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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Effects of Simulated Microgravity and LINC-Complex on Chromosome 8 of Human Mammary Cells

Previously, human breast epithelial cells were studied under simulated microgravity to determine the role of the LINC-complex in maintaining nuclear morphology and gene expression. Data from that study was used in this project to understand how the LINC-complex influences gene expression at chromosome 8 under simulated microgravity. Differentially expressed genes found in clusters typically indicate a molecular relationship amongst them. Visual and data analyses (GO, pathways) identified 51 genes within clusters on chromosome 8 across various simulated microgravity conditions that did not share any molecular relationship. Additional results also determined that cells with a disrupted LINC-complex experienced more differential gene expression than the control, and that extended periods of simulated microgravity exacerbated differential gene expression in chromosome 8 of LINC-disrupted cells. These results suggest that the stressful simulated microgravity environment coupled with disrupted biological processes, such as in the case of the LINC-complex, can increase differential gene expression in chromosomes. Future studies where additional analyses are performed to further analyze gene expression of clusters under simulated microgravity could potentially elucidate the molecular relationship amongst affected genes.

Simulated microgravity↗
NASA NTRS2006

Analysis of Material Sample Heated by Impinging Hot Hydrogen Jet in a Non-Nuclear Tester

A computational conjugate heat transfer methodology was developed and anchored with data obtained from a hot-hydrogen jet heated, non-nuclear materials tester, as a first step towards developing an efficient and accurate multiphysics, thermo-fluid computational methodology to predict environments for hypothetical solid-core, nuclear thermal engine thrust chamber. The computational methodology is based on a multidimensional, finite-volume, turbulent, chemically reacting, thermally radiating, unstructured-grid, and pressure-based formulation. The multiphysics invoked in this study include hydrogen dissociation kinetics and thermodynamics, turbulent flow, convective and thermal radiative, and conjugate heat transfers. Predicted hot hydrogen jet and material surface temperatures were compared with those of measurement. Predicted solid temperatures were compared with those obtained with a standard heat transfer code. The interrogation of physics revealed that reactions of hydrogen dissociation and recombination are highly correlated with local temperature and are necessary for accurate prediction of the hot-hydrogen jet temperature.

Wang, Ten-See↗
NASA NTRS1973

A high-resolution Fourier Transform Spectrometer for planetary spectroscopy

The employment of a high-resolution Fourier Transform Spectrometer (FTS) is described for planetary and other astronomical spectroscopy in conjunction with the 88-inch telescope at Mauna Kea Observatory. The FTS system is designed for a broad range of uses, including double-beam laboratory spectroscopy, infrared gas chromatography, and nuclear magnetic resonance spectroscopy. The data system is well-suited to astronomical applications because of its great speed in acquiring and transforming data, and because of the enormous storage capability of the magnetic tape unit supplied with the system. The basic instrument is outlined 2nd some of the initial results from the first attempted use on the Mauna Kea 88-inch telescope are reported.

Cruikshank, D. P.↗
NASA NTRS1976

Background

An analysis was made of the UF6 fueled gas core reactor as a function of cavity reactor criticality and fluid mechanics tests, investigations of uranium optical emission spectra, and radiant heat transfer power plant studies. Data are also given on nuclear and thermodynamic cycle analysis.

Source record↗
NASA NTRS1985

Space radiation studies

The overall data flow diagram for the nuclear radiation monitor to fly on Spacelab 2 was revised. The use of structured techniques for the software design appears to be working well. An example of the PASCAL pseudocode written to develop and document the software design is included.

Source record↗
NASA NTRS1987

Star formation in the merging Galaxy NGC3256

The central 5 kpc of the ultra-luminous merging galaxy NGC 3256 was mapped at J, H, K, L, and 10 micrometer, and a 2 micrometer spectra of the nuclear region was obtained. This data was used to identify and characterize the super starburst which has apparently been triggered and fuelled by the merger of two gas rich galaxies. It is also shown that the old stellar population has relaxed into a single spheroidal system, and that a supernova driven wind might eventually drive any remaining gas from the system to leave a relic which will be indistinguishable from an elliptical galaxy.

