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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 NTRS1978

Inert gas thrusters

Inert gas thrusters have continued to be of interest for space propulsion applications. Xenon is of interest in that its physical characteristics are well suited to propulsion. High atomic weight and low tankage fraction were major factors in this choice. If a large amount of propellant was required, so that cryogenic storage was practical, argon is a more economical alternative. Argon was also the preferred propellant for ground applications of thruster technology, such as sputter etching and deposition. Additional magnetic field measurements are reported. These measurements should be of use in magnetic field design. The diffusion of electrons through the magnetic field above multipole anodes was studied in detail. The data were consistent with Bohm diffusion across a magnetic field. The theory based on Bohm diffusion was simple and easily used for diffusion calculations. Limited startup data were obtained for multipole discharge chambers. These data were obtained with refractory cathodes, but should be useful in predicting the upper limits for starting with hollow cathodes.

Kaufman, H. R.↗

NASA NTRS1980

Comparison of radar derived slant path rain attenuations with the COMSTAR beacon fades at 28.56 GHz for summer and winter periods

An experiment for testing and improving the accuracy of radar derived slant path attenuations of a 28.56-GHz COMSTAR beacon signal is described. The results of an additional data base consisting of five rain days during fall-winter periods of 1978-1979 are considered, over which 715 min of simultaneous radar and disdrometer data were obtained.

Goldhirsh, J.↗

NASA NTRS1983

A study of space station needs, attributes and architectural options. Volume 2: Technical. Book 1: Mission requirements. Appendixes 1 and 2

The space station mission requirements data base consists of 149 attached and free-flying missions each of which is documented by a set of three interrelated documents: (1) NASA LaRC Data Sheets - with three sheets comprising a set for each payload element described. These sheets contain user payload element data necessary to drive Space Station architectural options. (2) GDC-derived operations descriptions that supplement the LaRC payload element data in the operations areas such as further descriptions of crew involvement, EVA, etc. (3) Payload elements synthesis sheets used by GDC to provide requirements traceability to data sources and to provide a narrative describing the basis for formulating the payload element requirements.

Source record↗

NASA NTRS1990

Photometry of 50 suspected variable stars

Fifty stars have been chosen as suspected variable stars and analyzed for variability. A large portion of this sample are stars that are either proved active chromosphere stars or are candidates for such activity. The photometric data base consists of differential V measurements of the Vanderbilt 16 inch (41 cm) automatic photoelectric telescope and 25 observers at 26 observatories worldwide. Published photometric data have also been utilized, with proper adjustments made to ensure that all magnitudes are differential. Searches for photometric period, amplitudes, and times of minimum light showed 68 percent of the sample to be photometrically variable with periods found for 34. Two stars were deemed norvariable for the period of observation. Conclusive statements could not be made concerning the photometric variability of the 14 remaining stars.

Hooten, James T.↗

NASA NTRS1994

The Effects of Vortex Ingestion on the Flow in a Diffusing S-duct

An experimental study of the effects of an ingested vortex on the flowfield of a diffusing S-duct is reported. The vortex is generated through the use of a stationary pinwheel device mounted upstream of the diffusing S-duct. Three test conditions vary the location of the vortex in the duct inlet crossplane. For each condition of ingested vortex, a baseline S-duct and an S-duct with an array of vortex generators is examined. The data taken consist of duct inlet and exit crossplane surveys of velocity and total pressure. Duct surface flow visualization and static pressure are also recorded. The data acquired in these tests are compared to identical S-duct data taken in the absence of the ingested vortex. The ingested vortex is observed to have a strong influence on the flowfield inside (and exiting) the S-duct, but only when the vortex impinges at the inlet crossplane location coincident with the crossplane location of downstream flow separation within the duct. When the ingested vortex impinges at this location it reduces the extent of flowfield separation inside the baseline duct and promotes stronger crossflow in the exit plane of both the baseline duct and the duct with installed vortex generators. This enhanced crossflow also strengthens the vortices shed from the vortex generators. The other impingement locations of the ingested vortex are found to produce little effect on the flowfield of the duct with or without vortex generators.

