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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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NASA NTRS2022

Moist Convection in the Giant Planet Atmospheres

The outer planets of our Solar System display a myriad of interesting cloud features, of different colors and sizes. The differences between the types of observed clouds suggest a complex interplay between the dynamics and chemistry at play on these atmospheres. Particularly, the stark difference between the banded structures of Jupiter and Saturn, vs the sporadic clouds on the ice giants highlights the varieties in dynamic, chemical and thermal processes that shape these atmospheres. Since the early explorations of these planets by spacecrafts, such as Voyager and Voyager 2, there are many outstanding questions about the long term stability of the observed features. One hypothesis is that the internal heat generated during the formation of these planets is transported to the upper atmosphere through latent heat release from convecting clouds (i.e., moist convection). In this review, we present evidences of moist convective activity on the gas giant atmospheres of our Solar System from remote sensing data, both from ground- and space-based observations. We detail the processes that drive moist convective activity, both in terms of the dynamics as well as the microphysical processes that shape the resulting clouds. Finally, we also discuss the effects of moist convection on shaping the large scale dynamics (such as jet structures on these planets).

Planetary Science↗
NASA NTRS1982

Conditions of formation of pyroxene excentroradial chondrules

Understanding the exact mechanism of origin of chondrules and the attendant physical conditions remains a key factor in understanding the early evolution of the solar system. The present investigation is concerned with an interpretation of the range of cooling histories needed to make chondrules. Chondrule-like spherules were formed in dynamic crystallization experiments, using gas-mixing facilities. It is found that textures in pyroxene-rich chondrules are well reproduced in the laboratory by cooling melts of chondrule composition from just above the liquidus. The range of pyroxene dendrite widths is slightly greater for natural chondrules than for droplets cooled from 50 C/hr to greater than 3000 C/hr. A blanketing medium of variable thickness explains the cooling rates lower than expected for radiative cooling. Experimental results, textures indicating incomplete melting, and isotopic disequilibrium are compatible with reheating of primitive material in the early solar nebula.

Hewins, R. H.↗
NASA NTRS2015

Using Technology to Better Characterize the Apollo Sample Suite: A Retroactive PET Analysis and Potential Model for Future Sample Return Missions

From 1969-1972 the Apollo missions collected 382 kg of lunar samples from six distinct locations on the Moon. Studies of the Apollo sample suite have shaped our understanding of the formation and early evolution of the Earth-Moon system, and have had important implications for studies of the other terrestrial planets (e.g., through the calibration of the crater counting record) and even the outer planets (e.g., the Nice model of the dynamical evolution of the Solar System). Despite nearly 50 years of detailed research on Apollo samples, scientists are still developing new theories about the origin and evolution of the Moon. Three areas of active research are: (1) the abundance of water (and other volatiles) in the lunar mantle, (2) the timing of the formation of the Moon and the duration of lunar magma ocean crystallization, (3) the formation of evolved lunar lithologies (e.g., granites) and implications for tertiary crustal processes on the Moon. In order to fully understand these (and many other) theories about the Moon, scientists need access to "new" lunar samples, particularly new plutonic samples. Over 100 lunar meteorites have been identified over the past 30 years, and the study of these samples has greatly aided in our understanding of the Moon. However, terrestrial alteration and the lack of geologic context limit what can be learned from the lunar meteorites. Although no "new" large plutonic samples (i.e., hand-samples) remain to be discovered in the Apollo sample collection, there are many large polymict breccias in the Apollo collection containing relatively large (approximately 1 cm or larger) previously identified plutonic clasts, as well as a large number of unclassified lithic clasts. In addition, new, previously unidentified plutonic clasts are potentially discoverable within these breccias. The question becomes how to non-destructively locate and identify new lithic clasts of interest while minimizing the contamination and physical degradation of the samples.

