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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 37 records · Page 2
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NASA NTRS2016

Fate of Water Pumped from Underground and Contributions to Sea Level Rise

The contributions from terrestrial water sources to sea-level rise, other than ice caps and glaciers, are highly uncertain and heavily debated1-5. Recent assessments indicate that groundwater depletion (GWD) may become the most important positive terrestrial contribution6-10 over the next 50 years, probably equal in magnitude to the current contributions from glaciers and ice caps6. However, the existing estimates assume that nearly 100% of groundwater extracted eventually ends up in the oceans. Owing to limited knowledge of the pathways and mechanisms governing the ultimate fate of pumped groundwater, the relative fraction of global GWD that contributes to sea-level rise remains unknown. Here, using a coupled climate-hydrological model11,12 simulation, we show that only 80% of GWDends up in the ocean. An increase in runo to the ocean accounts for roughly two-thirds, whereas the remainder results from the enhanced net flux of precipitation minus evaporation over the ocean, due to increased atmospheric vapour transport from the land to the ocean. The contribution of GWD to global sea-level rise amounted to 0.02 (+/- 0.004)mm yr(sup-1) in 1900 and increased to 0.27 (+/- 0.04)mm yr(sup-1) in 2000. This indicates that existing studies have substantially overestimated the contribution of GWD to global sea-level rise by a cumulative amount of at least 10 mm during the twentieth century and early twenty-first century. With other terrestrial water contributions included, we estimate the net terrestrial water contribution during the period 1993-2010 to be +0.12 +/-0.04)mm yr(sup-1), suggesting that the net terrestrialwater contribution reported in the IPCC Fifth Assessment Report report is probably overestimated by a factor of three.

water↗
NASA NTRS2016

The Fate of Trace Contaminants in a Crewed Spacecraft Cabin Environment

Trace chemical contaminants produced via equipment offgassing, human metabolic sources, and vehicle operations are removed from the cabin atmosphere by active contamination control equipment and incidental removal by other air quality control equipment. The fate of representative trace contaminants commonly observed in spacecraft cabin atmospheres is explored. Removal mechanisms are described and predictive mass balance techniques are reviewed. Results from the predictive techniques are compared to cabin air quality analysis results. Considerations are discussed for an integrated trace contaminant control architecture suitable for long duration crewed space exploration missions.

Perry, Jay L.↗
NASA NTRS2017

The Incidence and Fate of Volatile Methyl Siloxanes in a Crewed Spacecraft Cabin

Volatile methyl siloxanes (VMS) arise from diverse, pervasive sources aboard crewed spacecraft ranging from materials offgassing to volatilization from personal care products. These sources lead to a persistent VMS compound presence in the cabin environment that must be considered for robust life support system design. Volatile methyl siloxane compound stability in the cabin environment presents an additional technical issue because degradation products such as dimethylsilanediol (DMSD) are highly soluble in water leading to a unique load challenge for water purification processes. The incidence and fate of VMS compounds as observed in the terrestrial atmosphere, water, and surface (soil) environmental compartments have been evaluated as an analogy for a crewed cabin environment. Volatile methyl siloxane removal pathways aboard crewed spacecraft are discussed and a material balance accounting for a DMSD production mechanism consistent with in-flight observations is presented.

Perry, Jay L.↗
NASA NTRSDate not supplied

CDKN1A/P21’S Role in Osteoprogenitor Fate Regulation in Response to Mechanical Loading: A Single Cell Resolution Investigation

