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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14
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NASA NTRS1977

The Apollo 16 deep drill core

Numerous investigations have been undertaken on samples from the Apollo 16 deep drill core. These studies are diverse in character and range from grain size analyses, through chemical and mineralogical studies to investigations of nuclear particle tracks, rare gases, and isotopic abundances. In order to comprehend the significance of the studies of the mineral chemistry of the clasts below 1 mm in size in several samples with respect to other studies, it became obvious that a review of all previous works was desireable. After reviewing the available literature it can be concluded that only four major stratigraphic divisions exist in the core section. Whether these represent four single events or multi-stage events within one unit is uncertain; however, it appears that accumulation of the material in the core has taken place during a period of 1 billion years, and that the material is predominantly of locally derived Highlands origin.

Meyer, H. O. A.↗
NASA NTRS2015

REE Partitioning in Lunar Minerals

Rare earth elements (REE) are an extremely useful tool in modeling lunar magmatic processes. Here we present the first experimentally derived plagioclase/melt partition coefficients in lunar compositions covering the entire suite of REE. Positive europium anomalies are ubiquitous in the plagioclase-rich rocks of the lunar highlands, and complementary negative Eu anomalies are found in most lunar basalts. These features are taken as evidence of a large-scale differentiation event, with crystallization of a global-scale lunar magma ocean (LMO) resulting in a plagioclase flotation crust and a mafic lunar interior from which mare basalts were subsequently derived. However, the extent of the Eu anomaly in lunar rocks is variable. Fagan and Neal [1] reported highly anorthitic plagioclase grains in lunar impact melt rock 60635,19 that displayed negative Eu anomalies as well as the more usual positive anomalies. Indeed some grains in the sample are reported to display both positive and negative anomalies. Judging from cathodoluminescence images, these anomalies do not appear to be associated with crystal overgrowths or zones.

Rapp, J. F.↗
NASA NTRS1986

Targeted flight opportunities with large area collectors

A major factor in the stratospheric collection process is the relative density of particles at the collection altitude. With current aircraft-borne collector plate geometries, one potential extraterrestrial particle of about 10 micron diameter is collected approximately every hour. However, a new design for the collector plate, termed the Large Area Collector (LAC), allows a factor of 10 improvement in collection efficiency over current conventional geometry. The implementation of LAC design on future stratospheric collection flights will provide many opportunities for additional data on both terrestrial and extraterrestrial phenomena. With the improvement in collection efficiency, LAC's may provide a suitable number of potential extraterrestrial particles in one short flight of between 4 and 8 hours duration. Alternatively, total collection periods of approximately 40 hours enhance the probability that rare particles can be retrieved from the stratosphere. This latter approach is of great value for the cosmochemist who may wish to perform sophisticated analyses on interplanetary dust greater than a picogram. The former approach, involving short duration flights, may also provide invaluable data on the source of many extraterrestrial particles. The time dependence of particle entry to the collection altitude is an important parameter which may be correlated with specific global events (e.g., meteoroid streams) provided the collection time is known to an accuracy of 2 hours.

Mackinnon, I. D. R.↗
NASA NTRS2005

Radiation Protection for Lunar Mission Scenarios

Preliminary analyses of shielding requirements to protect astronauts from the harmful effects of radiation on both short-term and long-term lunar missions have been performed. Shielding needs for both solar particle events (SPEs) and galactic cosmic ray (GCR) exposure are discussed for transit vehicles and surface habitats. This work was performed under the aegis of two NASA initiatives. The first study was an architecture trade study led by Langley Research Center (LaRC) in which a broad range of vehicle types and mission scenarios were compared. The radiation analysis for this study primarily focused on the additional shielding mass required to protect astronauts from the rare occurrence of a large SPE. The second study, led by Johnson Space Center (JSC), involved the design of lunar habitats. Researchers at LaRC were asked to evaluate the changes to mission architecture that would be needed if the surface stay were lengthened from a shorter mission duration of 30 to 90 days to a longer stay of 500 days. Here, the primary radiation concern was GCR exposure. The methods used for these studies as well as the resulting shielding recommendations are discussed. Recommendations are also made for more detailed analyses to minimize shielding mass, once preliminary vehicle and habitat designs have been completed. Here, methodologies are mapped out and available radiation analysis tools are described. Since, as yet, no dosimetric limits have been adopted for missions beyond low earth orbit (LEO), radiation exposures are compared to LEO limits. Uncertainties associated with the LEO career effective dose limits and the effects of lowering these limits on shielding mass are also discussed.

