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At least 685 records · Page 38
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NASA NTRS1976

Energy storage possibilities of atomic hydrogen

Several recent experiments designed to produce and store macroscopic quantities of atomic hydrogen are discussed. The bulk, ground state properties of atomic hydrogen, deuterium, and tritium systems are calculated assuming that all pair interactions occur via the atomic triplet potential. The conditions required to obtain this system, including inhibition of recombination through the energetically favorable singlet interaction, are discussed. The internal energy, pressure, and compressibility are calculated applying the Monte Carlo technique with a quantum mechanical variational wavefunction. The system studied consisted of 32 atoms in a box with periodic boundary conditions. Results show that atomic triplet hydrogen and deuterium remain gaseous at 0 K; i.e., the internal energy is positive at all molar volumes considered.

Etters, R. D.↗
NASA NTRS1977

Disposal of hypergolic propellants, phase 6 task 4. Disposal pond products

Waste monomethyl hydrazine scrubber liquor, consisting of aqueous solutions containing small amounts of CH4, Cl2, CH3Cl, CH2Cl2, and CHCl3 as well as large amounts of CH3OH is scheduled to be dumped in stabilization ponds along with nitrate and nitrite salt solutions obtained as waste liquors from the N2O4 scrubbers. The wastes are investigated as to the hazardous materials generated by such combinations of items as described as well as the finite lifetime of such materials in the stabilization ponds. The gas liquid chromatograph was used in the investigation. A series of experiments designed to convert nitrate and nitrite salts to the environmentally innocuous N2O and N2 using solar energy is reported. Results indicate that this solar conversion is feasible.

Cohenour, B. C.↗
NASA NTRS1976

Viking on Mars - A preliminary survey

Selection of landing site, observations of Martian topography from orbit, a log of entry into the Martian atmosphere and landing operations, and soil experiments executed at the landing site are recounted. Several photographs overviewing Martian terrain from orbit (1600 to 1900 km up) are shown. Soil sampling and analysis experiments and experiments designed to detect biotic activity (pyrolysis, labeled release of 14-carbon-tagged CO2, gas exchange and vapor chromatography, pyrolytic release) are described and some preliminary results reported. Results on surface geology and chemical composition of the Martian atmosphere are cited.

Young, R. S.↗
NASA NTRS1977

Reanalysis of the Apollo cosmic gamma-ray spectrum in the 0.3 to 10 MeV energy region

Additional data obtained from the Apollo 16 and Apollo 17 missions, together with collateral calculations on background radiation effects, have made possible an improved subtraction of unwanted backgrounds from the diffuse cosmic gamma-ray data previously reported from Apollo 15. As a result, the 1- to 10-MeV spectrum is lowered significantly and connects smoothly with recent data at other energies. The inflection reported previously is much less pronounced and has no more than a 1.5-sigma significance. Sky occultation by the Apollo 16 spacecraft shows the bulk of the 0.3- to 1-MeV radiation to be diffuse. The analysis of spurious backgrounds points to important improvements for future experiments designed for this spectral region.

Trombka, J. I.↗
NASA NTRS1977

A methodology for experimentally based determination of gap shrinkage and effective lifetimes in the emitter and base of p-n junction solar cells and other p-n junction devices

An experimentally based methodology that determines the effective gap shrinkage and lifetime in the emitter of a p-n junction solar cell is described which provides an experimental means for assessing the importance of gap shrinkage relative to that of large recombination rates in the highly doped emitter. The base lifetime is also determined. The methodology pertains to a solar cell after the junction is formed, so that each material parameter determined includes the effects of the processing used in junction fabrication. The methodology consists of strategy and procedures for designing experiments and interpreting data consistently with the physical mechanisms governing device behavior. This careful linking to the device physics uncover the material parameters concealed in the data. To illustrate the procedures, they are applied to an n(+)-p solar cell having substrate resistivity of about 0.1 ohm-cm.

