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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Implementation of the NASA AG-Bed Rest Pilot

To examine the efficacy of artificial gravity (AG) as a countermeasure to spaceflight deconditioning, intermittent AG produced by a horizontal short-radius centrifuge (SRC) was utilized on human test subjects deconditioned by bed rest. This poster will present the subject screening, study design, logistics, and implementation of the 41 day pilot study conducted at the University of Texas Medical Branch, Galveston, TX bed rest facility. An extensive screening process was employed to exclude subjects that were dissimilar to the U.S. astronaut population. Candidates underwent a modified U.S. Air Force Class III physical and tests of bone density, cardiovascular fitness, vestibular system function, psychological fitness and centrifuge tolerance. 15 subjects completed the study; 7 control and 8 AG treatment. All provided written consent to volunteer after the nature of the study and its hazards were clearly explained to them. Standard conditions were strictly regulated; Ta = 72 +/- 2 F, humidity = 70 +/- 5%, light/dark cycle 16h:8h. All fluid intake (minimum 28.5 ml/kg body weight/day) and urine output was monitored. Caloric intake was adjusted as necessary to maintain body weight. Carbohydrate, fat and protein were provided in a ratio of 55:30:15. Phosphorus intake was 1400 mg/d, sodium intake was 2 mmol/kg/d, potassium intake was 1.3 mmol/kg/d, and dietary calcium intake was 1000 mg/d. A physician examined each subject daily. During the first 11 days of the study protocol, subjects were ambulatory, but confined to the facility. Subjects participated in multiple baseline tests of bone, muscle, cardiovascular, sensory-motor, immunological, and psychological function. On the 12th day, subjects entered the bed rest phase of the study, during which they were confined to strict 6? head down tilt bed rest for 21 days. Beginning 24 hrs into this period, treatment subjects received 1 hour daily exposures to artificial gravity which was produced by spinning the subjects on a 3.0 m radius SRC. They were oriented radially in the supine position so that the centrifugal force was aligned with their long body axis, and while spinning, they #stood# on a force plate, supporting the centrifugal loading (2.5 g at the feet, 1.0 g at the heart). The subject station allowed free translation over approximately 10 cm to ensure full loading of the lower extremities and to allow for anti-orthostatic muscle contractions. Control subjects were positioned on the centrifuge but did not spin. Following the bed rest phase, subjects were allowed to ambulate again, but remained within the facility for an additional 9 days and participated in multiple follow-up tests of physiological function.

Warren, L. E.↗
NASA NTRS1972

Effect of a 30-day isolation stress on calcium, phosphorus and other excretory products in an unrestrained chimpanzee.

An unrestrained chimpanzee was studied in an isolation chamber and in his home cage environment. The study consisted of 49 urine collection days (14 days pre-, 5 days post- and 30 days of isolation), and then of 10 days in the home cage. Dietary intake, urine and fecal data were obtained. The effect of isolation on various excretory parameters was studied. Urine samples were analyzed for volume, osmolarity, creatinine, creatine, urea-N, 17-hydroxy corticosteroids, VMA, calcium and inorganic phosphorus. One way analyses of variance performed on the urinary excretion parameters showed all except creatinine excretion to vary significantly during periods of the study. The changes observed in calcium and phosphorus were highly significant. The data suggests that the calcium to phosphorus excretion ratio might serve as a physiological stress indicator of Selye's adaptation syndrome (period of resistance).

Sabbot, I. M.↗
NASA NTRS1984

Interactions of the marine phosphorus and carbon cycles

About 30 to 50% of the fluvial P-input to the oceans derives from release of reactive-P from particles during their passage through estuaries. The input is matched by P-removal into three approximately equivalent sink: (1) burial in phosphorites on productive shelves; (2) burial with (org) in the deep-sea; and (3) burial with biogenic calcite in the deep-sea. The P/C burial ratio in these three phases is very different: P/C (org) approximately .004; P/C (CaCO3) approximately .001; and P/C (PHOS) approximately .03. The removal mechanisms are all coupled to primary production in the surface ocean, but the details of the feedback mechanisms controlling the steady-state nutrient and carbon budgets in the sea are doscured by lack of knowledge of how the P/C ratios in the sinks adjust, and how shifts in oceanic nutrients affect oceanic ecology and the relative fraction of biogenic CaCO3 and (org) production.