Clowdsley, Martha S.↗
NASA NTRS2007

NASA Tech Briefs, January 2007

Topics covered include: Flexible Skins Containing Integrated Sensors and Circuitry; Artificial Hair Cells for Sensing Flows; Video Guidance Sensor and Time-of-Flight Rangefinder; Optical Beam-Shear Sensors; Multiple-Agent Air/Ground Autonomous Exploration Systems; A 640 512-Pixel Portable Long-Wavelength Infrared Camera; An Array of Optical Receivers for Deep-Space Communications; Microstrip Antenna Arrays on Multilayer LCP Substrates; Applications for Subvocal Speech; Multiloop Rapid-Rise/Rapid Fall High-Voltage Power Supply; The PICWidget; Fusing Symbolic and Numerical Diagnostic Computations; Probabilistic Reasoning for Robustness in Automated Planning; Short-Term Forecasting of Radiation Belt and Ring Current; JMS Proxy and C/C++ Client SDK; XML Flight/Ground Data Dictionary Management; Cross-Compiler for Modeling Space-Flight Systems; Composite Elastic Skins for Shape-Changing Structures; Glass/Ceramic Composites for Sealing Solid Oxide Fuel Cells; Aligning Optical Fibers by Means of Actuated MEMS Wedges; Manufacturing Large Membrane Mirrors at Low Cost; Double-Vacuum-Bag Process for Making Resin- Matrix Composites; Surface Bacterial-Spore Assay Using Tb3+/DPA Luminescence; Simplified Microarray Technique for Identifying mRNA in Rare Samples; High-Resolution, Wide-Field-of-View Scanning Telescope; Multispectral Imager With Improved Filter Wheel and Optics; Integral Radiator and Storage Tank; Compensation for Phase Anisotropy of a Metal Reflector; Optical Characterization of Molecular Contaminant Films; Integrated Hardware and Software for No-Loss Computing; Decision-Tree Formulation With Order-1 Lateral Execution; GIS Methodology for Planning Planetary-Rover Operations; Optimal Calibration of the Spitzer Space Telescope; Automated Detection of Events of Scientific Interest; Representation-Independent Iteration of Sparse Data Arrays; Mission Operations of the Mars Exploration Rovers; and More About Software for No-Loss Computing.

Source record↗
NASA NTRS1986

Biological extinction in earth history

Virtually all plant and animal species that have ever lived on the earth are extinct. For this reason alone, extinction must play an important role in the evolution of life. The five largest mass extinctions of the past 600 million years are of greatest interest, but there is also a spectrum of smaller events, many of which indicate biological systems in profound stress. Extinction may be episodic at all scales, with relatively long periods of stability alternating with short-lived extinction events. Most extinction episodes are biologically selective, and further analysis of the victims and survivors offers the greatest chance of deducing the proximal causes of extinction. A drop in sea level and climatic change are most frequently invoked to explain mass extinctions, but new theories of collisions with extraterrestrial bodies are gaining favor. Extinction may be constructive in a Darwinian sense or it may only perturb the system by eliminating those organisms that happen to be susceptible to geologically rare stresses.

