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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Midinfrared spectral investigations of carbonates: Analysis of remotely sensed data

Recent airborne thermal infrared observations of Mars from the Kuiper Airborne Observatory (KAO) have provided evidence for the presence of carbonates, sulfates, and hydrates. Using the optical properties of calcite and anhydrite, it was estimated that CO3's and SO4's constituted about 1 to 3 and 10 to 15 wt. percent, repectively of the materials composing the atmospheric dust. Using the derived value as an estimate of total CO3 abundance, and making an assumption that the CO3's were uniformly distributed within the Martian regolith, it was estimated that such a CO3 reservoir could contain roughly 2 to 5 bars of CO2. While the results indicate that several volatile-bearing materials are present on Mars, the observations from the KAO are inherently limited in their ability to determine the spatial distributions of these materials. However, previous spacecraft observations of Mars provide both the spectral coverage necessary to identify these materials, as well as the potential for investigating their spatial variability. This has prompted us to pursue a reinvestigation of the Mariner 6 and 7 infrared spectrometer and Mariner 9 infrared interferometer spectrometer observations. The former data have been recently made available in digital format and calibration of wavelengths and intensities are almost complete. Additionally, we are pursuing the derivation of optical constants of more appropriate carbonates and sulfates.

Roush, T.↗
NASA NTRS1990

Magnetic islands in the near geomagnetic tail and its implications for the mechanism of 1054 UT CDAW 6 substorm

During the 1054 UT CDAW 6 substorm event, two ISEE spacecraft observed dynamic changes in the magnetic field and in the flux of energetic particles in the near-earth plasma sheet. In the substorm growth phase, the magnetic field at both ISEE spacecraft became tail-like. Following expansion phase onset, two small scale magnetic islands were observed moving tailward at a velocity of about 580 km/s. The passage of these two magnetic islands was coincident with bursts of tailward streaming energetic particles. The length of the magnetic loops was estimated to have been about 2 to 3 earth radii while the height of the loops was less than 0.5 earth radii. The magnetic islands were produced by multipoint reconnection processes in the near tail plasma sheet which may have been associated with the formation of the near-earth neutral line and the subsequent formation of a large scale plasmoid. The near-earth neutral line retreated tailward later in the expansion phase, as suggested by the reversal of the streaming of energetic particles.

Lin, N.↗
NASA NTRS1993

Simultaneous observations of solar MeV particles in a magnetic cloud and in the earth's northern tail lobe - Implications for the global field line topology of magnetic clouds and for the entry of solar particles into the magnetosphere during cloud passage

Simultaneous ISEE 3 and IMP 8 spacecraft observations of magnetic fields and flow anisotropies of solar energetic protons and electrons during the passage of an interplanetary magnetic cloud show various particle signature differences at the two spacecraft. These differences are interpretable in terms of the magnetic line topology of the cloud, the connectivity of the cloud field lines to the solar surface, and the interconnection between the magnetic fields of the magnetic clouds and of the earth. These observations are consistent with a magnetic cloud model in which these mesoscale configurations are curved magnetic flux ropes attached at both ends to the sun's surface, extending out to 1 AU.

Farrugia, C. J.↗
NASA NTRS1987

Comet thermal modeling

The past year was one of tremendous activity because of the appearance of Halley's Comet. Observations of the comet were collected from a number of sources and compared with the detailed predictions of the comet thermal modeling program. Spacecraft observations of key physical parameters for cometary nucleus were incorporated into the thermal model and new cases run. These results have led to a much better understanding of physical processes on the nucleus and have pointed the way for further improvements to the modeling program. A model for the large-scale structure of cometary nuclei was proposed in which comets were envisioned as loosely bound agglomerations of smaller icy planetesimals, essentially a rubble pile of primordial dirty snowballs. In addition, a study of the physical history of comets was begun, concentrating on processes during formation and in the Oort cloud which would alter the volatile and nonvolatile materials in cometary nuclei from their pristine state before formation.