Froelich, P. N.↗
NASA NTRS2010

Thermal Properties of Lunar Regolith Simulants

Various high temperature chemical processes have been developed to extract oxygen and metals from lunar regolith. These processes are tested using terrestrial analogues of the regolith. But all practical terrestrial analogs contain H2O and/or OH(-), the presence of which has substantial impact on important system behaviors. We have undertaken studies of lunar regolith simulants to determine the limits of the simulants to validate key components for human survivability during sustained presence on the moon. Differential Thermal Analysis (DTA) yields information on phase transitions and melting temperatures. Themo-Gravimetric Analysis (TGA) with mass spectrometric (MS) determination of evolved gas species yields chemical information on various oxygenated volatiles (water, carbon dioxide, sulfur oxides, nitrogen oxides and phosphorus oxides) and their evolution temperature profiles. The DTA and TGAMS studies included JSC-1A fine, NU-LHT-2M and its proposed feed stocks: anorthosite; dunite; HQ (high quality) glass and the norite from which HQ glass is produced. Fig 1 is a data profile for anorthosite. The DTA (Fig 1a) indicates exothermic transitions at 355 and 490 C and endothermic transitions at 970 and 1235 C. Below the 355 C transition, water (Molecular Weight, MW, 18 in Fig 1c) is lost accounting for approximately 0.1% mass loss due to water removal (Fig 1b). Just above 490 C a second type of water is lost, presumably bound in lattices of secondary minerals. Between 490 and the 970 transition other volatile oxides are lost including those of hydrogen (third water type), carbon (MW = 44), sulfur (MW = 64 and 80), nitrogen (MW 30 and 46) and possibly phosphorus (MW = 79, 95 or 142). Peaks at MW = 35 and 19 may be attributable to loss of chlorine and fluorine respectively. Negative peaks in the NO (MW = 30) and oxygen (MW = 32) MS profiles may indicate the production of NO2 (MW = 46). Because so many compounds are volatilized in this temperature range quantification of the mass loss associated with individual species is difficult. Similar information will be presented for the other materials studied in this investigation.

Street, Kenneth↗
NASA NTRS2010

Thermal Properties of Lunar Regolith Simulants

Various high temperature chemical processes have been developed to extract oxygen and metals from lunar regolith. These processes are tested using terrestrial analogues of the regolith. But all practical terrestrial analogs contain H2O and/or OH-, the presence of which has substantial impact on important system behaviors. We have undertaken studies of lunar regolith simulants to determine the limits of the simulants to validate key components for human survivability during sustained presence on the moon. Differential Thermal Analysis (DTA) yields information on phase transitions and melting temperatures. Themo-Gravimetric Analysis (TGA) with mass spectrometric (MS) determination of evolved gas species yields chemical information on various oxygenated volatiles (water, carbon dioxide, sulfur oxides, nitrogen oxides and phosphorus oxides) and their evolution temperature profiles. The DTA and TGAMS studies included JSC-1A fine, NU-LHT-2M and its proposed feed stocks: anorthosite; dunite; HQ (high quality) glass and the norite from which HQ glass is produced. Fig 1 is a data profile for anorthosite. The DTA (Fig 1a) indicates exothermic transitions at 355 and 490 C and endothermic transitions at 970 and 1235 C. Below the 355 C transition, water (Molecular Weight, MW, 18 in Fig 1c) is lost accounting for approximately 0.1% mass loss due to water removal (Fig 1b). Just above 490 C a second type of water is lost, presumably bound in lattices of secondary minerals. Between 490 and the 970 transition other volatile oxides are lost including those of hydrogen (third water type), carbon (MW = 44), sulfur (MW = 64 and 80), nitrogen (MW 30 and 46) and possibly phosphorus (MW = 79, 95 or 142). Peaks at MW = 35 and 19 may be attributable to loss of chlorine and fluorine respectively. Negative peaks in the NO (MW = 30) and oxygen (MW = 32) MS profiles may indicate the production of NO2 (MW = 46). Because so many compounds are volatilized in this temperature range quantification of the mass loss associated with individual species is difficult. Similar information will be presented for the other materials studied in this investigation.

