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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 NTRS1992

LDEF SP-HVDE (Space Plasma-High Voltage Drainage Experiment) post-flight results: Leakage current and discharge

TRW designed and fabricated two identical SP-HVDE trays which were flown in the NASA LDEF (Long Duration Exposure Facility) for 5.75 years in the LEO (low earth orbit) environment. One tray was placed near the leading edge and one near the trailing edge, and investigations were performed to compare the environmental interactions on the dielectric samples of the two trays. Each tray consisted of six assemblies with Kapton dielectric samples of varying thicknesses (i.e., 2 mils, 3 mil, and 5 mils) biased under +/- 300 V, +/- 500 V, and +/- 1000 V. The original objective was successfully achieved by measuring the first in-flight average leakage current through the samples. Less than 5 percent of the post-flight coulometers behaved anomalously. The data should be valuable to the design and evaluation of spacecraft with high voltage systems. M/D (micrometeoroid and debris) impacts over the dielectric samples were examined using a SEM (Scanning Electron Microscope) and an EDS (Energy Dispersive x-ray Spectrometer). These impact sites were sprayed by silver which were most likely caused either by the impact or a 'local ESD' (electrostatic discharge).

Yaung, J. Y.↗
NASA NTRS2011

Stratospheric Collection of Dust from Comet 73P/Schwassmann-Wachmann 3

Interplanetary dust particles (IDPs) collected in the stratosphere are unique materials that are compositionally distinct from meteorites. Astronomical observations and dynamical models indicate that both asteroids and short-period comets are significant sources of IDPs. IDPs having fragile, porous structures, unequilibrated, anhydrous mineralogy, and high atmospheric entry velocities are thought to derive from comets, whereas asteroidal IDPs are identified by their compact structure, hydrated mineralogy and low atmospheric entry velocities. Uncertainty remains in the classification of asteroidal and cometary IDPs owing to our limited sampling of comets and the asteroid belt and the complex dynamical histories of most IDPs in space. Most IDPs spend thousands of years in space prior to being accreted by the Earth. During this time, dust particles undergo orbital evolution, including gradual reduction in their perihelion and eccentricity as a result of Poynting-Robertson drag. Planetary encounters may also significantly change their orbital parameters. Consequently, it is generally not possible to identify the specific parent body of a given IDP. However, it has been proposed that it is possible to identify dust from comets that have formed Earth-crossing dust trails. In this case, the dust particles have been in space for such a short period of time (a few decades or less) that their orbits have not significantly changed. Furthermore, these fresh IDPs could be identified in the laboratory from their short space-exposure histories (low solar noble gas abundance and lack of solar flare tracks). NASA flew several dedicated IDP collection missions attempting to collect dust from comet 26P/Grigg-Skjellerup, the best candidate identified. Remarkably, many particles from those collectors exhibit unusual properties, including low abundances of solar noble gases and high abundances of presolar grains. These observations are consistent with the dust particles originating from comet Grigg-Skjellerup (hereafter G-S). This study considers the prospects for collection of dust from comet 73P/Schwassmann-Wachmann 3 (hereafter SW3). SW3 is a small (2 km diameter) Jupiter family comet whose perihelion is close to and just inside the Earth's orbit. The orbit of SW3 is suitable for producing a low-velocity Earth-crossing dust stream and is the likely parent of the Tau Herculid meteor stream. This study complements a previously published model of the SW3 meteor stream that predicted a very low level of activity for grains 100 micron -- 100 mm in size.