Zeigler, R. A.↗
NASA NTRS1991

Performance characteristics of the imaging MAMA detector systems for SOHO, STIS, and FUSE/Lyman

Imaging Extreme Ultraviolet (EUV) Multi-Anode Microchannel Array (MAMA) detector systems with formats of 360 x 1024 pixels and pixel dimensions of 25 x 25 sq microns are being fabricated and tested for flight in two instruments on the ESA/NASA Solar and Heliospheric Observatory (SOHO). In addition, very-large-format (1024 x 1024)- and (2048 x 2048)-pixel Far Ultraviolet (FUV) and EUV MAMA detectors with pixel dimensions of 25 x 25 sq microns are being fabricated and tested for use in the NASA Goddard Space Flight Center's Hubble Space Telescope Imaging Spectrograph (STIS), a second-generation instrument scheduled for in-orbit installation in 1997. Finally, FUV MAMA detectors with formats of 224 x 960 pixels and pixel dimensions of 14 x 14 sq microns are being evaluated as prototypes of the detector for the prime FUV spectrograph of the Far Ultraviolet Spectroscopic Explorer (FUSE/Lyman) mission. The configurations and performance characteristics of the different detector systems are described, and the plans for further development of the Advanced Technology MAMA detector system discussed.

Timothy, J. G.↗
NASA NTRS1993

Classical novae - Contributions to the interstellar medium

Theoretical results predicting yields of various isotopes in nova outbursts are reviewed. Emphasis is placed on the stardust and gas-phase chemical anomalies that may be contributed to the Galactic ISM by classic novae. It is concluded that most of the heavy isotope anomalies are produced by about 25 percent of novae that occur in systems containing massive O-Ne-Mg white dwarfs. The dust-production scenario for novae is summarized, and it is argued that explosions on O-Ne-Mg white dwarfs may lead to the formation of dust grains that carry the Ne-E and Mg-26 anomalies. Quantitative constraints are placed on the degree to which classical novae participate in the production of chemical anomalies, both in the primitive solar system and on a Galactic scale.

Gehrz, Robert D.↗
NASA NTRS2011

3D Orbit Visualization for Earth-Observing Missions

This software visualizes orbit paths for the Orbiting Carbon Observatory (OCO), but was designed to be general and applicable to any Earth-observing mission. The software uses the Google Earth user interface to provide a visual mechanism to explore spacecraft orbit paths, ground footprint locations, and local cloud cover conditions. In addition, a drill-down capability allows for users to point and click on a particular observation frame to pop up ancillary information such as data product filenames and directory paths, latitude, longitude, time stamp, column-average dry air mole fraction of carbon dioxide, and solar zenith angle. This software can be integrated with the ground data system for any Earth-observing mission to automatically generate daily orbit path data products in Google Earth KML format. These KML data products can be directly loaded into the Google Earth application for interactive 3D visualization of the orbit paths for each mission day. Each time the application runs, the daily orbit paths are encapsulated in a KML file for each mission day since the last time the application ran. Alternatively, the daily KML for a specified mission day may be generated. The application automatically extracts the spacecraft position and ground footprint geometry as a function of time from a daily Level 1B data product created and archived by the mission s ground data system software. In addition, ancillary data, such as the column-averaged dry air mole fraction of carbon dioxide and solar zenith angle, are automatically extracted from a Level 2 mission data product. Zoom, pan, and rotate capability are provided through the standard Google Earth interface. Cloud cover is indicated with an image layer from the MODIS (Moderate Resolution Imaging Spectroradiometer) aboard the Aqua satellite, which is automatically retrieved from JPL s OnEarth Web service.

Jacob, Joseph C.↗
NASA NTRS1989

The interiors of Pluto and Charon - Structure, composition, and implications

Recent models of the internal structure of Pluto and Charon, made possible by analysis of the Pluto/Charon mutual events are reviewed. At a mean density of just over 2 g/cu cm and a predicted rock mass fraction of roughly 0.7, the Pluto/Charon system is significantly rockier than the icy satellites of the giant planets, a contrast which may reflect its formation in a CO-rich outer solar nebula rather than a circumplanetary nebula. Pluto and Charon may in fact be so rocky that they lost volatiles early in their history (possibly during a Charon-forming impact event), although this is still an open issue.

Simonelli, Damon P.↗
NASA NTRS2011

Contributions of the NASA's Chandra X-Ray Observatory

NASA's Chandra X-ray Observatory performed its first observations over a decade ago. Chandra's spectacular images and detailed spectra of astrophysical systems ranging from solar system objects to distant galaxies and galaxy clusters have provided information on such diverse topics as the properties of planetary and cometary atmospheres, stellar formation and demise, black hole-galaxy-cluster interactions, and properties of dark matter and dark energy. This presentation highlights some discoveries made with Chandra and briefly discusses future prospects.

