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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Distinct requirements for TrkB and TrkC signaling in target innervation by sensory neurons

Signaling by brain-derived neurotrophic factor (BDNF) via the TrkB receptor, or by neurotrophin-3 (NT3) through the TrkC receptor support distinct populations of sensory neurons. The intracellular signaling pathways activated by Trk (tyrosine kinase) receptors, which in vivo promote neuronal survival and target innervation, are not well understood. Using mice with TrkB or TrkC receptors lacking the docking site for Shc adaptors (trkB(shc/shc) and trkC(shc/shc) mice), we show that TrkB and TrkC promote survival of sensory neurons mainly through Shc site-independent pathways, suggesting that these receptors use similar pathways to prevent apoptosis. In contrast, the regulation of target innervation appears different: in trkB(shc/shc) mice neurons lose target innervation, whereas in trkC(shc/shc) mice the surviving TrkC-dependent neurons maintain target innervation and function. Biochemical analysis indicates that phosphorylation at the Shc site positively regulates autophosphorylation of TrkB, but not of TrkC. Our findings show that although TrkB and TrkC signals mediating survival are largely similar, TrkB and TrkC signals required for maintenance of target innervation in vivo are regulated by distinct mechanisms.

Non-NASA Center↗
NASA NTRS2023

Survival of Juvenile Florida Scrub-Jays is Habitat Specific, Positively Correlated With Month and Negatively Correlated With Male Breeder Death

Juvenile survival in birds is difficult to estimate but this vital rate can be an important consideration for management decisions. We estimated juvenile survival of cooperatively breeding Florida Scrub-Jays (Aphelocoma coerulescens) in a landscape degraded by fire suppression and fragmentation using data from marked (n = 325) and unmarked juveniles (n = 1,306) with an integrated hierarchical Bayesian model. To assess the combined analyses, we also analyzed these datasets separately, with a Cormack-Jolly-Seber (CJS) model (marked) and young model (unmarked). Our data consisted of monthly censuses of territorial family groups from Florida Scrub-Jay populations in East Central Florida collected over a 22-yr period. Juvenile survival was estimated from July when young Florida Scrub-Jays begin developing independence to March when they become first year individuals and grouped according to the habitat quality class of their natal territory that were based on shrub height (with intermediate shrub heights being optimal and short and tall shrub heights being suboptimal) and the presence of sandy openings (the preferred open having many sandy openings; closed not having enough). Parameter estimates in the combined analysis were intermediate to the separate analyses. Notable differences among the separate analyses were that suboptimal habitat survival was lower in the unmarked analysis, the unmarked analysis showed a linear effect of time not seen in the marked analysis, and there was an effect of male breeder death in the marked but not unmarked analysis. The combined data analysis provided more inference than did either data set analyzed separately including juveniles in optimal-closed territories unexpectedly had higher survival than those in optimal-open, survival increased through time, and male breeder death had a negative effect on survival. This study suggests that optimal-closed habitat may play an important role in juvenile Florida Scrub-Jay survival perhaps by providing better cover from predators and warrants further investigation for management implications.

Florida Scrub-Jay↗
NASA NTRS2012

Can Terrestrial Microbes Grow on Mars?