Wendt, B. J.↗

NASA NTRS2012

Global Distribution of Extreme Precipitation and High-Impact Landslides in 2010 Relative to Previous Years

It is well known that extreme or prolonged rainfall is the dominant trigger of landslides worldwide. While research has evaluated the spatiotemporal distribution of extreme rainfall and landslides at local or regional scales using in situ data, few studies have mapped rainfall-triggered landslide distribution globally due to the dearth of landslide data and consistent precipitation information. This study uses a newly developed Global Landslide Catalog (GLC) and a 13-year satellite-based precipitation record from TRMM data. For the first time, these two unique products provide the foundation to quantitatively evaluate the co-occurrence of precipitation and landslides globally. Evaluation of the GLC indicates that 2010 had a large number of high-impact landslide events relative to previous years. This study considers how variations in extreme and prolonged satellite-based rainfall are related to the distribution of landslides over the same time scales for three active landslide areas: Central America, the Himalayan Arc, and central-eastern China. Several test statistics confirm that TRMM rainfall generally scales with the observed increase in landslide reports and fatal events for 2010 and previous years over each region. These findings suggest that the co-occurrence of satellite precipitation and landslide reports may serve as a valuable indicator for characterizing the spatiotemporal distribution of landslide-prone areas in order to establish a global rainfall-triggered landslide climatology. This study characterizes the variability of satellite precipitation data and reported landslide activity at the globally scale in order to improve landslide cataloging, forecasting and quantify potential triggering sources at daily, monthly and yearly time scales.

Kirschbaum, Dalia↗

NASA NTRS2017

Data Recovery Effort of Nimbus Era Observations by the NASA GES DISC

NASA launched seven Nimbus meteorological satellites in the 1960s and 70s. These satellites carried instruments for making observations of the Earth in the visible, infrared, ultraviolet, and microwave wavelengths. The original data archive consisted of a combination of magnetic tapes and various film media. As these media are well past their expected end of life, the valuable data they contain are now being migrated to the GES DISC modern online archive. The process involves recovering the digital data files from the tapes as well as scanning images of the data from film strips. This presentation will address the status and challenges of recovering the Nimbus data. The old data products were written on now obsolete hardware systems and outdated file formats. They lack any metadata standards and each product is often written in its own proprietary file structure. This requires creating metadata by reading the contents of the old data files. The job is tedious and laborious, as documentation may be incomplete, data files and tapes are sometimes corrupted, or were improperly copied at the time they were created.

Nimbus↗

NASA NTRS1997

The Galileo Tape Recorder Rewind Operation Anomaly

On October 10, 1995, the Galileo spacecraft executed a sequence to record two approach images of Jupiter on the spacecraft's tape recorder, rewind the tape, and play back the images at the appropriate data rate consistent with the downlink performance.

flight↗

NASA NTRS1993

Observations of aerosol by the HALOE experiment onboard UARS - A preliminary validation

The HALOE experiment measures vertical profiles of aerosol extinction at five infrared wavelengths. Four of these observations are obtained using a combination of gas filter and broadband radiometer measurements in bands of HF, HCl, CH4, and NO centered at wavelengths of 2.45, 3.40, 3.45, and 5.26 microns, respectively. The fifth is obtained using broadband radiometer measurements of CO2 transmission at 2.79 microns. Error analysis shows that the random extinction uncertainties are generally less than 10 percent in the aerosol layer, increasing to over 20 percent at the profile tops. HALOE spectral extinction measurements are shown to be consistent with predicted spectral extinction for stratospheric sulfate aerosol. Profile comparisons between HALOE and independent sources result in generally good agreement in the shape and magnitude of peak extinction and the altitude where the peak extinction occurs. In addition, global aerosol distributions obtained from the data are consistent with expected aerosol morphology. Although the validation is preliminary, the HALOE aerosol data appear to be of excellent quality and to accurately represent optical characteristics and distribution of the aerosols.

Hervig, Mark E.↗

NASA NTRS1981

The Martian twilight

The changing sky brightness during the Martian twilight as measured by the Viking lander cameras is shown to be consistent with data obtained from sky brightness measurements. An exponential distribution of dust with a scale height of 10 km, equal to the atmospheric scale height, is consistent with the shape of the light curve. Multiple scattering resulting from the forward scattering peak of large particles makes a major contribution to the intensity of the twilight. The spectral distribution of light in the twilight sky may require slightly different optical properties for the scattering particles at high levels from those of the aerosol at lower levels.

