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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

Space Environmental Exposure of the MISSE 9-15 Polymers and Composites Experiment 1-4 (PCE 1-4)

Spacecraft in low Earth orbit (LEO) are subjected to harsh environmental conditions, including radiation (cosmic rays, ultraviolet (UV), x-ray and charged particle radiation), micrometeoroids and orbital debris, temperature extremes, thermal cycling, and atomic oxygen (AO). These environmental exposures can result in erosion, embrittlement and optical property degradation of susceptible materials threatening spacecraft performance and durability. To increase our understanding of effects such as AO erosion and radiation induced embrittlement of spacecraft materials, NASA Glenn Research Center has developed a series of experiments that were flown as part of the Materials International Space Station Experiment (MISSE) missions on the exterior of the International Space Station (ISS). These experiments have provided critical space environmental durability data such as AO erosion data of polymers and composites, and radiation induced mechanical property degradation of spacecraft insulation materials, after long term space exposure. Recently, four Glenn experiments with 365 flight samples were flown on ISS’s MISSE-Flight Facility (MISSE-FF). These experiments are the Polymers and Composites Experiment-1 (PCE-1) flown as part of the MISSE-9 mission, the PCE-2 flown as part of the MISSE-10 mission, the PCE-3 flown as part of the MISSE-12 and MISSE-15 missions, and the PCE-4 flown as part of the MISSE-13 mission. This paper provides details on the space environment exposure of Glenn’s PCE 1-4 flight samples. Passive samples were flown in each flight orientation for post-flight AO fluence determination and on-orbit contamination analyses. Solar exposure estimates were computed by Aegis Aerospace, Inc. The environment exposure details include the total space vacuum duration, time on the MISSE-FF, the direct space exposure duration, the AO fluence and the computed mission Equivalent Sun Hours (ESH) solar exposure. Typical on-orbit temperatures are also provided along with a summary of analyses of PCE 1-4 contamination witness samples. Knowledge of the space environmental exposure of the PCE 1-4 flight samples is crucial for flight data interpretation.

Atomic oxygen↗
NASA NTRS2001

Collision phenomena involving highly-charged ions in astronomical objects

A description of the role of highly charged ions in various astronomical objects; includes the use of critical quantities such as cross sections for excitation, charge-exchange, X-ray emission, radiative recombination (RR) and dielectronic recombination (DR); and lifetimes, branching ratios, and A-values.

highly charged ions x-ray spectra excitation lifet↗
NASA NTRS2021

The Far Ultraviolet M-dwarf Evolution Survey. I. The Rotational Evolution of High-energy Emissions

M-dwarf stars are prime targets for exoplanet searches because of their close proximity and favorable properties for both planet detection and characterization. However, the potential habitability and atmospheric characterization of these exoplanetary systems depends critically on the history of high-energy stellar radiation from X-rays to NUV, which drive atmospheric mass loss and photochemistry in the planetary atmospheres. With the Far Ultraviolet M-dwarf Evolution Survey, we have assessed the evolution of the FUV radiation, specifically eight prominent emission lines, including Lyα, of M-dwarf stars with stellar rotation period and age. We demonstrate tight power-law correlations between the spectroscopic FUV features, and measure the intrinsic scatter of the quiescent FUV emissions. The luminosity evolution with rotation of these spectroscopic features is well-described by a broken power law, saturated for fast rotators, and decays with increasing Rossby number, with a typical power-law slope of −2, although likely shallower for Lyα. Our regression fits enable FUV emission-line luminosity estimates relative to bolometric from known rotation periods to within ∼0.3 dex, across eight distinct UV emission lines, with possible trends in the fit parameters as a function of source layer in the stellar atmosphere. Our detailed analysis of the UV luminosity evolution with age further shows that habitable-zone planets orbiting lower-mass stars experience much greater high-energy radiative exposure relative the same planets orbiting more massive hosts. Around early- to mid-M dwarfs, these exoplanets, at field ages, accumulate up to 10–20× more EUV energy, relative to modern Earth. Moreover, the bulk of this UV exposure likely takes place within the first Gyr of the stellar lifetime.