Messenger, Scott R.↗
NASA NTRS1999

A New Frontier Beckons: Space Exploration in the 21st Century

Throughout recorded history, small groups of explorers have Pushed back the edge of the frontier and opened up new territories for others to follow. As the 20th Century closes, history will record that in the 1960's humankind opened the vast frontier beyond Earth's atmosphere. Although the Apollo program blazed a trail of exploration to the Moon, the development of space has only reached into low Earth orbit. The Space Shuttle and International Space Station programs, and the communication and scientific satellite networks established in orbit around the Earth, are all stepping stones that will enable explorers to venture once again beyond our home planet. Exploration is difficult. It is difficult for the people and machines that travel in extreme environments and endure harsh conditions, and it is difficult for the national leaders who must champion and fund the programs that lead to discovery and reward. Christopher Columbus spent many years meeting with the Kings of Portugal, England, and France only to see his dream of sailing west into the vast Atlantic with ships and crew. discredited. Queen Isabella of Spain was willing to look beyond the many problems plaguing her own shores and see the potential reward for her investment in the future. The voyages of Columbus set the stage for more Spanish explorers, who turned Spain into a great world power. The Apollo program and the unpiloted Lunar Orbiter, Surveyor, Mariner and Viking spacecraft that NASA launched in the 1966's &1970's were our country's first investment, in the exploration of the solar system. These human and robotic missions rewarded us with the first close views of the lunar and martian surfaces, and laid before our eyes territories as vast as all the continents of Earth combined. The Lunar Prospector, Near Earth Asteroid Rendezvous, and Mars Pathfinder and Global Surveyor missions are continuing our scientific conquest of the inner solar system, leading the way for humans to follow.

Mendell, Wendell W.↗
NASA NTRS2004

Propulsion Options for the LISA Mission

The LISA mission is a constellation of three spacecraft operating at 1 AU from the Sun in a position trailing the Earth. After launch, a propulsion module provides the AV necessary to reach this operational orbit, and separates from the spacecraft. A second propulsion system integrated with the spacecraft maintains the operational orbit and reduces nongravitational disturbances on the instruments. Both chemical and electrical propulsion systems were considered for the propulsion module, and this trade is presented to show the possible benefits of an EP system. Several options for the orbit maintenance and disturbance reduction system are also briefly discussed, along with several important requirements that suggest the use of a FEEP thruster system.

Cardiff, Eric H.↗
NASA NTRS2005

A Search for Meteor Shower Signatures in the LDEF IDE Data

For 346 days after the deployment of the LDEF satellite on April 7, 1984, the tape recorder belonging to the Interplanetary Dust Experiment (DE) stored information on over 15,000 impacts made by submicron and larger-size particles on its metal oxide silicon (MOS) detectors. These detectors were mounted on trays facing in six orthogonal directions - LDEF ram and trailing edge, the poles of the LDEF orbit (north and south), and radially inward (towards the Earth) and outward (towards space). The 13.1 second time resolution provided by the IDE electronics, combined with the high sensitivity of the MOS detectors and large collecting area (approximately 1 sq.m) of the experiment, conclusively showed that the small particle environment at the LDEF altitude of 480 km was highly time-variable, with particle fluxes spanning over four orders of magnitude. A large number of the 15,000 impacts recorded by IDE occurred in groups, which were of two types - the spikes, single, isolated events of high intensity and the multiple orbit event sequences (MOES), which were series of events separated in time by integer multiples of the LDEF orbital period. Even though the spikes were generally more intense, the MOES could be quite long-lived, some lasting for many days. A previous paper by Cooke et al. attributed the MOES to impacts by man-made debris particles in orbits intersecting that of LDEF. The 20 day longevity of one of these events - termed the May Swarm - led to the suggestion that the debris particles must be con- stantly replenished by their source, as the orbits of micron sized particles will rapidly decay under the influence of radiation pressure and other non-gravitational forces, entering Earth's atmosphere after only a few revolutions. However, the date of onset of the May Swarm (May 22) and the long duration of this event may indicate a possible correlation with the annual Arietid meteor shower, which peaks around June 8. As this seemed to hold the promise of a less artificial explanation than a satellite or rocket body continuously dribbling debris, it was decided to take a fresh look at parts of the IDE data set in an attempt to detect meteor showers within the impact record.