Raup, D. M.↗
NASA NTRS2014

The Central Engine of GRB 130831A and the Energy Breakdown of a Relativistic Explosion

Gamma-ray bursts (GRBs) are the most luminous explosions in the Universe, yet the nature and physical properties of their energy sources are far from understood. Very important clues, however, can be inferred by studying the afterglows of these events. We present optical and X-ray observations of GRB 130831A obtained by Swift, Chandra, Skynet, Reionization And Transients Infra-Red camera, Maidanak, International Scientific Optical-Observation Network, Nordic Optical Telescope, Liverpool Telescope and Gran Telescopio Canarias. This burst shows a steep drop in the X-ray light curve at asymptotically equal to 10(exp 5) s after the trigger, with a power-law decay index of alpha that is approximately 6. Such a rare behaviour cannot be explained by the standard forward shock (FS) model and indicates that the emission, up to the fast decay at 10(exp 5) s, must be of internal origin, produced by a dissipation process within an ultrarelativistic outflow. We propose that the source of such an outflow, which must produce the X-ray flux for an asymptotically equal to 1 d in the cosmological rest frame, is a newly born magnetar or black hole. After the drop, the faint X-ray afterglow continues with a much shallower decay. The optical emission, on the other hand, shows no break across the X-ray steep decrease, and the late-time decays of both the X-ray and optical are consistent. Using both the X-ray and optical data, we show that the emission after an asymptotically equal to 10(exp 5) scan be explained well by the FS model. We model our data to derive the kinetic energy of the ejecta and thus measure the efficiency of the central engine of a GRB with emission of internal origin visible for a long time. Furthermore, we break down the energy budget of this GRB into the prompt emission, the late internal dissipation, the kinetic energy of the relativistic ejecta,and compare it with the energy of the associated supernova, SN 2013 fu.

radiation mechanisms: non-thermal – shock waves ↗
NASA NTRS2021

Identification of a Local Sample of Gamma-Ray Bursts Consistent with a Magnetar Giant Flare Origin

Cosmological gamma-ray bursts (GRBs) are known to arise from distinct progenitor channels: short GRBs mostly from neutron star mergers and long GRBs from a rare type of core-collapse supernova (CCSN) called collapsars. Highly magnetized neutron stars called magnetars also generate energetic, short-duration gamma-ray transients called magnetar giant flares (MGFs). Three have been observed from the Milky Way and its satellite galaxies, and they have long been suspected to constitute a third class of extragalactic GRBs. We report the unambiguous identification of a distinct population of four local (<5 Mpc) short GRBs, adding GRB 070222 to previously discussed events. While identified solely based on alignment with nearby star-forming galaxies, their rise time and isotropic energy release are independently inconsistent with the larger short GRB population at >99.9% confidence. These properties, the host galaxies, and non-detection in gravitational waves all point to an extragalactic MGF origin. Despite the small sample, the inferred volumetric rates for events above 4 × 10(exp 44) erg of R(sub MGF) =3.8(sup +4.0)(sub -3.1) ×10(exp 5) Gpc(exp -3) yr(exp -1) make MGFs the dominant gamma-ray transient detected from extragalactic sources. As previously suggested, these rates imply that some magnetars produce multiple MGFs, providing a source of repeating GRBs. The rates and host galaxies favor common CCSN as key progenitors of magnetars.

Gamma-ray bursts↗
NASA NTRS1986

ISEE-1 and 2 observations of magnetic flux ropes in the magnetotail - FTE's in the plasma sheet?

Magnetic field observations on ISEE-1 and 2 in and near the neutral sheet about 20 Re down the near-earth magnetotail reveal the occurrence of structures resembling magnetic flux ropes. Both electric field and fast plasma data show that these structures convect across the spacecraft at speeds of 200 - 600 km/s, and that they have scale sizes of roughly 3 5 Re. The rope axis orientation is across the tail, approximately in the -Y GSM direction. Their magnetic structure is strikingly similar to magnetic flux ropes observed in the Venus ionosphere, and to flux transfer events observed at the dayside magnetopause. The total field-aligned current within these ropes may approach a million amps. These structures may arise because of patchy reconnection within the plasma sheet, or may be tearing islands formed when the plasma sheet magnetic field has a cross-tail component. Plasma sheet flux ropes are not a common feature at ISEE orbital altitudes; this suggests that near-earth neutral line formation within ISEE apogee (22 Re) may be equally rare.