J Sebastian Pineda↗
NASA NTRS1997

CGRO Observations

This final report presents an investigation of the CGRO (Compton Gamma Ray Observatory) observations. The investigation includes: Diffuse Gamma-Ray Emission at High Latitudes; and Echoes in X-Ray Novae; A Localized Excess of Gamma-Radiation; Transient Hard X-Ray Emission from Globular Clusters; and A Search for Be/X-Ray Binaries in Hard X-Rays; Hard X-Ray Emission from X-Ray Bursters; X-Ray Transients in Star-Forming Regions; Gamma-ray Emission from Globular Clusters; Shock High Energy Emission from Be-Star/Pulsar System PSR 1259-63m; Gamma-Ray Spectroscopy of Nearby OB Associations; Long Term Hard X-Ray Monitoring of X-Ray Busters; and Periodic Hard X-Ray Emission from GRO J1849-03.

Kaaret, Philip↗
NASA NTRS1999

The Mean Curvature of the Influence Surface of Wave Equation With Sources on a Moving Surface

The mean curvature of the influence surface of the space-time point (x, t) appears in linear supersonic propeller noise theory and in the Kirchhoff formula for a supersonic surface. Both these problems are governed by the linear wave equation with sources on a moving surface. The influence surface is also called the Sigma - surface in the aeroacoustic literature. This surface is the locus, in a frame fixed to the quiescent medium, of all the points of a radiating surface f(x, t) = 0 whose acoustic signals arrive simultaneously to an observer at position x and at the time t. Mathematically, the Sigma- surface is produced by the intersection of the characteristic conoid of the space-time point (x, t) and the moving surface. In this paper, we derive the expression for the local mean curvature of the Sigma - space of the space-time point for a moving rigid or deformable surface f(x, t) = 0. This expression is a complicated function of the geometric and kinematic parameters of the surface f(x, t) = 0. Using the results of this paper, the solution of the governing wave equation of high speed propeller noise radiation as well as the Kirchhoff formula for a supersonic surface can be written as very compact analytic expression.

Farassat, F.↗
NASA NTRS1988

Production of the diffuse X-ray background spectrum by active galactic nuclei

This paper proposes a class of models in which the intensity and spectrum of the X-ray background radiation between 0.2 and 160 keV can be produced by active galactic nuclei. The key assumption of these models is that the spectra of active galactic nuclei are not described by a single power law. No evolution of the X-ray spectra of active galactic nuclei is required.

Schwartz, D. A.↗
NASA NTRS2005

Interaction of Superconducting YBa2Cu(sub 3-x)Zn(sub x)O(sub 7-y) with MeV Radiation

When the high Tc superconductor Y-Ba-Cu-O is cooled with liquid nitrogen, the conduction holes form a macroscopic collective or entangled state. While collective effects have been observed with radiation energies up to 5 eV, no high-sensitivity experiments have previously been carried out to search for comparable effects with MeV radiation. Here an experiment using a pair of scintillation counters arranged to search for changes in the natural background of high energy radiation adjacent to a warm and cold Y-Ba-Cu-O superconductor is described. The experiment showed a shift toward higher pulse heights when the SC was cooled, with a 4 standard deviation excess of 9.12+/-2.28 events/ksec over the range of 0 to 18 MeV. The net difference spectrum shows a 5.5 standard deviation excess signal for the range of 3 to 6 MeV.