Cooke, William J.↗
NASA NTRS1990

The Space Station decision - Incremental politics and technological choice

Using primary documents and interviews with participants, this book describes the events that led up to the 1984 decision that NASA should build a permanently occupied, international space station in low earth orbit. The role that civil servants in NASA played in initiating the program is highlighted. The trail of the Space Station proposal as its advocates devised strategies to push it through the White House policy review process is followed. The critical analysis focuses on the way in which 'incrementalism' (the tendency of policy makers to introduce incremental changes once projects are under way) operated in connection with the Space Station program. The book calls for a commitment to a long-range space policy.

Mccurdy, Howard E.↗
NASA NTRS1992

Compositional analysis and classification of projectile residues in LDEF impact craters

This catalog contains preliminary analyses of residues of hypervelocity projectiles that encountered gold substrates exposed by instrument A0187-1 on the Long Duration Exposure Facility (LDEF). This instrument was on LDEF's trailing edge where relative encounter speeds should be lowest for any non-spinning platform in low Earth orbit (LEO). Approximately 0.6 m(exp 2) of Au substrates yielded 198 impact craters greater than 20 micrometers in diameter. Some 30 percent of the craters were made by natural cosmic dust particles and some 15 percent by man-made objects. Some 50 percent of all features, however, have residues, if any, that are beyond the detection threshold of the SEM-EDXA method used. The purpose of this catalog is to provide detailed evidence and criteria that may be used to arrive at specific particle types on a case-by-case basis and to group such particles into compositional classes. Clearly this is a somewhat interpretative undertaking. For that reason, we encourage and solicit critique and comments from those interested in the systematic analysis of all impact features on LDEF.

Horz, Friedrich↗
NASA NTRS1992

Long Duration Exposure Facility M0003-5 thermal control coatings on DoD flight experiment

The M0003-5 thermal control coatings and materials orbited on the LDEF M0003 Space Environment Effects on Spacecraft Materials were a part of a Wright Laboratories Materials Directorate larger experiment. They were selected from new materials which emerged from development programs during the 1978-1982 time frame. Included were materials described in the technical literature which were being considered or had been applied to satellites. Materials that had been exposed on previous satellite materials experiments were also included to provide data correlation with earlier space flight experiments. The objective was to determine the effect of the LDEF environment on the physical and optical properties of thermal control coatings and materials. One hundred and two specimens of various pigmented organic and inorganic coatings, metallized polymer thin films, optical solar reflectors, and mirrors were orbited on LDEF. The materials were exposed in four separate locations on the vehicle. The first set was exposed on the direct leading edge of the satellite. The second set was exposed on the direct trailing edge of the vehicle. The third and fourth sets were exposed in environmental exposure control canisters (EECC) located 30 degrees off normal to the leading and trailing edges. The purpose of the experiment was to understand the changes in the properties of materials before and after exposure to the space environment and to compare the changes with predictions based on laboratory experiments. The basic approach was to measure the optical and physical properties of materials before and after long-term exposure to a low earth orbital environment comprised of UV, VUV, electrons, protons, atomic oxygen, thermal cycling, vacuum, debris, and micrometeoroids. Due to the unanticipated extended orbital flight of LDEF, the thermal control coatings and materials in the direct leading and trailing edge were exposed for a full five years and ten months to the space environment and the canister materials were exposed for approximately one year to the full environment.

Hurley, Charles J.↗
NASA NTRS1998

Mission goals of a 1998/1999 Leonid storm Multi-instrument Aircraft Campaign (MAC)

In November of 1998 (or in 1999 with about equal probability) will be our one chance in a lifetime to anticipate with some certainty the occurrence of a meteor storm. For a period of up to 2 hours, rates are expected to increase above 1 meteor per second for a naked eye observer. At that time, Earth passes through the outer regimes of the dust trail of comet 55P/Tempel-Tuttle. The high meteor flux offers unprecedented precision in characterizing the dust trail in terms of spatial and particle size distributions of dust grains and allows the measurement of composition, morphology and orbits of individual cometary grains relatively soon after ejection from the comet. By using the Earth's atmosphere as a detector for the dust trains, grains are sampled over a wide mass range, from the typical grain size of zodiacal dust (40 - 200 micron) up until the rare boulders that can still be lifted off the comet nucleus.