Lindholm, F. A.↗
NASA NTRS1977

Reanalysis of the Apollo cosmic gamma-ray spectrum in the 0.3 to 10 MeV energy region

Additional data obtained from the Apollo 16 and 17 missions, together with collateral calculations on background radiation effects, have made possible an improved subtraction of unwanted backgrounds from the diffuse cosmic gamma ray data previously reported from Apollo 15. As a result, the 1 to 10 MeV spectrum is lowered significantly and connects smoothly with recent data at other energies. The inflection reported previously is much less pronounced and has no more than 1.5 sigma significance. Sky occultation by the Apollo 16 spacecraft shows the bulk of the 0.3 to 1 MeV radiation to be diffuse. The analysis of spurious backgrounds points to important improvements for future experiments designed for this spectral region. A light-weight satellite design can give a fourfold improvement in the signal to noise for such a measurement. Use of an anisotropic central crystal, which spins quickly compared with possible time variations in detector background, would enable sensitive limits to be set on galactic plane and point source contributions.

Dyer, C. S.↗
NASA NTRS1977

Economic consequences of improved temperature forecasts: An experiment with the Florida citrus growers (control group results)

A demonstration experiment is being planned to show that frost and freeze prediction improvements are possible utilizing timely Synchronous Meteorological Satellite temperature measurements and that this information can affect Florida citrus grower operations and decisions. An economic experiment was carried out which will monitor citrus growers' decisions, actions, costs and losses, and meteorological forecasts and actual weather events and will establish the economic benefits of improved temperature forecasts. A summary is given of the economic experiment, the results obtained to date, and the work which still remains to be done. Specifically, the experiment design is described in detail as are the developed data collection methodology and procedures, sampling plan, data reduction techniques, cost and loss models, establishment of frost severity measures, data obtained from citrus growers, National Weather Service, and Federal Crop Insurance Corp., resulting protection costs and crop losses for the control group sample, extrapolation of results of control group to the Florida citrus industry and the method for normalization of these results to a normal or average frost season so that results may be compared with anticipated similar results from test group measurements.

Source record↗
NASA NTRS1978

The cosmic X-ray experiment aboard HEAO-1

The HEAO-1 A-2 experiment, designed to study the large scale structure of the galaxy and the universe at X-ray energies is described. The instrument consists of six gas proportional counters of three types nominally covering the energy ranges of 0.15-3 keV, 1.2-20 keV, and 2.5-60 keV. The two low energy detectors have about 400 sq cm open area each while the four others have about 800 sq cm each. Dual field of view collimators allow the unambiguous determination of instrument internal background and diffuse X-ray brightness. Instrument characteristics and early performance are discussed.

Rothschild, R. E.↗
NASA NTRS1977

Apollo-Soyuz pamphlet no. 3: Sun, stars, in between

The structure of the sun and its surface temperature and brightness are discussed as background for explaining the ASTP joint experiment to photograph the solar corona from Soyuz while the Apollo spacecraft created an artificial eclipse by blocking out the sun. Stellar spectra, stellar evolution, and the Milky Way galaxy are explored in relation to the MA-083 experiment to survey the sky for extreme ultraviolet sources and background radiation. Interstellar gas and the spectrum of helium are discussed in relation to the MA-088 experiment designed to detect interstellar helium entering the solar system and to measure its density and motion.

Page, L. W.↗
NASA NTRS1978

The 70 S monosome accumulation and in vitro initiation complex formation by Escherichia coli ribosomes at 5 C

The inhibition of translation which is observed after shifting Escherichia coli to low temperature was investigated. 70 S ribosomes were isolated from E. coli 8 hours after a shift to 5 C synthesized protein in the absence of added mRNA (i.e., endogenous protein synthesis by 70 S monosomes) at a rate which was three times greater than the rate of endogenous protein synthesis by 70 S ribosomes which were isolated at the time of the shift to 5 C. Calculations based on the rates of endogenous protein synthesis and polyphenylalanine synthesis indicate that 70 S monosomes comprise only 0.1% of the total E. coli 70 S ribosome population after 8 hours at 5 c. Experiments designed to test initiation complex formation on ApUpG or formaldehyde treated MS-2 viral RNA demonstrated that, although the rate of formation of 30 S initiation complexes was not inhibited, the rate of formation of active 70 S initiation complexes, able to react with puromycin, was inhibited to a great extent at 5 C. A model depicting the effects of low temperature on the E. coli translation system is proposed.

