1990-12-01

interface with the AAARF main process . The source code for the AAARF class-common library is in the common subdi- rectory and consists of the following files... for public release; distribution unlimited AFIT/GCE/ENG/90D-07 Graphical Representation of Parallel Algorithmic Processes THESIS Presented to the...goal of this study is to develop an algorithm animation facility for parallel processes executing on different architectures, from multiprocessor

Dawn at Vesta: An overview after the Dawn mission

NASA Astrophysics Data System (ADS)

Zambon, Francesca

2016-07-01

Vesta, the second largest object in the main asteroid belt of our Solar System, was explored by the Dawn mission for over a year [1, 2]. Dawn is equipped with the Framing Camera (FC) [3], which provides geological and compositional analysis, the Visible and InfraRed (VIR) mapping spectrometer [4], which allowed a comprehensive mineralogical mapping of the surface, and the Gamma Ray and Neutron Detector (GRaND) [5], which reveals the elemental composition. A wealth of data acquired by these three instruments allowed for improving the knowledge on the surface and near-surface properties of Vesta. Dawn covered a large fraction of Vesta' surface. Dawn's mission at Vesta has been divided into four different phases based on the spacecraft altitude [1], which resulted in a variety of pixel resolutions, reaching down to ~70 m/pixel for VIR and ~25 m/pixel for the FC. Pyroxene absorptions are the most prominent visible-to-near infrared spectral features of Vesta [6]. The overall mineralogy is consistent with howardite-eucrite-diogenite (HED) meteorites [7, 8]. More specifically, VIR spectra, acquired in the overall range 0.25-5.1 μm at spatial scales ranging from tens of meters to tens of kilometers, are consistent with a surface covered by a howardite-like regolith containing various proportions of eucrite and diogenite at different locations [9, 10]. Diogenite shows up in localized regions and mostly occurs in the southern polar region within the Rheasilvia impact basin [10]. Lithologies other than HEDs were indeed revealed by VIR spectra at the local scale. Olivine-rich deposits have been detected in Bellicia and Arruntia craters as well as in a limited number of other sites [11, 12, 13], while a large number of bright [14] and dark units [15, 16, 17] overlay Vesta'surface. Spectrally distinct, eucrite-rich ejecta have been observed in the Oppia and Octavia ejecta, interpreted to be glassy impact melt [18, 19]. VIR spectral analysis highlights a shallow 2.8-μm band diagnostic of OH-bearing phases [20]. This feature is mostly associated with dark material, which is believed to be exogenous material delivered by carbonaceous asteroids over time [16]. However, OH-rich material has been found to correlate with moderate-reflectance such as small spectrally distinct patches in the Oppia region [18], and a large circular area including Bellicia and Arruntia craters [21]. Compared to dark units, bright material units have a much weaker 2.8-μm band [14]. These units are interpreted to have an endogenous origin, therefore representing the relatively uncontaminated indigenous Vesta basaltic soil [16]. [1] Russell, C.T., Raymond, C.A., Space Sci. Rev. 163, 3-23, 2011. [2] Russell, C.T. et al., Science, 336, 684, 2012. [3] Sierks, H. et al., Space Sci. Rev. 163, 263-327, 2011. [4] De Sanctis et al., Space Sci. Rev. 163, 329-369, 2011. [5] Prettyman, T.H. et al., Space Sci. Rev. 163, 371-459, 2011. [6] McCord, Science 168, 1445-1447, 1970. [7] Drake, University of Arizona Press, 1979. [8] Feierberg and Drake, Science 209, 805-807, 1980. [9] De Sanctis et al., Science 336, 697-700, 2012. [10] Ammannito, E. et al., Maps 48, 2185-2198, 2013. [11] Ammannito, E. et al., Nature 504, 112-125, 2013. [12] Ruesch, O. et al, JGR 119-9, 2078-2108, 2014. [13] Palomba et al., Icarus 258, p. 120-134, 2015. [14] Zambon et al., Icarus 240, p. 73-85, 2014. [15] Jaumann et al., Science, 336 (6082), 687, 2012. [16] McCord et al., Nature 491, 83-86, 2012. [17] Palomba et al., Icarus 240, 58-72, 2014. [18] Le Corre, et al., Icarus, 226-2, 1568-1594, 2013. [19] Tosi et al., Icarus 259, 129-149, 2015. [20] De Sanctis et al., Astrophys. J. Lett. 758, L36, 2012. [21] Combe et al., Icarus 259, 53-71, 2015

Unique crater morphologies on Vesta, and the context of a deep regolith and intermediate gravity

NASA Astrophysics Data System (ADS)

Hoffmann, M.; Nathues, A.; Vincent, J. B.; Sierks, H.

2012-04-01

The Dawn spacecraft orbiting the minor planet Vesta has revealed details of the surface properties on a key object for the understanding of the evolution processes in an early epoch of our planetary system. In order to understand these phenomena the three dimensional structure of the surface must be deduced from identifiable processes known to be present elsewhere in the planetary system. Therefore the morphology of impact craters and their geological context (Keil 2002, Clark et al. 2002) plays an important role. They expose material at significant depth in the surface layers, they show a chronologic sequence of rearrangement of the original uppermost layer of Vesta, and their apparent mechanical properties fill the gap between topographic roughness and micro-structural photometric roughness and porosity. Many impact craters on Vesta show significant differences to impact craters on the Moon and Mercury, where their morphology is basically dominated by a rigid surface, and to those on volatile-rich surfaces like on Mars or the icy satellites of the outer planets. The closest match with Vestan crater morphologies is that with those on Lutetia (Vincent et al. 2012). This similarity can be seen by signs of granular fluidity in land-slide phenomena. A prominent and unique property of craters on Vesta is the occurrence of features showing singular concentric central pits, which so far have been associated with liquid materials: either molten rock on Mercury or the Moon, or the liquefaction of ice on Mars, Ganymede, and Callisto (Schultz, 1988). Selected from a collection of 200 sample features in the diameter range 1 to 30 km, some prototypes of this type are presented as indicators of such a porous regolith. The prototypes include simple hopper-shaped to pan-shaped features (the basic structure), but also a subclass with approximately circular symmetric multiple-depression structure (features typically larger than 10 km), and a subclass with unusual halo shapes not observed in regular impact craters. Main criteria of establishment of a causal link between the outer halo and the inner depression are the unique coincidence of their morphologies, the consistency from an 'evolutionary' point of view, and a statistically significant excess with respect to the expected number of chance configurations. These criteria have been tested and confirmed. The variety of features with the basic structure is consistent with more than a single kind of process. Several active and passive modes of their generation could be identified by the observational evidence, e.g. the collapse of a porous area shaken by the seismic wave from an impact into a regolith layer with high porosity. The required geophysical context is the presence of a sufficiently deep layer of regolith, a suitable distribution of size and shapes of its constituents, a deposit under low velocity and low pressure conditions, and a specific seismic history. These conditions are met by the giant impacts on Vesta, the 'intermediate' gravity (escape velocity sufficient for retention of ejecta but small for complete structural destruction by re-impactors), and the environment of craters of intermediate diameter (in the range of 10 km). Then significantly deep layers with similar properties can be created with the intact porosity of a fractal aggregate (Kaye, 1989). Diagnostic data are the histograms of the local distribution, the determination of surface roughness on all scales. Test areas on opposite sides of Vesta with areas of 400 km2 show differences in the abundance of pit craters to normal ones by a factor of two. Locally the fraction of pit craters exceeds 50% of all, whereas elsewhere they are obviously rare. Since under-abundance is found in the low albedo hemisphere of Vesta, a correlation with composition is indicated. The existence of the necessary conditions for the formation of a porous regolith has been tested by calculation of the trajectories of crater ejecta on the rapidly rotating object Vesta. Results show that on the trailing side of the original impact the opportunity for very slow re-impacts (less than a few meters per second) is significantly enhanced. Also the traveling times for the seismic wave and the arrival of ejecta have been compared, resulting in consistent details of the distance distribution of the related compactions. Further evidence comes from the analysis of brightness profiles of the surface which demonstrates local smoothing. The distribution of diameter ratio of halo to central depression matches that found for the Iovian satellite Callisto, thus hinting to the granular fluidity of the regolith on Vesta. Another unique type of interacting craters on Vesta is shown, which is related to different stages of compaction of the regolith. Concluding, it is shown that for individual features strong indications are found for a common origin of a crater and a surrounding halo by identifiable processes. A completely equivalent environment of impacts has been created by Lohse et al (2004) in laboratory, resulting in strikingly similar features. Therefore the paradigms of crater erosion and saturation have to be expanded to porous collapses. Age determinations by crater counts are affected. Although it is obvious that also some of these features were created by chance, even then the outcome in the sense of a compaction process can be studied.

KSC-07pd2583

NASA Image and Video Library

2007-09-27

KENNEDY SPACE CENTER, FLA. -- Rising above a cloud-filled horizon, the Delta II rocket carrying the Dawn spacecraft roars into the sky. Liftoff was at 7:34 a.m. EDT from Pad 17-B at Cape Canaveral Air Force Station. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Kim Shiflett

KSC-07pd1654

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- NASA's Dawn spacecraft moves out of the Astrotech facility in Titusville, Fla., for transportation to Launch Pad 17-B at Cape Canaveral Air Force Station, and mate to the Delta II launch vehicle. Launch is scheduled for July 7. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Troy Cryder.

KSC-07pd2584

NASA Image and Video Library

2007-09-27

KENNEDY SPACE CENTER, FLA. -- The Delta II rocket with the Dawn spacecraft on top waits in the early morning light for launch. Liftoff was at 7:34 a.m. EDT from Pad 17-B at Cape Canaveral Air Force Station. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Kim Shiflett

KSC-07pd2585

NASA Image and Video Library

2007-09-27

KENNEDY SPACE CENTER, FLA. -- Rising into billowing clouds above the horizon, the Delta II rocket carrying the Dawn spacecraft roars into the sky. Liftoff was at 7:34 a.m. EDT from Pad 17-B at Cape Canaveral Air Force Station. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/George Shelton

KSC-07pd1661

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- At the top of Launch Pad 17-B, at Cape Canaveral Air Force Station, workers help to guide NASA’s Dawn spacecraft into position for stacking with the Delta II launch vehicle. Launch is scheduled for July 7. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA’s first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Troy Cryder.

KSC-07pd2586

NASA Image and Video Library

2007-09-27

KENNEDY SPACE CENTER, FLA. -- Leaving the clouds behind, the Delta II rocket carrying the Dawn spacecraft arcs through the blue sky over the Atlantic Ocean. Liftoff was at 7:34 a.m. EDT from Pad 17-B at Cape Canaveral Air Force Station. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/George Shelton

KSC-07pd1663

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- At Launch Pad 17-B, at Cape Canaveral Air Force Station, workers position NASA's Dawn spacecraft to mate it with the Delta II launch vehicle below. Launch is scheduled for July 7. Dawn is the ninth mission in NASA’s Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA’s first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Troy Cryder.

KSC-07pd1659

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- At Launch Pad 17-B, at Cape Canaveral Air Force Station, NASA's Dawn spacecraft is hoisted up on the pad in preparation for stacking with the Delta II launch vehicle. Launch is scheduled for July 7. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Troy Cryder.

KSC-07pd1662

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- At Launch Pad 17-B, at Cape Canaveral Air Force Station, workers position NASA’s Dawn spacecraft to lower it toward the Delta II launch vehicle. Launch is scheduled for July 7. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA’s first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Troy Cryder.

KSC-07pd1660

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- At the top of Launch Pad 17-B, at Cape Canaveral Air Force Station, workers help to guide NASA’s Dawn spacecraft into position for stacking with the Delta II launch vehicle. Launch is scheduled for July 7. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA’s first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Troy Cryder.

Exogenic olivine on Vesta from Dawn Framing Camera color data

NASA Astrophysics Data System (ADS)

Nathues, Andreas; Hoffmann, Martin; Schäfer, Michael; Thangjam, Guneshwar; Le Corre, Lucille; Reddy, Vishnu; Christensen, Ulrich; Mengel, Kurt; Sierks, Holger; Vincent, Jean-Baptist; Cloutis, Edward A.; Russell, Christopher T.; Schäfer, Tanja; Gutierrez-Marques, Pablo; Hall, Ian; Ripken, Joachim; Büttner, Irene

2015-09-01

In this paper we present the results of a global survey of olivine-rich lithologies on (4) Vesta. We investigated Dawn Framing Camera (FC) High Altitude Mapping Orbit (HAMO) color cubes (∼60 m/pixel resolution) by using a method described in Thangjam et al. (Thangjam, G., Nathues, A., Mengel, K., Hoffmann, M., Schäfer, M., Reddy, V., Cloutis, E.A., Christensen, U., Sierks, H., Le Corre, L., Vincent, J.-B, Russell, C.T. [2014b]. Meteorit. Planet. Sci. arXiv:1408.4687 [astro-ph.EP]). In total we identified 15 impact craters exhibiting olivine-rich (>40 wt.% ol) outcrops on their inner walls, some showing olivine-rich material also in their ejecta and floors. Olivine-rich sites are concentrated in the Bellicia, Arruntia and Pomponia region on Vesta's northern hemisphere. From our multi-color and stratigraphic analysis, we conclude that most, if not all, of the olivine-rich material identified is of exogenic origin, i.e. remnants of A- or/and S-type projectiles. The olivine-rich lithologies in the north are possibly ejecta of the ∼90 km diameter Albana crater. We cannot draw a final conclusion on their relative stratigraphic succession, but it seems that the dark material (Nathues, A., Hoffmann, M., Cloutis, E.A., Schäfer, M., Reddy, V., Christensen, U., Sierks, H., Thangjam, G.S., Le Corre, L., Mengel, K., Vincent, J.-B., Russell, C.T., Prettyman, T., Schmedemann, N., Kneissl, T., Raymond, C., Gutierrez-Marques, P., Hall, I. Büttner, I. [2014b]. Icarus (239, 222-237)) and the olivine-rich lithologies are of a similar age. The origin of some potential olivine-rich sites in the Rheasilvia basin and at crater Portia are ambiguous, i.e. these are either of endogenic or exogenic origin. However, the small number and size of these sites led us to conclude that olivine-rich mantle material, containing more than 40 wt.% of olivine, is basically absent on the present surface of Vesta. In combination with recent impact models of Veneneia and Rheasilvia (Clenet, H., Jutzi, M., Barrat, J.-A., Gillet, Ph. [2014]. Lunar Planet Sci. 45, #1349; Jutzi, M., Asphaug, E., Gillet, P., Barrat, J.-A., Benz, W. [2013]. Nature 494, 207-210), which predict an excavation depth of up to 80 km, we are confident that the crust-mantle depth is significantly deeper than predicted by most evolution models (30 km; Mittlefehldt, D.W. [2014]. Asteroid 4 Vesta: A Fully Differentiated Dwarf Planet. NASA Technical Reports Server (20140004857.pdf)) or, alternatively, the olivine-content of the (upper) mantle is lower than our detection limit, which would lead to the conclusion that Vesta's parent material was already depleted in olivine compared to CI meteorites.

Distributed Storage Algorithm for Geospatial Image Data Based on Data Access Patterns.

PubMed

Pan, Shaoming; Li, Yongkai; Xu, Zhengquan; Chong, Yanwen

2015-01-01

Declustering techniques are widely used in distributed environments to reduce query response time through parallel I/O by splitting large files into several small blocks and then distributing those blocks among multiple storage nodes. Unfortunately, however, many small geospatial image data files cannot be further split for distributed storage. In this paper, we propose a complete theoretical system for the distributed storage of small geospatial image data files based on mining the access patterns of geospatial image data using their historical access log information. First, an algorithm is developed to construct an access correlation matrix based on the analysis of the log information, which reveals the patterns of access to the geospatial image data. Then, a practical heuristic algorithm is developed to determine a reasonable solution based on the access correlation matrix. Finally, a number of comparative experiments are presented, demonstrating that our algorithm displays a higher total parallel access probability than those of other algorithms by approximately 10-15% and that the performance can be further improved by more than 20% by simultaneously applying a copy storage strategy. These experiments show that the algorithm can be applied in distributed environments to help realize parallel I/O and thereby improve system performance.

Ar-39-Ar-40 Ages of Euerites and the Thermal History of Asteroid 4-Vesta

NASA Technical Reports Server (NTRS)

Bogard, Donald D.; Garrison, Daniel H.

2002-01-01

Eucrite meteorites are igneous rocks that derive from a large asteroid, probably 4 Vesta. Prior studies have shown that after eucrites formed, most were subsequently metamorphosed to temperatures up to equal to or greater than 800 C, and much later many were brecciated and heated by large impacts into the parent body surface. The uncommon basaltic, unbrecciated eucrites also formed near the surface but presumably escaped later brecciation, whereas the cumulate eucrites formed at depth where metamorphism may have persisted for a considerable period. To further understand the complex HED parent body thermal history, we determined new Ar-39-Ar-40 ages for nine eucrites classified as basaltic but unbrecciated, six eucrites classified as cumulate, and several basaltic-brecciated eucrites. Relatively precise Ar-Ar ages of two cumulate eucrites (Moama and EET87520) and four unbrecciated eucrites give a tight cluster at 4.48 +/1 0.01 Gyr. Ar-Ar ages of six additional unbrecciated eucrites are consistent with this age, within their larger age uncertainties. In contrast, available literature data on Pb-Pb isochron ages of four cumulate eucrites and one unbrecciated eucrite vary over 4.4-4.515 Gyr, and Sm-147 - Nd-143 isochron ages of four cumulate and three unbrecciated eucrites vary over 4.41-4.55 Gyr. Similar Ar-Ar ages for cumulate and unbrecciated eucrites imply that cumulate eucrites do not have a younger formation age than basaltic eucrites, as previously proposed. Rather, we suggest that these cumulate and unbrecciated eucrites resided at depth where parent body temperatures were sufficiently high to cause the K-Ar and some other chronometers to remain open diffusion systems. From the strong clustering of Ar-Ar ages at approximately 4.48 Gyr, we propose that these meteorites were excavated from depth in a single large impact event approximately 4.48 Gyr ago, which quickly cooled the samples and started the K-Ar chronometer. A large (approximately 460 km) crater postulated to exist on Vesta may be the source of these eucrites and of many smaller asteroids thought to be spectrally or physically associated with Vesta. Some Pb-Pb and Sm-Nd ages of cumulate and unbrecciated eucrites are consistent with the 4.48 Gyr Ar-Ar age, and the few older Pb-Pb and Sm-Nd ages may reflect isotopic closure prior to the large cratering event. One cumulate eucrite gives an Ar-Ar age of 4.25 Gyr; three additional cumulate eucrites give Ar-Ar ages of 3.4-3.7 Gyr; and two unbrecciated eucrites give Ar-Ar ages of approximately 3.55 Gyr. We attribute these younger ages to later impact heating. In addition, we find Ar-Ar impact-reset ages of several brecciated eucrites and eucritic clasts in howardites to fall in the range of 3.5-4.1 Gyr. Among these, Piplia Kalan, the first eucrite to show evidence for extinct 26 Al, was strongly impact heated approximately3.5 Gyr ago. When these data are combined with eucrite Ar-Ar ages in the literature, they confirm the previous suggestion that several large impact heating events occurred on Vesta over the time period approximately 4.1-3.4 Gyr ago. The onset of major impact heating may have occurred at similar times for both Vesta and the Moon, but impact heating appears to have persisted to a somewhat later time on Vesta compared to the Moon.

Log-less metadata management on metadata server for parallel file systems.

PubMed

Liao, Jianwei; Xiao, Guoqiang; Peng, Xiaoning

2014-01-01

This paper presents a novel metadata management mechanism on the metadata server (MDS) for parallel and distributed file systems. In this technique, the client file system backs up the sent metadata requests, which have been handled by the metadata server, so that the MDS does not need to log metadata changes to nonvolatile storage for achieving highly available metadata service, as well as better performance improvement in metadata processing. As the client file system backs up certain sent metadata requests in its memory, the overhead for handling these backup requests is much smaller than that brought by the metadata server, while it adopts logging or journaling to yield highly available metadata service. The experimental results show that this newly proposed mechanism can significantly improve the speed of metadata processing and render a better I/O data throughput, in contrast to conventional metadata management schemes, that is, logging or journaling on MDS. Besides, a complete metadata recovery can be achieved by replaying the backup logs cached by all involved clients, when the metadata server has crashed or gone into nonoperational state exceptionally.

Log-Less Metadata Management on Metadata Server for Parallel File Systems

PubMed Central

Xiao, Guoqiang; Peng, Xiaoning

2014-01-01

This paper presents a novel metadata management mechanism on the metadata server (MDS) for parallel and distributed file systems. In this technique, the client file system backs up the sent metadata requests, which have been handled by the metadata server, so that the MDS does not need to log metadata changes to nonvolatile storage for achieving highly available metadata service, as well as better performance improvement in metadata processing. As the client file system backs up certain sent metadata requests in its memory, the overhead for handling these backup requests is much smaller than that brought by the metadata server, while it adopts logging or journaling to yield highly available metadata service. The experimental results show that this newly proposed mechanism can significantly improve the speed of metadata processing and render a better I/O data throughput, in contrast to conventional metadata management schemes, that is, logging or journaling on MDS. Besides, a complete metadata recovery can be achieved by replaying the backup logs cached by all involved clients, when the metadata server has crashed or gone into nonoperational state exceptionally. PMID:24892093

Prediction and Confirmation of V-type Asteroids Beyond 2.5 AU Based on SDSS Colors

NASA Astrophysics Data System (ADS)

Binzel, Richard P.; Masi, G.; Foglia, S.

2006-09-01

We apply a taxonomic classification system developed by Masi et al. (2006, submitted to Icarus) to identify C-, S-, and V-type asteroids present within the 3rd Release of the Sloan Digital Sky Survey Moving Object Catalog (SDSS MOC3). The classifications deduced by Masi et al. for 43,000 asteroids using SDSS colors are based on the taxonomy of Bus (1999; MIT Ph.D. thesis). To link SDSS colors to the Bus taxonomy, Masi et al. (2006) use 149 objects measured in common by both SDSS and the Small Main-Belt Asteroid Spectroscopic Survey (SMASS) (Bus and Binzel 2002, Icarus 158, 106). We report results of direct testing of SDSS V-type classification predictions for six objects, where the tests were performed by visible wavelength spectroscopy (Lazzaro et al. 2004, Icarus 172, 179) and target of opportunity near-infrared spectroscopy obtained using the NASA Infrared Telescope Facility (IRTF). Vesta-like spectra and a V-type taxonomy are confirmed for five of the six predicted V-type objects sampled. Most interestingly, the SDSS taxonomy correctly predicted the V-type spectral characteristics for asteroid (21238) 1995 WV7, a 6 km asteroid located far from Vesta across the 3:1 mean motion resonance at 2.54 AU. (Proper elements a,e,i: 2.54 AU, 0.14, and 10.8 deg.) Given the 2 km/sec ejection velocity required from Vesta to reach the current orbit, and the difficulty of migrating across the 3:1 resonance (at 2.5 AU) by a process such as Yarkovsky drift or via secular resonances (Carruba et al. 2005, Astron. Astrophys. 441, 819), asteroid 21238 may be a new candidate for a basaltic asteroid having no relationship to Vesta.

The compositional diversity of non-Vesta basaltic asteroids

NASA Astrophysics Data System (ADS)

Leith, Thomas B.; Moskovitz, Nicholas A.; Mayne, Rhiannon G.; DeMeo, Francesca E.; Takir, Driss; Burt, Brian J.; Binzel, Richard P.; Pefkou, Dimitra

2017-10-01

We present near-infrared (0.78-2.45 μm) reflectance spectra for nine middle and outer main belt (a > 2.5 AU) basaltic asteroids. Three of these objects are spectrally distinct from all classifications in the Bus-DeMeo system and could represent spectral end members in the existing taxonomy or be representatives of a new spectral type. The remainder of the sample are classified as V- or R-type. All of these asteroids are dynamically detached from the Vesta collisional family, but are too small to be intact differentiated parent bodies, implying that they originated from differentiated planetesimals which have since been destroyed or ejected from the solar system. The 1- and 2-μm band centers of all objects, determined using the Modified Gaussian Model (MGM), were compared to those of 47 Vestoids and fifteen HED meteorites of known composition. The HEDs enabled us to determine formulas relating Band 1 and Band 2 centers to pyroxene ferrosilite (Fs) compositions. Using these formulas we present the most comprehensive compositional analysis to date of middle and outer belt basaltic asteroids. We also conduct a careful error analysis of the MGM-derived band centers for implementation in future analyses. The six outer belt V- and R-type asteroids show more dispersion in parameter space than the Vestoids, reflecting greater compositional diversity than Vesta and its associated bodies. The objects analyzed have Fs numbers which are, on average, between five and ten molar percent lower than those of the Vestoids; however, identification and compositional analysis of additional outer belt basaltic asteroids would help to confirm or refute this result. Given the gradient in oxidation state which existed within the solar nebula, these results tentatively suggest that these objects formed at either a different time or location than 4 Vesta.

The Regolith of 4 Vesta - Inferences from Howardites

NASA Technical Reports Server (NTRS)

Mittlefehldt, D. W.; Herrin, J. S.; Cartwright, J. A.