Lewis, R. A.↗
NASA NTRS2017

Genetic Correlation with the DNA Repair Assay in Mice Exposed to High-LET

We hypothesize that DNA damage induced by high local energy deposition, occurring when cells are traversed by high-LET (Linear Energy Transfer) particles, can be experimentally modeled by exposing cells to high doses of low-LET. In this work, we validate such hypothesis by characterizing and correlating the time dependence of 53BP1 radiation-induced foci (RIF) for various doses and LET across 72 primary skin fibroblast from mice. This genetically diverse population allows us to understand how genetic may modulate the dose and LET relationship. The cohort was made on average from 3 males and 3 females belonging to 15 different strains of mice with various genetic backgrounds, including the collaborative cross (CC) genetic model (10 strains) and 5 reference mice strains. Cells were exposed to two fluences of three HZE (High Atomic Energy) particles (Si 350 megaelectronvolts per nucleon, Ar 350 megaelectronvolts per nucleon and Fe 600 megaelectronvolts per nucleon) and to 0.1, 1 and 4 grays from a 160 kilovolt X-ray. Individual radiation sensitivity was investigated by high throughput measurements of DNA repair kinetics for different doses of each radiation type. The 53BP1 RIF dose response to high-LET particles showed a linear dependency that matched the expected number of tracks per cell, clearly illustrating the fact that close-by DNA double strand breaks along tracks cluster within one single RIF. By comparing the slope of the high-LET dose curve to the expected number of tracks per cell we computed the number of remaining unrepaired tracks as a function of time post-irradiation. Results show that the percentage of unrepaired track over a 48 hours follow-up is higher as the LET increases across all strains. We also observe a strong correlation between the high dose repair kinetics following exposure to 160 kilovolts X-ray and the repair kinetics of high-LET tracks, with higher correlation with higher LET. At the in-vivo level for the 10-CC strains, we observe that drops in the number of T-cells and B-cells found in the blood of mice 24 hours after exposure to 0.1 gray of 320 kilovolts X-ray correlate well with slower DNA repair kinetics in skin cells exposed to X-ray. Overall, our results suggest that repair kinetics found in skin is a surrogate marker for in-vivo radiation sensitivity in other tissue, such as blood cells, and that such response is modulated by genetic variability.

cosmic radiation↗
NASA NTRS1981

A new transition radiation detector for cosmic ray nuclei

Test measurements on materials for transition radiation detectors at a low Lorentz factor are reported. The materials will be based on board Spacelab-2 for determining the composition and energy spectra of nuclear cosmic rays in the 1 TeV/nucleon range. The transition radiation detectors consist of a sandwich of radiator-photon detector combinations. The radiators emit X-rays and are composed of polyolefin fibers used with Xe filled multiwired proportional chamber (MWPC) detectors capable of detecting particle Lorentz factors of several hundred. The sizing of the detectors is outlined, noting the requirement of a thickness which provides a maximum ratio of transition radiation to total signal in the chambers. The fiber radiator-MWPC responses were tested at Fermilab and in an electron cyclotron. An increase in transition radiation detection was found as a square power law of Z, and the use of six radiator-MWPC on board the Spacelab-2 is outlined.

Lheureux, J.↗
NASA NTRS2014

Space Radiation and Risks to Human Health

The radiation environment in space poses significant challenges to human health and is a major concern for long duration manned space missions. Outside the Earth's protective magnetosphere, astronauts are exposed to higher levels of galactic cosmic rays, whose physical characteristics are distinct from terrestrial sources of radiation such as x‐rays and gamma‐rays. Galactic cosmic rays consist of high energy and high mass nuclei as well as high energy protons; they impart unique biological damage as they traverse through tissue with impacts on human health that are largely unknown. The major health issues of concern are the risks of radiation carcinogenesis, acute and late decrements to the central nervous system, degenerative tissue effects such as cardiovascular disease, as well as possible acute radiation syndromes due to an unshielded exposure to a large solar particle event. The NASA Human Research Program's Space Radiation Program Element is focused on characterization and mitigation of these space radiation health risks along with understanding these risks in context of the other biological stressors found in the space environment. In this overview, we will provide a description of these health risks and the Element's research strategies to understand and mitigate these risks.

Huff, Janice L.↗
NASA NTRS2014

Space Radiation and Risks to Human Health

The radiation environment in space poses significant challenges to human health and is a major concern for long duration manned space missions. Outside the Earth's protective magnetosphere, astronauts are exposed to higher levels of galactic cosmic rays, whose physical characteristics are distinct from terrestrial sources of radiation such as x‐rays and gamma‐rays. Galactic cosmic rays consist of high energy and high mass nuclei as well as high energy protons; they impart unique biological damage as they traverse through tissue with impacts on human health that are largely unknown. The major health issues of concern are the risks of radiation carcinogenesis, acute and late decrements to the central nervous system, degenerative tissue effects such as cardiovascular disease, as well as possible acute radiation syndromes due to an unshielded exposure to a large solar particle event. The NASA Human Research Program's Space Radiation Program Element is focused on characterization and mitigation of these space radiation health risks along with understanding these risks in context of the other biological stressors found in the space environment. In this overview, we will provide a description of these health risks and the Element's research strategies to understand and mitigate these risks.