Elphic, R. C.↗
NASA NTRS1993

Primary differentiation in the early Earth: Nd and Sr isotopic evidence from diamondiferous eclogites for both old depleted and old enriched mantle, Yakutia, Siberia

Ancient, stable, continental cratons possess thick, subcontinental-lithospheric mantle 'keels' which favor particularly the emplacement of diamondiferous kimberlites and included peridotites and eclogites. These refractory mantle samples of the roots provide hard constraints on the theories of formation, growth, and evolution of these cratons. Xenoliths containing only primary garnet and clinopyroxene (eclogites), although rare in most kimberlites, can retain the geochemical signatures of their parent protoliths (e.g., subducted oceanic crust, ancient mantle) thus offering the opportunity to address mantle processes which may have taken place at earlier times in the Earth's history. In fact, it has been postulated that some eclogites are residues from the accretion of the early Earth. Nd and Sr isotopic data are presented which may be interpreted as evidence of an early (greater than 4 Ga) mantle differentiation event. The kimberlites of Yakutia are located both marginal and central to the Siberian craton, and a wide variety of xenoliths are present within them. The Siberian mantle samples have received little attention in the western world, largely because suitable suites of Yakutian samples have not been readily available. Importantly, there is evidence that metasomatism of the Siberian lithosphere has been considerably less intense or extensive than for the Kaapvaal craton. Therefore, it should be considerably easier to elicit the igneous/metamorphic histories of Siberian kimberlitic xenoliths. One of the notable features of the Siberian eclogites is the common appearance of diamonds, especially in the Mir and Udachnaya pipes. In all, eight eclogite samples (eight garnet separates and eight clinopyroxene separates) have been analyzed to date on the Udachnaya pipe, seven from our group.

Snyder, Gregory A.↗
NASA NTRS1994

The role of extinction in evolution

The extinction of species is not normally considered an important element of neodarwinian theory, in contrast to the opposite phenomenon, speciation. This is surprising in view of the special importance Darwin attached to extinction, and because the number of species extinctions in the history of life is almost the same as the number of originations; present-day biodiversity is the result of a trivial surplus of originations, cumulated over millions of years. For an evolutionary biologist to ignore extinction is probably as foolhardy as for a demographer to ignore mortality. The past decade has seen a resurgence of interest in extinction, yet research on the topic is still at a reconnaissance level, and our present understanding of its role in evolution is weak. Despite uncertainties, extinction probably contains three important elements. (i) For geographically widespread species, extinction is likely only if the killing stress is one so rare as to be beyond the experience of the species, and thus outside the reach of natural selection. (ii) The largest mass extinctions produce major restructuring of the biosphere wherein some successful groups are eliminated, allowing previously minor groups to expand and diversify. (iii) Except for a few cases, there is little evidence that extinction is selective in the positive sense argued by Darwin. It has generally been impossible to predict, before the fact, which species will be victims of an extinction event.

Review, Tutorial↗
NASA NTRS2013

The Astrophysical Multimessenger Observatory Network (AMON)

We summarize the science opportunity, design elements, current and projected partner observatories, and anticipated science returns of the Astrophysical Multimessenger Observatory Network (AMON). AMON will link multiple current and future high-energy, multimessenger, and follow-up observatories together into a single network, enabling near real-time coincidence searches for multimessenger astrophysical transients and their electromagnetic counterparts. Candidate and high-confidence multimessenger transient events will be identified, characterized, and distributed as AMON alerts within the network and to interested external observers, leading to follow-up observations across the electromagnetic spectrum. In this way, AMON aims to evoke the discovery of multimessenger transients from within observatory subthreshold data streams and facilitate the exploitation of these transients for purposes of astronomy and fundamental physics. As a central hub of global multimessenger science, AMON will also enable cross-collaboration analyses of archival datasets in search of rare or exotic astrophysical phenomena.

comparison↗
NASA NTRS2003

Experimental Simulation of Shock Reequilibration of Fluid Inclusions During Meteorite Impact