Weissman, Paul R.↗
NASA NTRS1996

Magnetopause Transects

A novel method is described for reconstruction of two-dimensional current-layer structures from measurements taken by a single spacecraft traversing the layer. In its present form, the method is applicable only to 2D magnetohydrostatic structures that are passively convected past the observing spacecraft. It is tested on a magnetopause crossing of the tangential-discontinuity type by the spacecraft AMPTE/IRM. The magnetic structures recovered include a magnetic island located between two X-type nulls as well as a magnetic 'worm hole' through which a bundle of weak magnetic flux appears to connect the magnetosphere and the magnetosheath.

Sonnerup, B. U. O↗
DOE OSTI2025

Observation of a Knotted Electron Diffusion Region in Earth's Magnetotail Reconnection

Magnetic reconnection is a fundamental plasma process that alters the magnetic field topology and releases magnetic energy. Most numerical simulations and spacecraft observations assume a two‐dimensional diffusion region, with the electron diffusion region (EDR) embedded in the same plane as the ion diffusion region (IDR) and a uniform guide field throughout. Using observations from Magnetospheric Multiscale mission, we report a non‐coplanar, knotted EDR in Earth's magnetotail current sheet. The reconnection plane of the knotted EDR deviates by approximately 38° from that of the IDR, with the guide field exhibiting both a 38° directional shift and a twofold increase in amplitude. Moreover, the Hall magnetic field is bipolar in the EDR but quadrupolar in the IDR, indicating different Hall current structures at electron and ion scales. These observations highlight the importance of three‐dimensional effects and illustrate the complexity of multiscale coupling between the EDR and IDR during reconnection studies.

diffusion region↗
NASA NTRS1990

Atmospheric drag perturbations on the Mars Observer Orbiter

The nominal launch date of the Mars Observer spacecraft is 09 - 16 - 02, with Mars encounter on 08 - 19 - 93 and the mapping orbit established on 12 - 06 - 93. Because this orbit is nearly circular at low altitude (361 km), both gravity and atmospheric drag will dominate the orbital evolution and are also the major error sources. This paper provides: (1) a summary of atmospheric density and errors for the Mars Observer orbit and time frame, (2) an assessment of spacecraft-position errors using current density estimates, and (3) an estimate of atmospheric density modeling improvement directly from the Doppler data acquired during flight operations. With an improved gravity field model, reconstructed spacecraft-position errors are at the level of 0.5 km (1sigma). However, when predicting the spacecraft's position over 14 days, the density error (at the 90-percent confidence level) dominates, yielding a down-track error of almost 70 km. By modeling the mean atmospheric density, this error can be reduced by at least a factor of two.

Esposito, P. B.↗
DOE OSTI2024

Observation and Numerical Simulation of Cold Ions Energized by EMIC Waves

This is the first report of significant energization (up to 7,000 eV) of low-energy He + ions, which occurred simultaneously with H-band electromagnetic ion cyclotron (EMIC) wave activity, in a direction mostly perpendicular to the ambient magnetic field. The event was detected by the Arase satellite in the dayside plasmatrough region off the magnetic equator on 15 May 2019. The peak energy of the He + flux enhancements is mostly above 1,000 eV. At some interval, the He + ions are energized up to ~7,000 eV. The H-band waves are excited in a frequency band between the local crossover and helium gyrofrequencies and are close to a linear polarization state with weakly left-handed or right-handed polarization. The normal angle of the waves exhibits significant variation between 0° and 80°, indicating a non-parallel propagation. Here, we run a hybrid code with parameters estimated from the Arase observations to examine the He + energization. The simulations show that cold He + ions are energized up to more than 1,000 eV, similar to the spacecraft observations. From the analysis of the simulated wave fields and cold plasma motions, we found that the ratio of the wave frequency to He + gyrofrequency is a primary factor for transverse energization of cold He + ions. As a consequence of the numerical analysis, we suggest that the significant transverse energization of He + ions observed by Arase is attributed to H-band EMIC waves excited near the local helium gyrofrequency.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1986

Space Telescope Antenna Pointing System analysis and test

The Space Telescope (ST), carrying five astronomy instruments, is a long-life spacecraft designed to achieve and maintain ultrafine stabilization jitter performance. The rms jitter specification for pointing performance is 7 marcsec (1sigma) during periods of scientific observation. Spacecraft attitude control is achieved by onboard computer processing of attitude and rate sensor data to generate reaction-wheel torque commands. The ST Antenna Pointing System is used to position a high-gain antenna for relaying science and engineering data from the spacecraft to the ground station.