Kahn, R.↗

NASA NTRS1989

Labeled trees and the efficient computation of derivations

The effective parallel symbolic computation of operators under composition is discussed. Examples include differential operators under composition and vector fields under the Lie bracket. Data structures consisting of formal linear combinations of rooted labeled trees are discussed. A multiplication on rooted labeled trees is defined, thereby making the set of these data structures into an associative algebra. An algebra homomorphism is defined from the original algebra of operators into this algebra of trees. An algebra homomorphism from the algebra of trees into the algebra of differential operators is then described. The cancellation which occurs when noncommuting operators are expressed in terms of commuting ones occurs naturally when the operators are represented using this data structure. This leads to an algorithm which, for operators which are derivations, speeds up the computation exponentially in the degree of the operator. It is shown that the algebra of trees leads naturally to a parallel version of the algorithm.

Grossman, Robert↗

NASA NTRS2013

Constraints on Galactic Cosmic-Ray Origins from Elemental and Isotopic Composition Measurements

The most recent measurements by the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE) satellite of ultra-heavy cosmic ray isotopic and elemental abundances will be presented. A range of isotope and element ratios, most importantly Ne-22/Ne-20, Fe-58/Fe-56, and Ga-31/Ge -32 show that the composition is consistent with source material that is a mix of approx 80% ISM (with Solar System abundances) and 20% outflow/ejecta from massive stars. In addition, our data show that the ordering of refractory and volatile elements with atomic mass is greatly improved when compared to an approx 80%/20% mix rather than pure ISM, that the refractory and volatile elements have similar slopes, and that refractory elements are preferentially accelerated by a factor of approx 4. We conclude that these data are consistent with an OB association origin of GCRs.

Galactic Cosmic Rays↗

NASA NTRS2006

Development and Implementation of a Comprehensive Radiometric Validation Protocol for the CERES Earth Radiation Budget Climate Record Sensors

The CERES Flight Models 1 through 4 instruments were launched aboard NASA's Earth Observing System (EOS) Terra and Aqua Spacecraft into 705 Km sun-synchronous orbits with 10:30 a.m. and 1:30 p.m. equatorial crossing times. These instruments supplement measurements made by the CERES Proto Flight Model (PFM) instrument launched aboard NASA's Tropical Rainfall Measuring Mission (TRMM) into a 350 Km, 38-degree mid-inclined orbit. CERES Climate Data Records consist of geolocated and calibrated instantaneous filtered and unfiltered radiances through temporally and spatially averaged TOA, Surface and Atmospheric fluxes. CERES filtered radiance measurements cover three spectral bands including shortwave (0.3 to 5 microns), total (0.3 to 100 microns) and an atmospheric window channel (8 to 12 microns). The CERES Earth Radiation Budget measurements represent a new era in radiation climate data, realizing a factor of 2 to 4 improvement in calibration accuracy and stability over the previous ERBE climate records, while striving for the next goal of 0.3-percent per decade absolute stability. The current improvement is derived from two sources: the incorporation of lessons learned from the ERBE mission in the design of the CERES instruments and the development of a rigorous and comprehensive radiometric validation protocol consisting of individual studies covering different spatial, spectral and temporal time scales on data collected both pre and post launch. Once this ensemble of individual perspectives is collected and organized, a cohesive and highly rigorous picture of the overall end-to-end performance of the CERES instrument's and data processing algorithms may be clearly established. This approach has resulted in unprecedented levels of accuracy for radiation budget instruments and data products with calibration stability of better than 0.2-percent and calibration traceability from ground to flight of 0.25-percent. The current work summarizes the development, philosophy and implementation of the protocol designed to rigorously quantify the quality of the data products as well as the level of agreement between the CERES TRMM, Terra and Aqua climate data records.