Huff, Janice L.↗
NASA NTRS1986

Dose protraction studies with low- and high-LET radiations on neoplastic cell transformation in vitro

The effects of the low- and high-LET radiation (by X-rays, Co-60, and heavy ions) on the transformation of neoplastic cells were studied using cultured C3H10T1/2 mouse embryo cells. The transformed colonies in the confluent cell monolayers were recognized as focuses composed of highly polar fibroblastic multilayered criss-cross arrays of densely stained cells. For the low-LET radiation, there was a decrease in cell killing and cell transformation frequency when cells were irradiated with fractionated doses and at a low dose rate, indicating that cultured mammalian cells can repair both subtransformation and potential transformation lesions. No sparing effect, however, was found for the high-LET radiation. An enhancement of cell transformation was observed for low-dose/rate argon (400 MeV/u; 120 keV/micron) and iron particles (600 MeV/u; 200 keV/micron). The molecular mechanism for this enhancement effect is not known.

Yang, Tracy Chui-Hsu↗
NASA NTRS1985

Search for gamma rays of energy 10(15) eV from Cygnus X-3

Finite flux of excess radiation of energy 10 to the 15th power has been reported by two groups from the direction of Cygnus X-3, with the characteristic periodicity of 4.8 hrs. Samorski and Stamm find that the muon content of the showers generated by this excess radiation is about 77% of that in normal cosmic ray showers, whereas the expectation for gamma ray showers is less than 10%. It is thus difficult to understand the nature of the radiation arriving from the direction of Cygnus X-3. Samorski and Stamm measured the muon densities close to the core (approx. 10 m), where contamination due to other components is severe. Even though this does not explain the high ratio of muon densities, measurements should be carried out away from the core to establish the nature of the radiation. In order to establish the signal from Cygnus X-3 and its muon content with better statistical significance, an extensive air shower array, specifically designed for this purpose was operated at Kolar Gold Fields (longitude: 78 deg .3 E; latitude: + 12 deg .95; atmospheric depth: 920 q/square centimeters) since September, 1984. The details of the array and the accuracy of arrival direction measurements are discussed.

Bhat, P. N.↗
NASA NTRS1976

Non-thermal processes in large solar flares

The paper examines the significance of particle acceleration processes in large solar flares, and the importance of accelerated particles in the generation of other flare phenomena. Comprehensive observations of the August 1972 series of large flares were used to obtain quantitative estimates of the energetic particle populations, the electromagnetic emissions, and the mass ejections. The fluxes of energetic electrons and protons were derived from observed X-ray and gamma-ray emissions, respectively. The energy input into the solar atmosphere from the collisional losses of these energetic particles is computed as a function of overlying column density, under the assumption that particles are accelerated at a point high in the solar atmosphere and then precipitate down to denser layers. The flash phase radiation, soft X-ray flare plasma, and the interplanetary shock wave can be consistently and quantitatively explained as a result of the interaction of nonrelativistic electrons with the solar atmosphere.

Lin, R. P.↗
NASA NTRS1982

The X-ray binary, UW CMa

The UW CMa is a close, eclipsing binary composed of an O7f primary with a stron wind and a less luminous O-type companion. It was found that UW CMa a variable X-ray source, whose X-ray variations are in phase with its optical light curve. Since both components of the binary system are O stars, accretion by a compact object is ruled out as a mechanism for generating X-rays. The UW CMa represents a new class of X-ray binaries, in which X-rays result from the collision of a wind from one star with the surface or wind of the other star. It is hypothesised that the impact of a wind against a star generates a shock wave about 0.25 stellar radii above the stellar surface, and material behind the shock front, heated to bout 10 million degrees, radiates the X-ray apparent X-ray variability is due to its location between the two stars, where it undergoes eclipses. The high temperature region maintains an ionization cavity in the wind, as detected with IUE. The ionization cavity is the source of depletion of absorbing ions in the wind between the two stars.

Heap, S. R.↗