Dodder, R.↗
NASA NTRS2019

Estimating Total Open Heliospheric Magnetic Flux

Over the solar-activity cycle, there are extended periods where significant discrepancies occur between the spacecraft-observed total (unsigned) open magnetic flux and that determined from coronal models. In this article, the total open heliospheric magnetic flux is computed using two different methods and then compared with results obtained from insitu interplanetary magnetic-field observations. The first method uses two different types of photospheric magnetic-field maps as input to the Wang–Sheeley–Arge (WSA) model: i) traditional Carrington or diachronic maps, and ii) Air Force Data Assimilative Photospheric Flux Transport model synchronic maps. The second method uses observationally derived helium and extreme-ultraviolet coronal-hole maps overlaid on the same magnetic-field maps in order to compute total open magnetic flux. The diachronic and synchronic maps are both constructed using magnetograms from the same source, namely the National Solar Observatory Kitt Peak Vacuum Telescope and Vector Spectromagnetograph. The results of this work show that the total open flux obtained from observationally derived coronal holes agrees remarkably well with that derived from WSA, especially near solar minimum. This suggests that, on average, coronal models capture well the observed large-scale coronal-hole structure over most of the solar cycle. Both methods show considerable deviations from total open flux deduced from spacecraft data, especially near solar maximum, pointing to something other than poorly determined coronal-hole area specification as the source of these discrepancies.

Wallace, S.↗
NASA NTRS1994

An expert system for diagnosing anomalies of spacecraft

Although the analysis of anomalous behavior of satellites is difficult because it is a very complex process, it is important to be able to make an accurate assessment in a timely manner when the anomaly is observed. Spacecraft operators may have to take corrective action or to 'safe' the spacecraft; space-environment forecasters may have to assess the environmental situation and issue warnings and alerts regarding hazardous conditions, and scientists and engineers may want to gain knowledge for future designs to mitigate the problems. Anomalies can be hardware problems, software errors, environmentally induced, or even the cause of workmanship. Spacecraft anomalies attributable to electrostatic discharges have been known to cause command errors. A goal is to develop an automated system based on this concept to reduce the number of personnel required to operate large programs or missions such as Hubble Space Telescope (HST) and Mission to Planet Earth (MTPE). Although expert systems to detect anomalous behavior of satellites during operations are established, diagnosis of the anomaly is a complex procedure and is a new development.

Lauriente, Michael↗
NASA NTRS2010

THEMIS Observations of Directly-Driven Pi2 Pulsations

The THEMIS tail seasons have provided an unprecedented opportunity to examine the causal relationship between midtail plasma flows and low latitude Pi2 pulsations. We present several events where multiple THEMIS spacecraft observed magnetotail flow bursts which were followed up to several minutes later by ground Pi2 pulsations. We find good agreement with the waveforms of the flow bursts and flank Pi2, in agreement with the hypothesis that Pi2 at low-latitude on the flank are directly-driven by periodic variations in the flow bursts. For at least I event we are able to follow the Pi2 impulses from the periodic flow bursts on the nightside. to ground Pi2 at the flanks, and finally through the dayside magnetosphere as observed by GOES. We further place the physical mechanism generating these Pi2 into the context of sub storm onset. We conclude by discussing the sequence and coupling of events that are necessary to explain the correlation, and the constraints this places on models of transient magnetospheric transport.