The theme for AbSciCon 2012 is "Exploring Life: Past and Present, Near and Far." The conference will address our current understanding of life - from processes at the molecular level to those which operate at planetary scales. Studying these aspects of life on Earth provides an essential platform from which to examine the potential for life on other worlds, both within our solar system and beyond. Mars exhibits a variety of extreme environments characterized by high UV and ionizing radiation flux, low pressure anoxic atmosphere, scarce or absent liquid water, extreme low temperatures, etc. The ability of terrestrial microorganisms to survive and adapt to the Mars environment has profound implications for astrobiology, planetary protection, and Mars life detection missions. At the NASA Ames Synthetic Biology Initiative, we believe that synthetic biology has the potential to revolutionize human space exploration. As such, the initiative is dedicated to applying the tools and techniques of synthetic biology to space exploration and astrobiology. Biological solutions will be invaluable for space exploration because they are not resource intensive, and they are versatile and self-renewing. An understanding of how to work with DNA in an unfavorable environment is paramount to utilizing biological tools on space missions. Furthermore, the ability to adjust life to the parameters of Mars is vital both to discovering what life on Mars might look like, and to using biological tools under such conditions. As a first step, we need an energy-efficient, low cost means of transporting, storing, and protecting genomic DNA, DNA parts, and whole microbial strains. Our goal is to develop and demonstrate viable and superior alternatives to standard DNA storage methods, which can be optimized to the conditions of space exploration, using synthetic biology as a tool. This includes protocols and kit designs for easy and repeatable DNA and strain recovery from protective storage conditions. We are constructing newly engineered genetic parts for different valuable host organisms, designed to increased long-term survival and functional retention. These methods should be applied for DNA and strain storage and transportation. In parallel, we seek inspiration from natural organisms that have developed means for survival in extreme environmental conditions. We are utilizing novel techniques for analysis of lipid biomarkers in the Antarctic Dry Valleys in order to identify resident microbes in the Antarctic soil and permafrost, as well as biomarker fossils of organisms that survived in the valleys in ages past. Through the identification of these life forms, we hope to understand and draw on new biological tools and strategies for synthetic biological applications on Mars.

Rothschild, Lynn↗
NASA NTRS1992

Survival of epiphytic bacteria from seed stored on the Long Duration Exposure Facility (LDEF)

Microbial contamination in American spacecraft has previously been documented, however, potential risks to plants and humans in future space based controlled ecological life support systems (CELSS) have yet to be addressed directly. The current study was designed to determine the survival of microorganisms exposed to the relatively harsh conditions found in low Earth orbit (LEO). Total mean dosage for flight and ground control seeds were 210.2 and 0.9 rads, respectively. Bacteria were isolated by plating samples of seedwashings onto dilute tryptic soy agar. Pure isolates of morphologically distinct bacteria were obtained by standard microbiological procedures. Bacteria were grouped according to colony type and preliminary identification was completed using a fatty acid analysis system. Bacillus spp. were the primary microorganisms that survived on seed during the experiment. Results support the hypothesis that terrestrial microorganisms can survive long periods of time in relatively harsh LEO environments.

Schuerger, Andrew C.↗
NASA NTRS1992

Size effects in models for mechanically-stressed protein crystals and aggregates

As protein aggregates increase in size, they become easier to disrupt mechanically. Using the scaling properties of models proposed to govern protein aggregation, the effect of thermal vibrations and gravity are investigated as deforming forces. For typical protein assemblies made of 30 A proteins, the assembled diameter must remain less than 100-10,000 times the molecular radius to survive in finite thermal and gravity fields. The analysis predicts the following experimental outcomes: (1) reductions in gravitational strain should favor larger protein aggregates; (2) in comparing the aggregate stability of different proteins, the addition of peptide chains should stabilize against thermal strain, but should not affect gravitational strain; (3) critical aggregate sizes should show significant (exponential) sensitivity to cluster geometry, solution preparation and growth conditions. The analysis is extended to consider qualitative size effects in crystal damage during X-ray exposure.