Fluid inclusions are microscopic volumes of fluid trapped within minerals as they precipitate. Fluid inclusions are common in terrestrial minerals formed under a wide array of geological settings from surface evaporite deposits to kimberlite pipes. While fluid inclusions in terrestrial rocks are the rule rather than the exception, only few fluid inclusion-bearing meteorites have been documented. The rarity of fluid inclusions in meteoritic material may be explained in two ways. First, it may reflect the absence of fluids (water?) on meteorite parent bodies. Alternatively, fluids may have been present when the rock formed, but any fluid inclusions originally trapped on the parent body were destroyed by the extreme P-T conditions meteorites often experience during impact events. Distinguishing between these two possibilities can provide significant constraints on the likelihood of life on the parent body. Just as textures, structures, and compositions of mineral phases can be significantly altered by shock metamorphism upon hypervelocity impact, fluid inclusions contained within component minerals may be altered or destroyed due to the high pressures, temperatures, and strain rates associated with impact events. Reequilibration may occur when external pressure-temperature conditions differ significantly from internal fluid isochoric conditions, and result in changes in fluid inclusion properties and/or textures. Shock metamorphism and fluid inclusion reequilibration can affect both the impacted target material and the meteoritic projectile. By examining the effects of shock deformation on fluid inclusion properties and textures we may be able to better constrain the pressure-temperature path experienced by shocked materials and also gain a clearer understanding of why fluid inclusions are rarely found in meteoritic samples.

Madden, M. E. Elwood↗
NASA NTRS2021

The 2019 Southern Hemisphere Stratospheric Polar Vortex Weakening and Its Impacts

This study offers an overview of the low-frequency (i.e., monthly to seasonal) evolution, dynamics, predictability, and surface impacts of a rare Southern Hemisphere (SH) stratospheric warming that occurred in austral spring 2019. Between late August to mid- September 2019, the stratospheric circumpolar westerly jet weakened rapidly, and Antarctic stratospheric temperatures rose dramatically. The deceleration of the vortex at 10 hPa was as drastic as that of the first ever observed major sudden stratospheric warming in the SH during 2002, while the mean Antarctic warming over the course of spring 2019 broke the previous record of 2002 by ~50% in the mid-stratosphere. This event was preceded by a poleward shift of the SH polar night jet in the uppermost stratosphere in early winter, which was then followed by record-strong planetary wave-one activity propagating upward from the troposphere in August that acted to dramatically weaken the polar vortex throughout the depth of the stratosphere. The weakened vortex winds and elevated temperatures moved downward to the surface from mid-October to December, promoting a record strong swing of the Southern Annular Mode (SAM) to its negative phase. This record-negative SAM appeared to be a primary driver of the extreme hot and dry conditions over subtropical eastern Australia that accompanied the severe wildfires that occurred in late spring 2019. State-of-the-art dynamical seasonal forecast systems skillfully predicted the significant vortex weakening of spring 2019 and subsequent development of negative SAM from as early as late July.

Antarctic Oscillation↗
NASA NTRSDate not supplied

The Effects of Experimentally Induced Zircon Annealing on Melt Inclusion-Zircon Geochemistry: A Case Study of Archean Zircon From the Barberton Complex