Graham, James R.↗
NASA NTRS1997

Apoptosis: a mechanism contributing to remodeling of skeletal muscle in response to hindlimb unweighting

The role of apoptosis in the elimination of myonuclei during hindlimb unloading-induced atrophy and the inhibition of apoptosis in the prevention of muscle atrophy were examined. The number of nuclei demonstrating double-stranded DNA fragmentation seen by terminal deoxynucleotidyl transferase (TDT) histochemical staining, an indicator of apoptosis, was significantly increased after 14 days of suspension. Double staining with TDT and antilaminin immunohistochemistry revealed that some TDT-positive nuclei were within the fiber lamina and were most likely myonuclei. The number of fibers containing morphologically abnormal nuclei was also significantly greater in suspended compared with control rats. Combined treatment with growth hormone and insulin-like growth factor I (GH/ IGF-I) and resistance exercise attenuated the increase in TDT-positive nuclei (approximately 26%, P > 0.05) and significantly decreased the number of fibers with morphologically abnormal nuclei. The data suggest that 1) "programmed nuclear death" contributes to the elimination of myonuclei and/or satellite cells from atrophying fibers, and 2) GH/IGF-I administration plus muscle loading ameliorates the apoptosis associated with hindlimb unloading.

Non-NASA Center↗
NASA NTRS2014

NuSTAR Observations of the Magnetar 1E 2259+586

We report on new broad band spectral and temporal observations of the magnetar 1E 2259+586, which is located in the supernova remnant CTB 109. Our data were obtained simultaneously with the Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift, and cover the energy range from 0.5-79 keV. We present pulse profiles in various energy bands and compare them to previous RXTE results. The NuSTAR data show pulsations above 20 keV for the first time and we report evidence that one of the pulses in the double-peaked pulse profile shifts position with energy. The pulsed fraction of the magnetar is shown to increase strongly with energy. Our spectral analysis reveals that the soft X-ray spectrum is well characterized by an absorbed double blackbody or blackbody plus power-law model in agreement with previous reports. Our new hard X-ray data, however, suggest that an additional component, such as a power law, is needed to describe the NuSTAR and Swift spectrum. We also fit the data with the recently developed coronal outflow model by Beloborodov for hard X-ray emission from magnetars. The outflow from a ring on the magnetar surface is statistically preferred over outflow from a polar cap.

X-rays: individual↗
NASA NTRS2003

Evaluation of Production Cross Sections of Li, Be, B in CR

Accurate evaluation of the production cross section of light elements is important for models of cosmic ray (CR) propagation, galactic chemical evolution, and cosmological studies. However, the experimental spallation cross section data are scarce and often unavailable to CR community while semi-empirical systematics are frequently wrong by a significant factor. Running sophisticated nuclear codes is not an option of choice for everyone either. We use the Los Alamos versions of the Quark-Gluon String Model code LAQGSM and the improved Cascade-Exciton Model code CEM2k together with all available data from Los Alamos Nuclear Laboratory (LANL) nuclear database to produce evaluated production cross sections of isotopes of Li, Be, and B suitable for astrophysical applications. The LAQGSM and CEM2k models have been shown to reproduce well nuclear reactions and hadronic data in the range 0.01-800 GeV/nucleon.

Moskalenko, I. V.↗
NASA NTRS1972

Manned space flight nuclear system safety. Volume 4: Space shuttle nuclear system transportation. Part 1: Space shuttle nuclear safety

An analysis of the nuclear safety aspects (design and operational considerations) in the transport of nuclear payloads to and from earth orbit by the space shuttle is presented. Three representative nuclear payloads used in the study were: (1) the zirconium hydride reactor Brayton power module, (2) the large isotope Brayton power system and (3) small isotopic heat sources which can be a part of an upper stage or part of a logistics module. Reference data on the space shuttle and nuclear payloads are presented in an appendix. Safety oriented design and operational requirements were identified to integrate the nuclear payloads in the shuttle mission. Contingency situations were discussed and operations and design features were recommended to minimize the nuclear hazards. The study indicates the safety, design and operational advantages in the use of a nuclear payload transfer module. The transfer module can provide many of the safety related support functions (blast and fragmentation protection, environmental control, payload ejection) minimizing the direct impact on the shuttle.