Street, Kenneth↗
NASA NTRS2015

Recognizing Sulfate and Phosphate Complexes Adsorbed onto Nanophase Weathering Products on Mars

Nanophase weathering products (i.e., secondary phases that lack long-range atomic order) have been recognized on the martian surface via orbital observations and in-situ measurements from landed missions. Allophane, a poorly crystalline, hydrated aluminosilicate, has been identified at the regional scale in models of thermal-infrared (TIR) data from the Thermal Emission Spectrometer (TES) and at the local scale from visible/near-IR (VNIR) data from the Compact Reconnaissance Impact Spectrometer for Mars (CRISM) instrument and phase calculations of Alpha Particle X-ray Spectrometer (APXS) data of rocks encountered by the Mars Exploration Rovers (MER) Spirit and Opportunity. Nanophase iron oxides (npOx) have been recognized in rocks and soils measured by the Mössbauer Spectrometer on Spirit and Opportunity. Furthermore, analyses of X-ray diffraction data measured by the CheMin instrument onboard the Mars Science Laboratory rover Curiosity indicate rock and soil samples are comprised of approx. 20-50 wt.% X-ray amorphous materials. Chemical measurements by landed missions indicate the presence of sulfur and phosphorus in martian rocks in soils, and APXS data from Gusev crater demonstrate abundances of up to approx. 5 wt.% P2O5 and approx. 30 wt.% SO3. However, the speciation of phosphorus and sulfur is not always evident. On Earth, phosphate and sulfate anions can be chemisorbed onto the surfaces of nanophase weathering products. This process may also occur on Mars, and calculations of the composition of the amorphous component at Gale crater using CheMin mineral models and APXS data show that amorphous material is enriched in volatiles, including S. Here, we examine the ability to detect chemisorbed sulfate and phosphate complexes by analyzing sulfate- and phosphate-adsorbed nanophase weathering products using instruments similar to those on landed and orbital missions.

Rampe, E. B.↗
NASA NTRS1980

The combined effects of ionizing radiation and weightlessness on calcium and phosphorus content in the mineral fraction of the calcified tissues in the rat skeleton

Phosphorus and calcium content in the ash from skeletal bones (ribs, scapula, vertebra, and crus) of 30 rats exposed to ionizing radiation (800 rads) on the flight of the Kosmos 690 biosatellite was studied. A 10 percent decrease in ash content coefficient and 29 percent decrease in phosphorus content was found immediately after the flight, and a 9 percent decrease in phosphorus content persisted after 26 days of readaptation to terrestrial conditions.

Prokhonchukov, A. A.↗
NASA NTRS1985

Role of carbonic anhydrase in bone - Plasma acetazolamide concentrations associated with inhibition of bone loss

The effects of acetazolamide and benzolamide on bone formation are examined. Solutions of acetazolamide and benzolamide with 1 M THAM/tris(hydromethyl)aminoethane/ or without 1 M THAM were injected subcutaneous with a minipump and into the food of Sprague-Dawley rats. The data reveal that for 8-day and 12-day infusions only acetazolamide combined with 1 M THAM caused any reduction in bone loss and there were no changes in body weights, food consumption and plasma calcium and phosphorus values. Following 8 days of infusion of acetazolamide with 1 M THAM at infusion rates of 0.5, 5.0, and 50 micrograms/hr, no reduction was detected at 0.5 microgram/hr, a 30 percent reduction occurred at 5.0 micrograms/hr and a 49 percent decrease at 50 micrograms/hr. In the benzolamide experiment it was observed that 0.5 percent of the solution in the food caused no reduction in bone loss; however, infusions with benzolamide plus 1 M THAM resulted in a bone loss reduction of 30 percent at 5.0 micrograms/hr, and a 49 percent decrease at 50 micrograms/hr. Acetazolamide levels in the plasma at 50 micrograms/hr doses are calculated as ranging from 99 ng/ml-223 ng/ml and as 46 ng/ml at 5 micrograms/hr doses.

Kenny, A. D.↗
NASA NTRS1971

Absolute transition probabilities of phosphorus.

