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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Contamination in Orbit of GOES-8

The GOES-8 satellite has lost some of its ability to dissipate heat over time. This is shown by the temperature increases over time of spacecraft and instrument components that are cooled with optical solar reflector (OSR) radiators. Contamination has a significant, well-documented effect on the solar absorptance (a(sub s)) of OSRs. This document attempts to discern how much molecular contamination has collected on the Imager and Sounder radiant coolers by analyzing the increase in temperature of the vacuum cooler housing. In the first part, temperature change is transformed into solar absorptance units by a method devised by ITT. The second part transfomis the solar absorptance gain into a molecular film thickness.

Sanders, Jack T.↗
NASA NTRS2014

Molecular Gas Clumps from the Destruction of Icy Bodies in the beta Pictoris Debris Disk

Many stars are surrounded by disks of dusty debris formed in the collisions of asteroids, comets and dwarf planets. But is gas also released in such events? Observations at sub-mm wavelengths of the archetypal debris disk around β Pictoris show that 0.3% of a Moon mass of carbon monoxide orbits in its debris belt. The gas distribution is highly asymmetric, with 30% found in a single clump 85 AU from the star, in a plane closely aligned with the orbit of the inner planet, beta Pic b. This gas clump delineates a region of enhanced collisions, either from a mean motion resonance with an unseen giant planet, or from the remnants of a collision of Mars-mass planets.

wavelengths↗
NASA NTRS1976

Atomic and molecular oxygen densities in the lower thermosphere

The Atmospheric Explorer-C satellite used a neutral mass spectrometer containing a quasi-open ion source operating either in normal mode or in one that utilizes the satellite velocity to distinguish between incoming ambient particles and ambient particles which have struck instrument surfaces and become accommodated. An analysis was made of data from the mass spectrometer for those orbits when the open ion source operated either partially or entirely in the fly-through mode. A comparison of N2 density, total O density and O2/N2 density values at 200 km was made. The average N2 and O2 density values agree well with previous rocket soundings and other studies. It is believed that the individual absolute number densities obtained in the normal mode of operation are accurate to within 20% while those deduced from fly-through data may be accurate to only 30%.

Nier, A. O.↗
NASA NTRS1978

Ultraviolet photometry from the orbiting astronomical observatory. XXX - The Orion reflection nebulosity

Surface-brightness measurements are presented that cover the region of Orion in nine intermediate-width bandpasses ranging from 4250 to 1550 A. The existence of an extended ultraviolet reflection nebulosity in this area is confirmed, and the characteristics of its spectrum and spatial distribution are derived. The observations are consistent with a model in which the dense molecular cloud complex in Orion is illuminated by the foreground Orion aggregate of early-type stars. The interpretation is complicated by the fact that foreground dust may contribute to the observed scattered light. The scattering particles in the cloud appear to exhibit a wavelength-dependent albedo similar to that found for interstellar grains in general, with a strong indication that the phase function changes to a less forward-scattering form in the ultraviolet.

Witt, A. N.↗
NASA NTRS2017

EcAMSat and BioSentinel: Autonomous Bio Nanosatellites Addressing Strategic Knowledge Gaps for Manned Spaceflight Beyond LEO

Manned missions beyond low Earth orbit (LEO) require that several strategic knowledge gaps about the effects of space travel on the human body be addressed. NASA Ames Research Center has been the leader in developing autonomous bio nanosatellites, including past successful missions for GeneSat, PharmaSat, and OOREOS, that tackled some of these issues. These nanosatellites provide in situ measurements, which deliver insight into the dynamic changes in cell behavior in microgravity. In this talk, two upcoming bio nanosatellites developed at Ames, the E. coli Antimicrobial Satellite (EcAMSat) and BioSentinel, will be discussed. Both satellites contain microfluidic systems that precisely deliver nutrients to the microorganisms stored within wells of fluidic cards. Each well, in turn, has its own 3-color LED and detector system which is used to monitor changes in metabolic activity with alamarBlue, a redox indicator, and the optical density of the cells. EcAMSat investigates the effects of microgravity on bacterial resistance to antimicrobial drugs, vital knowledge for understanding how to maintain the health of astronauts in long-term and beyond LEO spaceflight. The behavior of wild type and mutant uropathic E. coli will be compared in microgravity and with ground data to help understand the molecular mechanisms behind antibiotic resistance and how these phenotypes might change in space. BioSentinel seeks to directly measure the effects of space radiation on budding yeast S. cerevisiae, particularly double strand breaks (DSB). While hitching a ride on the SLS EM-1 mission (Orions first unmanned mission to the moon) in 2018, BioSentinel will be kicked off and enter into a heliocentric orbit, becoming the first study of the effects of radiation on living organisms outside LEO since the Apollo program. The yeast are stored in eighteen independent 16-well microfluidic cards, which will be individually activated over the 12 month mission duration. In addition to the wild type and radiation-sensitive mutant strains, a BioSentinel strain of yeast has been developed, which requires a DSB to reactivate growth, thereby allowing for a direct measurement of DSBs caused by radiation. These two missions demonstrate the utility of using autonomous nanosatellites to address strategic knowledge gaps in the push to once again extend manned spaceflight beyond LEO.