Jenniskens, P.↗
NASA NTRS1993

Spacecraft materials: Comparison between flight results obtained on LDEF and MIR

Two flight experiments dedicated to the study of the performance of materials in space have been carried out. Material samples have been exposed passively to low-Earth orbit (LEO) environment, then retrieved for laboratory study. The first experiment was conducted in the framework of the FRECOPA project and was flown on the trailing edge of the Long Duration Exposure Facility (LDEF) (exposure to vacuum and ultraviolet (UV) radiation for 5.5 years). The experiment COMES was installed outside of the MIR space station during an extravehicular activity; it was exposed to vacuum, O-atoms, and UV radiation for 1.1 year; and it was brought back to Earth by cosmonauts. The difference in exposure conditions and the use of transparent filters protecting some samples of COMES enable to differentiate the effects of UV radiation and oxygen atoms. The degradations of several thermal control coatings (paints, metalized polymeric films with and without ITO), structural materials, and optical components have been observed, measured, and compared after these two flight experiments. This paper summarizes various 'lessons learned' that can be used to identify aspects of space aging, to orient future research in this field, and to assist in spacecraft design.

Guillaumon, Jean-Claude↗
NASA NTRS1991

LDEF space environments overview

The Long Duration Exposure Facility (LDEF) was launched into an Earth orbit during a period of minimum solar activity. It was retrieved almost 6 years later during a period of near maximum solar activity. In flight, the LDEF was passively stabilized in three axes and it flew in a near circular orbit having an inclination of 28.5 degs and an initial altitude of approx. 257 nautical miles. When the LDEF was retrieved, the orbit had decayed to an altitude of approx. 180 nautical miles. Specifically, the LDEF flew with one surface always facing the trailing direction, one surface facing Earth, and one surface facing into space. These facts made the LDEF an ideal platform to expose experiments to study the space environments and the effects of these environments on spacecraft materials and systems. An overview is provided of the specific space environments to which the LDEF experiments were exposed. The specific features are also pointed out of the LDEF that allow the effects of different environments to be isolated.

Kinard, William H.↗
NASA NTRS1996

Workshop on evolution of igneous asteroids: Focus on Vesta and the HED meteorites

Recently, the geology of the surface of Vesta has been coming to light. In 1983 Gaffey first began showing maps of the surface geology of Vesta constructed from numerous spectra obtained at different times as the asteroid rotated. By noting the details of spectral variation with rotation, he was able to develop two possible gross-scale geologic maps of Vesta showing the distributions of mafic and ultramafic materials. These maps were published in 1997. Finally, the capabilities of the Hubble Space Telescope were brought to bear on Vesta and images with a resolution of about 50 km were obtained using four different filters by Binzel and co-workers. Maps produced by this team published in 1997 began to reveal the geology of Vesta in sufficient detail that crude interpretations of the geologic history of the asteroid could be attempted. Additionally, in 1993 Binzel and Xu published a study of small asteroids in the region near Vesta in orbital-element space. In this study, they showed that there are a number of asteroids a few kilometers in size with reflectance spectra like that of Vesta that form a trail in orbital-element space from near Vesta to near resonances that can more easily supply material to near-Earth space. Binzel and Xu thus concluded that these small asteroids were spells of Vesta ejected by impact and that some of their brethren had been perturbed to Earth-approaching orbits. They suggested that these latter were the immediate parents of HED meteorites. This seemed to remove a long-standing dynamical objection to Vesta as the HED parent body, as discussed by Wasson and Wetherill in 1979. Within the last few years, NASA has initiated the Discovery program of low-cost, rapid-timescale development, exploration missions. Vesta has been proposed as an object worthy of study by a Discovery mission, although a Vesta mission has not yet been selected. With all the recent activity aimed at studying Vesta and the HED meteorites, and the possibility of a space mission to Vesta, we felt that time was ripe to convene a workshop bringing together astronomers, meteoriticists, and planetary geologists to focus on what could be learned about the geologic evolution of Vesta through integrating astronomical and HED meteorite studies. This, of course, assumes that the HED meteorites are from Vesta, and this issue was specifically addressed (but not resolved) in the workshop. Indeed, it seems likely that this issue can only be resolved by returning samples from Vesta for detailed study on Earth. The workshop was held at the LPI on October 16-18,1996, and was attended by some 70 scientists. Sessions included a set of talks on Earth- and space-based astronomical observations of Vesta plus the evidence pro and con for Vesta being the HED parent body, talks on the petrology and geochemistry of HED meteorites, talks on the formation and dynamics of ejecta from Vesta, talks on the thermal history of asteroids and HED meteorites, volcanic processes and differentiation history, and a short session devoted to possible missions to Vestal By all accounts, the workshop was considered a great success, although this is the opinion of a biased set of observers.