Forces generated by gravity in load-bearing tissues such as bone marrow promote stem cell-based tissue-regenerative processes by increasing proliferation and differentiation of tissue progenitors. Conversely, in microgravity, mouse bone marrow mesenchymal and hematopoietic precursors down-regulate differentiation markers and up-regulate stemness maintenance genes. During microgravity, these transcriptomic changes are associated with Cdkn1a overexpression in osteoprogenitors, and further the homozygous deletion of the CDKN1a gene in the mouse model results in elevated stem-cell based regeneration of severed digits and ear-hole punches. In this work we sought to test the hypothesis that gravity mechanotransduction regulates mesenchymal stem cell derived osteoprogenitor based osteogenesis by modulating proliferation and differentiation fates at specific cell cycle stages via a p21/CDKN1a-regulated mechanism.. To test our hypothesis, we isolated primary mouse bone marrow osteoprogenitors from Cdkn1a-/- (null) or wildtype mice, cultured the cells for 7-days unloaded in osteogenic differentiation media, to allow commitment of the adherent cell population, and subsequently, cultured an additional 48-hours under cyclic stretch or static control loading conditions. After 48-hours of dynamic mechanical loading, we used a 10X Genomics Chromium/Single Cell controller to generate bar-coded single cell Illumina libraries and sequenced expressomes for 6,000 static control and 6,000 cyclic stretch cells for each genotype. Stage-specific single cell analyses show Cdkn1a-/- osteogenic cultures are more differentiated with fewer progenitors, and that cyclic stretch further promotes the conversion of progenitors to osteoblasts in both wildtype and Cdkn1a-/- backgrounds. The proportion of late mineralizing osteoblasts doubled in Cdkn1a-/- cultures, but is not affected by load. Finally, single cell expression of Cdkn1a, in the wildtype cells, is most strongly suppressed by cyclic stretch both in early and late osteoblasts, and minimally in the progenitor population. Collectively, our results support the hypothesis that Cdkn1a constitutively plays a mechano-reversible anti-proliferative role during stem cell-based bone tissue regeneration, and suggests a new molecular target to counter regenerative deficits caused by disuse.

Eduardo Almeida↗
NASA NTRS1974

Ecological effects and environmental fate of solid rocket exhaust

Specific target processes were classified as to the chemical, chemical-physical, and biological reactions and toxic effects of solid rocket emissions within selected ecosystems at Kennedy Space Center. Exposure of Citris seedlings, English peas, and bush beans to SRM exhaust under laboratory conditions demonstrated reduced growth rates, but at very high concentrations. Field studies of natural plant populations in three diverse ecosystems failed to reveal any structural damage at the concentration levels tested. Background information on elemental composition of selected woody plants from two terrestrial ecosystems is reported. LD sub 50 for a native mouse (peromysous gossypinus) exposed to SRM exhaust was determined to be 50 ppm/g body weight. Results strongly indicate that other components of the SRM exhaust act synergically to enhance the toxic effects of HCl gas when inhaled. A brief summary is given regarding the work on SRM exhaust and its possible impact on hatchability of incubating bird eggs.

Nimmo, B.↗
NASA NTRS1975

Fate in humans of the plasticizer, DI (2-ethylhexyl) phthalate, arising from transfusion of platelets stored in vinyl plastic bags

Platelet concentrates were shown to contain 18-38 mg/100 ml of a phthalate plasticizer (DEHP) which arose by migration from the vinyl plastic packs in which the plateletes were prepared and stored. Transfusion of these platelets into 6 adult patients with leukemia resulted in peak blood plasma levels of DEHP ranging from 0.34 - 0.83 mg/100 ml. The blood levels fell mono-exponentially with a mean rate of 2.83 percent per minute and a half-life of 28.0 minutes. Urine was assayed by a method that would measure unchanged DEHP as well as all phthalic acid-containing metabolities. In two patients, at most 60 and 90% of the infused dose, respectively, was excreted in the urine collected for 24 hours post-transfusion. These estimates, however, could be high due to the simultaneous excretion of DEHP remaining from previous transfusions or arising from uncontrolled environmental exposures.

Rubin, R. J.↗
NASA NTRS1976

Martian volatiles - Their degassing history and geochemical fate

Implications of the Ar-40 content of the Martian atmosphere for Martian volatile history are considered. It is assumed that the potassium content of both Mars and earth is similar to that of normal chondrites, that Mars possesses a water content similar to that of normal chondrites, and that earth's water content is equal to or somewhat less than Mars'. A simple earth-analogous Mars degassing model is outlined in which the Martian surface volatile inventory is presumed to be identical to earth's, but scaled to the smaller mass and surface area of Mars. Physical storage of volatiles in the Martian regolith is examined along with the occurrence of volatile-containing mineral phases in the regolith, exospheric escape as a massive volatile sink, and the effect of the time history of degassing on the surface volatile inventory. Implications of earth's degassing history for Mars are assessed, and models describing the overall intensity of Mars degassing are presented. It is concluded that the maximum amounts of water and other volatiles that could be stored in the Martian regolith are marginally compatible with those required by the earth-analogous model, although a lower atmospheric Ar-40 concentration and regolith volatile inventory would be easier to reconcile with observational constraints.

Fanale, F. P.↗
NASA NTRS1978

What is the fate of interplanetary dust

The following general picture of the interplanetary dust is presented: (1) size distribution; (2) spatial distribution; (3) composition; (4) dynamics; and (5) origin. The solar probe mission provides a unique opportunity to study the evolution of the interplanetary dust and its eventual destruction near the sun. Two destructive processes (fragmentation and vaporization) of interplanetary dust are discussed.