Crystalline melt inclusions (MIs) in Archean zircons can potentially constrain the evolution of magmatic processes. However, to obtain a homogeneous glassy MI representative of the parent melt, devitrified MIs must be heated at temperatures above the liquidus. Although, it is well known that radiation damaged domains in MI-host zircon undergo temperature-time dependent annealing, the effects of annealing on zircon stable isotope and trace element compositions has received less attention. In this study, we heated multiple aliquots of low-magnetism zircons with relatively low levels of radiation damage (Deff<9.6x1014 α-events/mg) from a 3.304 Ga tonalite gneiss xenolith from the Barberton greenstone belt (sample B87-18; Kamo and Davis, 1994) in an internally-heated pressure vessel at 0.4GPa and 1000–1200°C. Zircons were imaged by SEM (CL, BSE) to determine the zoning patterns around the MIs. The radiation damage preserved in the heated and unheated zircons was determined by measuring broadening of the 3(SiO4) Raman stretching band of zircon (FWHM). Oxygen isotope ratios (δ18O), OH/O ratios, and trace and rare earth element (TREE) concentrations were measured in the zircons and MIs using SIMS. The FWHM and Raman shift of the zircon 3(SiO4) band show a systematic increase of zircon crystallinity with increasing experimental temperature. Despite increasing crystallinity, the 3(SiO4) FWHM is not correlated with δ18O(Zrn) values in the heated or unheated zircons, suggesting that δ18O was not altered by laboratory heating in these low initial radiation damage zircons. FWHM and OH/O are positively correlated in both heated and unheated zircons. The unheated zircons have the largest FWHM and OH/O (OH/OMAX=3.5×10-4) suggesting that H2O was lost during experimental heating due to the progressive annealing of radiation-damaged domains in the zircons. Zircon TREE concentrations and FWHM values are not correlated despite the presence of TREE altered domains in both the heated and unheated zircons. Our results demonstrate that pre-experimental zircon TREE concentrations and δ18O(Zrn) remain intact during laboratory heating of crystalline MIs in zircon, while secondary H2O hosted in radiation damaged domains is partially lost. Thus, MIs in low initial radiation damage Archean zircon are a potentially viable tool for constraining melt compositions.

Joseph P. Gonzalez↗
NASA NTRS1987

Microstructures in type III events in the solar wind

A model is presented for the generation and evolution of bump-in-tail driven Langmuir waves in the solar wind during type III emission which removes a number of apparent inconsistencies between theory and observations. Growth rates and energy densities of Langmuir waves are considerably enhanced, permitting growth to overcome linear scattering losses, and also allowing nonlinear decay into ion-acoustic waves, in line with observations. Estimates are made of the probability distribution p(E), of wave field strengths E, based on linear and nonlinear wave-packet evolution, yielding p(E) approximately equal to E exp -alpha, alpha greater than or equal to 3. This helps explain why very high values of E are rarely found in the measured spiky wave turbulence.

Melrose, D. B.↗
NASA NTRS1974

K-Ar analysis of Apollo 11 fines 10084

Regolithic history of Mare Tranquillitatus is studied with rare gas and mass spectrometric techniques. Grain size-ordinate intercept analysis is applied to bulk soil, ilmenite, and plagioclase separates obtained from 1 mm or smaller fines sample 10084,48. K-Ar ages for ilmenite, plagioclase, and total soil separates are determined to be 2.80, 3.38 and 4.00 AE, respectively. It appears that 10084,48 may consist primarily of two components. In this view, the first is locally derived, forms 65-75% of the present day regolith and may show that a local degassing event(s) occurred between 2.8 and 3.5 AE ago. The second component is similar to material from the lunar highlands. It may be local or foreign in origin and contributes the remaining 25-35% of the soil. This component exhibits an age of 4.00 AE and is either slightly older than, or contemporaneous with, the oldest of the returned Apollo 11 basalts. Within the limits of experimental error, the trapped Ar-38/Ar-36 ratio is constant at 0.1890 for all the soil components examined.

Basford, J. R.↗
NASA NTRS1984

Cosmic ray exposure of SNC meteorites and constraints on their derivation from Mars

There is chemical, mineralogical, and isotopic evidence that several rare meteorites originated from the planet Mars. The eight specimens (4 sphergottites, 3 nakhlites, and 1 chassignite) possess a variety of characteristics that suggest a mutual relationship. It can be predicted with reasonable confidence that these SNC meteorites were exposed to cosmic rays at relatively shallow depths for three distinct periods of time during the past approximately 10 million years. Within the context of a Martian origin, this implies that either relatively large objects were ejected from Mars at a common time and underwent three disruptive events in space or that three ejection events occurred within the past approximately 10 million years on restricted segments of Martian terrain with 1300 million year-old rocks. If mechanisms can be identified which satisfy the geochemical properties of SNC meteorites, as well as their cosmic ray exposure, and dynamical problems associated with ejection out of a large gravity field, then the case for the SNC meteorites being samples of Mars can become stronger.

Bogard, D. D.↗