Noever, David A.↗
NASA NTRS2000

NASA GRC Technology Development Project for a Stirling Radioisotope Power System

NASA Glenn Research Center (GRC), the Department of Energy (DOE), and Stirling Technology Company (STC) are developing a Stirling convertor for an advanced radioisotope power system to provide spacecraft on-board electric power for NASA deep space missions. NASA GRC is conducting an in-house project to provide convertor, component, and materials testing and evaluation in support of the overall power system development. A first characterization of the DOE/STC 55-We Stirling Technology Demonstration Convertor (TDC) under the expected launch random vibration environment was recently completed in the NASA GRC Structural Dynamics Laboratory. Two TDCs also completed an initial electromagnetic interference (EMI) characterization at NASA GRC while being tested in a synchronized, opposed configuration. Materials testing is underway to support a life assessment of the heater head, and magnet characterization and aging tests have been initiated. Test facilities are now being established for an independent convertor performance verification and technology development. A preliminary Failure Mode Effect Analysis (FMEA), initial finite element analysis (FEA) for the linear alternator, ionizing radiation survivability assessment, and radiator parametric study have also been completed. This paper will discuss the status, plans, and results to date for these efforts.

Thieme, Lanny G.↗
NASA NTRS1996

Radiation-induced chromosomal instability in human mammary epithelial cells

Karyotypes of human cells surviving X- and alpha-irradiation have been studied. Human mammary epithelial cells of the immortal, non-tumorigenic cell line H184B5 F5-1 M/10 were irradiated and surviving clones isolated and expanded in culture. Cytogenetic analysis was performed using dedicated software with an image analyzer. We have found that both high- and low-LET radiation induced chromosomal instability in long-term cultures, but with different characteristics. Complex chromosomal rearrangements were observed after X-rays, while chromosome loss predominated after alpha-particles. Deletions were observed in both cases. In clones derived from cells exposed to alpha-particles, some cells showed extensive chromosome breaking and double minutes. Genomic instability was correlated to delayed reproductive death and neoplastic transformation. These results indicate that chromosomal instability is a radiation-quality-dependent effect which could determine late genetic effects, and should therefore be carefully considered in the evaluation of risk for space missions.

NASA Center JSC↗
NASA NTRS2007

Recommendations for Exploration Space Medicine from the Apollo Medical Operations Project

Introduction: A study was requested in December, 2005 by the Space Medicine Division at the NASA-Johnson Space Center (JSC) to identify Apollo mission issues relevant to medical operations that had impact to crew health and/or performance. The objective was to use this new information to develop medical requirements for the future Crew Exploration Vehicle (CEV), Lunar Surface Access Module (LSAM), Lunar Habitat, and Advanced Extravehicular Activity (EVA) suits that are currently being developed within the exploration architecture. Methods: Available resources pertaining to medical operations on the Apollo 7 through 17 missions were reviewed. Ten categories of hardware, systems, or crew factors were identified in the background research, generating 655 data records in a database. A review of the records resulted in 280 questions that were then posed to surviving Apollo crewmembers by mail, face-to-face meetings, or online interaction. Response analysis to these questions formed the basis of recommendations to items in each of the categories. Results: Thirteen of 22 surviving Apollo astronauts (59%) participated in the project. Approximately 236 pages of responses to the questions were captured, resulting in 107 recommendations offered for medical consideration in the design of future vehicles and EVA suits based on the Apollo experience. Discussion: The goals of this project included: 1) Develop or modify medical requirements for new vehicles; 2) create a centralized database for future access; and 3) take this new knowledge and educate the various directorates at NASA-JSC who are participating in the exploration effort. To date, the Apollo Medical Operations recommendations are being incorporated into the exploration mission architecture at various levels and a centralized database has been developed. The Apollo crewmembers input has proved to be an invaluable resource, prompting ongoing collaboration as the requirements for the future exploration missions continue to evolve and be refined.

Scheuring, R. a.↗
NASA NTRS1973

Mycological studies housed in the Apollo 16 microbial ecology evaluation device

Survival, death, and phenotype count have yielded variation in the number of fungi recovered from the controls and the flight exposed cuvettes during preliminary analysis of postflight first phase data. Also the preliminary analysis was indicative that fungi exposed to specific space flight conditions demonstrated variable survival rates and phenotype counts. Specific space flight conditions included full light space exposure for Chaetomium globosum, exposure at 300- and 254-nanometer wavelengths for Rhodotorula rubra, full light and 280-nanometer wavelength exposure for Trichophyton terrestre, and 254-nanometer wavelength exposure for Saccharomyces cerevisiae. In general, phenotype counts for flight cuvettes and survival rates for control cuvettes were higher compared with the remaining cuvettes.