Hanner, M. S.↗
NASA NTRS1980

The fate of the downgoing slab - A study of the moment tensors from body waves of complex deep-focus earthquakes

Two large, complex deep-focus earthquakes are analyzed, using body waves, to determine the relative locations and equivalent forces of the component events. Details of the source mechanism determination are given, with special emphasis on the means of comparing results for double-couple and more general models. The formalism includes a description of a method for calculating the confidence ellipses around the principal axes of the moment tensor. An interpretation of the results suggests that the mechanism of deep-focus earthquakes is controlled by the buoyancy of the slab and the change in viscosity at the 650 km discontinuity.

Strelitz, R. A.↗
NASA NTRS1980

The fate of the hydroxyl radical in the earth's primitive atmosphere and implications for the production of molecular oxygen

Behavior of the hydroxyl radical produced by the photolysis of water vapor in the earth's early atmosphere is examined. Because of the substantial OH radical reactivity with trace species (CO, HCl, SO2, H2S, NH3, and CH4) the formation of molecular oxygen may be prevented, even at a trace species mixing ratio. The photolysis rate of H2O, with corrections for hydrogen exospheric escape, is capable of describing the oxidation of the atmosphere and crust but may not be used to determine the rate of molecular oxygen generation without consideration of the various OH-trace species reactions.

Vander Wood, T. B.↗
NASA NTRS1983

Fate of very low-mass secondaries in accreting binaries and the 1.5-ms pulsar

It is shown analytically that the canonical stability postulate for low-mass binaries can be inaccurate when the secondary component mass is less than 0.02 solar mass. The adjustable evolutionary parameter h is demonstrated to have a value (in terms of the mass flow effects) of 2/3, less than which catastrophic instability and tidal disruption of the secondary might occur. The disrupted secondary would be reduced to a remnant significantly smaller in mass than the earth, and not be observable visually. Additionally, close passage by another star could accelerate or initiate the process. The model is applicable to the pulsar binary PSR1937+214, and is noted not to conflict with spin-up theories.

Ruderman, M. A.↗
NASA NTRS1986

A simulation analysis of the fate of phytoplankton within the mid-Atlantic bight

A time-dependent, three-dimensional simulation model of wind-induced changes of the circulation field, of light and nutrient regulation of photosynthesis, of vertical mixing as well as algal sinking, and of herbivore grazing stress, is used to analyze the seasonal production, consumption, and transport of the spring bloom within the mid-Atlantic Bight. The particular case (c) of a 58-day period in February-April 1979, simulated primary production, based on both nitrate and recycled nitrogen, with a mean of 0.62 g C sq m/day over the whole model domain, and an export at the shelf-break off Long Island of 2.60 g ch1 sq m/day within the lower third of the water column. About 57% of the carbon fixation was removed by herbivores, with 21% lost as export, either downshelf or offshore to slope waters, after the first 58 days of the spring bloom. Extension of the model for another 22 days of case (c) increased the mean export to 27%, while variation of the model's parameters in 8 other cases led to a range in export from 8% to 38% of the average primary production. Spatial and temporal variations of the simulated albal biomass, left behind in the shelf water column, reproduced chlorophyll fields sensed by satellite, shipboard, and in situ instruments.

Walsh, J. J.↗
NASA NTRS1987

The fate of the earth in the red giant envelope of the sun

The effect on the earth of entering the red giant envelope of the future sun is studied. Employing a 30-zone red giant model, the earth orbital decay timescale, neglecting ablation/vaporization, is determined to be of the order of 200 years, rendering earth survival impossible. The effects of ablation/vaporization processes are found to increase the ballistic coefficient of earth, thereby setting the 200-year decay timescale as an upper limit.

Goldstein, J.↗
NASA NTRS1990

Toward understanding the fate of dust lost from the Martian satellites

The dynamics of small dust grains ejected from the Martian satellites is investigated, considering both the solar radiation perturbation and electromagnetic forces since the grains move in a magnetized plasma. Lorentz forces can dramatically change the nature of the trajectories, resulting in, for example, prolonged lifetimes for submicron-sized grains moving through an idealized model. It is suggested that a permanent, nonuniform and time-dependent dust halo of grains predominantly around 0.1 micron may exist about Mars.

Horanyi, M.↗