Use of a gas-driven shock tube to measure the absolute strengths of 21 P I lines and 126 P II lines (from 3300 to 6900 A). Accuracy for prominent, isolated neutral and ionic lines is estimated to be 28 to 40% and 18 to 30%, respectively. The data and the corresponding theoretical predictions are examined for conformity with the sum rules.-

Miller, M. H.↗
NASA NTRS1986

Process research of non-Czochralski silicon material

Simultaneous diffusion of liquid precursors containing phosphorus and boron into dendritic web silicon to form solar cell structures was investigated. A simultaneous junction formation techniques was developed. It was determined that to produce high quality cells, an annealing cycle (nominal 800 C for 30 min) should follow the diffusion process to anneal quenched-in defects. Two ohm-cm n-base cells were fabricated with efficiencies greater than 15%. A cost analysis indicated that the simultansous diffusion process costs can be as low as 65% of the costs of the sequential diffusion process.

Campbell, R. B.↗
NASA NTRS1994

Effects of Growth Hormone/IGF-I and Exercise on Unloaded Bones

Growth hormone (GH) and insulin-like growth factor-I (IGF-I) in combination with exercise prevent muscle atrophy induced by unloading in the tail-suspension rat model for space flight (Gosselink et al, FASEB J 1994). This study evaluated the effects of these treatments on bone. Hypophysectomized rats were suspended (S) and treated with 1mg/kg/day CH plus IGF-I (H) or vehicle (Sal) daily by injection and exercised (Ex) by 3 climbs up a 1m ladder carrying a load equal to 30% the initial body weight (BW) 3x/day for 10 days. Tibial epiphysis (Epi) widths were measured by micrometry and femoral Bone Mineral Content (fBMC) in excised femurs by DEXA (Lunar DPX-L). Serum calcium (Ca) and phosphorus (Pi) were measured by COBAS Autoanalyzer (Roche Diag.). Ambulatory (Amb)-H treated rats showed growth rates of 6.6+-0.9 g/day, similar to S-H-Ex and higher than S-H (3.210.6, p less than 0.05) and S-Sal (-0.711.0, p less than 0.05). Epi widths were 10% lower in S-Sal, and S-Sal-Ex, and increased 100% in all H groups. fBMC was less in S than Amb, only when all S groups are compared to both Amb groups (p less than 0.03). H treatment increased fBMC (p less than 0.05) but reduced fBMC/100g BW in all H groups (p less than 0.001). The reduced density of H bone cannot be attributed to low circulating Ca. and Pi since they were higher in H than Sal (p less than 0.001). H treatment for 10 days in doses sufficient to support normal growth in BW failed to produce normal Epi widths or fBMC, even when combined with exercise. The suspension effect observed in Epi widths was not corrected by H or Ex alone, but was improved by H plus a This regimen. although effective in preventing muscle atrophy, failed to return bone measures, Epi widths and fBMC, to normal.

Harper, J. S.↗
NASA NTRS1973

Plasma electrolytes, pH, and ECG during and after exhaustive exercise.

Ten men worked on a bicycle ergometer at increasing work loads to exhaustion in 15 min. Each performed one test breathing air and another with added CO2 in random sequence. ECG was recorded during exercise and for 30 min of recovery. Arterial samples for blood gases, pH, and electrolytes were drawn at rest, in the last minute of exercise and at 1, 4, 10, 20, and 30 min thereafter. A striking increase in the amplitude of T and P waves was observed reaching a maximum in the first 2 min after exercise. All electrolytes measured were increased at the end of exercise, most markedly potassium (60%) and phosphorus (53%). Potassium dropped faster than all others to below resting values in 4 min coinciding with the lowest levels in plasma bicarbonate. ECG alterations were not closely related in time with any single factor such as potassium, but appeared to reflect an interaction of the transient mineral and acid-base imbalance during and immediately following exhaustive exercise.