2011-01-01

Asteroid 4 Vesta is quite likely the parent asteroid of the howardite, eucrite and diogenite meteorites - the HED clan. Eucrites and diogenites are the products of igneous processes; the former are basaltic composition rocks from flows, and shallow and deep intrusive bodies, whilst the latter are cumulate orthopyroxenites thought to have formed deep in the crust. Impact processes have excavated these materials and mixed them into a suite of polymict breccias. Howardites are polymict breccias composed mostly of clasts and mineral fragments of eucritic and diogenitic parentage, with neither end-member comprising more than 90% of the rock. Early work interpreted howardites as representing the lithified regolith of their parent asteroid. Recently, howardites have been divided into two subtypes; fragmental howardites, being a type of non-regolithic polymict breccia, and regolithic howardites, being lithified remnants of the active regolith of 4 Vesta. We are in the thralls of a collaborative investigation of the record of impact mixing contained within howardites, which includes studies of their mineralogy, petrology, bulk rock compositions, and bulk rock and clast noble gas contents. One goal of our investigation is to test the hypothesis that some howardites represent breccias formed from an ancient, well-mixed regolith on Vesta. Another is to use our results to further understand regolith processing on differentiated asteroids as compared to what has been learned from the Moon. We have made petrographic observations and electron microprobe analyses on 21 howardites and 3 polymict eucrites. We have done bulk rock analyses using X-ray fluorescence spectrometry and are completing inductively coupled plasma mass spectrometry analyses. Here, we discuss our petrologic and bulk compositional results in the context of regolith formation. Companion presentations describe the noble gas results and compositional studies of low-Ca pyroxene clasts.

Mineralogical Composition of the Different Types of Bright Deposits on Vesta

NASA Technical Reports Server (NTRS)

Zambon, F.; Capaccioni, F.; DeSanctis, M. C.; Ammannito, E.; Li, J.-Y.; Longobardo, A.; Mittlefehldt, D. W.; Palomba, E.; Pieters, C. M.; Schroeder, S. E.;

Geological Structures in the WaIls of Vestan Craters

NASA Technical Reports Server (NTRS)

Mittlefehldt, David; Nathues, A.; Beck, A. W.; Hoffmann, M.; Schaefer, M.; Williams, D. A.

2014-01-01

A compelling case can be made that Vesta is the parent asteroid for the howardite, eucrite and diogenite (HED) meteorites [1], although this interpretation has been questioned [2]. Generalized models for the structure of the crust of Vesta have been developed based on petrologic studies of basaltic eucrites, cumulate eucrites and diogenites. These models use inferred cooling rates for different types of HEDs and compositional variations within the clan to posit that the lower crust is dominantly diogenitic in character, cumulate eucrites occur deep in the upper crust, and basaltic eucrites dominate the higher levels of the upper crust [3-5]. These models lack fine-scale resolution and thus do not allow for detailed predictions of crustal structure. Geophysical models predict dike and sill intrusions ought to be present, but their widths may be quite small [6]. The northern hemisphere of Vesta is heavily cratered, and the southern hemisphere is dominated by two 400-500 km diameter basins that excavated deep into the crust [7-8]. Physical modeling of regolith formation on 300 km diameter asteroids predicts that debris layers would reach a few km in thickness, while on asteroids of Vesta's diameter regolith thicknesses would be less [9]. This agrees well with the estimated =1 km thickness of local debris excavated by a 45 km diameter vestan crater [10]. Large craters and basins may have punched through the regolith/megaregolith and exposed primary vestan crustal structures. We will use Dawn Framing Camera (FC) [11] images and color ratio maps from the High Altitude and Low Altitude Mapping Orbits (HAMO, 65 m/pixel; LAMO, 20 m/pixel) to evaluate structures exposed on the walls of craters: two examples are discussed here.

Scattering V-type asteroids during the giant planet instability: a step for Jupiter, a leap for basalt

NASA Astrophysics Data System (ADS)

Brasil, P. I. O.; Roig, F.; Nesvorný, D.; Carruba, V.

2017-06-01

V-type asteroids are a taxonomic class whose surface is associated with a basaltic composition. The only known source of V-type asteroids in the Main Asteroid Belt is (4) Vesta, which is located in the inner part of the Main Belt. However, many V-type asteroids cannot be dynamically linked to Vesta, in particular, those asteroids located in the middle and outer parts of the Main Belt. Previous works have failed to find mechanisms to transport V-type asteroids from the inner to the middle and outer belts. In this work, we propose a dynamical mechanism that could have acted on primordial asteroid families. We consider a model of the giant planet migration known as the jumping Jupiter model with five planets. Our study is focused on the period of 10 Myr that encompasses the instability phase of the giant planets. We show that, for different hypothetical Vesta-like paleo-families in the inner belt, the perturbations caused by the ice giant that is scattered into the asteroid belt before being ejected from the Solar system are able to scatter V-type asteroids to the middle and outer belts. Based on the orbital distribution of V-type candidates identified from the Sloan Digital Sky Survey and the VISTA Survey colours, we show that this mechanism is efficient enough provided that the hypothetical paleo-family originated from a 100 to 500 km crater excavated on the surface of (4) Vesta. This mechanism is able to explain the currently observed V-type asteroids in the middle and outer belts, with the exception of (1459) Magnya.

DOVIS 2.0: an efficient and easy to use parallel virtual screening tool based on AutoDock 4.0.

PubMed

Jiang, Xiaohui; Kumar, Kamal; Hu, Xin; Wallqvist, Anders; Reifman, Jaques

2008-09-08

Small-molecule docking is an important tool in studying receptor-ligand interactions and in identifying potential drug candidates. Previously, we developed a software tool (DOVIS) to perform large-scale virtual screening of small molecules in parallel on Linux clusters, using AutoDock 3.05 as the docking engine. DOVIS enables the seamless screening of millions of compounds on high-performance computing platforms. In this paper, we report significant advances in the software implementation of DOVIS 2.0, including enhanced screening capability, improved file system efficiency, and extended usability. To keep DOVIS up-to-date, we upgraded the software's docking engine to the more accurate AutoDock 4.0 code. We developed a new parallelization scheme to improve runtime efficiency and modified the AutoDock code to reduce excessive file operations during large-scale virtual screening jobs. We also implemented an algorithm to output docked ligands in an industry standard format, sd-file format, which can be easily interfaced with other modeling programs. Finally, we constructed a wrapper-script interface to enable automatic rescoring of docked ligands by arbitrarily selected third-party scoring programs. The significance of the new DOVIS 2.0 software compared with the previous version lies in its improved performance and usability. The new version makes the computation highly efficient by automating load balancing, significantly reducing excessive file operations by more than 95%, providing outputs that conform to industry standard sd-file format, and providing a general wrapper-script interface for rescoring of docked ligands. The new DOVIS 2.0 package is freely available to the public under the GNU General Public License.

Parallel line analysis: multifunctional software for the biomedical sciences

NASA Technical Reports Server (NTRS)

Swank, P. R.; Lewis, M. L.; Damron, K. L.; Morrison, D. R.

1990-01-01

An easy to use, interactive FORTRAN program for analyzing the results of parallel line assays is described. The program is menu driven and consists of five major components: data entry, data editing, manual analysis, manual plotting, and automatic analysis and plotting. Data can be entered from the terminal or from previously created data files. The data editing portion of the program is used to inspect and modify data and to statistically identify outliers. The manual analysis component is used to test the assumptions necessary for parallel line assays using analysis of covariance techniques and to determine potency ratios with confidence limits. The manual plotting component provides a graphic display of the data on the terminal screen or on a standard line printer. The automatic portion runs through multiple analyses without operator input. Data may be saved in a special file to expedite input at a future time.

''Towards a High-Performance and Robust Implementation of MPI-IO on Top of GPFS''

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prost, J.P.; Tremann, R.; Blackwore, R.

2000-01-11

MPI-IO/GPFS is a prototype implementation of the I/O chapter of the Message Passing Interface (MPI) 2 standard. It uses the IBM General Parallel File System (GPFS), with prototyped extensions, as the underlying file system. this paper describes the features of this prototype which support its high performance and robustness. The use of hints at the file system level and at the MPI-IO level allows tailoring the use of the file system to the application needs. Error handling in collective operations provides robust error reporting and deadlock prevention in case of returning errors.

Comparative Planetary Mineralogy: Basaltic Plagioclase from Earth, Moon, Mars and 4 Vesta

NASA Technical Reports Server (NTRS)

Karner, J. M.; Papike, J. J.; Shearer, C. K.

2003-01-01

Major, minor and trace element analysis of silicates has allowed for the study of planetary basalts in a comparative planetary mineralogy context. We continue this initiative by exploring the chemistry of plagioclase feldspar in basalts from the Earth, Moon, Mars and 4 Vesta. This paper presents new data on plagioclase from six terrestrial basalt suites including Keweenawan, Island Arc, Hawaiian, Columbia Plateau, Taos Plateau, and Ocean Floor; six lunar basalt suites including Apollo 11 Low K, Apollo 12 Ilmenite, Apollo 12 Olivine, Apollo 12 Pigeonite, Apollo 15 Olivine, and Apollo 15 Pigeonite; two basaltic martian meteorites, Shergotty and QUE 94201; and one unequilibrated eucrite, Pasamonte.

KSC-07pd1664

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- At Launch Pad 17-B, at Cape Canaveral Air Force Station, the Delta II launch vehicle with NASA’s Dawn spacecraft mission logo can be seen as it is moved into position for stacking with the Delta II launch vehicle. Launch is scheduled for July 7. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA’s first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Troy Cryder.

KSC-07pd1656

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- At Launch Pad 17-B, at Cape Canaveral Air Force Station, workers attach a crane to NASA's Dawn spacecraft. It will be lifted into the mobile service tower for mating to the Delta II launch vehicle.Launch is scheduled for July 7. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Troy Cryder.

KSC-07pd2062

NASA Image and Video Library

2007-07-22

KENNEDY SPACE CENTER, FLA. — Sitting on a transporter, the Dawn spacecraft arrives at the Astrotech payload processing facility. Dawn was returned from Launch Pad 17-B at Cape Canaveral Air Force Station to Astrotech to await a new launch date. The launch opportunity extends from Sept. 7 to Oct. 15. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA’s first purely scientific mission powered by three solar electric ion propulsion engines. NASA/Charisse Nahser

KSC-07pd1655

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- NASA's Dawn spacecraft, mated to the Delta II upper stage booster, arrives at Launch Pad 17-B at Cape Canaveral Air Force Station. It will be lifted into the mobile service tower for mating to the Delta II launch vehicle. Launch is scheduled for July 7. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Troy Cryder.

KSC-07pd2063

NASA Image and Video Library

2007-07-22

KENNEDY SPACE CENTER, FLA. — The Dawn spacecraft is moved inside the Astrotech payload processing facility. Dawn was returned from Launch Pad 17-B at Cape Canaveral Air Force Station to Astrotech to await a new launch date. The launch opportunity extends from Sept. 7 to Oct. 15. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA’s first purely scientific mission powered by three solar electric ion propulsion engines. NASA/Charisse Nahser

KSC-07pd1653

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- Inside the Astrotech Facility in Titusville, Fla., NASA’s Dawn spacecraft is ready to be transported to Launch Pad 17-B at Cape Canaveral Air Force Station, for mate to the Delta II launch vehicle. Launch is scheduled for July 7. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Troy Cryder.

KSC-07pd1658

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- At Launch Pad 17-B, at Cape Canaveral Air Force Station, workers prepare NASA's Dawn spacecraft mated to the Delta II upper stage booster, for hoisting up into the mobile service tower. Dawn will be mated with the Delta II launch vehicle. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Troy Cryder.

KSC-07pd1657

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- At Launch Pad 17-B, at Cape Canaveral Air Force Station, workers attach a crane to NASA's Dawn spacecraft mated to the Delta II upper stage booster, in preparation for stacking with the Delta II launch vehicle. Launch is scheduled for July 7. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Troy Cryder.

Towards Calibrating the Vestan Regolith: Correlating the Petrology, Chemistry and Spectroscopy of Howardites

NASA Technical Reports Server (NTRS)

Mittlefehldt, D. W.; Ammannito, E.; Hiroi, T.; De Angelis, S.; Di Iorio, T.; Pieters, C. M.; De Sanctis, C.

2013-01-01

The Dawn spacecraft carries a visible and infrared mapping spectrometer (VIR) [1] that has acquired spectra for the wavelength range 0.25-5.0 µm at various spatial resolutions covering much of the vestan surface [2]. Through comparison of VIR spectra with laboratory spectra of howardite, eucrite and diogenite meteorites, the distribution of more diogenite-rich and more eucrite-rich terranes on Vesta have been mapped [3], but these maps are qualitative in nature. The available laboratory spectra are not well-integrated with detailed sample petrology or composition limiting their utility for lithologic mapping. Importantly, howardites are now recognized to come in two subtypes, regolithic and fragmental [4]. The former are breccias assembled in part from true regolith, while the latter have had much less exposure to the space environment. We are attempting to develop a more quantitative basis for mapping the distribution of lithologic types on Vesta through acquiring laboratory spectra on splits of howardites that have been petrologically and chemically characterized [5]. Noble gas analyses have been done on some allowing identification of those howardites that have been exposed in the true regolith of Vesta [6].

Understanding Volatile Occurrence on Vesta Using Bistatic Radar and GRaND Observations by the Dawn Mission

NASA Astrophysics Data System (ADS)

Palmer, E. M.; Heggy, E.; Kofman, W. W.

2016-12-01

The first orbital bistatic radar experiment was conducted by Dawn at Asteroid Vesta, where Dawn's HGA was used to transmit X-band radio waves and Earth's Deep Space Network (DSN) 70-meter antennas were used to receive. Due to the opportunistic nature of the experiment, the HGA remained in a fixed orientation toward the Earth such that surface radar reflections occurred at grazing incidence angles of 89° just before and after Dawn's occultation behind Vesta. Among the 16 observed echo sites, we find that σ0ranges from -12 dB to -20 dB and has corresponding RMS slopes ranging from 1°- 8°. To assess potential volatile presence, we compare the distribution of RMS slopes to subsurface hydrogen concentrations observed by Dawn's Gamma Ray and Neutron Detector (GRaND) to 1 m depth. While Vesta's surface is thought to have been largely depleted of volatiles during its differentiation, observations by Dawn'sGRaND and VIR instruments suggest the potential introduction of hydrated material through meteoritic impacts. We identify seven sites of potential volatile occurrence—where low roughness (<5°) is observed to be coupled with high content of hydrated materials (0.025 - 0.04 wt%). Such sites support the possibility of volatile presence, as the regolith should otherwise be particularly rough in the absence of smoothening processes such as the melting, run-off and recrystallization of water ice after an impact. The sites correspond to occultation entry orbit numbers 635, 644 and 719—which overlap Divalia Fossae, Marcia crater ejecta and Octavia crater, respectively—and exit orbit numbers 377, 406, 407 and 720—overlapping northern cratered trough terrain, dark material near Aruntia crater and the cratered highlands. Toward comparing volatile occurrence on other small bodies, Dawn'sBSR experiment at Asteroid Ceres raises new questions. How does the range of decimeter-scale RMS slopes compare with Vesta's surface? How well does the distribution of RMS slopes correlate with GRaND's map of subsurface hydrogen concentration? In addition to optimizing future missions' landing and surface trafficability, characterizing small body surface roughness using BSR will enable further investigation into the relationship between volatile presence and decimeter-scale surface roughness.

The Geology of the Marcia Quadrangle of Asteroid Vesta: Assessing the Effects of Large, Young Craters

NASA Technical Reports Server (NTRS)

Williams, David A.; Denevi, Brett W.; Mittlefehldt, David W.; Mest, Scott C.; Schenk, Paul M.; Yingst, R. Aileen; Buczowski, Debra L.; Scully, Jennifer E. C.; Garry, W. Brent; McCord, Thomas B.;

A numerical model of the physical and chemical evolution of Vesta

NASA Astrophysics Data System (ADS)

Mizzon, H.; Monnereau, M.; Toplis, M. J.; Prettyman, T. H.; McSween, H. Y.; Raymond, C. A.; Russell, C. T.

2015-10-01

Vesta is a 262 km radius asteroid that has been proposed as the parent body of the Howardite- Eucrite-Diogenite family of meteorites. The observations of the Dawn spacecraft confirm the idea that this protoplanet underwent magmatic differentiation, providing evidence for regions of the upper crust rich in basaltic (eucritic) lithologies, while regions that have experienced excavation related to large impacts (i.e. Rheasilvia) are richer in pyroxene-dominated (diogenitic) lithologies [1,2]. One of the most striking results of the Dawn mission is the absence of olivine at the near-surface, even in the deep Rheasiliva basin. This observation has been used to question the chondritic nature of bulk Vesta and/or question its status as an intact protoplanet [3]. From a geochemical point of view, the HED meteorites are consistent with chondritic precursors [4], but petrological models have met difficulties explaining both eucrites and diogenites in a unified way [5]. These models comprise two extreme endmember scenarios: the first considers the partial melting of the primitive mantle of Vesta, followed by melt extraction [6], while the second involves the solidification of an initially entirely molten magma ocean [7]. In the latter case, major-element chemistry of eucrites and diogenites can be reproduced [7], but not the extreme range of trace element concentrations observed in diogenites [8]. More importantly, the physics of melt migration seems to preclude the existence of a global magma ocean, assuming that 26Al is the only heat source capable of extensively producing melt in early small bodies. This is because plagioclase is one of the first phases to melt, thus early formed liquids are Al-rich. Rapid migration of such liquids redistributes 26Al, limiting melt production where liquid has been lost [9,10]. This idea was explored by [11], who qualitatively suggested that the first melts formed would migrate to the surface (as eucrites), while the lower mantle would become enriched in refractory olivine through its downward compaction. This last point potentially explains the lack of this mineral near Vesta's surface. The aim of work presented here is to quantitatively explore this idea by computing the mineralogy as a function of depth and time, using a set of numerical solutions of conservative equations and an appropriate phase diagram.

The petrology and chronology of NWA 8009 impact melt breccia: Implication for early thermal and impact histories of Vesta

NASA Astrophysics Data System (ADS)

Liao, Shiyong; Hsu, Weibiao

2017-05-01

Studies of petrology, mineralogy and geochronology of eucrites are keys to reconstruct the thermal and impact history of 4 Vesta, the proposed parent body for HED meteorites. Here we report the petrography, mineralogy and geochemistry of NWA 8009, a newly found eucritic impact-melt breccia, and present SIMS U-Pb ages of zircon and phosphates. NWA 8009 consists of coarse- and fine-grained lithic and mineral clasts set in fine-grained recrystallized matrix. It was derived from a protolith of monomict non-cumulate eucrite. Evidence for intense shock metamorphism observed in NWA 8009 includes mosaicism, deformed exsolution lamellae and partial melting of pyroxene, melting and incipient flow of plagioclase, planar fractures and granular textures of zircon. These shock effects indicate NWA 8009 was subjected to an impact metamorphism with peak pressure of ∼50-60 GPa and post-shock temperature of ∼1160-1200 °C. NWA 8009 is among the most intensely shocked HEDs reported yet. After the impact, the sample was buried near the surface in target rocks and experienced rapid cooling (∼23 °C/h) and annealing, resulting in recrystallization of the matrix and devitrification of plagioclase and silica glasses. U-Pb isotopic system of apatite within plagioclase groundmass of lithic clasts is completely reset and constrains the timing of impact at 4143 ± 61 Ma, providing a new robust impact age on Vesta. Combined with the presence of synchronous impact resetting events, especially those recorded by Lu-Hf, Sm-Nd, and Pb-Pb isotopic systems, we identified a period of high impacts flux at ca. 4.1-4.2 Ga on Vesta. This impact flux occurred coincident with the uptick at ca. 4.1-4.2 Ga in impact age spectra of the moon, probably reflects widespread intense bombardment throughout the inner solar system at ca. 4.1-4.2 Ga. Based on evidence from zircon chemical zoning, petrographic occurrences, as well as the distinctive Zr/Hf ratios, we suggested that zircons in NWA 8009 have had a metamorphic, instead of magmatic origin. They mainly crystallized from melts produced by partial melting of mesostasis area due to reheating event during early global thermal metamorphism, rather than by Zr release from Zr-rich minerals. The U-Pb isotopic system in zircons was not disturbed by subsequent impacts, the weighted-mean 207Pb/206Pb age of 4560 ± 8 Ma represents the timing of zircon growth during thermal metamorphism. Zircons from NWA 8009 and other eucrites may share a common origin during metamorphic growth events, and constraining the global thermal metamorphism on Vesta at ca. 4.55 Ga. The main heat sources responsible for global metamorphism in basaltic crust of Vesta might be heating from the hot interior, especially heat flow related to magmatism, rather than impact.

Developing a Hadoop-based Middleware for Handling Multi-dimensional NetCDF

NASA Astrophysics Data System (ADS)

Li, Z.; Yang, C. P.; Schnase, J. L.; Duffy, D.; Lee, T. J.

2014-12-01

Climate observations and model simulations are collecting and generating vast amounts of climate data, and these data are ever-increasing and being accumulated in a rapid speed. Effectively managing and analyzing these data are essential for climate change studies. Hadoop, a distributed storage and processing framework for large data sets, has attracted increasing attentions in dealing with the Big Data challenge. The maturity of Infrastructure as a Service (IaaS) of cloud computing further accelerates the adoption of Hadoop in solving Big Data problems. However, Hadoop is designed to process unstructured data such as texts, documents and web pages, and cannot effectively handle the scientific data format such as array-based NetCDF files and other binary data format. In this paper, we propose to build a Hadoop-based middleware for transparently handling big NetCDF data by 1) designing a distributed climate data storage mechanism based on POSIX-enabled parallel file system to enable parallel big data processing with MapReduce, as well as support data access by other systems; 2) modifying the Hadoop framework to transparently processing NetCDF data in parallel without sequencing or converting the data into other file formats, or loading them to HDFS; and 3) seamlessly integrating Hadoop, cloud computing and climate data in a highly scalable and fault-tolerance framework.

76 FR 20750 - Self-Regulatory Organizations; EDGX Exchange, Inc.; Notice of Filing and Immediate Effectiveness...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-13

... on the Exchange's Internet Web site at http://www.directedge.com . \\3\\ A Member is any registered... strategy to the ROUD/ROUE routing strategies is Parallel D or Parallel 2D with the DRT (Dark routing... one method. The Commission will post all comments on the Commission's Internet Web site ( http://www...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collins, Benjamin S.

The Futility package contains the following: 1) Definition of the size of integers and real numbers; 2) A generic Unit test harness; 3) Definitions for some basic extensions to the Fortran language: arbitrary length strings, a parameter list construct, exception handlers, command line processor, timers; 4) Geometry definitions: point, line, plane, box, cylinder, polyhedron; 5) File wrapper functions: standard Fortran input/output files, Fortran binary files, HDF5 files; 6) Parallel wrapper functions: MPI, and Open MP abstraction layers, partitioning algorithms; 7) Math utilities: BLAS, Matrix and Vector definitions, Linear Solver methods and wrappers for other TPLs (PETSC, MKL, etc), preconditioner classes;more » 8) Misc: random number generator, water saturation properties, sorting algorithms.« less

Distributed File System Utilities to Manage Large DatasetsVersion 0.5

DOE Office of Scientific and Technical Information (OSTI.GOV)

2014-05-21

FileUtils provides a suite of tools to manage large datasets typically created by large parallel MPI applications. They are written in C and use standard POSIX I/Ocalls. The current suite consists of tools to copy, compare, remove, and list. The tools provide dramatic speedup over existing Linux tools, which often run as a single process.

Parallel log structured file system collective buffering to achieve a compact representation of scientific and/or dimensional data

DOEpatents

Grider, Gary A.; Poole, Stephen W.

2015-09-01

Collective buffering and data pattern solutions are provided for storage, retrieval, and/or analysis of data in a collective parallel processing environment. For example, a method can be provided for data storage in a collective parallel processing environment. The method comprises receiving data to be written for a plurality of collective processes within a collective parallel processing environment, extracting a data pattern for the data to be written for the plurality of collective processes, generating a representation describing the data pattern, and saving the data and the representation.

KSC-07pd2061

NASA Image and Video Library

2007-07-22

KENNEDY SPACE CENTER, FLA. — On Pad 17-B at Cape Canaveral Air Force Station, the Dawn spacecraft is safely secured on a transporter for its trip to Astrotech. Dawn is being returned to the Astrotech payload processing facility to await a new launch date. The launch opportunity extends from Sept. 7 to Oct. 15. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA’s first purely scientific mission powered by three solar electric ion propulsion engines. NASA/George Shelton

KSC-07pd2058

NASA Image and Video Library

2007-07-22

KENNEDY SPACE CENTER, FLA. — On Pad 17-B at Cape Canaveral Air Force Station, the Dawn spacecraft is lowered from the mobile service tower to the ground. Dawn is being returned to the Astrotech payload processing facility to await a new launch date. The launch opportunity extends from Sept. 7 to Oct. 15. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA’s first purely scientific mission powered by three solar electric ion propulsion engines. NASA/George Shelton

KSC-07pd2059

NASA Image and Video Library

2007-07-22

KENNEDY SPACE CENTER, FLA. — On Pad 17-B at Cape Canaveral Air Force Station, the Dawn spacecraft is lowered from the mobile service tower to the ground. Dawn is being returned to the Astrotech payload processing facility to await a new launch date. The launch opportunity extends from Sept. 7 to Oct. 15. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA’s first purely scientific mission powered by three solar electric ion propulsion engines. NASA/George Shelton

VESTA Project: Phase 0 report

NASA Technical Reports Server (NTRS)

Perret, A.