Volz, P. A.↗
NASA NTRS1985

Structural analysis model validation using modal test data

The design of a structure which can survive a prescribed dynamic environment is generally based on the use of an analytical model of the structure. The modal test is employed to verify the analytical model. This paper is concerned with the involved validation process, taking into account modal test results from realistic complex spacecraft structural systems as examples to demonstrate the proposed validation procedure. Attention is given to a load analysis model definition, a pretest analysis and test/analysis model, and the correlation parameters. Coordinate transformation is considered along with mode identification, frequency orthogonality, effective mass, mode shape, local kinetic energy, modal force, strain energy, and modal forces by acceleration measurements. Two examples are used to illustrate the procedure.

Chen, J.-C.↗
NASA NTRS1991

Survival of epiphytic bacteria from seed stored on the Long Duration Exposure Facility (LDEF)

This study was designed to determine the survival of microorganisms exposed to the relatively harsh conditions found in low Earth orbit (LEO). Seed of corn, sunflower, canteloupe, zucchini, bean, pea, and pumpkin cultivars were packaged in two 18 x 2.5 cm aluminum tubes; wall thickness for each tube was 1.33 mm. One seed tube was attacked to payload M0006, tray C-2; a second tube was stored at room temperature in a lab on Earth. Five lithium fluoride thermoluminescent dosimetry wafers (TLD-100 wafers) were placed in each aluminum tube. The total mean dosages for flight and ground-control TLD wafers were 210.0 and 0.9 rads, respectively. Seeds were washed for 2 hrs in a phosphate buffered saline solution. Bacteria were isolated by plating samples of the seed-washings onto dilute tryptic soy agar. Pure isolates of morphologically distinct bacteria were obtained by standard microbiological procedures. Bacteria were grouped according to colony-type and preliminary identification was completed using a fatty-acid analysis system. Bacillus spp. were the primary microoganisms that survived on seed during the experiment. Bacterial diversity and relative abundance were similar for the ground flight seed. Bacillus subtilus, B. pumilus, B. licheniformis, B. polymyxa, B. megaterium, and B. pabuli were isolated most frequently. Members of the genera Kurthia, Listeria, Micrococcus, and Arthrobacter were also isolated from flight and ground control seed. Results support the hypothesis that terrestrial microorganisms can survive long periods of time in the relatively harsh LEO environment.

Schuerger, Andrew C.↗
NASA NTRSDate not supplied

Surviving Night at the Lunar South Pole: Exploring Viability of Radioisotope Power Systems for a Crewed Rover

Spacecraft thermal environments tend to be extreme, and the lunar surface is no exception. Future lunar missions aim to explore the lunar south pole region, focusing on permanently shadowed region (PSRs) that may act as cold traps for volatile elements such as hydrogen. By careful selection of landing sites, the longest continuous period devoid of insolation near these PSRs can be reduced significantly from the maximum of 354 hours. Future NASA missions aim to allow exploration of PSRs with a crewed lunar rover. Program architectures may impose a requirement that the vehicle be able to survive repeated lunar nights. Surface temperatures at southern latitudes can be lower than 100K during night, causing significant energy demands heating components above keep-alive temperatures. This adversely affects lunar programs which are heavily mass-constrained. A technical exploration of various radioisotope power systems and their viability, benefits, and drawbacks was completed. An analysis was also performed examining potential vehicular mass reduction and increased lunar night survivability due to the inclusion of radioisotope power sources. The results of this analysis were compared to a baseline non-nuclear vehicle utilizing only batteries and solar arrays for energy storage.