Kepko, L.↗
NASA NTRS1998

The Development of Kolmogoroff-Like Power Spectra in the Expanding Solar Wind

Power spectra of the solar wind fluctuations consistently exhibit a -5/3 power-law slope consistent with the idea that the medium is undergoing a turbulent cascade as seen in ordinary fluids. This is surprising both because the radial streams and the magnetic field threading the plasma will induce anisotropies and because the expansion of the wind will tend to lead to the suppression of nonlinear cascades. These conditions violate the assumptions used by Kolmogoroff to derive the -5/3 law. We have studied this issue using a compressible IMHD code in spherical coordinates and have shown that a -5/3 spectrum results from a broad-band flat-spectrum input condition that is sheared and distorted by a current sheet as the wind expands. We determine spectra from time series taken at selected points in the domain as is done with observational spacecraft data. The spectra are very like those we have seen in nonexpanding runs and exhibit evolution and compressive characteristics very similar to those seen in observations. We will report on these results in addition to a new set of runs intended to constrain the necessary and sufficient conditions for the spectra to have this form. The simulation also allows us to examine the anisotropy for the spectra to attempt to determine why the result of an isotropic magnetofluid is obtained in a highly anisotropic situation.

Goldstein, M. L.↗
NASA NTRS2006

Comets, Asteroids, Meteorites, and the Origin of the Biosphere

During the past few decades, the delivery of water, organics, and prebiotic chemicals to the Biosphere of Earth during the Hadean (4.5-3.8 Ga) period of heavy bombardment by comets and asteroids has become more widely accepted. Comets are still largely regarded as frigid, pristine bodies of protosolar nebula material that are devoid of liquid water and therefore unsuitable for life. Complex organic compounds have been observed in comets and on the water-rich asteroid 1998 KY26 and near IR observations have indicated the presence of crystalline water ice and ammonia hydrate on the large Kuiper Belt object (50000) Quaoar that has resurfacing suggesting cryovolcanic outgassing. Spacecraft observations of the chemical compositions and characteristics of the nuclei of several comets (Halley, Borrelly, Wild 2, and Tempel 1) have shown that comets contain complex organic chemicals; that water is the predominant volatile; and that extremely high temperatures (approx. 350-400 K) can be reached on the surfae of the very black (albedo approx. 0.03) nuclei of comets when they approach the Sun. Impact craters and pinnacles observed on comet Wild 2 suggest a thick crust. Episodic outbursts and jets from the nuclei of several comets indicate that localized regimes of liquid water and water vapor can periodically exist beneath the comet crust. The Deep Impact mission found the temperature of the nucleus of comet Tempel 1 at 1.5 AU varied from a minimum of 280 plus or minus 8 K the 330K (57 C) on the sunlit side. In this paper it is argued that that pools and films of liquid water exist (within a wide range of temperatures) in cavities and voids just beneath the hot, black crust. The possibility of liquid water existing over a wide range of temperatures significantly enhances the possibility that comets might contain niches suitable for the growth of microbial communities and ecosystems. These regimes would be ideal for the growth of psychrophilic, mesophilic, and thermophilic photoautotrophs and chemolithotrophs such as the motile filamentous cyanobacteria (e.g., Calothrix, Oscillatoria, Phormidium, and Spirulina) that grow in geothermal springs and geysers of Earth at temperatures ranging fiom 320K to 345K and are also found growing in cold polar desert soils. The mineralized remains of morphotypes of all of these cyanobacteria have also been found in the Orgueil CI1 and the Murchison CN2 carbonaceous meteorites that may derive from cometary parent bodies. Observational results that support the hypothesis that liquid water can in active regions just beneath the surface of comets and that comets, carbonaceous meteorites, and asteroids may have played a significant role in the origin and evolution of the Biosphere and in the distribution of microbial life throughout the Solar System.