Weisskopf, Martin C.↗
NASA NTRS2021

Spectrally Blue Parent Body of Asteroid (162173) Ryugu and its Hydrothermal History

Small rubble pile asteroids record the thermal evolution of their much larger parent bodies. However, recent ‘space weathering’ and/or ‘solar heating’ create ambiguities between the uppermost layer observable by remote-sensing and the pristine material from the parent body. Hayabusa2 remote-sensing observations found that on the asteroid (162173) Ryugu both north and south pole regions preserve the material least processed by space weathering: spectrally blue carbonaceous chondritic material with a 0.7-μm band absorption, indicative of Fe-bearing phyllosilicates. This discovery suggests that Ryugu’s parent body experienced intensive aqueous alteration and subsequent thermal metamorphism at 670 – 970 K. Ryugu’s parent body was heated by radioactive decay of short-lived radionuclides possibly because of its early formation 2-2.5 Ma. Ryugu’s parent body which is spectrally blue represents some of the most ancient of carbonaceous chondritic compositions from the solar system. The samples being brought to Earth by Hayabusa2 will give us our first insights into this epoch in solar system history.

Eri Tatsumi↗
NASA NTRSDate not supplied

Early Aqueous Alteration of Ryugu’s Parent Body – Insight from In-situ Isotopic Analyses

The Hayabusa2 mission returned approximately 5.4 g of highly aqueously-altered material resembling the CI (Ivuna-type) chondrites from the C-type asteroid Ryugu. To understand the timing and duration of aqueous alteration on Ryugu’s parent body, we measured the 53Mn-53Cr (t1/2 = 3.7 Myr) ages of dolomite, breunnerite, and Ca-carbonate minerals in Ryugu particles A0037 and C0009 using secondary ion mass spectrometry (SIMS) with the UCLA CAMECA ims-1290 instrument with Hyperion II oxygen plasma source. Using these carbonate formation ages, we estimate the accretion time and size of Ryugu’s parent body to have been within the first 1.8 million years of Solar System history in a planetesimal less than ~20 km in diameter, or within a larger body which was disrupted and reassembled. To further constrain the conditions of aqueous alteration, we measured the δ13C, δ18O, and Δ17O of Ryugu dolomite, Ca-carbonate, and magnetite using the UCLA CAMECA ims-1290. The results of our stable isotopic analyses show that the earliest stages of aqueous alteration occurred at low temperatures (between 0 and 20 °C), that the initial fluid was enriched in the heavy 13C, 17O and 18O isotopes, and that the fluid evolved towards lighter carbon and oxygen isotopic compositions as alteration proceeded.

Astromaterials↗
NASA NTRSDate not supplied

Asteroid (142) Polana at 3 µm and its Connection to Primitive Near-Earth Asteroids

Impacts between asteroid-sized objects have dominated the solar system's history and played a significant role in forming asteroid families. The New Polana family is a low-inclination and the most prominent low-albedo family within the inner Main Belt between the v6 secular resonance at ~2.0 AU and the 3:1 mean-motion resonance with Jupiter at ~2.5 AU [1]. This family formed over 2000 Myr ago and is parented by the B-type asteroid (142) Polana [1]. [2] and [3] found that primitive near-Earth asteroids (NEAs), including Hayabusa2’s asteroid target (162173) Ryugu and OSIRIS-REx’s asteroid target (101955) Bennu, are likely disrupted fragments that originated during the formation of the New Polana family. Other possible sources of primitive NEAs in the inner Main Belt include the Clarissa, Erigone, Polana, and Sulamitis, families and the collisionally evolved background asteroids outside these families [2, 4]. The age of the solar system is longer than the collisional lifetime of asteroid Bennu [5], a rubble pile asteroid with a mean diameter of 490.06 ± 0.16 m [6] and a spinning top-like shape [7]. Asteroid 142 Polana, the largest remnant of the New Polana family [1], has been spectrally (~0.5-2.5 µm) and dynamically linked to asteroid Bennu [e.g., 2]. Bennu’s spectra were measured over the wavelength range from 0.4 to 4.3 µm with OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS) [8]. Here, we investigate the compositional linkage of asteroids Polana and Bennu using 3-µm Polana spectra measured at the Infrared Telescope Facility (IRTF)