1986-01-01

This report presents the results of technical studies conducted at CNES/PMF/APS between October 1984 and September 1985 on the VESTA project. These preliminary studies were conducted to establish mission feasibility in terms ofthe trajectory and the scientific objectives, and to determine the type of interfaces which will be required with the Soviets and to measure the magnitude of French participation. A joint French-Soviet report recommends that the project enter phase A, and was approved by CNES and INTERCOSMOS in September, 1985. The mission analysis is made for a mid-1991 launch, and a development schedule for an end-1992 launch is suggested. The decision to postpone the mission was made during the course of the study.

Petrologic and Chemical Characterization of a Suite of Antarctic Diogenites

NASA Technical Reports Server (NTRS)

Mittlefehldt, D. W.; Mertzman, S. A.; Peng, Z. X.; Mertzman, K. R.

2013-01-01

The origin of diogenites, ultramafic cumulates related to eucrites, is an unresolved problem [1]. Most diogenites are orthopyroxenites, a few are harzburgites [2], and some are transitional to cumulate eucrites [1, 3]. Cumulate eucrites are gabbros formed by crystal fractionation from basaltic eucrites [4]. The consensus view is that basaltic eucrites are residual melts from global-magma-ocean crystallization on their parent asteroid [4] which is plausibly Vesta [5]. However, the petrologic and compositional characteristics of diogenites seem to preclude a magma ocean origin [1, 4]. We are doing a petrologic and chemical study of new or unusual diogenites with the ultimate goals of constraining their genesis, and the geologic evolution of Vesta.

A Note on Compiling Fortran

DOE Office of Scientific and Technical Information (OSTI.GOV)

Busby, L. E.

Fortran modules tend to serialize compilation of large Fortran projects, by introducing dependencies among the source files. If file A depends on file B, (A uses a module defined by B), you must finish compiling B before you can begin compiling A. Some Fortran compilers (Intel ifort, GNU gfortran and IBM xlf, at least) offer an option to ‘‘verify syntax’’, with the side effect of also producing any associated Fortran module files. As it happens, this option usually runs much faster than the object code generation and optimization phases. For some projects on some machines, it can be advantageous tomore » compile in two passes: The first pass generates the module files, quickly; the second pass produces the object files, in parallel. We achieve a 3.8× speedup in the case study below.« less

A Massively Parallel Computational Method of Reading Index Files for SOAPsnv.

PubMed

Zhu, Xiaoqian; Peng, Shaoliang; Liu, Shaojie; Cui, Yingbo; Gu, Xiang; Gao, Ming; Fang, Lin; Fang, Xiaodong

2015-12-01

SOAPsnv is the software used for identifying the single nucleotide variation in cancer genes. However, its performance is yet to match the massive amount of data to be processed. Experiments reveal that the main performance bottleneck of SOAPsnv software is the pileup algorithm. The original pileup algorithm's I/O process is time-consuming and inefficient to read input files. Moreover, the scalability of the pileup algorithm is also poor. Therefore, we designed a new algorithm, named BamPileup, aiming to improve the performance of sequential read, and the new pileup algorithm implemented a parallel read mode based on index. Using this method, each thread can directly read the data start from a specific position. The results of experiments on the Tianhe-2 supercomputer show that, when reading data in a multi-threaded parallel I/O way, the processing time of algorithm is reduced to 3.9 s and the application program can achieve a speedup up to 100×. Moreover, the scalability of the new algorithm is also satisfying.

Basaltic material in the main belt: a tale of two (or more) parent bodies?

NASA Astrophysics Data System (ADS)

Ieva, S.; Dotto, E.; Lazzaro, D.; Fulvio, D.; Perna, D.; Epifani, E. Mazzotta; Medeiros, H.; Fulchignoni, M.

2018-06-01

The majority of basaltic objects in the main belt are dynamically connected to Vesta, the largest differentiated asteroid known. Others, due to their current orbital parameters, cannot be easily dynamically linked to Vesta. This is particularly true for all the basaltic asteroids located beyond 2.5 au, where lies the 3:1 mean motion resonance with Jupiter. In order to investigate the presence of other V-type asteroids in the middle and outer main belt (MOVs) we started an observational campaign to spectroscopically characterize in the visible range MOV candidates. We observed 18 basaltic candidates from TNG and ESO - NTT between 2015 and 2016. We derived spectral parameters using the same approach adopted in our recent statistical analysis and we compared our data with orbital parameters to look for possible clusters of MOVs in the main belt, symptomatic for a new basaltic family. Our analysis seemed to point out that MOVs show different spectral parameters respect to other basaltic bodies in the main belt, which could account for a diverse mineralogy than Vesta; moreover, some of them belong to the Eos family, suggesting the possibility of another basaltic progenitor. This could have strong repercussions on the temperature gradient present in the early Solar System, and on our current understanding of differentiation processes.

Spitzer IRS (8-30 micron) Spectra of Basaltic Asteroids 1459 Magnya and 956 Elisa: Mineralogy and Thermal Properties

NASA Technical Reports Server (NTRS)

Lim, Lucy F.; Emery, J. P.; Moskovitz, N. A.

2009-01-01

We report preliminary results from Spitzer IRS (Infrared Spectrograph) spectroscopy of 956 Elisa, 1459 Magnya, and other small basaltic asteroids with the Spitzer IRS. Program targets include members of the dynamical family of the unique large differentiated asteroid 4 Vesta ("Vestoids"), several outer-main-belt basaltic asteroids whose orbits exclude them from originating on 4 Vesta, and the basaltic near-Earth asteroid 4055 Magellan. The preliminary thermal model (STM) fit to the 5--35 micron spectrum of 956 Elisa gives a radius of 5.4 +/- 0.3 km and a subsolar- point temperature of 282.2 +/- 0.5 K. This temperature corresponds to eta approximately equals 1.06 +/- 0.02, which is substantially higher than the eta approximately equals 0.756 characteristic of large main-belt asteroids. Unlike 4 Vesta and other large asteroids, therefore, 956 Elisa has significant thermal inertia in its surface layer. The wavelength of the Christiansen feature (emissivity maximum near 9 micron), the positions and shapes of the narrow maxima (10 micron, 11 micron) within the broad 9--14 micron silicate band, and the 19--20 micron minimum are consistent with features found in the laboratory spectra of diogenites and of low-Ca pyroxenes of similar composition (Wo<5, En50-En75).

Bunburra Rockhole: Exploring the Geology of a New Differentiated Basaltic Asteroid

NASA Technical Reports Server (NTRS)

Benedix, G.K.; Bland, P. A.; Friedrich, J. M.; Mittlefehldt, D.; Sanborn, M. E.; Yin, Q.-Z.; Greenwood, R. C; Franchi, L. A.; Bevan, A. W. R.; Towner, M. C.;

Non-chondritic iron isotope ratios in planetary mantles as a result of core formation

NASA Astrophysics Data System (ADS)

Elardo, Stephen M.; Shahar, Anat

2017-02-01

Information about the materials and conditions involved in planetary formation and differentiation in the early Solar System is recorded in iron isotope ratios. Samples from Earth, the Moon, Mars and the asteroid Vesta reveal significant variations in iron isotope ratios, but the sources of these variations remain uncertain. Here we present experiments that demonstrate that under the conditions of planetary core formation expected for the Moon, Mars and Vesta, iron isotopes fractionate between metal and silicate due to the presence of nickel, and enrich the bodies' mantles in isotopically light iron. However, the effect of nickel diminishes at higher temperatures: under conditions expected for Earth's core formation, we infer little fractionation of iron isotopes. From our experimental results and existing conceptual models of magma ocean crystallization and mantle partial melting, we find that nickel-induced fractionation can explain iron isotope variability found in planetary samples without invoking nebular or accretionary processes. We suggest that near-chondritic iron isotope ratios of basalts from Mars and Vesta, as well as the most primitive lunar basalts, were achieved by melting of isotopically light mantles, whereas the heavy iron isotope ratios of terrestrial ocean floor basalts are the result of melting of near-chondritic Earth mantle.

76 FR 21076 - Self-Regulatory Organizations; EDGA Exchange, Inc.; Notice of Filing and Immediate Effectiveness...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-14

... on the Exchange's Internet Web site at http://www.directedge.com . \\3\\ A Member is any registered... Parallel D or Parallel 2D with the DRT (Dark routing technique) option on BZX. BZX charges $0.0020 per... the DRT (Dark routing technique) option on BZX or SCAN/STGY on Nasdaq OMX Exchange (``Nasdaq.'') BATS...

Spectral measurements of howardites in support of the interpretation of the Dawn VIR spectra at Vesta

NASA Astrophysics Data System (ADS)

De Angelis, S.; Ammannito, E.; Di Iorio, T.; De Sanctis, M.; Mittlefehldt, D.

2014-07-01

The howardites, eucrites, and diogenites constitute a suite of meteorite lithologies (HED) known to be related to asteroid Vesta [1]. Howardites are physical mixtures of eucrites and diogenites. Howardites are divided in two subtypes: regolithic howardites are actually linked to the true regolith, while fragmental howardites are simple polymict breccias [2]. Mapping of Vesta's surface, as obtained with data from Visible and Infrared mapping Spectrometer (VIR) on Dawn [3,4], showed that it is mainly howarditic, with few regions of diogenite-rich and eucrite-rich terrains [5, 6]. In order to map quantitatively the distribution of lithologic types on Vesta, we are carrying on a study of a set of well-characterized howardites [7]. Spectra were measured on sample powders sieved to 75 μ m in the laboratories of the Istituto di Astrofisica e Planetologia Spaziali (IAPS-INAF) in Rome (Italy) and Brown University, in Providence (USA). Here we report about the measurements done at IAPS-INAF. The spectra of 33 samples have been acquired with the S.LAB setup, consisting in the FieldSpec Pro spectrometer (range 0.35-2.5 μ m, spatial resolution 0.5 cm^2) coupled with a goniometer (incidence i=30°, emission e=0°) [8]. Some representative spectra of the measured howardites are shown in the figure. The spectra are characterized by the two broad Fe^{2+} absorption bands near 1 and 2 μ m (BI and BII) indicative of pyroxenes. Band parameters relative to BI and BII have been calculated using the algorithm developed to process VIR spectra [4]. This enables us to compare laboratory data directly with the VIR results. Other weaker absorptions also characterize some spectra: the 0.5 μ m feature (Mn^{2+} or Cr^{3+}) and the 1.2 μ m feature possibly due to Fe^{2+} in plagioclases. The PRA04401 sample is characterized by a pyroxene-carbonaceous matter mixture [7].

Experimental Constraints on a Vesta Magma Ocean

NASA Technical Reports Server (NTRS)

Hoff, C.; Jones, J. H.; Le, L.

2014-01-01

A magma ocean model was devised to relate eucrites (basalts) and diogenites (orthopyroxenites), which are found mixed together as clasts in a suite of polymict breccias known as howardites. The intimate association of eucritic and diogenitic clasts in howardites argues strongly that these three classes of achondritic meteorites all originated from the same planetoid. Reflectance spectral evidence (including that from the DAWN mission) has long suggested that Vesta is indeed the Eucrite Parent Body. Specifically, the magma ocean model was generated as follows: (i) the bulk Vesta composition was taken to be 0.3 CV chondrite + 0.7 L chondrite but using only 10% of the Na2O from this mixture; (ii) this composition is allowed to crystallize at 500 bar until approx. 80% of the system is solid olivine + low-Ca pyroxene; (iii) the remaining 20% liquid crystallizes at one bar from 1250C to 1110C, a temperature slightly above the eucrite solidus. All crystallization calculations were performed using MELTS. In this model, diogenites are produced by cocrystallization of olivine and pyroxene in the >1250C temperature regime, with Main Group eucrite liquids being generated in the 1300-1250C temperature interval. Low-Ca pyroxene reappears at 1210C in the one-bar calculations and fractionates the residual liquid to produce evolved eucrite compositions (Stannern Trend). We have attempted to experimentally reproduce the <1250C portion of the MELTS Vesta magma ocean. In the MELTS calculation, the change from 500 bar to one bar results in a shift of the olivine:low-Ca pyroxene boundary so that the 1250C liquid is now in the olivine field and, consequently, olivine should be the first-crystallizing phase, followed by low-Ca pyroxene at 1210C, and plagioclase at 1170C. Because at one bar the olivine:low-Ca pyroxene boundary is a peritectic, fractional crystallization of the 1210C liquid proceeds with only pyroxene crystallization until plagioclase appears. Thus, the predictions of the MELTS calculation are clear and straightforward.

Volatile Content of 4-Vesta: Evidence from Unequilibrated Eucrites

NASA Technical Reports Server (NTRS)

Sarafian, A. R.; Nielsen, S. G.; Marschall, H. R.; Gaetani, G. A.; Hauri, E. H.; Righter, K.; Berger, E. L.

2017-01-01

Eucrites are a class of basaltic meteorites that, along with the howardites and diogenites, likely derive from the asteroid 4-Vesta. This asteroid is depleted in moderately volatile elements relative to the Earth and carbonaceous chondrites. Extrapolation of this depletion trend predicts that bulk silicate 4-Vesta (BSV) contains at most 250-1000 µg/g H2O, which is approximately a factor of two lower than the H2O content of Earth. To obtain more accurate H2O and F estimates for BSV, we examined four unequilibrated antarctic meteorites, Yamato(Y)-793548, Y-82210, Y-75011, and Y-74450, by EPMA and SIMS. Pyroxenes contain MgO-rich cores and FeO-rich rims, consistent with primary magmatic zoning. Volatile concentrations generally follow patterns expected for growth zoning with lower values in the cores and higher in the rims. These features indicate that thermal metamorphism and other post-crystallization processes did not significantly perturb the volatile contents of these unequilibrated eucrite pyroxenes. We used these data to derive best estimates for the BSV H2O and F content based on experimentally determined pyroxene-melt partition coefficients and models for magma generation on Vesta. In addition, we measured D/H in the early crystallizing pyroxenes and late crystallzing apatites. We find that the D/H of pyroxene and apatite are within error of one another as well as previous measurements of apatite in equilibrated eucrites. These results imply that degassing was minimal or did not fractionate D/H. Degassing may have been limited if eucrites were shallowly emplaced sills or dykes, or the total H2O content of the magmas was too low for vapor saturation. An alternative mechanism for limited D/H fractionation is that degassing did occur, but the H2/H2O of the exsolved vapor was approximately 15:85, as predicted from experiments.

Thermal measurements of dark and bright surface features on Vesta as derived from Dawn/VIR

USGS Publications Warehouse

Tosi, Federico; Capria, Maria Teresa; De Sanctis, M.C.; Combe, J.-Ph.; Zambon, F.; Nathues, A.; Schröder, S.E.; Li, J.-Y.; Palomba, E.; Longobardo, A.; Blewett, D.T.; Denevi, B.W.; Palmer, E.; Capaccioni, F.; Ammannito, E.; Titus, Timothy N.; Mittlefehldt, D.W.; Sunshine, J.M.; Russell, C.T.; Raymond, C.A.; Dawn/VIR Team,

2014-01-01

Remote sensing data acquired during Dawn’s orbital mission at Vesta showed several local concentrations of high-albedo (bright) and low-albedo (dark) material units, in addition to spectrally distinct meteorite impact ejecta. The thermal behavior of such areas seen at local scale (1-10 km) is related to physical properties that can provide information about the origin of those materials. We use Dawn’s Visible and InfraRed (VIR) mapping spectrometer hyperspectral data to retrieve surface temperatures and emissivities, with high accuracy as long as temperatures are greater than 220 K. Some of the dark and bright features were observed multiple times by VIR in the various mission phases at variable spatial resolution, illumination and observation angles, local solar time, and heliocentric distance. This work presents the first temperature maps and spectral emissivities of several kilometer-scale dark and bright material units on Vesta. Results retrieved from the infrared data acquired by VIR show that bright regions generally correspond to regions with lower temperature, while dark regions correspond to areas with higher temperature. During maximum daily insolation and in the range of heliocentric distances explored by Dawn, i.e. 2.23-2.54 AU, the warmest dark unit found on Vesta rises to a temperature of 273 K, while bright units observed under comparable conditions do not exceed 266 K. Similarly, dark units appear to have higher emissivity on average compared to bright units. Dark-material units show a weak anticorrelation between temperature and albedo, whereas the relation is stronger for bright material units observed under the same conditions. Individual features may show either evanescent or distinct margins in the thermal images, as a consequence of the cohesion of the surface material. Finally, for the two categories of dark and bright materials, we were able to highlight the influence of heliocentric distance on surface temperatures, and estimate an average temperature rate change of 1% following a variation of 0.04 AU in the solar distance.

Mineralogical Analysis of the Oppia Quadrangle of Asteroid (4) Vesta: Evidence for Occurrence of Moderate-Reflectance Hydrated Minerals

NASA Technical Reports Server (NTRS)

Tosi, F.; Frigeri, A.; Combe, J.-Ph.; Zambon, F.; De Sanctis, M. C.; Ammannito, E.; Longobardo, A.; Hoffmann, M.; Nathues, A.; Garry, W. B.;

Geologic Mapping of Vesta

NASA Technical Reports Server (NTRS)

Yingst, R. A.; Mest, S. C.; Berman, D. C.; Garry, W. B.; Williams, D. A.; Buczkowski, D.; Jaumann, R.; Pieters, C. M.; De Sanctis, M. C.; Frigeri, A.;

Mineralogical Mapping of the Av-5 Floronia Quadrangle of Asteroid 4 Vesta

NASA Astrophysics Data System (ADS)

Combe, J.-Ph.; Fulchinioni, M.; McCord, T. B.; Ammannito, E.; De Sanctis, M. C.; Nathues, A.; Capaccioni, F.; Frigeri, A.; Jaumann, R.; Le Corre, L.; Palomba, E.; Preusker, F.; Reddy, V.; Stephan, K.; Tosi, F.; Zambon, F.; Raymond, C. A.; Russell, C. T.

2012-04-01

Asteroid 4 Vesta is currently under investigation by NASA's Dawn orbiter. The Dawn Science Team is conducting mineralogical mapping of Vesta's surface in the form of 15 quadrangle maps, and here we report results from the mapping of Floronia quadrangle Av-5. The maps are based on the data acquired by the Visible and Infrared Mapping Spectrometer (VIR-MS) and the Framing Camera (FC) (De Sanctis et al., this meeting). This abstract is focused on the analysis of band ratios, as well as the depth and position of the 2-µm absorption band of pyroxenes, but additional information will be presented. Absorption band depth is sensitive to abundance, texture and multiple scattering effects. Absorption band position is controlled by composition, shorter wavelength positions indicate less Calcium (and more Magnesium) in pyroxenes. The inferred composition is compared with that of Howardite, Eucite and Diogenite meteorites (HEDs). Diogenites are Mg-rich with large orthopyroxene crystals suggesting formation in depth; Eucrites are Ca-poor pyroxene, with smaller crystals. Av-5 Floronia Quadrangle is located between ~20-66˚N and 270˚-360˚E. It covers a portion of the heavily-cratered northern hemisphere of Vesta, and part of it is in permanent night, until August 2012. Long shadows make the visualization of albedo variations difficult, because of limited effectiveness of photometric corrections. Most of the variations of the band depth at 2 µm are partly affected by illumination geometry in this area. Only regional tendencies are meaningful at this time of the analysis. The 2-µm absorption band depth seems to be deeper towards the south of the quadrangle, in particular to the south of Floronia crater. It is not possible to interpret the value of the band depth in the floor the craters because of the absence of direct sunlight. However, the illuminated rims seem to have a deeper 2-µm absorption band, as does the ejecta from an unnamed crater located further south, within quadrangle Av-10 (Tosi et al., 2010, this meeting). The absorption band seems slightly shifted towards shorter wavelengths in the neighborhood of the same crater, which may indicate a more diogenitic composition, consistent with materials of the deeper crust. Relationships between craters, ejecta and composition will be investigated further. The authors acknowledge the support of the Dawn Science, Instrument and Operations Teams. This work was supported by the NASA Dawn Project under contract from UCLA and by the NASA Dawn at Vesta Participating Scientist program.

Micrometer-scale U-Pb age domains in eucrite zircons, impact re-setting, and the thermal history of the HED parent body

NASA Astrophysics Data System (ADS)

Hopkins, M. D.; Mojzsis, S. J.; Bottke, W. F.; Abramov, O.

2015-01-01

Meteoritic zircons are rare, but some are documented to occur in asteroidal meteorites, including those of the howardite-eucrite-diogenite (HED) achondrite clan (Rubin, A. [1997]. Meteorit. Planet. Sci. 32, 231-247). The HEDs are widely considered to originate from the Asteroid 4 Vesta. Vesta and the other large main belt asteroids record an early bombardment history. To explore this record, we describe sub-micrometer distributions of trace elements (U, Th) and 235,238U-207,206Pb ages from four zircons (>7-40 μm ∅) separated from bulk samples of the brecciated eucrite Millbillillie. Ultra-high resolution (∼100 nm) ion microprobe depth profiles reveal different zircon age domains correlative to mineral chemistry and to possible impact scenarios. Our new U-Pb zircon geochronology shows that Vesta's crust solidified within a few million years of Solar System formation (4561 ± 13 Ma), in good agreement with previous work (e.g. Carlson, R.W., Lugmair, G.W. [2000]. Timescales of planetesimal formation and differentiation based on extinct and extant radioisotopes. In: Canup, R., Righter, K. (Eds.), Origin of the Earth and Moon. University of Arizona Press, Tucson, pp. 25-44). Younger zircon age domains (ca. 4530 Ma) also record crustal processes, but these are interpreted to be exogenous because they are well after the effective extinction of 26Al (t1/2 = 0.72 Myr). An origin via impact-resetting was evaluated with a suite of analytical impact models. Output shows that if a single impactor was responsible for the ca. 4530 Ma zircon ages, it had to have been ⩾10 km in diameter and at high enough velocity (>5 km s-1) to account for the thermal field required to re-set U-Pb ages. Such an impact would have penetrated at least 10 km into Vesta's crust. Later events at ca. 4200 Ma are documented in HED apatite 235,238U-207,206Pb ages (Zhou, Q. et al. [2011]. Early basaltic volcanism and Late Heavy Bombardment on Vesta: U-Pb ages of small zircons and phosphates in eucrites. Lunar Planet. Sci. 42. Abstract #2575) and 40-39Ar age spectra (Bogard, D.D. [2011]. Chem. Erde 71, 207-226). Yet younger ages, including those coincident with the Late Heavy Bombardment (LHB; ca. 3900 Ma), are absent from Millbillillie zircon. This is attributable to primordial changes to the velocity distributions of impactors in the asteroid belt, and differences in mineral closure temperatures (Tc zircon ≫ apatite).

Vesta and low gravity impact mixing

NASA Astrophysics Data System (ADS)

Hoffmann, Martin; Nathues, Andreas; Vincent, Jean-Baptiste; Sierks, Holger

2013-04-01

Re-impacting material in the velocity range of a few meters per second to a couple of hundred meters per second encounters the surface of Vesta. Studying Vesta's ejecta blankets, this specific constraint has to be taken into account. As on other planetary bodies, young craters are characterized by ray patterns. Combining this information with the evidence of Vesta's unique compaction patterns, the kinematics of the deposition process and its consequences for the spectral properties can be studied. We attempt to tackle the following questions: From which depth of a primary crater and to which extent does ejected material contribute to the mixing of surface material? What are the consequences for the local morphology and a global layer of regolith? Experiments of slow impacts into granular material resulted in the following significant effects: 1) Different depth to diameter ratios, and different profiles of the impact crater have been found, indicating transition from three dimensional interaction to surface effects. 2) The inner surfaces as well as their ejecta blanket showed quite different mixtures of material from different depths of the target area. These are interpreted as the result of pattern formation, slope and boundary effects. 3) At sufficiently low velocity and suitable projectile density the transition from inelastic to elastic interaction has been observed. 4) Between the elastic response of very slow impacts and a violent irregular agitation of the material by faster impacts, a regime of de-voiding and hence of compaction has been observed. 5) The action of force chains (Daniels et al. 2004, Rivas et al. 2011) became apparent inside the granular material, which efficiently trap energy (Daraio et al. 2006) and lead to the ray system. These results confirm and expand previous experimental, simulated and theoretically investigated evidence on the behavior of mobilized granular material. As already demonstrated by Cook and Mortensen (1967), low velocity impacts into granular material lead to anything but a simple crater morphology. Unusual scaling laws (Uehara et al. 2003) and much more diverse phase patterns than in ordinary solid media have to be taken into account, if a consistent interpretation of the formation of a crater in very deep regolith is attempted (e.g. Opsomer et al. 2011). Additional effects are due to the low gravity environment on a small planetary body like Vesta (Tancredi et al. 2012). On Vesta many apparent counterparts to the results of the experiments can be found, as demonstrated by some examples. On a global scale, the multitude of small, unresolved primary and secondary impacts into the granular regolith contributes to the observed maturity on Vesta even after short time scales. References Cook, M. A., Mortensen, K. S. 1967. Impact cratering in granular materials. J. Appl. Phys. 38, 5125-5128. Daniels, K. E., Coppock, J. E., Behringer, R. P. 2004. Dynamics of meteor impacts. Chaos 14, 84. Daraio, C., Nesterenko, V. F., Herbold, E. B., Jin S. 2006. Energy trapping and shock desintegration in a composite granular medium. Phys. Rev. Lett. 96, 058002, 1-4. Opsomer, E., Ludewig, F., Vandewalle, N. 2011. Phase transitions in vibrated granular systems in microgravity. Phys. Rev. E84, 051306, 1-5. Rivas, N., Ponce, S., Gellet, B., Risso, D., Soto, R., Cordero, P. 2011. Sudden chain energy transfer events in vibrated granular media. Phys. Rev. Lett. 106, 088001, 1-4. Tancredi, G., Maciel, A., Heredia, L., Richeri, P., Nesmachnow, S. 2012. Granular physics in low-gravity environments using discrete element method. Monthly Not. Royal Astron. Soc. 420, 3368-3380. Uehara, J. S., Ambroso, M. A., Ojha, R. J., Durian, D. J. 2003. Low-speed impact craters in loose granular media. Phys. Rev. Lett. 90, 194301, 1-4.