Priestley, K. J.↗

NASA NTRS1983

Microwave and hard X-ray imaging of a solar flare on 1980 November 5

VLA and SMM hard X ray data on the solar flares of November 5, 1980 are analyzed and compared with data from other sources. The VLA provided measurements at 15 GHz at 10 sec intervals, using left and right circular polarizations with a 0.6 arcsec resolution. The hard X ray imaging spectrometer on the SMM obtained data in six bands from 3.5-30 keV, with 8 x 8 arcsec resolution and 1.5 sec separation. The data were examined for a possible nonthermal source for the microwave component of the emissions detected, the origin of 16-30 keV excess fluxes, the relation between the X ray and microwave sources, the magnetic connection between observed loops, and the physical characteristics of the radiating loop. The data were consistent with a model that assumes fast electrons are accelerated to a single power-law energy distribution and freely stream along the magnetic field. The data also agreed with a thick-target model for solar flare X ray emission.

Hoyng, P.↗

NASA NTRS1988

Loads and low frequency dynamics - An ENVIRONET data base

The loads and low frequency dynamics data base, part of Environet, is described with particular attention given to its development and contents. The objective of the data base is to provide the payload designer with design approaches and design data to meet STS safety requirements. Currently the data base consists of the following sections: abstract, scope, glossary, requirements, interaction with other environments, summary of the loads analysis process, design considerations, guidelines for payload design loads, information data base, and references.

Garba, John A.↗

NASA NTRS1986

The isotopes of hydrogen and helium in the Galactic cosmic radiation - Their source abundances and interstellar propagation

A self-consistent model describing the interstellar propagation of Galactic cosmic radiation is developed using low-energy measurements and calculations of the effects of interstellar propagation and solar modulation. The source ratio H-1/He-4 at constant energy per nucleon is determined to be 12.2 + or - 1.5, and the mean path length for an exponential path length weighting function required to account for the data is 7.2 + or - 1.0 g/sq cm. The measured H-2/He-4 and He-3/He-4 ratios do not vary by more than about 30 percent over the solar cycle. The behavior of the ratios during the solar cycle reflects the energy dependence of the local interstellar ratios, and leads to an energy dependence of the mean path length below 1 GeV per nucleon weaker than that inferred from boron/carbon. The source ratio H-1/He-4 inferred from the low-energy data is consistent both with the value inferred from high-energy cosmic ray data using a model of rigidity-dependent confinement and with the solar system abundance ratio.

Beatty, James J.↗

NASA NTRS1975

Measurement of the primary cosmic electron spectrum from 10 to about 250-GeV

The intensity and energy spectrum of primary cosmic electrons from 10 to approximately 250 GeV was studied using balloon-borne detectors. Both of the detectors were large area ionization calorimeters with frequent sampling of showering particles and were capable of energy resolution of approximately 7%. A time-of-flight system and detectors to sample the lateral properties of showers were used to examine and improve background rejection. The results of the balloon flights from Alamogordo, N.M. in 1970 and Cape Girardeau, Missouri in 1972 indicated that the primary cosmic ray electron differential energy spectrum exhibits no change of slope in the energy range measured and is well represented by a power law. These results indicate that the cosmic electron spectrum is steeper than the cosmic ray proton spectrum. It is shown that these data are consistent with the leakage lifetime model for the propagation of cosmic electrons in the Galaxy, although other more complex models cannot be excluded on the basis of these data.

Silverberg, R. F.↗

NASA NTRS1976

Measurement of the primary cosmic electron spectrum from 10 to about 250 GeV

The intensity and energy spectrum of primary cosmic electrons from 10 to about 250 GeV have been studied by using balloon-borne detectors. The detectors were large-area ionization calorimeters which sampled showering particles frequently and demonstrated an energy resolution of about 7% in calibration tests. On one of the flights a time-of-flight system and detectors to sample the lateral properties of showers were used to examine and to test background rejection. The results of the balloon flights from Alamogordo, N. Mex., in 1970 and Cape Girardeau, Mo., in 1972 indicated that the primary cosmic ray electron differential energy spectrum exhibits no change of slope in the energy range measured and is well represented by a power law. The results indicate that the cosmic electron spectrum is steeper than the cosmic ray proton spectrum. It is shown that these data are consistent with the leakage lifetime model for the propagation of cosmic electrons in the galaxy, although other more complex models cannot be excluded on the basis of these data.

Silverberg, R. F.↗