radioisotope↗
NASA NTRS1972

Post impact behavior of mobile reactor core containment systems

The reactor core containment vessel temperatures after impact, and the design variables that affect the post impact survival of the system are analyzed. The heat transfer analysis includes conduction, radiation, and convection in addition to the core material heats of fusion and vaporization under partially burial conditions. Also, included is the fact that fission products vaporize and transport radially outward and condense outward and condense on cooler surfaces, resulting in a moving heat source. A computer program entitled Executive Subroutines for Afterheat Temperature Analysis (ESATA) was written to consider this complex heat transfer analysis. Seven cases were calculated of a reactor power system capable of delivering up to 300 MW of thermal power to a nuclear airplane.

Puthoff, R. L.↗
NASA NTRS1977

The effect of increased gravitational stress on bone

A group of 34 adult male chickens were chronically accelerated over an 18-week period; for the last 4 weeks the surviving animals were subjected to a 3-g field. Males of a similar weight and age were used as static controls. The objective was to evaluate the effects of an altered gravitational state on the physical properties of the tibia bone tested for torsional fracture. Of the 34 initial animals, 15 survived for the entire period and were subjected to analysis. The results suggest that the altered morphology produced by increased gravitational fields does not materially affect bone strength, at least in torsion. Decreased bone diameters were accompanied by increased cortical thickness without change in the bone resistance to torsion. The findings of increased cortical thickness with decreased bone diameter suggest reversal of the usual cellular dynamics of adult bone. Data on bone ash and density failed to reveal any substantial changes in bone mineral or organic content. Histological examination of the cortical bone did not disclose any evidence of pathology.

Riggins, R. S.↗
NASA NTRS1980

Thermal stress response of General Purpose Heat Source (GPHS) aeroshell material

A thermal stress test was conducted to determine the ability of the GPHS aeroshell 3 D FWPF material to maintain physical integrity when exposed to a severe heat flux such as would occur from prompt reentry of GPHS modules. The test was performed in the Giant Planetary Facility at NASA's Ames Research Center. Good agreement was obtained between the theoretical and experimental results for both temperature and strain time histories. No physical damage was observed in the test specimen. These results provide initial corroboration both of the analysis techniques and that the GPHS reentry member will survive the reentry thermal stress levels expected.

Grinberg, I. M.↗
NASA NTRS2000

Hopanoid Biomarker Preservation In Coniform (Phormidium) Stromatolites in Siliceous Thermal Springs, Yellowstone National Park

The microbial communities that characterize modem hydrothermal ecosystems serve as modern analogs to those thought to have dominated early environments on Earth and possibly Mars. The importance of such hydrothermal systems as targets in exploring for an early biosphere on Mars is well established. Such work provides an important basis for the analysis of Martian samples associated with such environments. The surviving molecular structure and isotopic signature of diagnostic lipid biomarkers found as chemical fossils can provide a link between modern bacterially dominated ecosystems and their ancient counterparts. We are interested in the processes involved in the deposition and/or degradation of organic material in moderately thermal, silicifying microbial mats, particularly as this relates to the potential for preservation of some biomarker components known to be more highly resistant to microbial degradation. Several excellent biomarker molecules are associated with the cyanobacteria that dominate these mats, particularly the 2-methylbacteriohopanepolyols (2-MeBHP). These compounds are ubiquitous on Earth and are not easily degraded in nature, a fact documented by their detection in ancient Earth rocks dating back as far as 2,700 Ma.

Jahnke, Linda L.↗
NASA NTRS2005

A Genesis breakup and burnup analysis in off-nominal Earth return and atmospheric entry

The Genesis project conducted a detailed breakup/burnup analysis before the Earth return to determine if any spacecraft component could survive and reach the ground intact in case of an off-nominal entry. In addition, an independent JPL team was chartered with the responsibility of analyzing several definitive breakup scenarios to verify the official project analysis. This paper presents the analysis and results of this independent team.

off-nominal entry↗