Padgen, Mike↗
NASA NTRS1974

Skylab induced environment

This induced environment consists of particles and gases which emanate from the spacecraft in orbit and form the 'contamination cloud'. The presence of the cloud can present certain problems connected with scattering effects and the deposition of condensibles on optical surfaces. Measures taken to investigate these effects involved the placement of quartz crystal microbalance deposition monitors at certain locations to determine molecular film build-up during the flight.

Naumann, R. J.↗
NASA NTRS1981

Hot oxygen atoms in the upper atmosphere of Venus

Using data obtained by an ultraviolet spectrometer on the Pioneer-Venus Orbiter, energy and altitude distribution of nonthermal oxygen atoms in the Venus atmosphere for typical daytime and nighttime conditions are calculated using two different numerical methods. Agreement is found between results obtained by the two-stream transport method and the diffusion equation technique. Dissociative recombination of molecular oxygen ions and charge exchange of atomic oxygen ions with the neutral hydrogen and oxygen gas are the source terms, and calculations show that the dissociative recombination term is the dominant one. It is shown that measured hot atom concentrations exceed estimates of the thermal hydrogen atom concentrations derived from Brinton et al. (1980) over most of the daytime exosphere, and the calculated concentrations do so to an even greater extent. It is concluded that hot oxygen atoms are an important component of the dayside exosphere of Venus, their most important effect being the absorption of solar wind.

Nagy, A. F.↗
NASA NTRS1984

Measurements of the thermal plasma environment of the Space Shuttle

The paper presents some initial results on measurements of the thermal plasma environment obtained by a spherical retarding potential analyzer and a Langmuir probe flown on (STS-3) as part of the NASA Office of Space Science-1 payload in March 1982. One of the major effects observed is a higher degree of turbulence in the ambient plasma compared to what is observed from similar instruments flown on unmanned satellites. In addition we see the temperature of the thermal electrons elevated to values of 4000-5000 K. Associated with elevated electron temperatures are regions of enhanced plasma density resulting from the appearance of high densities of molecular ions. The thermal plasma data also show clear effects of an induced V x B.L potential at the location of the probes which matches that produced by an L vector linking the probes to the engine nozzles; thereby establishing the prime return current location on the Orbiter. The final observations discussed are the pronounced and complex wake effects resulting both from the main structure of the Orbiter and from the complex shapes of appendages attached to the Orbiter.

Raitt, W. J.↗
NASA NTRS2008

Estimated Environmental Exposures for MISSE-3 and MISSE-4

Describes the estimated environmental exposure for MISSE-2 and MISSE-4. These test beds, attached to the outside of the International Space Station, were planned for 3 years of exposure. This was changed to 1 year after MISSE-1 and -2 were in space for 4 years. MISSE-3 and -4 operate in a low Earth orbit space environment, which exposes them to a variety of assaults including atomic oxygen, ultraviolet radiation, particulate radiation, thermal cycling, and meteoroid/space debris impact, as well as contamination associated with proximity to an active space station. Measurements and determinations of atomic oxygen fluences, solar UV exposure levels, molecular contamination levels, and particulate radiation are included.

Finckenor, Miria M.↗
NASA NTRS2017

EcAMSat and BioSentinel: Autonomous Bio Nanosatellites Addressing Strategic Knowledge Gaps for Manned Spaceflight Beyond LEO