Source record↗
NASA NTRS2006

Identification of a Debris Cloud from the Nuclear Powered SNAPSHOT Satellite with Haystack Radar Measurements

Data from the MIT Lincoln Laboratory (MIT/LL) Long Range Imaging Radar (known as the Haystack radar) have been used in the past to examine families of objects from individual satellite breakups or families of orbiting objects that can be isolated in altitude and inclination. This is possible because for some time after a breakup, the debris cloud of particles can remain grouped together in similar orbit planes. This cloud will be visible to the radar, in fixed staring mode, for a short time twice each day, as the orbit plane moves through the field of view. There should be a unique three-dimensional pattern in observation time, range, and range rate which can identify the cloud. Eventually, through slightly differing precession rates of the right ascension of ascending node of the debris cloud, the observation time becomes distributed so that event identification becomes much more difficult. Analyses of the patterns in observation time, range, and range rate have identified good debris candidates released from the polar orbiting SNAPSHOT satellite (International Identifier: 1965-027A). For orbits near 90o inclination, there is essentially no precession of the orbit plane. The SNAPSHOT satellite is a well known nuclear powered satellite launched in 1965 to a near circular 1300 km orbit with an inclination of 90.3o. This satellite began releasing debris in 1979 with new pieces being discovered and cataloged over the years. 51 objects are still being tracked by the United States Space Surveillance Network. An analysis of the Haystack data has identified at least 60 pieces of debris separate from the 51 known tracked debris pieces, where all but 2 of the 60 pieces have a size less than 10cm. The altitude and inclination (derived from range-rate with a circular orbit assumption) are consistent with the SNAPSHOT satellite and its tracked debris cloud.

Stokely, C.↗
NASA NTRS1994

HST ultraviolet spectropolarimetry of NGC 1068

We present multiaperture spectropolarimetric observations of the Seyfert 2 galaxy NGC 1068. The nuclear region of NGC 1068 was observed with three apertures (4.3 sec x 1.4 sec., 1.0 sec., and 0.3 sec.) by the Hubble Space Telescope (HST). These ultraviolet data allow us to study the scattered, nuclear light without the complication of polarization dilution caused by strong unpolarized starlight. In particular, we can determine the mechanism of the scattering and the size scale of the scattering region. Our data confirm the findings of Antonicci & Miller (1985) and Code et al. (1993). Shortward of 2700 A, the continuum polarization is constant, P is approximately 16%, at a position angle of 97 deg, indicating electron scattering as the mechanism for the polarization. In addition, the narrow-line emission is much less polarized than the continuum, and two broad lines, Mg II lambda lambda 2796, 2804 and C III lambda 1909, are seen in polarized flux Ly-alpha and C IV are not included in our spectral region). The total flux data also indicate that from approximately 2200 A to approximately 3000 A, the spectrum of NGC 1068 is strongly affected by blended Fe II emission. These polarimetry data are explained by the occulation/reflection model proposed by Antonucci & Miller (1985). According to this model, NGC 1068 harbors a Seyfert 1 nucleus which is obscured along the line of sight by an opaque torus. The symmetry axis of the torus is alinged with the radio axis. Radiation from the broad-line region and feature continuum source can escape along the poles of the torus where it is scattered to us. This scattered light receives a partial linear polarization, perpendicular to the symmetry axis of the torus. Our measurements of the relative fluxes and polarized fluxes in the three apertures indicated that the scattering region is spatially extended on a scale of approximatley 1 sec. Also, in the 0.3 sec aperture, and to a lesser extent in the 1.0 sec aperture, the polarization is is somewhat higher, and the position angle somewhat lower, than in largest aperture. Presumably, isolating the central part of the relecting region results in less geometrical cancellation of the polarization and an angle indicative of the location of the innermost scattering paricles.