Driss Takir↗
NASA NTRS2000

Internal and External reconnection in a Series of Homologous Solar Flares

Using data from the Extreme Ultraviolet Telescope (EIT) on SOHO and the Soft X-ray Telescope (SXT) on Yohkoh, we examine a series of morphologically homologous solar flares occurring in NOAA AR 8210 over May 1-2, 1998. An emerging flux region (EFR) impacted against a sunspot to the west and next to a coronal hole to the east is the source of the repeated flaring. An SXT sigmoid parallels the EFR's neutral line at the site of the initial flaring in soft X-rays. In EIT, each flaring episode begins with the formation of a crinkle pattern external to the EFR. These EIT crinkles move out from, and then in toward, the EFR with velocities approximately 20 km/s. A shrinking and expansion of the width of the coronal hole coincides with the crinkle activity, and generation and evolution of a postflare loop system begins near the. time of crinkle formation. Using a schematic based on magnetograms of the region, we suggest that these observations are consistent with the standard reconnection-based model for solar eruptions, but modified by the presence of the additional magnetic fields of the sunspot and coronal hole. In the schematic, internal reconnection begins inside of the EFR-associated fields, unleashing a flare, postflare loops, and a CME. External reconnection, first occurring between the escaping CME and the coronal hole field, and second occurring between fields formed as a result of the first external reconnection, results in the EIT crinkles and changes in the coronal hole boundary. By the end of the second external reconnection, the initial setup is reinstated; thus the sequence can repeat, resulting in morphologically homologous eruptions. Our inferred magnetic topology is similar to that suggested in the "breakout model" of eruptions [Antiochos, 1998], although we cannot determine if our eruptions are released primarily by the breakout mechanism (external reconnection) or, alternatively, are released primarily by the internal reconnection.

Sterling, Alphonse C.↗
NASA NTRSDate not supplied

ICEE: Next Generation Exobiology and Astrobiology Studies

The presence of organic molecules, from simple to complex form are found in the ISM (interstellar medium). Perhaps the largest of these molecules are the PAHs, or polycyclic aromatic hydrocarbons, while smaller versions of PAHs have been identified in meteorites, IDPs (interplanetary dust particles) and comets within the Solar System. Life is comprised of organic molecules and, in one sense; the search for life is the search for and identification of organic molecules. This yields an interesting question. Can the organics in the ISM serve as the chemical feedstock to the prebiotic molecules identified in meteorites, comets and IDPs in a “Top-Down” synthesis mechanism? Most studies regarding the formation of prebiotic molecules focus on a “Bottoms-Up” mechanism, whereby simple organic compounds in ice form larger, more biologically relevant molecules when exposed to UV irradiation. Here we present a next generation experimental setup which focuses on if larger, interstellar organics, such as PAHs (polycyclic aromatic hydrocarbons) can serve as the chemical feedstock for the organic inventory found in the Solar System.

A. L. Mattioda↗
NASA NTRS1991

An IRAS search for extra-solar Oort clouds

The presumptively close connection between Oort cloud formation and planetary formation is that the detection of comet clouds around other stars would imply the presence of extrasolar planetary systems. Low-resolution IRAS data and an S/N-enhancement method are presently used to search 17 nearby stars for comet cloud-indicating IR emission. While no such detections were obtained, upper limits have been set for extrasolar Oort clouds (ESOCs) around the candidate stars; the nondetections may be a results either of the absence of the ESOCs around these stars or, with greater probability, of the sensitivity and background confusion limitations of IRAS data.