Manned missions beyond low Earth orbit (LEO) require that several strategic knowledge gaps about the effects of space travel on the human body be addressed. NASA Ames Research Center has been the leader in developing autonomous bio nanosatellites, including past successful missions for GeneSat, PharmaSat, and O/OREOS, that tackled some of these issues. These nanosatellites provide in situ measurements, which deliver insight into the dynamic changes in cell behavior in microgravity. In this talk, two upcoming bio nanosatellites developed at Ames, the E. coli Antimicrobial Satellite (EcAMSat) and BioSentinel, will be discussed. Both satellites contain microfluidic systems that precisely deliver nutrients to the microorganisms stored within wells of fluidic cards. Each well, in turn, has its own 3-color LED and detector system which is used to monitor changes in metabolic activity with alamarBlue, a redox indicator, and the optical density of the cells. EcAMSat investigates the effects of microgravity on bacterial resistance to antimicrobial drugs, vital knowledge for understanding how to maintain the health of astronauts in long-term and beyond LEO spaceflight. The behavior of wild type and mutant uropathic E. coli will be compared in microgravity and with ground data to help understand the molecular mechanisms behind antibiotic resistance and how these phenotypes might change in space. BioSentinel seeks to directly measure the effects of space radiation on budding yeast S. cerevisiae, particularly double strand breaks (DSB). While hitching a ride on the SLS EM-1 mission (Orion's first unmanned mission to the moon) in 2018, BioSentinel will be kicked off and enter into a heliocentric orbit, becoming the first study of the effects of radiation on living organisms outside LEO since the Apollo program. The yeast are stored in eighteen independent 16-well microfluidic cards, which will be individually activated over the 12 month mission duration. In addition to the wild type and radiation-sensitive mutant strains, a BioSentinel strain of yeast has been developed, which requires a DSB to reactivate growth, thereby allowing for a direct measurement of DSBs caused by radiation. These two missions demonstrate the utility of using autonomous nanosatellites to address strategic knowledge gaps in the push to once again extend manned spaceflight beyond LEO.

Padgen, Michael R.↗
NASA NTRS1989

Hypersonic rarefied flow about plates at incidence

The direct-simulation Monte Carlo method has been used in a numerical study of the transitional flow about two plate configurations at incidence; one of the two plates, both of which are 12 m long, has zero thickness, while the other has a thickness of 0.5 m and a node radius of 0.5 m. The flow conditions simulated are those of the Space Shuttle Orbiter during 7.5 km/hr reentry, in the 200-100 km altitude range encompassing most of the transitional flow for this vehicle. The results obtained clearly demonstrate that transitional effects are significant even at those altitudes where the flow about a typical space vehicle has been considered free-molecular.

Dogra, Virendra K.↗
NASA NTRS1992

Chemistry of the nightside ionosphere of Venus

The present 1D model of the nightside ionosphere of Venus assumes that ionization is maintained by day-to-night transport of atomic ions. Attention is given to the sources and sinks for molecular ions. If the ionosphere is primarily maintained by transport, the ratio of the peak densities of O(+) and O2(+) indicates the downward flux of O(+), independent of the absolute magnitudes of the densities. An examination is conducted of the inbound and outbound portions of six early nightside orbits with low periapsis.

Fox, J. L.↗
NASA NTRS1994

Local shear instabilities in weakly ionized, weakly magnetized disks

We extend the analysis of axisymmetric magnetic shear instabilities from ideal magnetohydrodynamic (MHD) flows to weakly ionized plasmas with coupling between ions and neutrals caused by collisions, ionization, and recombination. As part of the analysis, we derive the single-fluid MHD dispersion relation without invoking the Boussinesq approximation. This work expands the range of applications of these instabilities from fully ionized accretion disks to molecular disks in galaxies and, with somewhat more uncertainty, to protostellar disks. Instability generally requires the angular velocity to decrease outward, the magnetic field strengths to be subthermal, and the ions and neutrals to be sufficiently well coupled. If ionization and recombination processes can be neglected on an orbital timescale, adequate coupling is achieved when the collision frequency of a given neutral with the ions exceeds the local epicyclic freqency. When ionization equilibrium is maintained on an orbital timescale, a new feature is present in the disk dynamics: in contrast to a single-fluid system, subthermal azimuthal fields can affect the axisymmetric stability of weakly ionized two-fluid systems. We discuss the underlying causes for this behavior. Azimuthal fields tend to be stabilizing under these circumstances, and good coupling between the neutrals and ions requires the collision frequency to exceed the epicyclic frequency by a potentially large secant factor related to the magnetic field geometry. When the instability is present, subthermal azimuthal fields may also reduce the growth rate unless the collision frequency is high, but this is important only if the field strengths are very subthermal and/or the azimuthal field is the dominant field component. We briefly discuss our results in the context of the Galactic center circumnuclear disk, and suggest that the shear instability might be present there, and be responsible for the observed turbulent motions.