NWChem: A comprehensive and scalable open-source solution for large scale molecular simulations

NASA Astrophysics Data System (ADS)

Valiev, M.; Bylaska, E. J.; Govind, N.; Kowalski, K.; Straatsma, T. P.; Van Dam, H. J. J.; Wang, D.; Nieplocha, J.; Apra, E.; Windus, T. L.; de Jong, W. A.

2010-09-01

The latest release of NWChem delivers an open-source computational chemistry package with extensive capabilities for large scale simulations of chemical and biological systems. Utilizing a common computational framework, diverse theoretical descriptions can be used to provide the best solution for a given scientific problem. Scalable parallel implementations and modular software design enable efficient utilization of current computational architectures. This paper provides an overview of NWChem focusing primarily on the core theoretical modules provided by the code and their parallel performance. Program summaryProgram title: NWChem Catalogue identifier: AEGI_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGI_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Open Source Educational Community License No. of lines in distributed program, including test data, etc.: 11 709 543 No. of bytes in distributed program, including test data, etc.: 680 696 106 Distribution format: tar.gz Programming language: Fortran 77, C Computer: all Linux based workstations and parallel supercomputers, Windows and Apple machines Operating system: Linux, OS X, Windows Has the code been vectorised or parallelized?: Code is parallelized Classification: 2.1, 2.2, 3, 7.3, 7.7, 16.1, 16.2, 16.3, 16.10, 16.13 Nature of problem: Large-scale atomistic simulations of chemical and biological systems require efficient and reliable methods for ground and excited solutions of many-electron Hamiltonian, analysis of the potential energy surface, and dynamics. Solution method: Ground and excited solutions of many-electron Hamiltonian are obtained utilizing density-functional theory, many-body perturbation approach, and coupled cluster expansion. These solutions or a combination thereof with classical descriptions are then used to analyze potential energy surface and perform dynamical simulations. Additional comments: Full documentation is provided in the distribution file. This includes an INSTALL file giving details of how to build the package. A set of test runs is provided in the examples directory. The distribution file for this program is over 90 Mbytes and therefore is not delivered directly when download or Email is requested. Instead a html file giving details of how the program can be obtained is sent. Running time: Running time depends on the size of the chemical system, complexity of the method, number of cpu's and the computational task. It ranges from several seconds for serial DFT energy calculations on a few atoms to several hours for parallel coupled cluster energy calculations on tens of atoms or ab-initio molecular dynamics simulation on hundreds of atoms.

NIF Ignition Target 3D Point Design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, O; Marinak, M; Milovich, J

2008-11-05

We have developed an input file for running 3D NIF hohlraums that is optimized such that it can be run in 1-2 days on parallel computers. We have incorporated increasing levels of automation into the 3D input file: (1) Configuration controlled input files; (2) Common file for 2D and 3D, different types of capsules (symcap, etc.); and (3) Can obtain target dimensions, laser pulse, and diagnostics settings automatically from NIF Campaign Management Tool. Using 3D Hydra calculations to investigate different problems: (1) Intrinsic 3D asymmetry; (2) Tolerance to nonideal 3D effects (e.g. laser power balance, pointing errors); and (3) Syntheticmore » diagnostics.« less

A computer program for converting rectangular coordinates to latitude-longitude coordinates

USGS Publications Warehouse

Rutledge, A.T.

1989-01-01

A computer program was developed for converting the coordinates of any rectangular grid on a map to coordinates on a grid that is parallel to lines of equal latitude and longitude. Using this program in conjunction with groundwater flow models, the user can extract data and results from models with varying grid orientations and place these data into grid structure that is oriented parallel to lines of equal latitude and longitude. All cells in the rectangular grid must have equal dimensions, and all cells in the latitude-longitude grid measure one minute by one minute. This program is applicable if the map used shows lines of equal latitude as arcs and lines of equal longitude as straight lines and assumes that the Earth 's surface can be approximated as a sphere. The program user enters the row number , column number, and latitude and longitude of the midpoint of the cell for three test cells on the rectangular grid. The latitude and longitude of boundaries of the rectangular grid also are entered. By solving sets of simultaneous linear equations, the program calculates coefficients that are used for making the conversion. As an option in the program, the user may build a groundwater model file based on a grid that is parallel to lines of equal latitude and longitude. The program reads a data file based on the rectangular coordinates and automatically forms the new data file. (USGS)

KSC-07pd2592

NASA Image and Video Library

2007-09-27

KENNEDY SPACE CENTER, FLA. -- Nearly enveloped by the smoke after ignition, the Delta II rocket carrying NASA's Dawn spacecraft rises from the smoke and fire on the launch pad to begin its 1.7-billion-mile journey through the inner solar system to study a pair of asteroids. Liftoff was at 7:34 a.m. EDT from Pad 17-B at Cape Canaveral Air Force Station. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Sandra Joseph & Rafael Hernandez

Chemistry of Diogenites and Evolution of their Parent Asteroid

NASA Technical Reports Server (NTRS)

Mittlefehldt, D.W.; Beck, A.W.; McSween, H.Y.; Lee, C-T A.

2009-01-01

Diogenites are orthopyroxenite meteorites [1]. Most are breccias, but remnant textures indicate they were originally coarse-grained rocks, with grain sizes of order of cm. Their petrography, and major and trace element chemistry support an origin as crustal cumulates from a differentiated asteroid. Diogenites are genetically related to the basaltic and cumulate-gabbro eucrites, and the polymict breccias known as howardites, collectively, the HED suite. Spectroscopic observations, orbit data and dynamical arguments strongly support the hypothesis that asteroid 4 Vesta is the parent object for HED meteorites [2]. Here we discuss our new trace element data for a suite of diogenites and integrate these into the body of literature data. We use the combined data set to discuss the petrologic evolution of diogenites and 4 Vesta.

KSC-07pd2066

NASA Image and Video Library

2007-07-22

KENNEDY SPACE CENTER, FLA. — At the Astrotech payload processing facility, workers guide the movement of the upper canister being lifted from the Dawn spacecraft, seen encased in a protective cover. Dawn was returned from Launch Pad 17-B at Cape Canaveral Air Force Station to Astrotech to await a new launch date. The launch opportunity extends from Sept. 7 to Oct. 15. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA’s first purely scientific mission powered by three solar electric ion propulsion engines. NASA/Charisse Nahser

Do Mesosiderites Reside on 4 VESTA? an Assessment Based on Dawn Grand Data

NASA Technical Reports Server (NTRS)

Mittlefehldt, D. W.; Prettyman, T. H.; Reedy, R. C.; Beck, A. W.; Blewett, D. T.; Gaffey, M. J.; Lawrence, D. J.; McCoy, T. J.; McSween, H. Y., Jr.; Toplis, J. J.

2012-01-01

Almost a century ago, simple petrographic observations were used to suggest a close genetic link between eucrites and the silicates in mesosiderites [1]. Mesosiderites are composed of roughly equal proportions of silicates that are very similar in mineralogy and texture to howardites, and Fe, Ni metal (Fig. 1) [2]. This similarity has led some to conclude that mesosiderites come from the howardite, eucrite and diogenite (HED) parent asteroid [3, 4]. Subsequent petrologic study demonstrated a number of differences between mesosiderite silicates and HEDs that are more plausibly explained as requiring separate parent asteroids [5]. However, HEDs and mesosiderites are identical in oxygen isotopic composition, and this has been used to argue for a common parent 4 Vesta [6].

KSC-07pd1673

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- On Launch Pad 17-B at Cape Canaveral Air Force Station, workers supervise the lowering of NASA's Dawn spacecraft in the mobile service tower. The spacecraft is clad in a shipping canister for its transport from Astrotech in Titusville, Fla. The canister will be removed and the spacecraft prepared for launch. Launch is scheduled for July 7. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Cory Huston

Petrology and Composition of HED Polymict Breccias

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.; Herrin, J. S.; Mertzman, S. A.; Mertzman, K. R.

2010-01-01

The howardite, eucrite and diogenite (HED) clan of meteorites forms the largest suite of achondrites with over 900 named members. The HEDs are igneous rocks and breccias of igneous rocks from a differentiated asteroid [1]. The consensus view is that these rocks hail from the asteroid 4 Vesta, which will be the first target of NASA's Dawn mission. When Dawn arrives at Vesta, she will begin remote imagery and spectroscopy of the surface. The surface she will observe will be dominated by rocks and soils mixed through impact gardening. To help with the interpretation of the remotely sensed data, we have begun a project on the petrologic and compositional study of a suite of HED polymict breccias. Here we report on the preliminary findings of this project.

SciSpark: Highly Interactive and Scalable Model Evaluation and Climate Metrics

NASA Astrophysics Data System (ADS)

Wilson, B. D.; Palamuttam, R. S.; Mogrovejo, R. M.; Whitehall, K. D.; Mattmann, C. A.; Verma, R.; Waliser, D. E.; Lee, H.

2015-12-01

Remote sensing data and climate model output are multi-dimensional arrays of massive sizes locked away in heterogeneous file formats (HDF5/4, NetCDF 3/4) and metadata models (HDF-EOS, CF) making it difficult to perform multi-stage, iterative science processing since each stage requires writing and reading data to and from disk. We are developing a lightning fast Big Data technology called SciSpark based on ApacheTM Spark under a NASA AIST grant (PI Mattmann). Spark implements the map-reduce paradigm for parallel computing on a cluster, but emphasizes in-memory computation, "spilling" to disk only as needed, and so outperforms the disk-based ApacheTM Hadoop by 100x in memory and by 10x on disk. SciSpark will enable scalable model evaluation by executing large-scale comparisons of A-Train satellite observations to model grids on a cluster of 10 to 1000 compute nodes. This 2nd generation capability for NASA's Regional Climate Model Evaluation System (RCMES) will compute simple climate metrics at interactive speeds, and extend to quite sophisticated iterative algorithms such as machine-learning based clustering of temperature PDFs, and even graph-based algorithms for searching for Mesocale Convective Complexes. We have implemented a parallel data ingest capability in which the user specifies desired variables (arrays) as several time-sorted lists of URL's (i.e. using OPeNDAP model.nc?varname, or local files). The specified variables are partitioned by time/space and then each Spark node pulls its bundle of arrays into memory to begin a computation pipeline. We also investigated the performance of several N-dim. array libraries (scala breeze, java jblas & netlib-java, and ND4J). We are currently developing science codes using ND4J and studying memory behavior on the JVM. On the pyspark side, many of our science codes already use the numpy and SciPy ecosystems. The talk will cover: the architecture of SciSpark, the design of the scientific RDD (sRDD) data structure, our efforts to integrate climate science algorithms in Python and Scala, parallel ingest and partitioning of A-Train satellite observations from HDF files and model grids from netCDF files, first parallel runs to compute comparison statistics and PDF's, and first metrics quantifying parallel speedups and memory & disk usage.

Simulation of a Rotorcraft in Turbulent Flows

DTIC Science & Technology

1991-09-01

Knot) Aircraft Parallel Aircraft Parallel Aircraft Parallel To Ship’s To Port-To-Star- To Starboard- Centerline board Landing To-Port Landing Lineup ...Line Lineup Line 345 to 015/35 340 to 005/45 345 to 005145 016 t,) 040/30 006 to 035!35 006 to 025/40 041 to 180/45 036 to 050/30 026 to 040/30 181 to...WIND /FRA3 LOW REYNOLD’S NUMBER AERODYNAMICS FOR NACA0012 AIRFOIL REQUIRES DS/DM NACA0012/AIRFOIL NO SEQUENTIAL FILES REQUIRED INPUT FOR FORCE FRA3

Parallel sort with a ranged, partitioned key-value store in a high perfomance computing environment

DOEpatents

Bent, John M.; Faibish, Sorin; Grider, Gary; Torres, Aaron; Poole, Stephen W.

2016-01-26

Improved sorting techniques are provided that perform a parallel sort using a ranged, partitioned key-value store in a high performance computing (HPC) environment. A plurality of input data files comprising unsorted key-value data in a partitioned key-value store are sorted. The partitioned key-value store comprises a range server for each of a plurality of ranges. Each input data file has an associated reader thread. Each reader thread reads the unsorted key-value data in the corresponding input data file and performs a local sort of the unsorted key-value data to generate sorted key-value data. A plurality of sorted, ranged subsets of each of the sorted key-value data are generated based on the plurality of ranges. Each sorted, ranged subset corresponds to a given one of the ranges and is provided to one of the range servers corresponding to the range of the sorted, ranged subset. Each range server sorts the received sorted, ranged subsets and provides a sorted range. A plurality of the sorted ranges are concatenated to obtain a globally sorted result.

Moon Search Algorithms for NASA's Dawn Mission to Asteroid Vesta

NASA Technical Reports Server (NTRS)

Memarsadeghi, Nargess; Mcfadden, Lucy A.; Skillman, David R.; McLean, Brian; Mutchler, Max; Carsenty, Uri; Palmer, Eric E.

2012-01-01

A moon or natural satellite is a celestial body that orbits a planetary body such as a planet, dwarf planet, or an asteroid. Scientists seek understanding the origin and evolution of our solar system by studying moons of these bodies. Additionally, searches for satellites of planetary bodies can be important to protect the safety of a spacecraft as it approaches or orbits a planetary body. If a satellite of a celestial body is found, the mass of that body can also be calculated once its orbit is determined. Ensuring the Dawn spacecraft's safety on its mission to the asteroid Vesta primarily motivated the work of Dawn's Satellite Working Group (SWG) in summer of 2011. Dawn mission scientists and engineers utilized various computational tools and techniques for Vesta's satellite search. The objectives of this paper are to 1) introduce the natural satellite search problem, 2) present the computational challenges, approaches, and tools used when addressing this problem, and 3) describe applications of various image processing and computational algorithms for performing satellite searches to the electronic imaging and computer science community. Furthermore, we hope that this communication would enable Dawn mission scientists to improve their satellite search algorithms and tools and be better prepared for performing the same investigation in 2015, when the spacecraft is scheduled to approach and orbit the dwarf planet Ceres.

The Atlas of Vesta Spectral Parameters derived from Dawn/VIR data

NASA Astrophysics Data System (ADS)

Frigeri, A.; De Sanctis, M. C.; Ammannito, E.; Tosi, F.; Zambon, F.; Capaccioni, F.; Capria, M. T.; Palomba, E.; Longobardo, A.; Fonte, S.; Giardino, M.; Magni, G.; Jaumann, R.; Raymond, C. A.; Russell, C. T.

2013-09-01

The Dawn mission mapped Vesta from three different orbital heights during Survey orbit (2700 km altitude), HAMO (High Altitude Mapping Orbit, 700 km altitude), and LAMO (Low Altitude Mapping Orbit, 210 km altitude) [1]. From these orbits the Dawn's Visible and Infrared Mapping Spectrometer (VIR) acquired infrared and visible spectra from 0.2 to 5 microns, sampled in 864 channels with a spatial resolution reaching about 150 m/pixel. Studies of the comparison of spectra from remote sensed data and spectra from laboratory allows to synthesize spectral parameters, which can be combined to identify specific physical and compositional states. VIR spectra of Vesta, stored in about 4300 Planetary Data System (PDS) cubes, have been analyzed to derive spectral parameters, each of which is diagnostic of the associated mineralogy on the surface of the asteroid being observed [2]. Maps of spectral parameters show terrain units compositions in their stratigraphic context. Band centers and band depths are among the most important diagnostic parameters of the mineralogy in a spectrum. In most pyroxenes and in the basaltic achondrites there is a strong correlation between the position of BI center and BII center and the associated mineralogy. For example, orthopyroxene bands shift towards longer wavelengths with increasing amounts of iron, whereas clinopyroxene bands shift towards longer wavelengths with increasing calcium content. Band depth is related to scattering effects, thus can be related to the physical state of the material.

Experimental validation of depletion calculations with VESTA 2.1.5 using JEFF-3.2

NASA Astrophysics Data System (ADS)

Haeck, Wim; Ichou, Raphaëlle

2017-09-01

The removal of decay heat is a significant safety concern in nuclear engineering for the operation of a nuclear reactor both in normal and accidental conditions and for intermediate and long term waste storage facilities. The correct evaluation of the decay heat produced by an irradiated material requires first of all the calculation of the composition of the irradiated material by depletion codes such as VESTA 2.1, currently under development at IRSN in France. A set of PWR assembly decay heat measurements performed by the Swedish Central Interim Storage Facility (CLAB) located in Oskarshamm (Sweden) have been calculated using different nuclear data libraries: ENDF/B-VII.0, JEFF-3.1, JEFF-3.2 and JEFF-3.3T1. Using these nuclear data libraries, VESTA 2.1 calculates the assembly decay heat for almost all cases within 4% of the measured decay heat. On average, the ENDF/B-VII.0 calculated decay heat values appear to give a systematic underestimation of only 0.5%. When using the JEFF-3.1 library, this results a systematic underestimation of about 2%. By switching to the JEFF-3.2 library, this systematic underestimation is improved slighty (up to 1.5%). The changes made in the JEFF-3.3T1 beta library appear to be overcorrecting, as the systematic underestimation is transformed into a systematic overestimation of about 1.5%.

Petrology and Geochemistry of Unbrecciated Harzburgitic Diogenite MIL 07001: A Window Into Vestan Geological Evolution

NASA Technical Reports Server (NTRS)

Mittlefehldt, D. W.; Peng, Z. X.; Mertzman, S. A.; Mertzman, K. R.

2014-01-01

There is a strong case that asteroid 4 Vesta is the parent of the howardite, eucrite and diogenite (HED) meteorites. Models developed for the geological evolution of Vesta can satisfy the compositions of basaltic eucrites that dominate in the upper crust. The bulk compositional characteristics of diogenites - cumulate harzburgites and orthopyroxenites from the lower crust - do not fit into global magma ocean models that can describe the compositions of basaltic and cumulate eucrites. Recent more detailed formation models do make provision for a more complicated origin for diogenites, but this model has yet to be completely vetted. Compositional studies of bulk samples has led to the hypothesis that many diogenites were formed late by interaction of their parent melts with a eucritic crust, but those observations may alternatively be explained by subsolidus equilibration of trace elements between orthopyroxene and plagioclase and Ca-phosphate in the rocks. Differences in radiogenic Mg-26 content between diogenites and eucrites favors early formation of the former, not later formation. Understanding the origin of diogenites is crucial for understanding the petrologic evolution of Vesta. We have been doing coordinated studies of a suite of diogenites including petrologic investigations, bulk rock major and trace element studies, and in situ trace element analyses of orthopyroxene. Here we will focus on an especially unusual, and potentially key, diogenite, MIL 07001.

PDB Editor: a user-friendly Java-based Protein Data Bank file editor with a GUI.

PubMed

Lee, Jonas; Kim, Sung Hou

2009-04-01

The Protein Data Bank file format is the format most widely used by protein crystallographers and biologists to disseminate and manipulate protein structures. Despite this, there are few user-friendly software packages available to efficiently edit and extract raw information from PDB files. This limitation often leads to many protein crystallographers wasting significant time manually editing PDB files. PDB Editor, written in Java Swing GUI, allows the user to selectively search, select, extract and edit information in parallel. Furthermore, the program is a stand-alone application written in Java which frees users from the hassles associated with platform/operating system-dependent installation and usage. PDB Editor can be downloaded from http://sourceforge.net/projects/pdbeditorjl/.

Exploring Hardware-Based Primitives to Enhance Parallel Security Monitoring in a Novel Computing Architecture

DTIC Science & Technology

2007-03-01

software level retrieve state information that can inherently contain more contextual information . As a result, such mechanisms can be applied in more...ease by which state information can be gathered for monitoring purposes. For example, we consider soft security to allow for easier state retrieval ...files are to be checked and what parameters are to be verified. The independent auditor periodically retrieves information pertaining to the files in

Optimized distributed systems achieve significant performance improvement on sorted merging of massive VCF files.

PubMed

Sun, Xiaobo; Gao, Jingjing; Jin, Peng; Eng, Celeste; Burchard, Esteban G; Beaty, Terri H; Ruczinski, Ingo; Mathias, Rasika A; Barnes, Kathleen; Wang, Fusheng; Qin, Zhaohui S

2018-06-01

Sorted merging of genomic data is a common data operation necessary in many sequencing-based studies. It involves sorting and merging genomic data from different subjects by their genomic locations. In particular, merging a large number of variant call format (VCF) files is frequently required in large-scale whole-genome sequencing or whole-exome sequencing projects. Traditional single-machine based methods become increasingly inefficient when processing large numbers of files due to the excessive computation time and Input/Output bottleneck. Distributed systems and more recent cloud-based systems offer an attractive solution. However, carefully designed and optimized workflow patterns and execution plans (schemas) are required to take full advantage of the increased computing power while overcoming bottlenecks to achieve high performance. In this study, we custom-design optimized schemas for three Apache big data platforms, Hadoop (MapReduce), HBase, and Spark, to perform sorted merging of a large number of VCF files. These schemas all adopt the divide-and-conquer strategy to split the merging job into sequential phases/stages consisting of subtasks that are conquered in an ordered, parallel, and bottleneck-free way. In two illustrating examples, we test the performance of our schemas on merging multiple VCF files into either a single TPED or a single VCF file, which are benchmarked with the traditional single/parallel multiway-merge methods, message passing interface (MPI)-based high-performance computing (HPC) implementation, and the popular VCFTools. Our experiments suggest all three schemas either deliver a significant improvement in efficiency or render much better strong and weak scalabilities over traditional methods. Our findings provide generalized scalable schemas for performing sorted merging on genetics and genomics data using these Apache distributed systems.

Optimized distributed systems achieve significant performance improvement on sorted merging of massive VCF files

PubMed Central

Gao, Jingjing; Jin, Peng; Eng, Celeste; Burchard, Esteban G; Beaty, Terri H; Ruczinski, Ingo; Mathias, Rasika A; Barnes, Kathleen; Wang, Fusheng

2018-01-01

Abstract Background Sorted merging of genomic data is a common data operation necessary in many sequencing-based studies. It involves sorting and merging genomic data from different subjects by their genomic locations. In particular, merging a large number of variant call format (VCF) files is frequently required in large-scale whole-genome sequencing or whole-exome sequencing projects. Traditional single-machine based methods become increasingly inefficient when processing large numbers of files due to the excessive computation time and Input/Output bottleneck. Distributed systems and more recent cloud-based systems offer an attractive solution. However, carefully designed and optimized workflow patterns and execution plans (schemas) are required to take full advantage of the increased computing power while overcoming bottlenecks to achieve high performance. Findings In this study, we custom-design optimized schemas for three Apache big data platforms, Hadoop (MapReduce), HBase, and Spark, to perform sorted merging of a large number of VCF files. These schemas all adopt the divide-and-conquer strategy to split the merging job into sequential phases/stages consisting of subtasks that are conquered in an ordered, parallel, and bottleneck-free way. In two illustrating examples, we test the performance of our schemas on merging multiple VCF files into either a single TPED or a single VCF file, which are benchmarked with the traditional single/parallel multiway-merge methods, message passing interface (MPI)–based high-performance computing (HPC) implementation, and the popular VCFTools. Conclusions Our experiments suggest all three schemas either deliver a significant improvement in efficiency or render much better strong and weak scalabilities over traditional methods. Our findings provide generalized scalable schemas for performing sorted merging on genetics and genomics data using these Apache distributed systems. PMID:29762754

Reconstructing evolutionary trees in parallel for massive sequences.

PubMed

Zou, Quan; Wan, Shixiang; Zeng, Xiangxiang; Ma, Zhanshan Sam

2017-12-14

Building the evolutionary trees for massive unaligned DNA sequences is challenging and crucial. However, reconstructing evolutionary tree for ultra-large sequences is hard. Massive multiple sequence alignment is also challenging and time/space consuming. Hadoop and Spark are developed recently, which bring spring light for the classical computational biology problems. In this paper, we tried to solve the multiple sequence alignment and evolutionary reconstruction in parallel. HPTree, which is developed in this paper, can deal with big DNA sequence files quickly. It works well on the >1GB files, and gets better performance than other evolutionary reconstruction tools. Users could use HPTree for reonstructing evolutioanry trees on the computer clusters or cloud platform (eg. Amazon Cloud). HPTree could help on population evolution research and metagenomics analysis. In this paper, we employ the Hadoop and Spark platform and design an evolutionary tree reconstruction software tool for unaligned massive DNA sequences. Clustering and multiple sequence alignment are done in parallel. Neighbour-joining model was employed for the evolutionary tree building. We opened our software together with source codes via http://lab.malab.cn/soft/HPtree/ .

Trajectory design for an ion drive asteroids rendezvous mission launched into an Ariane geostationary transfer orbit

NASA Astrophysics Data System (ADS)

Pietrass, A. E.

1984-08-01

AMSAT has conceived an asteroid rendezvous mission which would consist of an Ariane-launched, 3-axis-stabilized, 350-kg spacecraft utilizing both mercury and solar electric ion propulsion. The spacecraft is to be equipped with a science instrument platform with a mass of approximately 30 to 50 kg. Practically uninterrupted earth departure opportunities are found for targets such as 4 Vesta, 8 Flora, and 19 Fortuna from 1986 through 1988. The 7 to 8 year mission would allow for a second rendezvous of 4 Vesta, and marginal additional fuel would make close flybys of targets feasible. Through the use of parameter optimization techniques, trajectories can be generated and the inclusion of constraints due to spacecraft techology, tour design, and navigation can be facilitated.