Mittlefehldt, D. W.↗
NASA NTRS1995

Effects of low earth orbit on the optical performance of multi-layer enhanced high reflectance mirrors

Two mirror designs developed for space applications were flown along with a standard mid-infrared design on the leading and trailing edges of the Long Duration Exposure Facility (LDEF). Preliminary observations of induced changes in optical performance of ZnS-coated mirrors and impact-related microstructural and microchemical effects are described in the proceedings of the First LDEF Post-Retrieval Symposium. In this paper, effects of the induced environment and meteoroid/debris impacts on mirror performance are described in more detail. Also, an analysis of reflectance spectra using the results of Auger and secondary ion mass spectroscopy (SIMS) profiling measurements are used to identify an optical-degradation mechanism for the ZnS-coated mirrors. Structural damage associated with a high-velocity impact on a (Si/Al2O3)-coated mirror was imaged optically and with scanning electron and atomic force microscopy (SEM and AFM). Scanning Auger and SIMS analysis provided chemical mapping of selected impact sites. The impact data suggest design and fabrication modifications for obtaining improved mechanical performance using a design variation identified in preflight laboratory simulations. Auger surface profile and SIMS imaging data verified the conclusion that secondary impacts are the source of contamination associated with the dendrites grown on the leading-edge ZnS-coated test samples. It was also found that dendrites can be grown in the laboratory by irradiating contaminated sites on a trailing-edge ZnS-coated sample with a rastered electron beam. These results suggest a mechanism for dendrite growth.

Donovan, Terence↗
NASA NTRS1991

The 1990 MB: The first Mars Trojan

Asteroid 1990 MB was discovered by D. H. Levy and H. E. Holt during the course of the Mars and Earth Crossing Asteroid and Comet Survey. An orbit based on a 9 day arc and the asteroid's location near Mars' L5 (trailing Lagrangean) longitude led E. Boswell to speculate that it might be in 1:1 resonance with Mars, analogous to the Trojan asteroids of Jupiter. Subsequent observations strengthened the possibility, and later calculations confirmed it. Thus 1990 MB is the first known asteroid in 1:1 resonance with a planet other than Jupiter. The existence of 1990 MB (a small body most likely between 2 and 4 km in diameter) provides remarkable confirmation of computer simulations. These self consistent n-body simulations demonstrated this sort of stability for Trojans of all the terrestrial planets over at least a 2 million year time base. The discovery of 1990 MB suggests that others of similar or smaller diameter may be found. Using hypothetical populations of Mars Trojans, their possible sky plane distributions were modeled as a first step in undertaking a systematic observational search of Mars' L4 and L5 libration regions.