Coester, N.↗
NASA NTRSDate not supplied

Timing, Abundance, and Spatial Extent of Initial Magmatism on the Moon Explained By Cumulate Mantle Overturn

We have recently quantified the timing, abundance, and spatial extent of lower mantle melting induced by cumulate overturn on the Moon through a series of 3D geodynamical models. Our dynamical modeling indicates that overturn of thin (~30-50 km) and weak ilmenite-bearing cumulates (IBC) triggers a rapid, short-lived, and widespread period of lower mantle melting which reproduces the key geochronological, volume, and spatial characteristics associated with the onset of secondary magmatism on the Moon (Figs. 1,2), and without energy contributions from KREEP (potassium, rare earth elements, phosphorus, radiogenic U, Th). Within the guiding paradigms of global differentiation via magma ocean crystallization and subsequent cumulate mantle overturn, our model provides explanation for near contemporaneous primary and secondary crust production constrained by geochronology of returned lunar samples and meteorites. In this abstract, we discuss our results in context with several intricacies of lunar chronology including models of a long-lived magma ocean, the hypothesis that mantle overturn was induced by the giant South Pole-Aitken basin forming impact, and ancient lunar zircon.

T. C. Prissel↗
NASA NTRS2020

The Chlorine-Isotopic Composition of Lunar KREEP From Magnesian-Suite Troctolite 76535

We conducted in-situ Cl isotopic measurements of apatite within intercumulus regions and within a holocrystalline olivine-hosted melt inclusion in magnesian-suite troctolite 76535 from Apollo 17. These data were collected to place constraints on the Cl-isotopic composition of the last liquid to crystallize from the lunar magma ocean (i.e., urKREEP, named after its enrichments in incompatible lithophile trace elements like potassium, rare earth elements, and phosphorus). The apatite in the olivine-hosted melt inclusion and within the intercumulus regions of the sample yielded Cl-isotopic compositions of 28.3 ± 0.9 ‰ (2σ) and 30.3 ± 1.1 ‰ (2σ), respectively. The concordance of these values from both textural regimes we analyzed indicates that the Cl-isotopic composition of apatites in 76535 likely represents the Cl-isotopic composition of the KREEP-rich magnesian-suite magmas. Based on the age of 76535, these results imply that the KREEP reservoir attained a Cl-isotopic composition of 28–30 ‰ by at least 4.31 Ga, consistent with the onset of Cl-isotopic fractionation at the time of lunar magma ocean crystallization or shortly thereafter. Moreover, lunar samples that yield Cl-isotopic compositions higher than the value for KREEP are likely affected by secondary processes such as impacts and/or magmatic degassing. The presence of KREEP-rich olivine-hosted melt inclusions within one of the most pristine and ancient KREEP-rich rocks from the Moon provides a new opportunity to characterize the geochemistry of KREEP. In particular, a broader analysis of stable isotopic compositions of highly and moderately volatile elements could provide an unprecedented advancement in our characterization of the geochemical composition of the KREEP reservoir and of volatile-depletion processes during magma ocean crystallization, more broadly.

Francis M. McCubbin↗
NASA NTRS1972

The effect of phosphorus on the formation of the Widmanstaetten pattern in iron meteorites.

Use of a combination of a revised Fe-Ni-P phase diagram and laboratory cooling experiments on Fe-Ni-P alloys to determine the effect of P on the formation of the Widmanstaetten pattern. From the phase diagram results, two reaction paths were found for the formation of kamacite (1) gamma (taenite) yields alpha (kamacite) + gamma (taenite) and (2) gamma yields gamma + Ph /phosphide, (FeNi)3P/ yields alpha + gamma + Ph. The reaction path gamma yields alpha + gamma is preferred at low P contents, while at higher P contents and at Ni contents greater than 7.0 wt.%, the reaction path gamma yields gamma + Ph yields alpha + gamma + Ph controls the formation of kamacite. Above 7 wt.% Ni, the effect of P on the equilibrium nucleation temperature of kamacite is quite small, less than about plus or minus 30 C with respect to the Fe-Ni binary diagram. The addition of P (greater than 0.1 wt.%) to meteorites promotes nucleation of kamacite at higher temperatures and effectively lowers the amount of undercooling necessary to nucleate kamacite homogeneously. Ni has just the opposite effect, decreasing the temperature of nucleation and increasing the amount of undercooling. It is concluded that significant amounts of undercooling, 50 to 100 C, are necessary for the nucleation of the Widmanstaetten structure in meteorites, and that chemical equilibrium is maintained in the various phases of slowly cooled iron meteorites to 650 C and probably to 600 C.

Goldstein, J. I.↗