Broeze, R. J.↗
NASA NTRS1977

Ultraviolet spectroscopy of the zodiacal light at 20-deg elongation

The zodiacal light at 20-deg elongation and 10-deg inclination was observed by rocket ultraviolet spectrometers at 10-15-A resolution in the spectral range 1200-3200 A during an experiment designed to observe comet Kohoutek (1973 XII). The data were obtained above 180 km when scattered horizon light in the startracker caused a loss of tracking on the comet. Airglow emission due to NO and O(+), identified spectroscopically and by its variation with altitude, is significant between 1900 and 2500 A. Longward of 2600 A, the spectrum matches that of the sun, and the derived value of the color ratio, relative to the visible, is 0.90 + or - 0.20. At 1600 A, an upper limit on the zodiacal-light emission of 0.07 R per A or 7 hundred-millionths erg/s per sq cm/sterad per A is obtained.

Feldman, P. D.↗
NASA NTRS1978

Bidirectional overadaptation achieved by executing leftward or rightward head movements during unidirectional rotation

Nine college age males, all prone to motion sickness, were subjects in an experiment designed to test adaptation to motion. Subjects were placed in a slow rotation room (SRR) for varying intervals and asked to perform headward movements. Degree of adaptation to the SRR was measured in the framework of 3 categories: reduction of ataxia, reduction of oculogyral illusion, and reduction of epiphenomena, which includes symptoms of motion sickness. 'Satisfactory' adaptation was acquired and retained in 7 of the 9 subjects. Tables are presented summarizing the results.

Graybiel, A.↗
NASA NTRS1978

Morphogenetic responses of cultured totipotent cells of carrot /Daucus carota var. carota/ at zero gravity

An experiment designed to test whether embryos capable of developing from isolated somatic carrot cells could do so under conditions of weightlessness in space was performed aboard the unmanned Soviet biosatellite Kosmos 782 under the auspices of the joint United States-Soviet Biological Satellite Mission. Space flight and weightlessness seem to have had no adverse effects on the induction of embryoids or on the development of their organs. A portion of the crop of carrot plantlets originated in space and grown to maturity were not morphologically different from controls.

Krikorian, A. D.↗
NASA NTRS1978

Transverse flat plate heat pipe experiment

This paper describes a Shuttle-launched flight experiment to evaluate the performance of a transverse flat plate heat pipe that serves as an integral temperature control/mounting panel for electronic equipment. A transverse heat pipe is a gas-controlled variable conductance heat pipe that can handle relatively large thermal loads. An experiment designed to flight test the concept over a 6-9 month period is self-sufficient with respect to electrical power, timing sequences, and data storage.

Edelstein, F.↗
NASA NTRS1978

Measurements of the spectrum and energy dependence of X-ray transition radiation

The results of experiments designed to test the theory of X-ray transition radiation and to verify the predicted dependence of the characteristic features of the radiation on the radiator dimensions are presented. The X-ray frequency spectrum produced by 5- to 9-GeV electrons over the range 4 to 30 keV was measured with a calibrated single-crystal Bragg spectrometer, and at frequencies up to 100 keV with an NaI scintillator. The interference pattern in the spectrum and the hardening of the radiation with increasing foil thickness are clearly observed. The energy dependence of the total transition-radiation intensity was studied using a radiator with large dimensions designed to yield energy-dependent signals at very high particle energies, up to E/mc-squared approximately equal to 100,000. The results are in good agreement with the theoretical predictions.

Cherry, M. L.↗
NASA NTRS1978

An experiment to measure interplanetary and solar electrons

The paper describes an ISEE experiment designed to study interplanetary and solar electrons in the energy range between solar wind and galactic cosmic rays. The instrumentation is designed to identify and measure electron fluxes with high energy resolution and high sensitivity from approximately 2 keV to 1 MeV. Angular distributions of these electrons will also be obtained; in addition, energetic ions above 50 keV will be measured. Measurements of particle acceleration in solar flares, solar radio emission, interplanetary particles and shock wave acceleration, and low energy electron propagation are discussed. The instrumentation is described with emphasis on the semiconductor telescopes, the electrostatic analyzer, and the electronics.

Anderson, K. A.↗
NASA NTRS1978

Role of gravity in early development

Centrifuging and clinostat experiments designed to determine the effect of gravity on the development of embryos are reviewed. It appears that the effect of zero gravity on development is negligible.

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