Innanen, Kimmo A.↗
NASA NTRS2016

Trending of SNPP Ephemeris and Its Implications on VIIRS Geometric Performance

This paper describes trends in the Suomi National Polar-orbiting Partnership (SNPP) spacecraft ephemeris data over the four and half years of on-orbit operations. It then discusses the implications of these trends on the geometric performance of the Visible Infrared Imaging Radiometer Suite (VIIRS), one of the instruments onboard SNPP. The SNPP ephemeris data includes time stamped spacecraft positions and velocities that are used to calculate the spacecraft altitude and sub-satellite locations. Through drag make-up maneuvers (DMUs) the orbital mean altitude (spacecraft altitude averaged over an orbit) has been maintained at 838.8 kilometers to within plus or minus 0.2 kilometers and the orbital period at 101.5 minutes to within plus or minus 0.2 seconds. The corresponding orbital mean velocity in the terrestrial frame of reference has been maintained at 7524 meters per second to within plus or minus 0.5 meters per second. Within an orbit, the altitude varies from 828 kilometers near 15 degrees North latitude to 856 kilometers near the South Pole. Inclination adjust maneuvers (IAMs) have maintained the orbit inclination angle at 98.67 degrees to within plus or minus 0.07 degrees and the sun-synchronous local time at ascending node (LTAN) at 13:28 to within plus or minus 5 minutes. Besides these trends, it is interesting to observe that the orbit's elliptic shape has its major axis linking the perigee and apogee shorter than the line linking the ascending node and the descending node. This effect is caused by the Earth's oblate spheroid shape and deviates from a Keplerian orbit theory in which the two orbiting bodies are point masses. VIIRS has 5 imagery resolution bands, 16 moderate resolution bands and a day-night band, with 32, 16 and 16 detectors, respectively, aligned in the spacecraft flight (also known as track) direction. For each band's sample within a scan, the detectors sample the Earth's surface simultaneously in the track direction in the Earth Centered Inertial frame of reference. The distance between the center of the area sensed by the trailing detectors of one scan and the leading detectors of the next includes a component caused by earth rotation. This earth rotation component is relatively small (approximately 70 meters per second) for an orbit like SNPP, but must be taken into account in the design of low-Earth orbit scanning sensors similar to VIIRS to ensure contiguous coverage at nadir.

SNPP↗
NASA NTRS2001

The Pioneer Missions

This article describes the major achievements of the Pioneer Missions and gives information about mission objectives, spacecraft, and launches of the Pioneers. Pioneer was the United States' longest running space program. The Pioneer Missions began forty years ago. Pioneer 1 was launched shortly after Sputnik startled the world in 1957 as Earth's first artificial satellite at the start of the space age. The Pioneer Missions can be broken down into four distinct groups: Pioneer (PN's) 1 through 5, which comprise the first group - the "First Pioneers" - were launched from 1958 through 1960. These Pioneers made the first thrusts into space toward the Moon and into interplanetary orbit. The next group - the "Interplanetary Pioneers" - consists of PN's 6 through 9, with the initial launch being in 1965 (through 1968); this group explored inward and outward from Earth's orbit and travel in a heliocentric orbit around the Sun just as the Earth. The Pioneer group consisting of 10 and 11 - the "Outer Solar System Pioneers" - blazed a trail through the asteroid belt and was the first to explore Jupiter, Saturn and the outer Solar System and is seeking the borders of the heliosphere and will ultimately journey to the distant stars. The final group of Pioneer 12 and 13 the "Planetary Pioneers" - traveled to Earth's mysterious twin, Venus, to study this planet.

Larry E. Lasher↗
NASA NTRS2018

Investigation into New Ground Based Communications Service Offerings in Response to SmallSat Trends

The number of NASA sponsored Small Satellite (SmallSat) missions is expected to continue to grow rapidly in the next decade and beyond. There is a growing trend towards more ambitious SmallSat missions, including formation flying (Constellation, Cluster, Trailing) SmallSats and SmallSats destined for lunar orbit and beyond. This paper will present an overview of new service offerings the NASA Near Earth Network (NEN) is currently investigating and demonstrating. It will describe the benefits that new service offerings such as Multiple Spacecraft Per Aperture (MSPA), Ground-based Phased Array (GBPA) antennas, Ground-based Aperture Arrays, and Ground-based Antenna Arraying could provide to individual or formation flying SmallSats anywhere from low-earth orbit to the Sun-Earth Lagrange point orbits. It will also present potential implementation options for future demonstrations at the NASA Goddard Space Flight Center (GSFC) Wallops Flight Facility (WFF) as well as goals and objectives of such demonstrations.

Schaire, Scott H.↗