KSC-07pd2591

NASA Image and Video Library

2007-09-27

KENNEDY SPACE CENTER, FLA. -- Against a backdrop of clouds on the horizon, the Delta II rocket carrying NASA's Dawn spacecraft rises from the smoke and fire on the launch pad to begin its 1.7-billion-mile journey through the inner solar system to study a pair of asteroids. Liftoff was at 7:34 a.m. EDT from Pad 17-B at Cape Canaveral Air Force Station. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Sandra Joseph & Rafael Hernandez

Observations of Hydrated Minerals on Asteroids: Pushing Back the Frontiers

NASA Technical Reports Server (NTRS)

2005-01-01

The three accomplishments during this grant include: 1) Travel to 2004 Division of Planetary Science (of American Astronomical Society) Conference in Louisville, KY and presentation of Rotationally resolved spectroscopy of Vesta in the 1-4 micron region, abstract 28.07. 2) Remote observations using the IRTF on 20-21 June 2004 and 28-3 1 August 2004, and reduction of data as described in the grant proposal and descoping document. These observations confirm the presence of two different band shapes among C-class asteroid spectra in the 3-micron region. This allowed a revision of the known distribution of Ceres- and Pallas-type objects. 3) Remote observations using the IRTF on 7-10 August 2004. These observations of Vesta were presented, and the manuscript will be submitted to Icarus in June.

An anomalous basaltic meteorite from the innermost main belt.

PubMed

Bland, Philip A; Spurny, Pavel; Towner, Martin C; Bevan, Alex W R; Singleton, Andrew T; Bottke, William F; Greenwood, Richard C; Chesley, Steven R; Shrbeny, Lukas; Borovicka, Jiri; Ceplecha, Zdenek; McClafferty, Terence P; Vaughan, David; Benedix, Gretchen K; Deacon, Geoff; Howard, Kieren T; Franchi, Ian A; Hough, Robert M

2009-09-18

Triangulated observations of fireballs allow us to determine orbits and fall positions for meteorites. The great majority of basaltic meteorites are derived from the asteroid 4 Vesta. We report on a recent fall that has orbital properties and an oxygen isotope composition that suggest a distinct parent body. Although its orbit was almost entirely contained within Earth's orbit, modeling indicates that it originated from the innermost main belt. Because the meteorite parent body would likely be classified as a V-type asteroid, V-type precursors for basaltic meteorites unrelated to Vesta may reside in the inner main belt. This starting location is in agreement with predictions of a planetesimal evolution model that postulates the formation of differentiated asteroids in the terrestrial planet region, with surviving fragments concentrated in the innermost main belt.

KSC-07pd1674

NASA Image and Video Library

2007-06-27

KENNEDY SPACE CENTER, FLA. -- On Launch Pad 17-B at Cape Canaveral Air Force Station, workers supervise the movement of NASA's Dawn spacecraft in the mobile service tower. The spacecraft is clad in a shipping canister for its transport from Astrotech in Titusville, Fla. The canister will be removed and the spacecraft will be mated with the Delta II launch vehicle in the tower. Launch is scheduled for July 7. Dawn is the ninth mission in NASA's Discovery Program. The spacecraft will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter. It is also NASA's first purely scientific mission powered by three solar electric ion propulsion engines. Photo credit: NASA/Cory Huston

Lessons from Vesta and Ceres

NASA Astrophysics Data System (ADS)

Russell, C. T.; Raymond, C. A.; McSween, H. Y.; Jaumann, R.; DeSanctis, M. C.; Nathues, A.; Prettyman, T.; Capria, M. T.; Pieters, C.; McFadden, L.; Ammannito, E.; Sykes, M. V.; McCord, T. B.; Zuber, M.; Smith, D.; Hoffman, M.; Scully, J. E. C.; Buczkowski, D.

2014-04-01

When first discovered, the bodies in the asteroid belt were considered the missing planet(s) between Mars and Jupiter. When their small size and large number become realized, they were deemed to be minor planets and then asteroids. They soon were considered to be simply airless bodies, consisting mostly of rocky material, some having iron cores. When Dawn reached Vesta, this picture was initially largely reinforced by the extensive southern basin and the battered northern hemisphere. A more accurate picture arises, using the color filters of the Framing Camera, in coordination with the nearinfrared spectrometer, revealing a diverse surface with different minerals and processes affecting regions on the surface in various ways. The variegated light and dark material and varying thermal properties indicate a complex surface. The water (OH) content of the surface is far from uniform. Examinations of the floors of Marcia and Cornelia revealed pits, and their crater walls have possibly water-carved gullies. The parent craters appear to have been formed in a wet surface, possibly ice melted in the crater-forming event. Figure 1 shows the latest mosaic of the vestan surface with the currently approved names for the surface features. It had been expected that olivine would be excavated in the southern basin but it was not to be found there. Surprisingly, patches of olivine-rich material were discovered in the north. Doubts arose as to whether a magma ocean hypothesis applies to Vesta, in spite of quantifying the mass of its core, and new ways to explain Vesta's petrogenesis were developed. Closer examination of the surface suggested more interesting scenarios, possible excavation of early volcanic materials, odd craters that seemed impossible to form with simple impacts, and a long ribbon of material stretching diagonally across the surface, possibly originating in the Marcia ejecta blanket. The relative youth of some of these features (ca 50 Ma) suggest Vesta has had planetary processes acting over much of its history and is very much a small terrestrial planet worthy of participating in the comparative planetology that aids our ability to understand these diverse family members. Ceres has yet to be visited by our spacecraft, but it too tells a story of active planetary processes. Ceres does not have meteorites or a family of small ceroids accompanying it in space, so we know little about its origins with any certainty. However, because it is large and has a low density, we believe it accreted late after the short-lived radionucleides had time to decay. It also seems to have continued to devolatize until the present. There were early 1 AU reports from observations at 1 AU of activity that have continued through the recent Herschel plume report. Dawn followed a simple mapping scenario at Vesta with initial low-resolution measurements in a Survey orbit followed by a High-Altitude Mapping Orbit which gave complete stereo imagery and extensive moderate resolution VIR IR and Framing Camera color data. A later Low-Altitude Mapping Orbit provided data on GRaND's elemental composition, gravity and localized high-resolution imagery and spectra. A second HAMO orbit completed the needed stereo data and other data over the northern quadrangles. The same mapping philosophy is planned for Ceres. There will be Survey, HAMO, and LAMO orbits, but once in Ceres orbit, Dawn is not expected to leave. Dawn has sufficient resources to achieve its science objectives but does not carry a large reserve for extended exploration.

Smooth pond-like deposits on asteroid 4 Vesta: First results from the Dawn mission.

NASA Astrophysics Data System (ADS)

Hiesinger, H.; Ruesch, O.; Jaumann, R.; Nathues, A.; Raymond, C. A.; Russell, C. T.

2012-04-01

The Dawn spacecraft arrived at Vesta on July 16, 2011 to study the asteroid with a Framing Camera (FC), a Visible & Infrared Spectrometer (VIR), and a Gamma Ray and Neutron Detector (GRaND) [1]. Dawn provides the first high-resolution data from its survey orbit, high-altitude mapping orbit (HAMO), and low-altitude mapping orbit (LAMO). FC data revealed smooth pond-like deposits of ambiguous origin, similar to deposits on other asteroids, including Eros and Itokawa [2,3]. Several scenarios for the origin of these deposits can be tested with Dawn data, including volcanism, impact sedimentation, impact melt deposition, dust levitation and transport, seismic shaking, or landslides. We measured 83 small (~7 km2 average size) smooth deposits distributed across the surface of Vesta. Most ponds on Vesta occur on the floors of impact craters and in irregular depressions. We did not observe inflow of material into the depressions. Most of these deposits have well-defined geological contacts, indicating that they are younger than the surrounding terrain. However, lunar impact melt pools that formed contemporaneously with surrounding ejecta blankets show similar stratigraphic relationships. Sometimes the albedo of these ponds is lower than the surrounding terrain, in other cases the ponds are indistinguishable from the adjacent terrain. The ponds preferentially occur in a band between -10 and 30 degrees latitude with fewer ponds north of ~30 degrees and even fewer ponds in the southern hemisphere, i.e., the Rheasilvia region. The largest cluster of ponds occurs in the vicinity of the Marcia impact crater, which is part of the so-called snowman craters. Similar, but smaller (<230 m diameter) smooth ponds were also reported from the surface of asteroid Eros [2]. Robinson et al. [2] found that most smooth ponds on Eros occur in equatorial regions and concluded that the most likely process for their formation is electrostatic levitation and redistribution of the finest regolith components (<100 µm). Sierks et al. [4] argued that along the terminator, particularly strong electric fields can develop between the sun-lit and shaded areas, e.g., within craters, resulting in particle motion from sun-lit to dark regions. Dust levitation and transport was also discussed for asteroid 25143 Itokawa [3]. [1] Russell et al., (2007), Earth Moon Planets, 101; [2] Robinson et al., (2002), Met. Planet. Sci., 37; [3] Yano et al., (2006), Science, 312; [4] Sierks et al., (2011), Space Sci. Rev., doi:10.1007/s11214-011-9745-4. This research has been supported by the German Space Agency (DLR) and NASA. We would like to thank the Dawn Operations Team for their success-ful planning and acquisition of high-quality Vesta data.

Magnetic fields on asteroid 4 Vesta recorded by the Millbillillie eucrite

NASA Astrophysics Data System (ADS)

Weiss, B. P.; Fu, R.

2011-12-01

The detection of past dynamo activity on the asteroid 4 Vesta would confirm the existence of a metallic core, placing important constraints on its accretional and thermal history. Knowledge of the strength and duration of a dynamo on 4 Vesta also has important implications for the theoretical understanding of dynamo generation in small bodies. Magnetic fields from a putative core dynamo may have been recorded as remanent magnetization in achondritic meteorites of the howardite-eucrite-diogenite (HED) clan, which are thought to originate from the asteroid. To search for evidence for past dynamo activity, we performed a paleomagnetic study of nine mutually oriented samples of the Millbillillie eucrite. We found that the magnitude and direction of the magnetization change systematically for samples progressively farther away from the fusion crust, indicating that the samples were not remagnetized on Earth and that the interior samples carry an extraterrestrial magnetization. The fusion crust is ~1000 times more magnetic per unit mass than the interior, which was likely a source of contamination in earlier studies of bulk samples from this meteorite. Two interior samples were subjected to alternating field (AF) demagnetization up to 290 mT. We found a high coercivity (HC) component of magnetization carried by grains with coercivities between 70 and 180 mT. The HC magnetization is approximately unidirectional in the subsamples. The AF demagnetization profile of this component is similar to that of an anhysteretic remanent magnetization (ARM), suggesting that it may represent a thermoremanent magnetization (TRM). Under this assumption, our ARM paleointensity experiments yield field strengths of 2-3 μT while our IRM paleointensities are between 5 and 8 μT. Ongoing analysis of additional samples will further test this result. The HC magnetization may record 1) transient impact-generated fields, 2) remanent crustal fields, or 3) dynamo fields. Case 1) is unlikely if the sample has a thermoremanence because stable magnetization over the wide coercivity range observed for the HC component requires a magnetic field stable for the duration of the cooling process. Furthermore, the characteristic coercivities of the HC magnetization are very high compared to typical values for shock remanent magnetization. In case 2), the strength of putative impact-generated crustal fields on the moon suggests that impacts on Vesta would have caused remanent crustal fields of < 2 μT strength, which is below our observed paleointensities. Remanent crustal fields stronger than ~2 μT require a different magnetizing source, such as an earlier dynamo. Together, these facts suggest that the HC magnetization is unlikely to be a result of meteoroid bombardment and more probably record dynamo fields or remanent crustal fields due to an earlier dynamo. We therefore regard our results as tentative evidence of a past dynamo on 4 Vesta

Evolution of asteroid (4) Vesta in the light of Dawn

NASA Astrophysics Data System (ADS)

Thangjam, Guneshwar; Mengel, Kurt; Nathues, Andreas; Schmidt, Kai H.; Hoffmann, Martin

2016-04-01

Asteroid (4) Vesta has been visited by the NASA Dawn spacecraft in 2011/12. The combination of compositional/elemental information from the three onboard instruments with mineralogical information from the howardite-eucrite-diogenite (HED) clan of stony achondrites has shed new light on the surface lithologic heterogeneity and the early evolution. Although petrologic/chemical models have tried to unravel the evolutionary processes, inconsistencies exist for some chemical major element/phase [e.g., 1, 2]. A revised evolutionary model is presented here [3]. The three oxygen isotope signature of HEDs and, thus, of proto-Vesta is best met by a mixture of 80% ordinary plus 20 % CV chondrites. Assuming a 27Al-triggered magma ocean within the first MA after accretion and taking into account the reliable major element data of the silicate fraction of the chondritic mixture results a crystallization sequence that differs from the earlier models [1, 2, 3]. The crystallized phase obtained by 'MELTS' software [4] starts with olivine and continues with minor olivine plus orthopyroxene until the liquid reaches a Kd value (partition coefficient) of 0.31 where the fractionated melt is in equilibrium with the residual liquid [5]. The abundance of minerals and rocks formed in this model are converted in volume proportions assuming a spherical shape of early Vesta (262 km radius) with a core (FeNi, FeNiS) radius of 110 km [6]. Two scenarios are considered to describe the early bulk silicate Vesta. First, the early-crystallized olivine accumulated at the base of the silicate shell is accounted for a dunitic lower mantle having a thickness of 46 km while the later crystallized phases form an orthopyroxenitic upper mantle and a crust of thickness 84 and 22 km, respectively. Second, an olivine-rich lower mantle that gradually changes to orthopyroxene-rich upper mantle is expected having an overall shell thickness of 137 km, with a 15 km thick crust. An important result is that the deep-seated olivine-rich mantle has not been accessible to the deep excavation processes by large impacts such as the Rheasilvia basin formation [7]. This is likely the reason why olivine-rich exposures detected by Dawn are of exogenic origin [8]. Reference: [1] Mandler B. E., Elkins-Tanton L. T. 2013. Meteorit. Planet. Sci. 48, 2333. [2] Toplis M.J., et al., 2013. Meteorit. Planet. Sci. 48, 2300. [3] Thangjam G., PhD thesis, (in publication process). [4] Ghiorso M.S., Sack R.O., 1995. Contributions to Mineralogy and Petrology 119, 197. [5] Takahasi E., Kushiro I., 1983. American Mineralogist. 68, 859. [6] Russell C.T., et al., 2012. Science 336, 684. [7] Clenet H., et al., 2014. Nature 511, 303. [8] Nathues A., et al., 2015. Icarus 258, 467.

Mineralogical and spectral analysis of Vesta's Gegania and Lucaria quadrangles and comparative analysis of their key features

NASA Astrophysics Data System (ADS)

Longobardo, Andrea; Palomba, Ernesto; De Sanctis, Maria Cristina; Zinzi, Angelo; Scully, Jennifer E. C.; Capaccioni, Fabrizio; Tosi, Federico; Zambon, Francesca; Ammannito, Eleonora; Combe, Jean-Philippe; Raymond, Carol A.; Russell, Cristopher T.

2015-10-01

This work is aimed at developing and interpreting infrared albedo, pyroxene and OH band depths, and pyroxene band center maps of Vesta's Gegania and Lucaria quadrangles, obtained from data provided by the Visible and InfraRed (VIR) mapper spectrometer on board NASA's Dawn spacecraft. The Gegania and Lucaria quadrangles span latitudes from 22°S to 22°N and longitudes from 0°E to 144°E. The mineralogical and spectral maps identify two large-scale units on this area of Vesta, which extend eastwards and westward of about 60°E, respectively. The two regions are not associated to large-scale geological units, which have a latitudinal distribution rather than longitudinal, but are defined by different contents of carbonaceous chondrites (CC): the eastern region, poor in CCs, is brighter and OH-depleted, whereas the western one, rich in CCs, is darker and OH-enriched. A detailed analysis of the small-scale units in these quadrangles is also performed. Almost all the units show the typical correspondence between high albedo, deep pyroxene bands, short band centers and absence of OH and vice versa. Only a few exceptions occur, such as the ejecta from the Aelia crater, where dark and bright materials are intimately mixed. The most characteristic features of these quadrangles are the equatorial troughs and the Lucaria tholus. The equatorial troughs consist of graben, i.e. a depression limited by two conjugate faults. The graben do not present their own spectral signatures, but spectral parameters similar to their surroundings, in agreement to their structural origin. This is observed also in graben outside the Gegania and Lucaria quadrangles. However, it is possible to observe other structural features, such as tectonic grooves, characterized by a changing composition and hence an albedo variation. This result is confirmed not only by mineralogical maps of Vesta, but also by analyzing the VIRTIS-Rosetta observations of Lutetia. The albedo change is instead a typical behavior of geomorphic grooves. Finally, ridges are characterized by a bluer color and, in some cases, shorter band centers than their surroundings, suggesting that they are composed of fresher materials. We also performed a comparative analysis between the three tholi of Vesta, i.e. Lucaria (which gives the name to its quadrangle), Aricia (in the Marcia quadrangle) and Brumalia (Numisia quadrangle). Whereas Brumalia tholus is a young magmatic intrusion, the absence of diogenites, the low albedo, and the orientation of Aricia and Lucaria tholi suggest that they are older features, which are covered by dark materials and therefore experienced a different geological history than Brumalia.

IOPA: I/O-aware parallelism adaption for parallel programs

PubMed Central

Liu, Tao; Liu, Yi; Qian, Chen; Qian, Depei

2017-01-01

With the development of multi-/many-core processors, applications need to be written as parallel programs to improve execution efficiency. For data-intensive applications that use multiple threads to read/write files simultaneously, an I/O sub-system can easily become a bottleneck when too many of these types of threads exist; on the contrary, too few threads will cause insufficient resource utilization and hurt performance. Therefore, programmers must pay much attention to parallelism control to find the appropriate number of I/O threads for an application. This paper proposes a parallelism control mechanism named IOPA that can adjust the parallelism of applications to adapt to the I/O capability of a system and balance computing resources and I/O bandwidth. The programming interface of IOPA is also provided to programmers to simplify parallel programming. IOPA is evaluated using multiple applications with both solid state and hard disk drives. The results show that the parallel applications using IOPA can achieve higher efficiency than those with a fixed number of threads. PMID:28278236

IOPA: I/O-aware parallelism adaption for parallel programs.

PubMed

Liu, Tao; Liu, Yi; Qian, Chen; Qian, Depei

2017-01-01

With the development of multi-/many-core processors, applications need to be written as parallel programs to improve execution efficiency. For data-intensive applications that use multiple threads to read/write files simultaneously, an I/O sub-system can easily become a bottleneck when too many of these types of threads exist; on the contrary, too few threads will cause insufficient resource utilization and hurt performance. Therefore, programmers must pay much attention to parallelism control to find the appropriate number of I/O threads for an application. This paper proposes a parallelism control mechanism named IOPA that can adjust the parallelism of applications to adapt to the I/O capability of a system and balance computing resources and I/O bandwidth. The programming interface of IOPA is also provided to programmers to simplify parallel programming. IOPA is evaluated using multiple applications with both solid state and hard disk drives. The results show that the parallel applications using IOPA can achieve higher efficiency than those with a fixed number of threads.

An Efficient Format for Nearly Constant-Time Access to Arbitrary Time Intervals in Large Trace Files

DOE PAGES

Chan, Anthony; Gropp, William; Lusk, Ewing

2008-01-01

A powerful method to aid in understanding the performance of parallel applications uses log or trace files containing time-stamped events and states (pairs of events). These trace files can be very large, often hundreds or even thousands of megabytes. Because of the cost of accessing and displaying such files, other methods are often used that reduce the size of the tracefiles at the cost of sacrificing detail or other information. This paper describes a hierarchical trace file format that provides for display of an arbitrary time window in a time independent of the total size of the file and roughlymore » proportional to the number of events within the time window. This format eliminates the need to sacrifice data to achieve a smaller trace file size (since storage is inexpensive, it is necessary only to make efficient use of bandwidth to that storage). The format can be used to organize a trace file or to create a separate file of annotations that may be used with conventional trace files. We present an analysis of the time to access all of the events relevant to an interval of time and we describe experiments demonstrating the performance of this file format.« less

Recent developments in user-job management with Ganga

NASA Astrophysics Data System (ADS)

Currie, R.; Elmsheuser, J.; Fay, R.; Owen, P. H.; Richards, A.; Slater, M.; Sutcliffe, W.; Williams, M.

2015-12-01

The Ganga project was originally developed for use by LHC experiments and has been used extensively throughout Run1 in both LHCb and ATLAS. This document describes some the most recent developments within the Ganga project. There have been improvements in the handling of large scale computational tasks in the form of a new GangaTasks infrastructure. Improvements in file handling through using a new IGangaFile interface makes handling files largely transparent to the end user. In addition to this the performance and usability of Ganga have both been addressed through the development of a new queues system allows for parallel processing of job related tasks.

Wall of Rheasilvia

NASA Image and Video Library

2012-03-21

This still from an animation made from data obtained by NASA Dawn spacecraft shows the topography of a portion of the wall and interior of the Rheasilvia impact basin in asteroid Vesta south-polar region.

Canuleia Crater

NASA Image and Video Library

2012-04-24

This image from NASA Dawn spacecraft of asteroid Vesta shows Canuleia crater, a large, irregularly shaped crater. Other interesting features of Canuleia include the diffuse bright material that is both inside and outside of its rim.

Template based parallel checkpointing in a massively parallel computer system

DOEpatents

Archer, Charles Jens [Rochester, MN; Inglett, Todd Alan [Rochester, MN

2009-01-13

A method and apparatus for a template based parallel checkpoint save for a massively parallel super computer system using a parallel variation of the rsync protocol, and network broadcast. In preferred embodiments, the checkpoint data for each node is compared to a template checkpoint file that resides in the storage and that was previously produced. Embodiments herein greatly decrease the amount of data that must be transmitted and stored for faster checkpointing and increased efficiency of the computer system. Embodiments are directed to a parallel computer system with nodes arranged in a cluster with a high speed interconnect that can perform broadcast communication. The checkpoint contains a set of actual small data blocks with their corresponding checksums from all nodes in the system. The data blocks may be compressed using conventional non-lossy data compression algorithms to further reduce the overall checkpoint size.

Database Reorganization in Parallel Disk Arrays with I/O Service Stealing

NASA Technical Reports Server (NTRS)

Zabback, Peter; Onyuksel, Ibrahim; Scheuermann, Peter; Weikum, Gerhard

1996-01-01

We present a model for data reorganization in parallel disk systems that is geared towards load balancing in an environment with periodic access patterns. Data reorganization is performed by disk cooling, i.e. migrating files or extents from the hottest disks to the coldest ones. We develop an approximate queueing model for determining the effective arrival rates of cooling requests and discuss its use in assessing the costs versus benefits of cooling.

Terascale Cluster for Advanced Turbulent Combustion Simulations

DTIC Science & Technology

2008-07-25

the system We have given the name CATS (for Combustion And Turbulence Simulator) to the terascale system that was obtained through this grant. CATS ...lnfiniBand interconnect. CATS includes an interactive login node and a file server, each holding in excess of 1 terabyte of file storage. The 35 active...compute nodes of CATS enable us to run up to 140-core parallel MPI batch jobs; one node is reserved to run the scheduler. CATS is operated and

Data General Corporation Advanced Operating System/Virtual Storage (AOS/ VS). Revision 7.60

DTIC Science & Technology

1989-02-22

control list for each directory and data file. An access control list includes the users who can and cannot access files as well as the access...and any required data, it can -5- February 22, 1989 Final Evaluation Report Data General AOS/VS SYSTEM OVERVIEW operate asynchronously and in parallel...memory. The IOC can perform the data transfer without further interventiin from the CPU. The I/O channels interface with the processor or system

Designing for Peta-Scale in the LSST Database

NASA Astrophysics Data System (ADS)

Kantor, J.; Axelrod, T.; Becla, J.; Cook, K.; Nikolaev, S.; Gray, J.; Plante, R.; Nieto-Santisteban, M.; Szalay, A.; Thakar, A.

2007-10-01

The Large Synoptic Survey Telescope (LSST), a proposed ground-based 8.4 m telescope with a 10 deg^2 field of view, will generate 15 TB of raw images every observing night. When calibration and processed data are added, the image archive, catalogs, and meta-data will grow 15 PB yr^{-1} on average. The LSST Data Management System (DMS) must capture, process, store, index, replicate, and provide open access to this data. Alerts must be triggered within 30 s of data acquisition. To do this in real-time at these data volumes will require advances in data management, database, and file system techniques. This paper describes the design of the LSST DMS and emphasizes features for peta-scale data. The LSST DMS will employ a combination of distributed database and file systems, with schema, partitioning, and indexing oriented for parallel operations. Image files are stored in a distributed file system with references to, and meta-data from, each file stored in the databases. The schema design supports pipeline processing, rapid ingest, and efficient query. Vertical partitioning reduces disk input/output requirements, horizontal partitioning allows parallel data access using arrays of servers and disks. Indexing is extensive, utilizing both conventional RAM-resident indexes and column-narrow, row-deep tag tables/covering indices that are extracted from tables that contain many more attributes. The DMS Data Access Framework is encapsulated in a middleware framework to provide a uniform service interface to all framework capabilities. This framework will provide the automated work-flow, replication, and data analysis capabilities necessary to make data processing and data quality analysis feasible at this scale.