Stern, S. Alan↗
NASA NTRS2011

What Turns Galaxies Off? the Different Morphologies of Star-Forming and Quiescent Galaxies Since z Approximates 2 from CANDELS

We use HST/WFC3 imaging from the CANDELS multicyc1e treasury survey, in conjunction with the Sloan Digital Sky Survey, to explore the evolution of galactic structure for galaxies with stellar masses > 3 x 10(exp 10) Solar Mass from Z= 2.2 to the present epoch, a time span of 10 Gyr. We explore the relationship between rest-frame optical color, stellar mass, star formation activity and the structural parameters of galaxies as determined from parametric fits to the surface brightness profiles of galaxies. We confirm the dramatic evolution from z= 2.2 to the present day in the number density of non-star-forming galaxies above 3 x 10(exp 10) Solar Mass reported by other authors. We find that the vast majority of these quiescent systems have concentrated light profiles, as parameterized by the Sersic index, and the population of concentrated galaxies grows similarly rapidly. We examine the joint distribution of star formation activity, Sersic index, stellar mass, mass divided by radius (a proxy for velocity dispersion), and stellar surface density. Quiescence correlates poorly with stellar mass at all z < 2.2 (given the approx < 0.2 dex scatter between halo mass and stellar mass at z approximates 0 inferred by More et al, this argues against halo mass being the only factor determining quiescence). Quiescence correlates better with Sersic index, 'velocity dispersion' and stellar surface density, where Sersic index correlates the best (increasingly so at lower redshift). Yet, there is significant scatter between quiescence and galaxy structure: while the vast majority of quiescent galaxies have prominent bulges, many of them have significant disks, and a number of bulge-dominated galaxies have significant star formation. Noting the rarity of quiescent galaxies without prominent bulges, we argue that a prominent bulge (and, perhaps by association, a supermassive black hole) is a necessary but not sufficient condition for quenching star formation on galactic scales over the last 10 Gyr; such a result is qualitatively consistent with the expectations of the AGN feedback paradigm.

Bell, Eric F.↗
NASA NTRS2001

Internal and External Reconnection Series Homologous Solar Flares

Using data from the extreme ultraviolet imaging telescope (EIT) on SOHO and the soft X-ray telescope (SXT) on Yohkoh, we examine a series of morphologically homologous solar flares occurring in National Oceanic and Atmospheric Administration (NOAA) active region 8210 over May 1-2, 1998. An emerging flux region (EFR) impacted against a sunspot to the west and next to a coronal hole to the east is the source of the repeated flaring. An SXT sigmoid parallels the EFR's neutral line at the site of the initial flaring in soft X rays. In EIT each flaring episode begins with the formation of a crinkle pattern external to the EFR. These EIT crinkles move out from, and then in toward, the EFR with velocities approx. 20 km/ s. A shrinking and expansion of the width of the coronal hole coincides with the crinkle activity, and generation and evolution of a postflare loop system begins near the time of crinkle formation. Using a schematic based on magnetograms of the region, we suggest that these observations are consistent with the standard reconnection-based model for solar eruptions but are modified by the presence of the additional magnetic fields of the sunspot and coronal hole. In the schematic, internal reconnection begins inside of the EFR-associated fields, unleashing a flare, postflare loops, and a coronal mass ejection (CME). External reconnection, first occurring between the escaping CME and the coronal hole field and second occurring between fields formed as a result of the first external reconnection, results in the EIT crinkles and changes in the coronal hole boundary. By the end of the second external reconnection, the initial setup is reinstated; thus the sequence can repeat, resulting in morphologically homologous eruptions. Our inferred magnetic topology is similar to that suggested in the "breakout model" of eruptions although we cannot determine if our eruptions are released primarily by the breakout mechanism (external reconnection) or, alternatively, primarily by the internal reconnection.

Sterling, Alphonse C.↗
NASA NTRS1977

Graphite grain surface reactions in interstellar and protostellar environments

Surface reactions on warm (at least 60 K) graphite grains between lattice C atoms and impinging H and O atoms within or in the vicinity of H II regions can provide a prolific source of H2CO and other interstellar molecules. It is proposed that similar reactions in the primitive solar nebula led to the formation of the organic molecules found in carbonaceous chondrites. From this and related evidence, it is argued that most of the solid material in the solar system may have originated as interstellar grains.

Barlow, M. J.↗
NASA NTRS1980

Mesospheric cloud formations

Formation of mesospheric clouds as a result of deposition of large amounts of H2O by the heavy lift launch vehicle (HLLV) of the solar power satellite system is discussed. The conditions which must be met in order to form and maintain clouds near the mesopause are described. The frequency and magnitude of H2O injections from the HLLV rocket exhaust are considered.

Forbes, J. M.↗