Hoover, Richard B.↗
NASA NTRS1988

Photometry of Pluto-Charon mutual events and Hirayama family asteroids

Once every 124 years, nature provides earth-bound astronomers with the opportunity to observe occultation and transit phenomena between Pluto and its satellite, Charon. Ground-based observations of these events will allow precise physical parameters for the Pluto-Charon system to be derived which are unlikely to be improved upon until in situ spacecraft observations are obtained. The proposed program will continue to support photometry observations from McDonald Observatory, a critical location in an international Pluto Campaign network. Knowledge of the diameters, masses, densities, and compositions derived from these observations will augment our understanding of Pluto's origin and its context within the problem of solar system formation. A second task will continue to research the evolutionary processes which have occurred in the asteroid belt by measuring the physical properties of specific Hirayama family members. Photoelectric lightcurve observations of Koronis and Themis family members will be used to investigate the individual catastrophic collision events which formed each family. By comparing these properties with results of laboratory and numerical experiments, the outcomes of catastrophic disruptions and collisional evolution may be more precisely determined.

Binzel, Richard P.↗
NASA NTRS1992

Vacuum ultraviolet detection of the VLISM-heliosphere interaction

As the neutral components of the interstellar gas flow through the heliosphere their spatial distribution is modified by charge exchange with the solar plasma, photoionization, and radiation pressure. The deep space probes Pioneers 10/11 and Voyagers 1/2 have provided an opportunity to investigate this distribution through VUV observations of the heliospheric glow. Since the interactions of the inflowing neutrals with the heliosphere depend on both space and time it is particularly useful to have multiple spacecraft observations. Pioneer 10 is in the downstream region of the inflowing interstellar breeze at 50 AU while Pioneer 11 and Voyager 2 are upstream at about 30 AU. Voyager 1 is also upstream at about 40 AU but at a heliographic latitude of + 30 deg. Both temporal and spatial effects are expected to be quite different for the upstream and downstream regions. Some of the recent VUV data and its implications with respect to the heliospheric structure will be presented.

Judge, D. L.↗
NASA NTRS2007

MeV Ion Anisotropies in the Vicinity of Interplanetary Shocks

The anticipated signatures of interplanetary shock acceleration to be found in energetic ion anisotropies in the vicinity of interplanetary shocks include near-isotropic particle distributions consistent with of diffusive shock acceleration, "pancake" distributions indicative of shock drift acceleration, and flow reversals, suggestive of a particle acceleration region passing by the observing spacecraft. In practice, while clear examples of these phenomena exist, more typically, particle anisotropies near interplanetary shocks show considerable variation in time and space, both in individual events and from event to event. We investigate the properties of MeV/n ions in the vicinity of a number of interplanetary shocks associated with the largest energetic particle events of solar cycle 23, and previous cycles, including their intensity-time profiles, anisotropies, and relationship with local solar wind structures, using observations from the IMP 8, ISEE-3, Helios 1 and 3 spacecraft. The aim is to help to understand the role of shocks in major solar energetic particle events.

Richardson, I. G.↗
NASA NTRS1993

Mars Observer screen display design for a multimission environment

The Multi Mission Control Team (MMCT) is responsible for support to real time operations of the Mars Observer Mission. The team has the responsibility for monitoring the ground data system for the integrity of the telemetry and command data links. It also supports the Mars Observers Spacecraft Team in monitoring spacecraft events. The Data Monitor and Display subsystem (DMD) workstation provides the data interface with the ground data system. DMD workstation displays were developed to support the Mission Controllers in accomplishing their assigned tasks for supporting the Mars Observer mission. The display design concepts that were used in the Mar Observer MMCT displays to minimize the cognitive demands on the controllers and enhance the MMCT operations were presented. The Data Monitor and Display subsystem (DMD) is the controllers window into the spacecraft and the ground data system. The DMD is a workstation that provides a variety of formatted data displays to the controller. The displays present both spacecraft telemetry data and ground system monitor data. Some displays are preplanned and developed prior to the operations in which they are used. These are called fixed displays and are quite versatile in format and content. Other displays and plots can be created in real time. These displays have limited formats but flexibility in content. These are called list or message displays. They can be rapidly generated by the controller as needed. The MMCT display repertoire provides a mix of displays appropriate to the needs of the MMCT controllers.

Chafin, Roy L.↗