Dark Crater Rims

NASA Image and Video Library

2013-01-03

These mosaic images from NASA Dawn mission show how dark, carbon-rich materials tend to speckle the rims of smaller craters or their immediate surroundings on the giant asteroid Vesta; Numisia Crater is shown at left.

Fresh Dark Ray Crater

NASA Image and Video Library

2011-10-15

The crater on asteroid Vesta shown in this image from NASA Dawn spacecraft was emplaced onto the ejecta blanket of two large twin craters. Commonly, rays from impact craters are brighter than the surrounding surface.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gibson, Garth

Petascale computing infrastructures for scientific discovery make petascale demands on information storage capacity, performance, concurrency, reliability, availability, and manageability. The Petascale Data Storage Institute focuses on the data storage problems found in petascale scientific computing environments, with special attention to community issues such as interoperability, community buy-in, and shared tools. The Petascale Data Storage Institute is a collaboration between researchers at Carnegie Mellon University, National Energy Research Scientific Computing Center, Pacific Northwest National Laboratory, Oak Ridge National Laboratory, Sandia National Laboratory, Los Alamos National Laboratory, University of Michigan, and the University of California at Santa Cruz. Because the Institute focusesmore » on low level files systems and storage systems, its role in improving SciDAC systems was one of supporting application middleware such as data management and system-level performance tuning. In retrospect, the Petascale Data Storage Institute’s most innovative and impactful contribution is the Parallel Log-structured File System (PLFS). Published in SC09, PLFS is middleware that operates in MPI-IO or embedded in FUSE for non-MPI applications. Its function is to decouple concurrently written files into a per-process log file, whose impact (the contents of the single file that the parallel application was concurrently writing) is determined on later reading, rather than during its writing. PLFS is transparent to the parallel application, offering a POSIX or MPI-IO interface, and it shows an order of magnitude speedup to the Chombo benchmark and two orders of magnitude to the FLASH benchmark. Moreover, LANL production applications see speedups of 5X to 28X, so PLFS has been put into production at LANL. Originally conceived and prototyped in a PDSI collaboration between LANL and CMU, it has grown to engage many other PDSI institutes, international partners like AWE, and has a large team at EMC supporting and enhancing it. PLFS is open sourced with a BSD license on sourceforge. Post PDSI funding comes from NNSA and industry sources. Moreover, PLFS has spin out half a dozen or more papers, partnered on research with multiple schools and vendors, and has projects to transparently 1) dis- tribute metadata over independent metadata servers, 2) exploit drastically non-POSIX Hadoop storage for HPC POSIX applications, 3) compress checkpoints on the fly, 4) batch delayed writes for write speed, 5) compress read-back indexes and parallelize their redistribution, 6) double-buffer writes in NAND Flash storage to decouple host blocking during checkpoint from disk write time in the storage system, 7) pack small files into a smaller number of bigger containers. There are two large scale open source Linux software projects that PDSI significantly incubated, though neither were initated in PDSI. These are 1) Ceph, a UCSC parallel object storage research project that has continued to be a vehicle for research, and has become a released part of Linux, and 2) Parallel NFS (pNFS) a portion of the IETF’s NFSv4.1 that brings the core data parallelism found in Lustre, PanFS, PVFS, and Ceph to the industry standard NFS, with released code in Linux 3.0, and its vendor offerings, with products from NetApp, EMC, BlueArc and RedHat. Both are fundamentally supported and advanced by vendor companies now, but were critcally transferred from research demonstration to viable product with funding from PDSI, in part. At this point Lustre remains the primary path to scalable IO in Exascale systems, but both Ceph and pNFS are viable alternatives with different fundamental advantages. Finally, research community building was a big success for PDSI. Through the HECFSIO workshops and HECURA project with NSF PDSI stimulated and helped to steer leveraged funding of over $25M. Through the Petascale (now Parallel) Data Storage Workshop series, www.pdsw.org, colocated with SCxy each year, PDSI created and incubated five offerings of this high-attendance workshop. The workshop has gone on without PDSI support with two more highly successfully workshops, rewriting its organizational structure to be community managed. More than 70 peer reviewed papers have been presented at PDSW workshops.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sublet, J.-Ch.; Koning, A.J.; Forrest, R.A.

The reasons for the conversion of the European Activation File, EAF into ENDF-6 format are threefold. First, it significantly enhances the JEFF-3.0 release by the addition of an activation file. Second, to considerably increase its usage by using a recognized, official file format, allowing existing plug-in processes to be effective; and third, to move towards a universal nuclear data file in contrast to the current separate general and special-purpose files. The format chosen for the JEFF-3.0/A file uses reaction cross sections (MF-3), cross sections (MF-10), and multiplicities (MF-9). Having the data in ENDF-6 format allows the ENDF suite of utilitiesmore » and checker codes to be used alongside many other utility, visualizing, and processing codes. It is based on the EAF activation file used for many applications from fission to fusion, including dosimetry, inventories, depletion-transmutation, and geophysics. JEFF-3.0/A takes advantage of four generations of EAF files. Extensive benchmarking activities on these files provide feedback and validation with integral measurements. These, in parallel with a detailed graphical analysis based on EXFOR, have been applied stimulating new measurements, significantly increasing the quality of this activation file. The next step is to include the EAF uncertainty data for all channels into JEFF-3.0/A.« less

Measurements of file transfer rates over dedicated long-haul connections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, Nageswara S; Settlemyer, Bradley W; Imam, Neena

2016-01-01

Wide-area file transfers are an integral part of several High-Performance Computing (HPC) scenarios. Dedicated network connections with high capacity, low loss rate and low competing traffic, are increasingly being provisioned over current HPC infrastructures to support such transfers. To gain insights into these file transfers, we collected transfer rate measurements for Lustre and xfs file systems between dedicated multi-core servers over emulated 10 Gbps connections with round trip times (rtt) in 0-366 ms range. Memory transfer throughput over these connections is measured using iperf, and file IO throughput on host systems is measured using xddprof. We consider two file systemmore » configurations: Lustre over IB network and xfs over SSD connected to PCI bus. Files are transferred using xdd across these connections, and the transfer rates are measured, which indicate the need to jointly optimize the connection and host file IO parameters to achieve peak transfer rates. In particular, these measurements indicate that (i) peak file transfer rate is lower than peak connection and host IO throughput, in some cases by as much as 50% or lower, (ii) xdd request sizes that achieve peak throughput for host file IO do not necessarily lead to peak file transfer rates, and (iii) parallelism in host IO and TCP transport does not always improve the file transfer rates.« less

Densely Cratered Terrain Near the Terminator

NASA Image and Video Library

2011-08-16

NASA Dawn spacecraft shows densely cratered terrain near Vesta terminator on August 6, 2011. This image was taken through the framing camera clear filter aboard the spacecraft. North is pointing towards the two oclock position.

Psyche: State of Knowledge from Ground-Based Observations

NASA Astrophysics Data System (ADS)

Reddy, V.; Shepard, M. K.; Takir, D.; Sanchez, J. A.; Richardson, J.; Emery, J. P.; Taylor, P. A.

2017-07-01

We present results from a multi-year campaign to characterize asteroid (16) Psyche, the target of NASA Discovery mission. Our results suggest that Psyche is covered with exogenic carbonaceous impactor similar to Vesta.

Contrast-Enhanced Image of Bellicia Crater

NASA Image and Video Library

2013-11-06

In this contrast-enhanced infrared image of Bellicia Crater on the giant asteroid Vesta, scientists from NASA Dawn mission can see signs of the mineral olivine. Olivine was not expected to be found at Bellicia.

Origin of Phobos and Deimos by the impact of a Vesta-to-Ceres sized body with Mars.

PubMed

Canup, Robin; Salmon, Julien

2018-04-01

It has been proposed that Mars' moons formed from a disk produced by a large impact with the planet. However, whether such an event could produce tiny Phobos and Deimos remains unclear. Using a hybrid N -body model of moon accumulation that includes a full treatment of moon-moon dynamical interactions, we first identify new constraints on the disk properties needed to produce Phobos and Deimos. We then simulate the impact formation of disks using smoothed particle hydrodynamics, including a novel approach that resolves the impact ejecta with order-of-magnitude finer mass resolution than existing methods. We find that forming Phobos-Deimos requires an oblique impact by a Vesta-to-Ceres sized object with ~10 -3 times Mars' mass, a much less massive impactor than previously considered.

Extending the Lunar Mapping and Modeling Portal - New Capabilities and New Worlds

NASA Technical Reports Server (NTRS)

Day, B.; Law, E.; Arevalo, E.; Bui, B.; Chang, G.; Dodge, K.; Kim, R.; Malhotra, S.; Sadaqathullah, S.; Schmidt, G.;

KSC-07pd1506

NASA Image and Video Library

2007-06-13

KENNEDY SPACE CENTER, FLA. -- Technicians at Astrotech are preparing the Dawn spacecraft for spin-balance testing. After the test, Dawn will then be mated to the upper stage booster, installed into a spacecraft transportation canister for the trip to Cape Canaveral Air Force Station and mated to the Delta II rocket at Launch Pad 17-B. The Dawn spacecraft will employ ion propulsion to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. Dawn's goal is to characterize the conditions and processes of the solar system's earliest epoch by investigating in detail these largest protoplanets that have remained intact since their formations. Ceres and Vesta reside in the extensive zone between Mars and Jupiter together with many other smaller bodies, called the asteroid belt. Dawn is scheduled to launch July 7. Photo credit: NASA/Jack Pfaller

KSC-07pd1508

NASA Image and Video Library

2007-06-13

KENNEDY SPACE CENTER, FLA. -- At Astrotech, the Dawn spacecraft is ready for spin-balance testing. After the test, Dawn will then be mated to the upper stage booster, installed into a spacecraft transportation canister for the trip to Cape Canaveral Air Force Station and mated to the Delta II rocket at Launch Pad 17-B. The Dawn spacecraft will employ ion propulsion to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. Dawn's goal is to characterize the conditions and processes of the solar system's earliest epoch by investigating in detail these largest protoplanets that have remained intact since their formations. Ceres and Vesta reside in the extensive zone between Mars and Jupiter together with many other smaller bodies, called the asteroid belt. Dawn is scheduled to launch July 7. Photo credit: NASA/Jack Pfaller

KSC-07pd1507

NASA Image and Video Library

2007-06-13

KENNEDY SPACE CENTER, FLA. -- Technicians at Astrotech check the Dawn spacecraft before spin-balance testing. After the test, Dawn will then be mated to the upper stage booster, installed into a spacecraft transportation canister for the trip to Cape Canaveral Air Force Station and mated to the Delta II rocket at Launch Pad 17-B.The Dawn spacecraft will employ ion propulsion to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. Dawn's goal is to characterize the conditions and processes of the solar system's earliest epoch by investigating in detail these largest protoplanets that have remained intact since their formations. Ceres and Vesta reside in the extensive zone between Mars and Jupiter together with many other smaller bodies, called the asteroid belt. Dawn is scheduled to launch July 7. Photo credit: NASA/Jack Pfaller

KSC-07pd1505

NASA Image and Video Library

2007-06-13

KENNEDY SPACE CENTER, FLA. -- Technicians at Astrotech prepare the Dawn spacecraft for spin-balance testing. After the test, Dawn will then be mated to the upper stage booster, installed into a spacecraft transportation canister for the trip to Cape Canaveral Air Force Station and mated to the Delta II rocket at Launch Pad 17-B. The Dawn spacecraft will employ ion propulsion to explore two of the asteroid belt's most intriguing and dissimilar occupants: asteroid Vesta and the dwarf planet Ceres. Dawn's goal is to characterize the conditions and processes of the solar system's earliest epoch by investigating in detail these largest protoplanets that have remained intact since their formations. Ceres and Vesta reside in the extensive zone between Mars and Jupiter together with many other smaller bodies, called the asteroid belt. Dawn is scheduled to launch July 7. Photo credit: NASA/Jack Pfaller

Lightcurve survey of V-type asteroids in the inner asteroid belt

NASA Astrophysics Data System (ADS)

Hasegawa, Sunao; Miyasaka, Seidai; Mito, Hiroyuki; Sarugaku, Yuki; Ozawa, Tomohiko; Kuroda, Daisuke; Nishihara, Setsuko; Harada, Akari; Yoshida, Michitoshi; Yanagisawa, Kenshi; Shimizu, Yasuhiro; Nagayama, Shogo; Toda, Hiroyuki; Okita, Kichi; Kawai, Nobuyuki; Mori, Machiko; Sekiguchi, Tomohiko; Ishiguro, Masateru; Abe, Takumi; Abe, Masanao

2014-06-01

We observed the lightcurves of 13 V-type asteroids [(1933) Tinchen, (2011) Veteraniya, (2508) Alupka, (3657) Ermolova, (3900) Knezevic, (4005) Dyagilev, (4383) Suruga, (4434) Nikulin, (4796) Lewis, (6331) 1992 FZ1, (8645) 1998 TN, (10285) Renemichelsen, and (10320) Reiland]. Using these observations we determined the rotational rates of the asteroids, with the exception of Nikulin and Renemichelsen. The distribution of rotational rates of 59 V-type asteroids in the inner main belt, including 29 members of the Vesta family, which are regarded as being ejecta from the asteroid (4) Vesta, is inconsistent with the best-fit Maxwellian distribution. This inconsistency may be due to the effect of thermal radiation Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) torques, which implies that the collision event that formed V-type asteroids is sub-billion to several billion years in age.

Extending the Lunar Mapping and Modeling Portal - New Capabilities and New Worlds

NASA Astrophysics Data System (ADS)

Day, B.; Law, E.; Arevalo, E.; Bui, B.; Chang, G.; Dodge, K.; Kim, R.; Malhotra, S.; Sadaqathullah, S.; Schmidt, G.; Bailey, B.

2015-10-01

NASA's Lunar Mapping and Modeling Portal (LMMP) provides a web-based Portal and a suite of interactive visualization and analysis tools to enable mission planners, lunar scientists, and engineers to access mapped lunar data products from past and current lunar missions (http://lmmp.nasa.gov). During the past year, the capabilities and data served by LMMP have been significantly expanded. New interfaces are providing improved ways to access and visualize data. At the request of NASA's Science Mission Directorate, LMMP's technology and capabilities are now being extended to additional planetary bodies. New portals for Vesta and Mars are the first of these new products to be released. This presentation will provide an overview of LMMP, Vesta Trek, and Mars Trek, demonstrate their uses and capabilities, highlight new features, and preview coming enhancements.

Crater Retention Ages from (4) Vesta Matching Independent Ar-Ar Ages of HED Meteorites

NASA Astrophysics Data System (ADS)

Schmedemann, Nico; Kneissl, Thomas; Ivanov, Boris A.; Michael, Gregory G.; Neukum, Gerhard; Nathues, Andreas; Sierks, Holger; Wagner, Roland; Krohn, Katrin; Le Corre, Lucille; Reddy, Vishnu; Ruesch, Ottaviano; Hiesinger, Harald; Jaumann, Ralf; Raymond, Carol A.; Russell, Christopher T.

2013-04-01

In July 2012 the Dawn spacecraft completed its mapping task of the Main Belt asteroid Vesta with a second high altitude mapping orbit. Dawn is now on its way to the dwarf planet (1) Ceres, where it will perform a similar mapping campaign like that at Vesta [1]. The Main Belt is the source region of most impactors in the inner solar system [2,3,4], making it a key region for understanding the early history of our Solar System. In order to determine absolute surface ages from Vesta we derived a crater production function and a chronology function for Vesta. We derived these functions from the respective lunar functions [2] and scaled [5] them to the impact conditions on Vesta [6]. In general we find good agreement between the derived crater production function and the measured crater distribution. However, we also find disagreement between 8 and 15 km crater size, on areas older ~2.2 Ga. Older areas show a steep (~-6 cumulative) slope, which we link to a decaying influence of the vestan collisional family (Vestoids). The lower boundary of 8 km crater size may be explained by fast ejected small spalls and/or a more efficient Yarkovsky effect [7]. This influence is not observed for instance inside the large Rheasilvia basin, which we date with ~2.2 Ga. Since the formation of this basin is believed to be a major source of replenishment of the Vestoids, it's currently observed cratering record is not indicative for the basin formation age in contrast to [8]. The young interior of the Rheasilvia basin is likely a result of repeated resets of the crater retention age due to mass wasting processes on the basin walls. We use topographic heights, which are less affected by mass wasting such as the top of the central peak of the basin as well as proximal ejecta blankets outside the basin to date the formation age of Rheasilvia. For the central peak we derive a surface age of 3.59 (+0.079/-0.18) Ga. The proximal ejecta blanket at the Oppia crater is dated with 3.62 (+0.054/-0.087) Ga and 3.63 (+0.058/-0.096) Ga. We also find seismic (miniscule ejecta blanket from Rheasilvia) resurfacing events in the time frame of ~3.56 to ~3.59 Ga at several areas in the northern hemisphere, indicative for a major seismic activity probably connected to the Rheasilvia formation. An antipodal activity is also suggested by hydrocode modeling [9]. By summation of age probability curves of measurements we link to the Rheasilvia formation, we find 3.58 (+0.07/-0.12) Ga. Using a similar attempt we find 3.75 (+0.05/-0.21) Ga for the Veneneia formation. Both crater retention ages correspond within the error bars with prominent peaks of independent Ar-Ar ages of Vesta related HED meteorites [10]. Acknowledgement: This work has been supported by the German Space Agency (DLR) on behalf of the Federal Ministry of Economics and Technology, grants 50OW1101(NS,TK), 50QM1001 (GM) and 50OW1102 (OR,HH). References: [1] Russell et al. (2007): Advances in Space Research 40(2): pp193-201, 2007. [2] Neukum and Ivanov: In: Gehrels T (ed) "Hazards due to comets and asteroids". University of Arizona Press, Tucson, 359-416, 1994. [3] O'Brien and Greenberg (2005): Icarus 178(1): 179-212. [4] Nesvorny et al. (2009): Icarus 200(2): 698-701. [5] Ivanov (2001): Chronology and Evolution of Mars 96, 87-104, 2001. [6] Schmedemann et al. (2012): 43.LPSC, The Woodlands, #1659. [7] Morbidelli et al. (2003): Icarus 162, 328-336. [8] Marchi et al. (2012): Science 336, 690. [9] Bowling et al. (2012): 75th Annual Meeting of the Meteoritical Society, 2012, Cairns, Australia. Meteoritics and Planetary Science Supplement, id.5256. [10] Bogard, D. D. (2011): Chemie der Erde - Geochemistry, vol. 71, issue 3: 207-226.

Visualization and Tracking of Parallel CFD Simulations

NASA Technical Reports Server (NTRS)

Vaziri, Arsi; Kremenetsky, Mark

1995-01-01

We describe a system for interactive visualization and tracking of a 3-D unsteady computational fluid dynamics (CFD) simulation on a parallel computer. CM/AVS, a distributed, parallel implementation of a visualization environment (AVS) runs on the CM-5 parallel supercomputer. A CFD solver is run as a CM/AVS module on the CM-5. Data communication between the solver, other parallel visualization modules, and a graphics workstation, which is running AVS, are handled by CM/AVS. Partitioning of the visualization task, between CM-5 and the workstation, can be done interactively in the visual programming environment provided by AVS. Flow solver parameters can also be altered by programmable interactive widgets. This system partially removes the requirement of storing large solution files at frequent time steps, a characteristic of the traditional 'simulate (yields) store (yields) visualize' post-processing approach.

ParCAT: A Parallel Climate Analysis Toolkit

NASA Astrophysics Data System (ADS)

Haugen, B.; Smith, B.; Steed, C.; Ricciuto, D. M.; Thornton, P. E.; Shipman, G.

2012-12-01

Climate science has employed increasingly complex models and simulations to analyze the past and predict the future of our climate. The size and dimensionality of climate simulation data has been growing with the complexity of the models. This growth in data is creating a widening gap between the data being produced and the tools necessary to analyze large, high dimensional data sets. With single run data sets increasing into 10's, 100's and even 1000's of gigabytes, parallel computing tools are becoming a necessity in order to analyze and compare climate simulation data. The Parallel Climate Analysis Toolkit (ParCAT) provides basic tools that efficiently use parallel computing techniques to narrow the gap between data set size and analysis tools. ParCAT was created as a collaborative effort between climate scientists and computer scientists in order to provide efficient parallel implementations of the computing tools that are of use to climate scientists. Some of the basic functionalities included in the toolkit are the ability to compute spatio-temporal means and variances, differences between two runs and histograms of the values in a data set. ParCAT is designed to facilitate the "heavy lifting" that is required for large, multidimensional data sets. The toolkit does not focus on performing the final visualizations and presentation of results but rather, reducing large data sets to smaller, more manageable summaries. The output from ParCAT is provided in commonly used file formats (NetCDF, CSV, ASCII) to allow for simple integration with other tools. The toolkit is currently implemented as a command line utility, but will likely also provide a C library for developers interested in tighter software integration. Elements of the toolkit are already being incorporated into projects such as UV-CDAT and CMDX. There is also an effort underway to implement portions of the CCSM Land Model Diagnostics package using ParCAT in conjunction with Python and gnuplot. ParCAT is implemented in C to provide efficient file IO. The file IO operations in the toolkit use the parallel-netcdf library; this enables the code to use the parallel IO capabilities of modern HPC systems. Analysis that currently requires an estimated 12+ hours with the traditional CCSM Land Model Diagnostics Package can now be performed in as little as 30 minutes on a single desktop workstation and a few minutes for relatively small jobs completed on modern HPC systems such as ORNL's Jaguar.

Characterizing output bottlenecks in a supercomputer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Bing; Chase, Jeffrey; Dillow, David A

2012-01-01

Supercomputer I/O loads are often dominated by writes. HPC (High Performance Computing) file systems are designed to absorb these bursty outputs at high bandwidth through massive parallelism. However, the delivered write bandwidth often falls well below the peak. This paper characterizes the data absorption behavior of a center-wide shared Lustre parallel file system on the Jaguar supercomputer. We use a statistical methodology to address the challenges of accurately measuring a shared machine under production load and to obtain the distribution of bandwidth across samples of compute nodes, storage targets, and time intervals. We observe and quantify limitations from competing traffic,more » contention on storage servers and I/O routers, concurrency limitations in the client compute node operating systems, and the impact of variance (stragglers) on coupled output such as striping. We then examine the implications of our results for application performance and the design of I/O middleware systems on shared supercomputers.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ilsche, Thomas; Schuchart, Joseph; Cope, Joseph

Event tracing is an important tool for understanding the performance of parallel applications. As concurrency increases in leadership-class computing systems, the quantity of performance log data can overload the parallel file system, perturbing the application being observed. In this work we present a solution for event tracing at leadership scales. We enhance the I/O forwarding system software to aggregate and reorganize log data prior to writing to the storage system, significantly reducing the burden on the underlying file system for this type of traffic. Furthermore, we augment the I/O forwarding system with a write buffering capability to limit the impactmore » of artificial perturbations from log data accesses on traced applications. To validate the approach, we modify the Vampir tracing tool to take advantage of this new capability and show that the approach increases the maximum traced application size by a factor of 5x to more than 200,000 processors.« less

A Shared Bombardment History

NASA Image and Video Library

2013-03-25

Studying meteorites from the asteroid Vesta helps scientists understand the event known as the lunar cataclysm, when a repositioning of the gas giant planets destabilized a portion of the asteroid belt and triggered a solar-system-wide bombardment.

A Valentine from Vesta

NASA Image and Video Library

2012-02-14

This image from NASA Dawn spacecraft, is based on a framing camera image that is overlain by a color-coded height representation of topography. This heart-shaped hollow is roughly 10 kilometers 6 miles across at its widest point.

The Automated Instrumentation and Monitoring System (AIMS) reference manual

NASA Technical Reports Server (NTRS)

Yan, Jerry; Hontalas, Philip; Listgarten, Sherry

1993-01-01

Whether a researcher is designing the 'next parallel programming paradigm,' another 'scalable multiprocessor' or investigating resource allocation algorithms for multiprocessors, a facility that enables parallel program execution to be captured and displayed is invaluable. Careful analysis of execution traces can help computer designers and software architects to uncover system behavior and to take advantage of specific application characteristics and hardware features. A software tool kit that facilitates performance evaluation of parallel applications on multiprocessors is described. The Automated Instrumentation and Monitoring System (AIMS) has four major software components: a source code instrumentor which automatically inserts active event recorders into the program's source code before compilation; a run time performance-monitoring library, which collects performance data; a trace file animation and analysis tool kit which reconstructs program execution from the trace file; and a trace post-processor which compensate for data collection overhead. Besides being used as prototype for developing new techniques for instrumenting, monitoring, and visualizing parallel program execution, AIMS is also being incorporated into the run-time environments of various hardware test beds to evaluate their impact on user productivity. Currently, AIMS instrumentors accept FORTRAN and C parallel programs written for Intel's NX operating system on the iPSC family of multi computers. A run-time performance-monitoring library for the iPSC/860 is included in this release. We plan to release monitors for other platforms (such as PVM and TMC's CM-5) in the near future. Performance data collected can be graphically displayed on workstations (e.g. Sun Sparc and SGI) supporting X-Windows (in particular, Xl IR5, Motif 1.1.3).