Antonucci, Robert↗
NASA NTRS2007

Testing in Support of Fission Surface Power System Qualification

The strategy for qualifying a FSP system could have a significant programmatic impact. The US has not qualified a space fission power system since launch of the SNAP-10A in 1965. This paper explores cost-effective options for obtaining data that would be needed for flight qualification of a fission system. Qualification data could be obtained from both nuclear and non-nuclear testing. The ability to perform highly realistic nonnuclear testing has advanced significantly throughout the past four decades. Instrumented thermal simulators were developed during the 1970s and 1980s to assist in the development, operation, and assessment of terrestrial fission systems. Instrumented thermal simulators optimized for assisting in the development, operation, and assessment of modern FSP systems have been under development (and utilized) since 1998. These thermal simulators enable heat from fission to be closely mimicked (axial power profile, radial power profile, temperature, heat flux, etc.) and extensive data to be taken from the core region. For transient testing, pin power during a transient is calculated based on the reactivity feedback that would occur given measured values of test article temperature and/or dimensional changes. The reactivity feedback coefficients needed for the test are either calculated or measured using cold/warm zero-power criticals. In this way non-nuclear testing can be used to provide very realistic information related to nuclear operation. Non-nuclear testing can be used at all levels, including component, subsystem, and integrated system testing. FSP fuels and materials are typically chosen to ensure very high confidence in operation at design burnups, fluences, and temperatures. However, facilities exist (e.g. ATR, HFIR) for affordably performing in-pile fuel and materials irradiations, if such testing is desired. Ex-core materials and components (such as alternator materials, control drum drives, etc.) could be irradiated in university or DOE reactors to ensure adequate radiation resistance. Facilities also exist for performing warm and cold zero-power criticals.

Houts, Mike↗
NASA NTRS2015

An Overview of NASA's Risk of Cardiovascular Disease from Radiation Exposure

The association between high doses of radiation exposure and cardiovascular damage is well established. Patients that have undergone radiotherapy for primary cancers of the head and neck and mediastinal regions have shown increased risk of heart and vascular damage and long-term development of radiation-induced heart disease [1]. In addition, recent meta-analyses of epidemiological data from atomic bomb survivors and nuclear industry workers has also shown that acute and chronic radiation exposures is strongly correlated with an increased risk of circulatory disease at doses above 0.5 Sv [2]. However, these analyses are confounded for lower doses by lifestyle factors, such as drinking, smoking, and obesity. The types of radiation found in the space environment are significantly more damaging than those found on Earth and include galactic cosmic radiation (GCR), solar particle events (SPEs), and trapped protons and electrons. In addition to the low-LET data, only a few studies have examined the effects of heavy ion radiation on atherosclerosis, and at lower, space-relevant doses, the association between exposure and cardiovascular pathology is more varied and unclear. Understanding the qualitative differences in biological responses produced by GCR compared to Earth-based radiation is a major focus of space radiation research and is imperative for accurate risk assessment for long duration space missions. Other knowledge gaps for the risk of radiation-induced cardiovascular disease include the existence of a dose threshold, low dose rate effects, and potential synergies with other spaceflight stressors. The Space Radiation Program Element within NASA's Human Research Program (HRP) is managing the research and risk mitigation strategies for these knowledge gaps. In this presentation, we will review the evidence and present an overview of the HRP Risk of Cardiovascular Disease and Other Degenerative Tissue Effects from Radiation Exposure.

Patel, Zarana S.↗
NASA NTRS1979

Remote monitoring of the Gravelly Run thermal plume at Hopewell and the thermal plume at the Surry Nuclear Power Plant on the James River

On May 17, 1977, a remote sensing experiment was conducted on the James River, Virginia, whereby thermal spectrometer and near-infrared photography data of thermal discharges at Hopewell and the Surry nuclear power plant were obtained by an aircraft for one tidal cycle. These data were used in subsequent investigations into the near field discharge trajectories. For the Gravelly Run thermal plume at Hopewell, several empirical expressions for the plume centerline were evaluated by comparisons of the computed trajectories and those observed in the remote sensing images.

Talay, T. A.↗