Blaes, Omer M.↗
NASA NTRS1985

Ultrasensitive Human Radiation Dosimetry

The problem we are addressing concerns the astronauts, and their exposure to radiation during spaceflight. The amount of this radiation is a variable depending on solar events and orbital characteristics. Our goal is to measure the total integrated quantity of radiation damage to the cell nucleus in astronauts or other people exposed to radiation. In my lab, we are turning up the microscope from the level of the chromosome, about eight orders of magnitude, to the molecular level. It is well known that radiation causes DNA and chromosome damage. We are developing methods to measure a specific molecular lesion. The lesion that we have selected to measure is thymidine diol, which is created by hydroxyl radicals adding across the 5.6 double bond of thymidine in DNA.

Hammen, Richard↗
NASA NTRS2015

Resource Prospector: Mission Goals, Relevance and Site Selection

Over the last two decades a wealth of new observations of the moon have demonstrated a lunar water system dramatically more complex and rich than was deduced following the Apollo era. Observation from the Lunar Prospector Neutron Spectrometer (LPNS) revealed enhancements of hydrogen near the lunar poles. This observation has since been confirmed by the Lunar Reconnaissance Orbiter (LRO) Lunar Exploration Neutron Detector (LEND) instrument. The Lunar Crater Observation and Sensing Satellite (LCROSS) mission targeted a permanently shadowed, enhanced hydrogen location within the crater Cabeus. The LCROSS impact showed that at least some of the hydrogen enhancement is in the form of water ice and molecular hydrogen (H2). Other volatiles were also observed in the LCROSS impact cloud, including CO2, CO, an H2S. These volatiles, and in particular water, have the potential to be a valuable or enabling resource for future exploration. In large part due to these new findings, the NASA Human Exploration and Operations Mission Directorate (HEOMD) have selected a lunar volatiles prospecting mission for a concept study and potential flight in CY2020. The mission includes a rover-borne payload that (1) can locate surface and near-subsurface volatiles, (2) excavate and analyze samples of the volatile-bearing regolith (up to 1 meter), and (3) demonstrate the form, extractability and usefulness of the materials.

Moon↗
NASA NTRS1992

All-electron molecular Dirac-Hartree-Fock calculations - Properties of the XH4 and XH2 molecules and the reaction energy XH4 yields XH2 + H2, X = Si, Ge, Sn, Pb

Relativistic corrections to a number of properties of the Group IV hydrides are calculated using the Dirac-Hartree-Fock method. The use of first-order perturbation theory is sufficient to obtain relativistic corrections for Ge, but the effects of spin-orbit interaction and other higher-order effects begin to show for Sn and become important for Pb. The energy of the reaction XH4 yields XH2 + H2 (X = Si, Ge, Sn, and Pb) is also calculated. The results are compared with relativistic effective core potential calculations, first-order perturbation theory calculations, and limited experimental data.

Dyall, Kenneth G.↗
NASA NTRS1972

Mass transport contamination study

A theoretical analysis was performed to determine the effects of outgassing and waste dumping on the contamination field around an orbiting spacecraft. The spacecraft was assumed to be spherical in shape with the mass flow emitting uniformly from the spherical surface at a constant rate and in a D'Lambertian spatial distribution. The outflow of gases were assumed to be neutrally charged and of a single species with a molecular weight characteristic of a composite of the actual species involved in the mass flow. The theoretical analysis showed that, for outgassing only, less than 1.5 percent of the outgas products will return to the Skylab spacecraft as a result of intermolecular collisions. When the total mass flow from the spacecraft, including waste dumps and reaction control motor firings, was considered, it was estimated that about 30 percent will return to the spacecraft.

Robertson, S. J.↗
NASA NTRS1976

Highlights in planetary spectroscopy 1962-75

Recent advances in spectroscopic studies of the planets with ground-based telescopes in the photomultiplier and IR spectral ranges are reviewed. Results of spectroscopic observations of Venus and Mars are briefly summarized, noting that the crucial problem confronting the interpretation of the Venusian spectrum is the nature of the clouds and that the outstanding problem in understanding the Martian atmosphere is the N2 or Ar concentration that may be present. Spectroscopic results for Jupiter, Saturn, Uranus, and Neptune are discussed, emphasizing observations of molecular hydrogen, HD, water, (C-13)H4, other hydrocarbons, and deuterated hydrocarbons. IR and visual spectroscopic observations of Titan and Io are reviewed which show that the CH4 bands in Titan's spectrum are pressure broadened and that a flattened ring of sodium is situated around Jupiter in the orbital plane of Io.

Muench, G.↗