Two-dimensional parallel array technology as a new approach to automated combinatorial solid-phase organic synthesis

PubMed

Brennan; Biddison; Frauendorf; Schwarcz; Keen; Ecker; Davis; Tinder; Swayze

1998-01-01

An automated, 96-well parallel array synthesizer for solid-phase organic synthesis has been designed and constructed. The instrument employs a unique reagent array delivery format, in which each reagent utilized has a dedicated plumbing system. An inert atmosphere is maintained during all phases of a synthesis, and temperature can be controlled via a thermal transfer plate which holds the injection molded reaction block. The reaction plate assembly slides in the X-axis direction, while eight nozzle blocks holding the reagent lines slide in the Y-axis direction, allowing for the extremely rapid delivery of any of 64 reagents to 96 wells. In addition, there are six banks of fixed nozzle blocks, which deliver the same reagent or solvent to eight wells at once, for a total of 72 possible reagents. The instrument is controlled by software which allows the straightforward programming of the synthesis of a larger number of compounds. This is accomplished by supplying a general synthetic procedure in the form of a command file, which calls upon certain reagents to be added to specific wells via lookup in a sequence file. The bottle position, flow rate, and concentration of each reagent is stored in a separate reagent table file. To demonstrate the utility of the parallel array synthesizer, a small combinatorial library of hydroxamic acids was prepared in high throughput mode for biological screening. Approximately 1300 compounds were prepared on a 10 μmole scale (3-5 mg) in a few weeks. The resulting crude compounds were generally >80% pure, and were utilized directly for high throughput screening in antibacterial assays. Several active wells were found, and the activity was verified by solution-phase synthesis of analytically pure material, indicating that the system described herein is an efficient means for the parallel synthesis of compounds for lead discovery. Copyright 1998 John Wiley & Sons, Inc.

Compiler-Directed File Layout Optimization for Hierarchical Storage Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Wei; Zhang, Yuanrui; Kandemir, Mahmut

File layout of array data is a critical factor that effects the behavior of storage caches, and has so far taken not much attention in the context of hierarchical storage systems. The main contribution of this paper is a compiler-driven file layout optimization scheme for hierarchical storage caches. This approach, fully automated within an optimizing compiler, analyzes a multi-threaded application code and determines a file layout for each disk-resident array referenced by the code, such that the performance of the target storage cache hierarchy is maximized. We tested our approach using 16 I/O intensive application programs and compared its performancemore » against two previously proposed approaches under different cache space management schemes. Our experimental results show that the proposed approach improves the execution time of these parallel applications by 23.7% on average.« less

Compiler-Directed File Layout Optimization for Hierarchical Storage Systems

DOE PAGES

Ding, Wei; Zhang, Yuanrui; Kandemir, Mahmut; ...

2013-01-01

File layout of array data is a critical factor that effects the behavior of storage caches, and has so far taken not much attention in the context of hierarchical storage systems. The main contribution of this paper is a compiler-driven file layout optimization scheme for hierarchical storage caches. This approach, fully automated within an optimizing compiler, analyzes a multi-threaded application code and determines a file layout for each disk-resident array referenced by the code, such that the performance of the target storage cache hierarchy is maximized. We tested our approach using 16 I/O intensive application programs and compared its performancemore » against two previously proposed approaches under different cache space management schemes. Our experimental results show that the proposed approach improves the execution time of these parallel applications by 23.7% on average.« less

78 FR 9687 - Prineville Energy Storage, LLC; Notice of Preliminary Permit Application Accepted for Filing and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-11

... PDCI to the Ponderosa substation, or (ii) the Bonneville Power Administration (BPA) existing transmission line corridor and then running parallel to the BPA line to the Ponderosa substation; and (9...

Parallel, Asynchronous Executive (PAX): System concepts, facilities, and architecture

NASA Technical Reports Server (NTRS)

Jones, W. H.

1983-01-01

The Parallel, Asynchronous Executive (PAX) is a software operating system simulation that allows many computers to work on a single problem at the same time. PAX is currently implemented on a UNIVAC 1100/42 computer system. Independent UNIVAC runstreams are used to simulate independent computers. Data are shared among independent UNIVAC runstreams through shared mass-storage files. PAX has achieved the following: (1) applied several computing processes simultaneously to a single, logically unified problem; (2) resolved most parallel processor conflicts by careful work assignment; (3) resolved by means of worker requests to PAX all conflicts not resolved by work assignment; (4) provided fault isolation and recovery mechanisms to meet the problems of an actual parallel, asynchronous processing machine. Additionally, one real-life problem has been constructed for the PAX environment. This is CASPER, a collection of aerodynamic and structural dynamic problem simulation routines. CASPER is not discussed in this report except to provide examples of parallel-processing techniques.

Successive Formation of Impact Craters

NASA Image and Video Library

2012-02-16

This image from NASA Dawn spacecraft shows two overlapping impact craters on asteroid Vesta. The rims of the craters are both reasonably fresh but the larger crater must be older because the smaller crater cuts across the larger crater rim.

Aricia Tholus

NASA Image and Video Library

2012-02-22

This image from NASA Dawn spacecraft shows Aricia Tholus, a dark hill located in asteroid Vesta Marcia quadrangle. Tholus is a word used to describe a small dome-like mountain or hill. Aricia was the name of a city in ancient Italy.

Dense Region of Impact Craters

NASA Image and Video Library

2011-09-23

NASA Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on Aug. 14 2011. This image was taken through the camera clear filter. The image has a resolution of about 260 meters per pixel.

A Virtual Observatory Approach to Planetary Data for Vesta and Ceres

NASA Astrophysics Data System (ADS)

Giardino, M.; Fonte, S.; Politi, R.; Ivanovski, S.; Longobardo, A.; Capria, M. T.; Erard, S.; De Sanctis, M. C.

2018-04-01

A virtual observatory service for DAWN/VIR spectral dataset is presented, based upon the IVOA standards adapted to the planetary field. Advantages of such an approach will be discussed, especially concerning interoperability and availability.

A New Spin on Vesta

NASA Image and Video Library

2010-10-08

Hubble Wide Field Camera 3 observed the potato-shaped asteroid in preparation for the visit by NASA Dawn spacecraft in 2011. This is one frame from a movie showing the difference in brightness and color on the asteroid surface.

Regolith Depth, Mobility, and Variability on Vesta from Dawn's Low Altitude Mapping Orbit

NASA Technical Reports Server (NTRS)

Denevi, B. W.; Coman, E. I.; Blewett, D. T.; Mittlefehldt, D. W.; Buczkowski, D. L.; Combe, J.-P.; De Sanctis, M. C.; Jaumann, R.; Li, J.-Y.; Marchi, S.;

Vesta surface thermal properties map

USGS Publications Warehouse

Capria, Maria Teresa; Tosi, F.; De Santis, Maria Cristina; Capaccioni, F.; Ammannito, E.; Frigeri, A.; Zambon, F; Fonte, S.; Palomba, E.; Turrini, D.; Titus, T.N.; Schroder, S.E.; Toplis, M.J.; Liu, J.Y.; Combe, J.-P.; Raymond, C.A.; Russell, C.T.

2014-01-01

The first ever regional thermal properties map of Vesta has been derived from the temperatures retrieved by infrared data by the mission Dawn. The low average value of thermal inertia, 30 ± 10 J m−2 s−0.5 K−1, indicates a surface covered by a fine regolith. A range of thermal inertia values suggesting terrains with different physical properties has been determined. The lower thermal inertia of the regions north of the equator suggests that they are covered by an older, more processed surface. A few specific areas have higher than average thermal inertia values, indicative of a more compact material. The highest thermal inertia value has been determined on the Marcia crater, known for its pitted terrain and the presence of hydroxyl in the ejecta. Our results suggest that this type of terrain can be the result of soil compaction following the degassing of a local subsurface reservoir of volatiles.

Effect of Silicon on Activity Coefficients of P, Bl, CD, SN, and AG in Liquid Fe-Si, and Implications for Differentiation and Core Formation

NASA Technical Reports Server (NTRS)

Righter, K.; Pando, K.; Ross, D. K.

2017-01-01

Cores of differentiated bodies (Earth, Mars, Mercury, Moon, Vesta) contain light elements such as S, C, Si, and O. We have previously measured small effects of Si on metal-silicate partitioning of Ni and Co [1,2], and larger effects for Mo, Ge, Sb, As [2]. The effect of Si on many siderophile elements could be an important, and as yet unquantified, influence on the core-mantle partitioning of SE. Here we report new experiments designed to quantify the effect of Si on the partitioning of Bi, Cd, Sn, Ag, and P between metal and silicate melt. The results will be applied to Earth, Mars, Mercury, Moon, and Vesta, for which we have excellent constraints on the mantle Bi, Cd, Sn, Ag, and P concentrations from mantle and/or basalt samples.

Effect of Silicon on Activity Coefficients of P, Bi, Cd, Sn, and Ag in Liquid Fe-Si, and Implications for Core Formation

NASA Technical Reports Server (NTRS)

Righter, K.; Pando, K.; Ross, D. K.; Righter, M.; Lapen, T. J.

2018-01-01

Cores of differentiated bodies (Earth, Mars, Mercury, Moon, Vesta) contain light elements such as S, C, Si, and O. We have previously measured small effects of Si on Ni and Co, and larger effects on Mo, Ge, Sb, As metal/silicate partitioning. The effect of Si on metal-silicate partitioning has been quantified for many siderophile elements, but there are a few key elements for which the effects are not yet quantified. Here we report new experiments designed to quantify the effect of Si on the partitioning of Bi, Cd, Sn, Ag, and P between metal and silicate melt. The results will be applied to Earth, Mars, Moon, and Vesta, for which we have good constraints on the mantle Bi, Cd, Sn, Ag, and P concentrations from mantle and/or basalt samples.

Bamgineer: Introduction of simulated allele-specific copy number variants into exome and targeted sequence data sets.

PubMed

Samadian, Soroush; Bruce, Jeff P; Pugh, Trevor J

2018-03-01

Somatic copy number variations (CNVs) play a crucial role in development of many human cancers. The broad availability of next-generation sequencing data has enabled the development of algorithms to computationally infer CNV profiles from a variety of data types including exome and targeted sequence data; currently the most prevalent types of cancer genomics data. However, systemic evaluation and comparison of these tools remains challenging due to a lack of ground truth reference sets. To address this need, we have developed Bamgineer, a tool written in Python to introduce user-defined haplotype-phased allele-specific copy number events into an existing Binary Alignment Mapping (BAM) file, with a focus on targeted and exome sequencing experiments. As input, this tool requires a read alignment file (BAM format), lists of non-overlapping genome coordinates for introduction of gains and losses (bed file), and an optional file defining known haplotypes (vcf format). To improve runtime performance, Bamgineer introduces the desired CNVs in parallel using queuing and parallel processing on a local machine or on a high-performance computing cluster. As proof-of-principle, we applied Bamgineer to a single high-coverage (mean: 220X) exome sequence file from a blood sample to simulate copy number profiles of 3 exemplar tumors from each of 10 tumor types at 5 tumor cellularity levels (20-100%, 150 BAM files in total). To demonstrate feasibility beyond exome data, we introduced read alignments to a targeted 5-gene cell-free DNA sequencing library to simulate EGFR amplifications at frequencies consistent with circulating tumor DNA (10, 1, 0.1 and 0.01%) while retaining the multimodal insert size distribution of the original data. We expect Bamgineer to be of use for development and systematic benchmarking of CNV calling algorithms by users using locally-generated data for a variety of applications. The source code is freely available at http://github.com/pughlab/bamgineer.

The Complicated Geologic History of Asteroid 4 Vesta

NASA Astrophysics Data System (ADS)

Taylor, G. J.

2009-06-01

Planetary scientists are pretty sure that almost all of the HED meteorites come from the fourth-largest asteroid, 4 Vesta. HED stands for the three types of rocks that make up the group. As cosmochemists have studied the meteorites over the years, their view of the geologic history of the asteroid has become progressively more complicated. Jean-Alix Barrat and Marcel Bohn (CNRS and University of Brest, France), Philippe Gillet (CNRS and Ecole Normale Supérieure de Lyon, France), and Akira Yamaguchi (National Institute of Polar Research, Tokyo, Japan) have found that Vesta is even more complicated--and interesting--than we thought. Barrat and his colleagues analyzed impact-produced glass spherules and fragments in several howardites (mixtures of the two other main types, eucrites and diogenites). Not surprisingly, most of the glasses have compositions similar to eucrites, which are basalts, or mixtures of them with diogenites, but a few are surprisingly rich in silicon and potassium (expressed as the percentages of SiO2 and K2O, respectively). In fact, the concentrations of these oxides are similar to granites, compositionally far from basalt. Their manufacture requires extensive crystallization of magma. Combined with a more subtle variation among the basalts, the emerging picture is one that includes formation of a basaltic crust, partial melting of parts of the crust, mixing of those melts with some (not all) magmas as they migrated through the crust, and extensive crystallization of magma bodies to produce residual magma resembling granites. On top of that, Vestan rocks were thermally metamorphosed and battered and mixed by impacts. A pretty complicated little planetary body!

The Enabling Use of Ion Propulsion on Dawn

NASA Astrophysics Data System (ADS)

Rayman, M.; Russell, C. T.; Raymond, C. A.; Mase, R. M.

2011-12-01

Dawn's mission to orbit both Vesta and Ceres is enabled by its use of ion propulsion. Even orbiting Vesta alone with conventional propulsion would have been unaffordable within the constraints of the Discovery Program, and orbiting both would have been impossible. In fact, no other spacecraft has been targeted to orbit two solar system destinations, which is only one of the many firsts that Dawn will achieve. The successful testing of ion propulsion on Deep Space 1 paved the way for Dawn not only to use the hardware with confidence but also to learn how to design the flight system and design the mission to take advantage of its capabilities. In addition to allowing Dawn to reach these two important targets, ion propulsion allows the spacecraft to accomplish significant changes in its orbit. Therefore, science observations of Vesta are planned from four different orbits, at varying altitudes and solar geometry. The use of ion propulsion results in a significant mission design effort since the trajectory is constantly being refined. This also creates a flexible mission architecture, which allows for optimization of the mission as conditions change. Solar electric ion propulsion is especially well suited to missions to the Main Asteroid Belt since solar energy is still a viable power source, whereas the size of the solar array needed beyond 3.5 AU is a potential limitation. Dawn has already surpassed the record for greatest propulsive velocity, but its greatest achievements will no doubt be the incredible bounty of science data enabled by this innovative flight system.

Compositional Diversity of the Vestan Regolith Derived from Howardite Compositions and Dawn VIR Spectra

NASA Technical Reports Server (NTRS)

Mittlefehldt, D. W.; Ammannito, E.; Hiroi, T.; DeAngeles, S.; Moriarty, D. P.; DiIorio, T.; Pieters, C. M.; DeSanctis, M. C.

2014-01-01

Howardite, eucrite and diogenite meteorites likely come from asteroid 4 Vesta [1]. Howardites - physical mixtures of eucrites and diogenites - are of two subtypes: regolithic howardites were gardened in the true regolith; fragmental howardites are simple polymict breccias [2]. The Dawn spacecraft imaged the howarditic surface of Vesta with the visible and infrared mapping spectrometer (VIR) resulting in qualitative maps of the distributions of distinct diogenite-rich and eucrite-rich terranes [3, 4]. We are developing a robust basis for quantitative mapping of the distribution of lithologic types using spectra acquired on splits of well-characterized howardites [5, 6]. Spectra were measured on sample powders sieved to <75 µm in the laboratories of the Istituto di Astrofisica e Planetologia Spaziali and Brown University. Data reduction was done using the methods developed to process Dawn VIR spectra [4]. The band parameters for the 1 and 2 µm pyroxene absorption features (hereafter BI and BII) can be directly compared to Dawn VIR results. Regolithic howardites have shallower BI and BII absorptions compared to fragmental howardites with similar compositions. However, there are statistically significant correlations between Al or Ca contents and BI or BII center wavelengths regardless of howardite subtype. Diogenites are poor in Al and Ca while eucrites are rich in these elements. The laboratory spectra can thus be directly correlated with the percentage of eucrite material contained in the howardites. We are using these correlations to quantitatively map Al and Ca distributions, and thus the percentage of eucritic material, in the current regolith of Vesta.

On the highly inclined vW leptokurtic asteroid families

NASA Astrophysics Data System (ADS)

Carruba, V.; Domingos, R. C.; Aljbaae, S.; Huaman, M.

2016-11-01

vW leptokurtic asteroid families are families for which the distribution of the normal component of the terminal ejection velocity field vW is characterized by a positive value of the γ2 Pearson kurtosis, I.e. they have a distribution with a more concentrated peak and larger tails than the Gaussian one. Currently, eight families are known to have γ2(vW) > 0.25. Among these, three are highly inclined asteroid families, the Hansa, Barcelona, and Gallia families. As observed for the case of the Astrid family, the leptokurtic inclination distribution seems to be caused by the interaction of these families with node secular resonances. In particular, the Hansa and Gallia family are crossed by the s - sV resonance with Vesta, that significantly alters the inclination of some of their members. In this work we use the time evolution of γ2(vW) for simulated families under the gravitational influence of all planets and the three most massive bodies in the main belt to assess the dynamical importance (or lack of) node secular resonances with Ceres, Vesta, and Pallas for the considered families, and to obtain independent constraints on the family ages. While secular resonances with massive bodies in the main belt do not significantly affect the dynamical evolution of the Barcelona family, they significantly increase the γ2(vW) values of the simulated Hansa and Gallia families. Current values of the γ2(vW) for the Gallia family are reached over the estimated family age only if secular resonances with Vesta are accounted for.

Reappraising Accretion to Vesta and the Angrite Parent Body Through Mineral-Scale Platinum Group Element and Os-Isotope Analyses

NASA Astrophysics Data System (ADS)

Riches, A. J. V.; Burton, K. W.; Nowell, G. M.; Dale, C. W.; Ottley, C. J.

2016-08-01

New methods presented here enable quantitative determination of mineral-scale PGE-abundances and Os-isotope compositions in meteorite materials thereby providing valuable new insight into planetary evolution.

Side by Side Views of a Dark Hill

NASA Image and Video Library

2011-09-02

NASA Dawn spacecraft obtained these side-by-side views of a dark hill of the surface of asteroid Vesta with its framing camera on August 19, 2011. The images have a resolution of about 260 meters per pixel.

Vesta Cratered Landscape: Double Crater and Craters with Bright Ejecta

NASA Image and Video Library

2011-11-23

This image from NASA Dawn spacecraft is dominated by a double crater which may have been formed by the simultaneous impact of a binary asteroid. Binary asteroids are asteroids that orbit their mutual center of mass.

Dark Material Associated with and between Craters

NASA Image and Video Library

2011-11-18

This image from NASA Dawn spacecraft shows areas of dark material which are both associated with impact craters and between these craters on asteroid Vesta. Dark material is seen cropping out of the rims and sides of the larger craters.

Apparent Brightness and Topography Images of Vibidia Crater

NASA Image and Video Library

2012-03-09

The left-hand image from NASA Dawn spacecraft shows the apparent brightness of asteroid Vesta surface. The right-hand image is based on this apparent brightness image, with a color-coded height representation of the topography overlain onto it.

Exploring Tectonic Activity on Vesta and Ceres

NASA Astrophysics Data System (ADS)

Buczkowski, D.; Scully, J. E. C.; Raymond, C. A.; Russell, C. T.

2017-12-01

Images of Vesta and Ceres taken by the Dawn spacecraft revealed large-scale linear structural features on both asteroids. We evaluate their morphology to determine 1) what processes caused them to form and 2) what implications this has for the history of Vesta and Ceres as planetary bodies. The Divalia Fossae are wide troughs bounded by steep scarps that encircle Vesta roughly aligned with the equator. Fault plane analysis suggests that their formation was triggered by the impact event that formed the Rheasilvia basin. The Saturnalia Fossae extend from Divalia to the northern polar region; fault plane analysis ties their formation to the Veneneia basin impact event. Also, it has been suggested that the elongate hill Brumalia Tholus could have been formed as a magmatic intrusion utilizing the subsurface Albalonga fracture as a conduit to the surface, intruding into and deforming the rock above it. Kilometer-scale linear structures cross much of the eastern hemisphere of Ceres. Many structures appear to be radial to the large craters Urvara and Yalode, and likely formed due to impact processes. However, the Samhain Catenae do not have any obvious relationship to a crater and the lack of raised rims makes it unlikely that these are secondary impacts; they are also crosscut by linear features radial to Urvara and Yalode, indicating they are not fractures formed during those impact events. Instead, the morphology of these structures more closely resembles that of pit crater chains (buried normal faults), and show en echelon orientation and S-shaped linkages. Polygonal craters, which form where there is pervasive subsurface fracturing, are widespread on Ceres, and those polygonal craters proximal to the Samhain Catenae have straight crater rims aligned with the structures. Several craters on Ceres have fractured floors, similar to lunar floor-fractured craters (FFCs), which are theorized to form from floor uplift due to magmatic intrusion. Large (>50 km) Ceres FFCs can have both radial and concentric fractures at the crater center, and/or concentric fractures near the crater wall. Smaller craters have a v-shaped moat separating the wall scarp from the crater interior, but different interior morphologies. A depth vs. diameter analysis shows that the Ceres FFCs are unusually shallow, consistent with the magmatic intrusion models.

Highly parallel reconfigurable computer architecture for robotic computation having plural processor cells each having right and left ensembles of plural processors

NASA Technical Reports Server (NTRS)

Fijany, Amir (Inventor); Bejczy, Antal K. (Inventor)

1994-01-01

In a computer having a large number of single-instruction multiple data (SIMD) processors, each of the SIMD processors has two sets of three individual processor elements controlled by a master control unit and interconnected among a plurality of register file units where data is stored. The register files input and output data in synchronism with a minor cycle clock under control of two slave control units controlling the register file units connected to respective ones of the two sets of processor elements. Depending upon which ones of the register file units are enabled to store or transmit data during a particular minor clock cycle, the processor elements within an SIMD processor are connected in rings or in pipeline arrays, and may exchange data with the internal bus or with neighboring SIMD processors through interface units controlled by respective ones of the two slave control units.

Mcqueuer

DOE Office of Scientific and Technical Information (OSTI.GOV)

2016-09-12

Mcqueuer is a simple tool that allows anyone from researchers to experienced developers to create multi-node/multi-core jobs by simply creating a file with a list of commands. Users simply combine tasks, which would otherwise each be their own job on the cluster, into a single file that is given to Mcqueuer. Mcqueuer then does the heavy lifting required to process the tasks in parallel in a single multi-node job. In addition, Mcqueuer provides load-balancing, which frees the user from having to worry about complex memory and CPU considerations, and instead focus on the processing itself.

A Lightweight, High-performance I/O Management Package for Data-intensive Computing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jun Wang

2007-07-17

File storage systems are playing an increasingly important role in high-performance computing as the performance gap between CPU and disk increases. It could take a long time to develop an entire system from scratch. Solutions will have to be built as extensions to existing systems. If new portable, customized software components are plugged into these systems, better sustained high I/O performance and higher scalability will be achieved, and the development cycle of next-generation of parallel file systems will be shortened. The overall research objective of this ECPI development plan aims to develop a lightweight, customized, high-performance I/O management package namedmore » LightI/O to extend and leverage current parallel file systems used by DOE. During this period, We have developed a novel component in LightI/O and prototype them into PVFS2, and evaluate the resultant prototype—extended PVFS2 system on data-intensive applications. The preliminary results indicate the extended PVFS2 delivers better performance and reliability to users. A strong collaborative effort between the PI at the University of Nebraska Lincoln and the DOE collaborators—Drs Rob Ross and Rajeev Thakur at Argonne National Laboratory who are leading the PVFS2 group makes the project more promising.« less

On Data Transfers Over Wide-Area Dedicated Connections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, Nageswara S.; Liu, Qiang

Dedicated wide-area network connections are employed in big data and high-performance computing scenarios, since the absence of cross-traffic promises to make it easier to analyze and optimize data transfers over them. However, nonlinear transport dynamics and end-system complexity due to multi-core hosts and distributed file systems make these tasks surprisingly challenging. We present an overview of methods to analyze memory and disk file transfers using extensive measurements over 10 Gbps physical and emulated connections with 0–366 ms round trip times (RTTs). For memory transfers, we derive performance profiles of TCP and UDT throughput as a function of RTT, which showmore » concave regions in contrast to entirely convex regions predicted by previous models. These highly desirable concave regions can be expanded by utilizing large buffers and more parallel flows. We also present Poincar´e maps and Lyapunov exponents of TCP and UDT throughputtraces that indicate complex throughput dynamics. For disk file transfers, we show that throughput can be optimized using a combination of parallel I/O and network threads under direct I/O mode. Our initial throughput measurements of Lustre filesystems mounted over long-haul connections using LNet routers show convex profiles indicative of I/O limits.« less

SDS: A Framework for Scientific Data Services

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Bin; Byna, Surendra; Wu, Kesheng

2013-10-31

Large-scale scientific applications typically write their data to parallel file systems with organizations designed to achieve fast write speeds. Analysis tasks frequently read the data in a pattern that is different from the write pattern, and therefore experience poor I/O performance. In this paper, we introduce a prototype framework for bridging the performance gap between write and read stages of data access from parallel file systems. We call this framework Scientific Data Services, or SDS for short. This initial implementation of SDS focuses on reorganizing previously written files into data layouts that benefit read patterns, and transparently directs read callsmore » to the reorganized data. SDS follows a client-server architecture. The SDS Server manages partial or full replicas of reorganized datasets and serves SDS Clients' requests for data. The current version of the SDS client library supports HDF5 programming interface for reading data. The client library intercepts HDF5 calls and transparently redirects them to the reorganized data. The SDS client library also provides a querying interface for reading part of the data based on user-specified selective criteria. We describe the design and implementation of the SDS client-server architecture, and evaluate the response time of the SDS Server and the performance benefits of SDS.« less

LVFS: A Scalable Petabye/Exabyte Data Storage System

NASA Astrophysics Data System (ADS)

Golpayegani, N.; Halem, M.; Masuoka, E. J.; Ye, G.; Devine, N. K.

2013-12-01

Managing petabytes of data with hundreds of millions of files is the first step necessary towards an effective big data computing and collaboration environment in a distributed system. We describe here the MODAPS LAADS Virtual File System (LVFS), a new storage architecture which replaces the previous MODAPS operational Level 1 Land Atmosphere Archive Distribution System (LAADS) NFS based approach to storing and distributing datasets from several instruments, such as MODIS, MERIS, and VIIRS. LAADS is responsible for the distribution of over 4 petabytes of data and over 300 million files across more than 500 disks. We present here the first LVFS big data comparative performance results and new capabilities not previously possible with the LAADS system. We consider two aspects in addressing inefficiencies of massive scales of data. First, is dealing in a reliable and resilient manner with the volume and quantity of files in such a dataset, and, second, minimizing the discovery and lookup times for accessing files in such large datasets. There are several popular file systems that successfully deal with the first aspect of the problem. Their solution, in general, is through distribution, replication, and parallelism of the storage architecture. The Hadoop Distributed File System (HDFS), Parallel Virtual File System (PVFS), and Lustre are examples of such file systems that deal with petabyte data volumes. The second aspect deals with data discovery among billions of files, the largest bottleneck in reducing access time. The metadata of a file, generally represented in a directory layout, is stored in ways that are not readily scalable. This is true for HDFS, PVFS, and Lustre as well. Recent experimental file systems, such as Spyglass or Pantheon, have attempted to address this problem through redesign of the metadata directory architecture. LVFS takes a radically different architectural approach by eliminating the need for a separate directory within the file system. The LVFS system replaces the NFS disk mounting approach of LAADS and utilizes the already existing highly optimized metadata database server, which is applicable to most scientific big data intensive compute systems. Thus, LVFS ties the existing storage system with the existing metadata infrastructure system which we believe leads to a scalable exabyte virtual file system. The uniqueness of the implemented design is not limited to LAADS but can be employed with most scientific data processing systems. By utilizing the Filesystem In Userspace (FUSE), a kernel module available in many operating systems, LVFS was able to replace the NFS system while staying POSIX compliant. As a result, the LVFS system becomes scalable to exabyte sizes owing to the use of highly scalable database servers optimized for metadata storage. The flexibility of the LVFS design allows it to organize data on the fly in different ways, such as by region, date, instrument or product without the need for duplication, symbolic links, or any other replication methods. We proposed here a strategic reference architecture that addresses the inefficiencies of scientific petabyte/exabyte file system access through the dynamic integration of the observing system's large metadata file.

Parallel processing optimization strategy based on MapReduce model in cloud storage environment

NASA Astrophysics Data System (ADS)

Cui, Jianming; Liu, Jiayi; Li, Qiuyan

2017-05-01

Currently, a large number of documents in the cloud storage process employed the way of packaging after receiving all the packets. From the local transmitter this stored procedure to the server, packing and unpacking will consume a lot of time, and the transmission efficiency is low as well. A new parallel processing algorithm is proposed to optimize the transmission mode. According to the operation machine graphs model work, using MPI technology parallel execution Mapper and Reducer mechanism. It is good to use MPI technology to implement Mapper and Reducer parallel mechanism. After the simulation experiment of Hadoop cloud computing platform, this algorithm can not only accelerate the file transfer rate, but also shorten the waiting time of the Reducer mechanism. It will break through traditional sequential transmission constraints and reduce the storage coupling to improve the transmission efficiency.

Large Subdued and Small Fresh Craters

NASA Image and Video Library

2012-03-27

This image from NASA Dawn spacecraft shows many large subdued craters that have smaller, younger craters on top of them on asteroid Vesta. There are two large subdued craters in the center of the image, which have very degraded and rounded rims.

Sharp Crater Rim with Dark Material and Boulders

NASA Image and Video Library

2012-03-02

This image from NASA Dawn spacecraft shows part of the sharp, fresh rim of a large crater on asteroid Vesta. There is some bright material slumping towards the center of this crater but this is mostly overshadowed by the dark material.

Forging Asteroid-Meteorite Relationships Through Reflectance Spectroscopy

NASA Technical Reports Server (NTRS)

Burbine, T. H.; Binzel, R. P.; Bus, S. J.; Buchanan, P. C.; Hinrichs, J. L.; Meibom, A.; Hiroi, T.; Sunshine, J. M.

2000-01-01

Near-infrared spectra were obtained for 196 asteroids as part of SMASSIR. SMASSIR focused on observing asteroids assumed to be one of the following: (1) olivine-rich, (2) objects with "Vesta-like spectra" (the "Vestoids"), and (3) postulated meteorite parent bodies.

Experiments and Analyses of Data Transfers Over Wide-Area Dedicated Connections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, Nageswara S.; Liu, Qiang; Sen, Satyabrata

Dedicated wide-area network connections are increasingly employed in high-performance computing and big data scenarios. One might expect the performance and dynamics of data transfers over such connections to be easy to analyze due to the lack of competing traffic. However, non-linear transport dynamics and end-system complexities (e.g., multi-core hosts and distributed filesystems) can in fact make analysis surprisingly challenging. We present extensive measurements of memory-to-memory and disk-to-disk file transfers over 10 Gbps physical and emulated connections with 0–366 ms round trip times (RTTs). For memory-to-memory transfers, profiles of both TCP and UDT throughput as a function of RTT show concavemore » and convex regions; large buffer sizes and more parallel flows lead to wider concave regions, which are highly desirable. TCP and UDT both also display complex throughput dynamics, as indicated by their Poincare maps and Lyapunov exponents. For disk-to-disk transfers, we determine that high throughput can be achieved via a combination of parallel I/O threads, parallel network threads, and direct I/O mode. Our measurements also show that Lustre filesystems can be mounted over long-haul connections using LNet routers, although challenges remain in jointly optimizing file I/O and transport method parameters to achieve peak throughput.« less

Purple L1 Milestone Review Panel GPFS Functionality and Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loewe, W E

2006-12-01

The GPFS deliverable for the Purple system requires the functionality and performance necessary for ASC I/O needs. The functionality includes POSIX and MPIIO compatibility, and multi-TB file capability across the entire machine. The bandwidth performance required is 122.15 GB/s, as necessary for productive and defensive I/O requirements, and the metadata performance requirement is 5,000 file stats per second. To determine success for this deliverable, several tools are employed. For functionality testing of POSIX, 10TB-files, and high-node-count capability, the parallel file system bandwidth performance test IOR is used. IOR is an MPI-coordinated application that can write and then read to amore » single shared file or to an individual file per process and check the data integrity of the file(s). The MPIIO functionality is tested with the MPIIO test suite from the MPICH library. Bandwidth performance is tested using IOR for the required 122.15 GB/s sustained write. All IOR tests are performanced with data checking enabled. Metadata performance is tested after ''aging'' the file system with 80% data block usage and 20% inode usage. The fdtree metadata test is expected to create/remove a large directory/file structure in under 20 minutes time, akin to interactive metadata usage. Multiple (10) instances of ''ls -lR'', each performing over 100K stats, are run concurrently in different large directories to demonstrate 5,000 stats/sec.« less

LMC: Logarithmantic Monte Carlo

NASA Astrophysics Data System (ADS)

Mantz, Adam B.

2017-06-01

LMC is a Markov Chain Monte Carlo engine in Python that implements adaptive Metropolis-Hastings and slice sampling, as well as the affine-invariant method of Goodman & Weare, in a flexible framework. It can be used for simple problems, but the main use case is problems where expensive likelihood evaluations are provided by less flexible third-party software, which benefit from parallelization across many nodes at the sampling level. The parallel/adaptive methods use communication through MPI, or alternatively by writing/reading files, and mostly follow the approaches pioneered by CosmoMC (ascl:1106.025).

Scalable Unix tools on parallel processors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gropp, W.; Lusk, E.

1994-12-31

The introduction of parallel processors that run a separate copy of Unix on each process has introduced new problems in managing the user`s environment. This paper discusses some generalizations of common Unix commands for managing files (e.g. 1s) and processes (e.g. ps) that are convenient and scalable. These basic tools, just like their Unix counterparts, are text-based. We also discuss a way to use these with a graphical user interface (GUI). Some notes on the implementation are provided. Prototypes of these commands are publicly available.

Predicting the Mineralogy of the HEDs and Vesta Using Both Meteoritic and Synthetic Samples

NASA Astrophysics Data System (ADS)

Mayne, R. G.; Lehman, K.

2012-12-01

Sample return missions are often viewed as the holy grail for planetary science. They enable us to directly correlate samples from the surface of their parent body with spacecraft data, greatly advancing our understanding of the relationship between the petrology and mineralogy of extraterrestrial materials and their corresponding spectra. The link between the Howardite-Eucrite-Diogenite (HED) group of meteorites and the asteroid Vesta provides us with one of the best opportunities for joint petrologic and spectral studies of an airless body. The HEDs can be seen as examples of many "natural" sample return missions. Terrestrial based studies of the HEDs can lead to improved data return from the Dawn mission, currently orbiting and analyzing Vesta. Pyroxenes dominate the HED spectra in the VISNIR region and, consequently, are the primary mineral that will be detected by the VIR instrument aboard Dawn. Previous studies have shown the importance of the high-Ca to low-Ca pyroxene ratio in spectral studies of asteroids, HCP/(HCP+LCP), hereafter referred to as HCP:LCP (Sunshine et al., 2004). This ratio is one of the few petrologic factors that can be predicted from VISNIR spectra and it can be used to indicate the amount of igneous differentiation that the measured surface or sample has undergone (Sunshine et al., 2004). The Modified Gaussian Model (Sunshine et al., 1990) allows to predict the HCP:LCP from spectra. The initial calibrations have been shown in several studies to predict the amount of HCP relative to LCP to within ±5-10 % (Sunshine and Pieters, 1993; Kanner et al., 2007), but for the eucrites this value was ±17 % (Mayne et al., 2010). This is likely because the current calibration for HCP:LCP was calculated using terrestrial composition pyroxene mixtures. The aim of this study is to improve current HCP:LCP calibrations for the HEDs and Vesta by using more Fe-rich, HED-like pyroxene compositions. Two eucrite composition end-member pyroxenes were synthesized by Donald Lindsley at SUNY-Stonybrook using the methods described in Turnock et al. (1973). The composition of the low- and high-Ca synthesized pyroxenes were Wo3.3En35.3Fs61.4 and Wo37.6En29.4Fs33.0 respectively. The pyroxenes were ground in an agate mortar and pestle and <45 μm powders were produced. These powders will be combined to produce a series of known mixtures: 100HCP; 75HCP:25LPC; 50HCP:50LCP; 25HCP:75LCP; 100LCP. The VISNIR (0.32-2.55 μm) spectra of each of these mixtures will be measured using the bidirectional reflectance spectrometer at the NASA/Keck Reflectance Equipment Laboratory (RELAB) at Brown University. The mixture spectra will be analyzed using MGM, with an aim of producing a calibration that allows the HCP:LCP to be accurately predicted for HED meteorites and Vesta. This calibration will be tested on eucrite spectra with a known HCP:LCP ratio from Mayne et al. (2010).

Core Formation on Asteroid 4 Vesta: Iron Rain in a Silicate Magma Ocean

NASA Astrophysics Data System (ADS)

Kiefer, W. S.; Mittlefehldt, D. W.

2017-07-01

Initially small liquid metal drops must grow to about 10 cm in size before sinking through the convecting silicate magma ocean to form a core. The required magma temperature is consistent with moderately siderophile element abundances in eucrites.

Flowing in, Flowing out of Aelia

NASA Image and Video Library

2013-12-16

This colorful composite image from NASA Dawn mission shows the flow of material inside and outside a crater called Aelia on the giant asteroid Vesta. To the naked eye, these structures would not be seen. But here, they stand out in blue and red.

Database Objects vs Files: Evaluation of alternative strategies for managing large remote sensing data

NASA Astrophysics Data System (ADS)

Baru, Chaitan; Nandigam, Viswanath; Krishnan, Sriram

2010-05-01

Increasingly, the geoscience user community expects modern IT capabilities to be available in service of their research and education activities, including the ability to easily access and process large remote sensing datasets via online portals such as GEON (www.geongrid.org) and OpenTopography (opentopography.org). However, serving such datasets via online data portals presents a number of challenges. In this talk, we will evaluate the pros and cons of alternative storage strategies for management and processing of such datasets using binary large object implementations (BLOBs) in database systems versus implementation in Hadoop files using the Hadoop Distributed File System (HDFS). The storage and I/O requirements for providing online access to large datasets dictate the need for declustering data across multiple disks, for capacity as well as bandwidth and response time performance. This requires partitioning larger files into a set of smaller files, and is accompanied by the concomitant requirement for managing large numbers of file. Storing these sub-files as blobs in a shared-nothing database implemented across a cluster provides the advantage that all the distributed storage management is done by the DBMS. Furthermore, subsetting and processing routines can be implemented as user-defined functions (UDFs) on these blobs and would run in parallel across the set of nodes in the cluster. On the other hand, there are both storage overheads and constraints, and software licensing dependencies created by such an implementation. Another approach is to store the files in an external filesystem with pointers to them from within database tables. The filesystem may be a regular UNIX filesystem, a parallel filesystem, or HDFS. In the HDFS case, HDFS would provide the file management capability, while the subsetting and processing routines would be implemented as Hadoop programs using the MapReduce model. Hadoop and its related software libraries are freely available. Another consideration is the strategy used for partitioning large data collections, and large datasets within collections, using round-robin vs hash partitioning vs range partitioning methods. Each has different characteristics in terms of spatial locality of data and resultant degree of declustering of the computations on the data. Furthermore, we have observed that, in practice, there can be large variations in the frequency of access to different parts of a large data collection and/or dataset, thereby creating "hotspots" in the data. We will evaluate the ability of different approaches for dealing effectively with such hotspots and alternative strategies for dealing with hotspots.

Geologic Mapping of Ejecta Deposits in Oppia Quadrangle, Asteroid (4) Vesta

NASA Technical Reports Server (NTRS)

Garry, W. Brent; Williams, David A.; Yingst, R. Aileen; Mest, Scott C.; Buczkowski, Debra L.; Tosi, Federico; Schafer, Michael; LeCorre, Lucille; Reddy, Vishnu; Jaumann, Ralf;

Surface mapping via unsupervised classification of remote sensing: application to MESSENGER/MASCS and DAWN/VIRS data.

NASA Astrophysics Data System (ADS)

D'Amore, M.; Le Scaon, R.; Helbert, J.; Maturilli, A.

2017-12-01

Machine-learning achieved unprecedented results in high-dimensional data processing tasks with wide applications in various fields. Due to the growing number of complex nonlinear systems that have to be investigated in science and the bare raw size of data nowadays available, ML offers the unique ability to extract knowledge, regardless the specific application field. Examples are image segmentation, supervised/unsupervised/ semi-supervised classification, feature extraction, data dimensionality analysis/reduction.The MASCS instrument has mapped Mercury surface in the 400-1145 nm wavelength range during orbital observations by the MESSENGER spacecraft. We have conducted k-means unsupervised hierarchical clustering to identify and characterize spectral units from MASCS observations. The results display a dichotomy: a polar and equatorial units, possibly linked to compositional differences or weathering due to irradiation. To explore possible relations between composition and spectral behavior, we have compared the spectral provinces with elemental abundance maps derived from MESSENGER's X-Ray Spectrometer (XRS).For the Vesta application on DAWN Visible and infrared spectrometer (VIR) data, we explored several Machine Learning techniques: image segmentation method, stream algorithm and hierarchical clustering.The algorithm successfully separates the Olivine outcrops around two craters on Vesta's surface [1]. New maps summarizing the spectral and chemical signature of the surface could be automatically produced.We conclude that instead of hand digging in data, scientist could choose a subset of algorithms with well known feature (i.e. efficacy on the particular problem, speed, accuracy) and focus their effort in understanding what important characteristic of the groups found in the data mean. [1] E Ammannito et al. "Olivine in an unexpected location on Vesta's surface". In: Nature 504.7478 (2013), pp. 122-125.

Spectral characterization of V-type asteroids - I. Space weathering effects and implications for V-type NEAs

NASA Astrophysics Data System (ADS)

Fulvio, Daniele; Perna, Davide; Ieva, Simone; Brunetto, Rosario; Kanuchova, Zuzana; Blanco, Carlo; Strazzulla, Giovanni; Dotto, Elisabetta

2016-01-01

Among main belt asteroids, V-types belonging to Vesta's dynamical family are known as `Vestoids' while those lying outside Vesta's family as `non-Vestoids'. V-types have also been found within the population of Near Earth Asteroids (NEAs). Several questions on Vesta, the V-types, and the Howardite-Eucrite-Diogenite meteorites are still unsolved, such as the genesis of each class/subclass, their evolution and mutual relationship, and the existence of other basaltic parent bodies. We present new NIR (0.8-2.4 μm) spectroscopic observations of seven non-Vestoids, carried out at the Telescopio Nazionale Galileo (TNG - INAF). We derived a number of spectral parameters (BI and BII centres, band separations, and BI slopes) and compared them with available spectra of V-types belonging to different subclasses (102 V-types in total), to highlight possible spectral differences useful to shed light on the questions mentioned above. We also considered the data from ion irradiation experiments performed on different samples of eucrites, simulating space weathering effects. Net discrepancies are seen for the BI slope distributions: NEAs show a distribution strongly different from all other V-type subclasses. Ion irradiation experiments induce strong effects on BI slope values and, as irradiation proceeds, the BI slope of eucrites quickly increases, changing the overall aspect of their VIS-NIR spectra (0.4-2.5 μm). Space weathering may explain the whole range of spectral slopes observed for all V-type subclasses. An exception is represented by NEAs, where moderate space weathering effects are evidenced. We propose that this is due to tidal perturbations exposing `fresh' unweathered surface grains during close encounters with the Earth, as previously found for Q-type NEAs.

Igneous lithologies on asteroid (4) Vesta mapped using gamma-ray and neutron data

NASA Astrophysics Data System (ADS)

Beck, Andrew W.; Lawrence, David J.; Peplowski, Patrick N.; Viviano-Beck, Christina E.; Prettyman, Thomas H.; McCoy, Timothy J.; McSween, Harry Y.; Yamashita, Naoyuki

2017-04-01

We use data collected by the Dawn Gamma-Ray and Neutron Detector (GRaND) at Vesta to map compositions corresponding to nearly pure igneous lithologies in the howardite, eucrite, diogenite (HED) meteorite clan (samples likely from Vesta). At the ∼300-km spatial scale of GRaND measurements, basaltic eucrite occurs on only 3% of the surface, whereas cumulate eucrite and orthopyroxenitic diogenite are not detected. The basaltic eucrite region is generally coincident with an area of the surface with thick regolith, elevated H, and moderate crater density, and may represent the best compositional sample of primordial vestan crust. We observe an absence of pure orthopyroxenitic diogenite terrains in the Rheasilvia basin and its ejecta, an observation corroborated by VIR (0.1%), which suggests the south-polar crust was a polymict mixture of igneous lithologies (howardite) at the time of the Rheasilvia impact, or was a thick basaltic eucrite crust with heterogeneously distributed orthopyroxenitic diogenite plutons. The most dominant igneous composition detected (11% of the surface) corresponds to one of the least-abundant igneous lithologies in the HED meteorite collection, the Yamato Type B diogenites (plagioclase-bearing pyroxenites). The distribution of Type B diogenite is spatially correlated with post-Rheasilvia craters in the north-polar region that are in close proximity to the Rheasilvia basin antipode. This suggests that north-polar Type B plutonism may have been associated with the Rheasilvia impact event. We propose that this was either through 1) uplift of pre-existing plutons at the antipode through focusing of Rheasilvia impact stress, or 2) Rheasilvia impact antipodal crustal melting, creating magmas that underwent fractionation to produce Type B plutons.

Communication library for run-time visualization of distributed, asynchronous data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rowlan, J.; Wightman, B.T.

1994-04-01

In this paper we present a method for collecting and visualizing data generated by a parallel computational simulation during run time. Data distributed across multiple processes is sent across parallel communication lines to a remote workstation, which sorts and queues the data for visualization. We have implemented our method in a set of tools called PORTAL (for Parallel aRchitecture data-TrAnsfer Library). The tools comprise generic routines for sending data from a parallel program (callable from either C or FORTRAN), a semi-parallel communication scheme currently built upon Unix Sockets, and a real-time connection to the scientific visualization program AVS. Our methodmore » is most valuable when used to examine large datasets that can be efficiently generated and do not need to be stored on disk. The PORTAL source libraries, detailed documentation, and a working example can be obtained by anonymous ftp from info.mcs.anl.gov from the file portal.tar.Z from the directory pub/portal.« less

Vesta: its shape and deformed equatorial belt predicted by the wave planetology

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

2012-09-01

At EPSC2011 we stated: "Expected detailed images of Vesta sent by DAWN spacecraft certainly will show a prominent tectonic (must be also compositional) dichotomy of this large asteroid. The assuredness is based on some mainly the HST photos and the wave planetology fundamental conception: Theorem 1 - " Ce lestial bodies are dichotomous""[1]. Now a convexo-concave shape of Vesta is well known but the huge deep depression of the south hemisphere is assigned to two random large impacts almost at one place [2, 3]. This supposition has a very small probability, besides the largest asteroid Ceres also has a large depression at one side (the Piazzi basin). The theorem 1 of the wave planetology explains that all celestial bodies (not only small ones) are subjected to a warping action of the fundamental wave1 uplifting one side and subsiding (pressing in) the opposite one. This is a manifestation of the orbital energy acting in any body moving in keplerian noncircular orbit with changing acceleration (a). Arising inertia-gravity force F= (a1 - a2) x m is very important because of large planetary masses (m) and large cosmic speeds. Increase and decrease of accelerations were much larger in the beginning of planetary formation when orbits were more elliptical. Thus, pressing in of the subsiding hemisphere-segment is so strong that it often squeezes out some mantle material appearing as elevation-mound (compare to the Hawaii in the Pacific basin and look at Hyperion with a large basin and a mound at its center, Fig, 1, 2). Vesta's prominent subsiding equatorial belt with graben systems [4] (Fig. 4, 5) is a manifestation of another general planetary rule : " Rotating celestial body tends to even angular momenta of tropics and extra-tropics by regulating mass distribution and distance to the rotation axis " [5-7]. Often observed a sensible difference in appearance and structure between tropical and extra-tropical zones of various heavenly bodies including rocky and gas planets, satellites and Sun compels to look for a common reason of such phenomenon [5-7]. All bodies rotate and their spherical shape makes zones at different latitudes to have differing angular momenta as a distance to the rotation axis diminishes gradually from the equator to the poles (Fig. 3) (this is felt particularly when one launches rockets into space - preferable cheaper launches are from the equatorial regions - Kourou in the French Guyana is better than Baikonur in Kazakhstan). One of remarkable changes occurs at tropics. As a total rotating planetary body tends to have angular momenta of its tectonic blocks equilibrated it starts mechanisms leveling this basic physical property. At tropical zones (bulged also due to the rotation ellipsoid) the outer shell - crust as a consequence tends to be destroyed, sunk, subsided and shrunk; a density of crust material changes; the atmosphere reacts changing chemistry and structure; in terrestrial anthroposphere man looses its mass and stature (well known pygmioidness process). Ext ratropical belts, on the contrary, tend to add material and increase radius. Thus, a body tends to be like a cucumber but mighty gravity always makes it globular. Traces of this cosmic "struggle" very often are seen on surfaces of heavenly bodies as structurally distinguished tropical and extra-tropical zones (Fig. 4- 6). At Earth the wide planetary long tropical zone is marked by destruction of the crust. It is demonstrated by development of numerous islands of the Malay Archipelago (the Sunda Isls, Maluku Isls, Philippines) between the Southeastern Asia and Australia. In Africa and South America huge depressions of the Congo and Amazon Rivers develop. Seismicity of the tropical zone is significantly higher than outside of it that means more intensive destruction in the crust and the upper mantle of tropics [5-7]. At Mars the widespread enigmat ic chaotic and fretted terrains at the highland-lowland boundary could be considered as traces of the crust destruction. At Saturn a wide tropical zone usually has higher albedo than extratropical ones. Relat ively heavier methane clouds in the H-He atmosphere are absent around the equator and concentrated on the higher latitudes. In the subsided tropical zone of Titan the darker methane lowlands (Fig. 6) are normally rippled in at least two directions with spacing a few km to 20 km. This planetary pattern is comparable with a behavior of the basalt floor of terrestrial oceans [5-7]. Asteroid (mini-planet) Vesta also demonstrates drastic structural difference between equatorial and extra-equatorial zones. Folded and subsided equator shows troughs encircling most of Vesta and being up to 20 kms wide (Fig. 4). The north-south dichotomy is obvious in subsided southern hemisphere (less cratered) and uplifted the northern one (more cratered). Mars shows the inverse dichotomy, Earth the east-west one. Vesta's positive Bouguer anomaly at the tropics (Fig. 5, [4]) is due to uplifted denser material compensating angular momentum loss because of subsiding equatorial belt (Fig. 4). Fig. 1. Vesta, PIA14315.JPG, south hemisphere with basin and central mound Fig. 2. Hyperion, PIA07761.JPG. 175 x 120 x 100 km. Hemisphere with depression and central mound (compare with the Vestan south hemisphere depression and central mound, Fig. 1).