Search NASA⌕ Search

SEARCH · Search NASA

Results for “NH3”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Spatially resolved reflectivities of Jupiter during the 1976 opposition

Spatially resolved absolute reflectivities of several regions of the Jovian disk in the wavelength region 3000 to 10760 A are presented. Spectra were obtained of the central meridian and limbs of the Equatorial Region, North Equatorial Belt, and North Tropical Zone. Equivalent widths of several CH4 and NH3 bands are measured. The spatial variations of continuum reflectivity and absorption band profiles are shown in various ratio spectra.

Woodman, J. H.↗
NASA NTRS1979

On the nature of the blue and ultraviolet absorption in the Jovian atmosphere

Spatially resolved reflectivities from 3000 to 6600 A of three positions from the center to the limb of the Jovian Equator, North Equatorial Belt, and North Tropical Zone are analyzed to determine the vertical distribution and wavelength dependence of various sources of blue and uv absorption. Six different models of the distribution of absorbing dust particles are examined. In each model, the variation of dust optical depth and cloud single-scattering albedo are determined. Only those models having dust above the upper NH3 cloud layer will fit the data. The high altitude dust distribution is approximately uniform over the three regions examined. The contrast in reflectivity of the belts and zones may be modeled by a different cloud single-scattering albedo in the different regions.

Cochran, W. D.↗
NASA NTRS1979

The role of phosphorus in the upper atmosphere of Jupiter

The reaction of elemental phosphorus and H atoms to form PH3 was observed and should be a major factor in the recycling of PH3 in the stratosphere of Jupiter. The formation of PH3 in this manner should predominate at high altitudes where, due to the very low temperatures, reactions that require higher activation energies than these atom reactions cannot occur. At lower altitudes, in the troposphere, the rapid formation of H atoms from the strong absorption of light by NH3 will contribute to phosphine production also in this same manner. Recent experiments have also shown that elemental phosphorus reacts readily with aqueous ammonia to form PH3. This reaction may also be important in the recycling of PH3 in the upper troposphere of Jupiter if water-ammonia clouds, as had been previously thought, exist. Considerations of the coloration of the Great Red Spot have been made based upon the nature of the phosphorus obtained by decomposition of the phosphine.

Howland, G. R.↗
NASA NTRS1978

Design theory and performance of cryogenic molecular adsorption refrigeration systems

Closed-cycle operation of molecular adsorption refrigeration systems (MARS) has been demonstrated by using thermally cycled zeolites to adsorb and desorb various gases under pressures of 20-60 atm. This paper develops three aspects of the design theory: the physical theory of molecular adsorption of small molecules such as A, N2, N2O and NH3, the design relations for closed-cycle flow for three or more compressors, and the coefficient of performance. This work is intended to demonstrate nonmechanical gas compression for various cryogenic gases than can compete with mechanical systems with a different mix of advantages and disadvantages.

Hartwig, W. H.↗
NASA NTRS1979

The origins and early histories of planetary atmospheres

Ancient dry river beds detected on Mars by the Viking spacecraft suggest that the early Martian atmosphere may have been much more massive than at present. Degassing of a late-accreting, volatile-rich veneer may account for the primitive atmosphere of both Mars and earth. The primitive earth atmosphere could have produced a greenhouse effect sufficient to maintain temperatures above 273 K without NH3 and with low solar luminosity. The Venutian veneer, according to preliminary Pioneer results, was probably richer in noble gases relative to carbon and nitrogen than were the Martian and earth veneers. The highly evolved atmosphere of Titan, the large satellite of Saturn, is also discussed.

Owen, T.↗
NASA NTRS1979

Infrared observations of the Jovian system from Voyager 1

The infrared spectroscopy and radiometry investigation has obtained spectra of Jupiter and its satellites between approximately 180 and 2500 kayser with a spectral resolution of 4.3 kayser. The Jupiter spectra show clear evidence of H2, CH4, C2H2, C2H6, CH3D, NH3, PH3, H2O, and GeH4. A helium concentration of 0.11 plus or minus 0.03 by volume is obtained. Meridional temperature cross sections show considerable structure. At high latitudes, the stratosphere is warmer in the north than in the south. The upper troposphere and lower stratosphere are locally cold over the Great Red Spot. Amalthea is warmer than expected. Considerable thermal structure is observed on Io, including a relatively hot region in the vicinity of a volcanic feature.

Hanel, R.↗
NASA NTRS1979

Abundance of organic compounds photochemically produced in the atmospheres of the Outer Planets

Organic photochemical syntheses in the Jovian atmosphere was simulated by irradiating, at 147 nm, gaseous mixtures of methane and ammonia with varying amounts of hydrogen. Some results relevant to the photochemistry of the Jupiter atmosphere at several tens of kilometers above the clouds were obtained: (1) a favorable effect of the pressure of high amounts of H2 on the yield of hydrocarbon synthesis when NH3 is mixed with CH4; (2) a very low yield of synthesis of unsaturated hydrocarbons in such conditions; and (3) the possibility of formation of detectable amounts of HCN and CH3CN.

Raulin, F.↗
NASA NTRS1979

The synthesis of complex molecules in interstellar clouds

The abundances of polyatomic molecules that may be formed by CH3(+) radiative association reactions in dense interstellar molecular clouds are reevaluated. The formation of a number of complex interstellar molecules via radiative association reactions involving ionic precursors other than CH3(+) is also investigated; these additional precursors include CH3O(+), CH3CO(+), CH5(+), HCO(+), NO(+), H2CN(+), C2H2(+), and NH3(+). The results indicate that the postulated gas-phase ion-molecule radiative association reactions could potentially explain the synthesis of most of the more complex species observed in dense molecular clouds such as Sgr B2. It is concluded, however, that in order to be conclusive, laboratory data are needed to show whether or not these reactions proceed at the required rates at low temperatures.

Huntress, W. T., Jr.↗
NASA NTRS1979

Identification of gaseous SO2 and new upper limits for other gases on Io

The identification of gaseous sulfur dioxide on Io by Voyager 1 is reported, and preliminary upper limits for other atmospheric gases are presented. Averaged spectra taken by the Voyager IRIS experiment in the range of 1,000 to 1,200/cm are interpreted as containing three fundamental sulfur dioxide bands, with intensities most nearly corresponding to an atmospheric model with a sulfur dioxide abundance of 0.2 cm atm. Upper limits for COS, CS2, SO3, H2S, CO2, O3, N2O, H2O, CH4, NH3 and HC1, not detected in the spectra, were calculated on the basis of the radiative transfer equation for temperatures of 130 and 250 K; a depletion of hydrogen, carbon and nitrogen is noted. It is suggested that a SO2 outgassing from a cooling sulfur extrusion is the major source of the observed atmospheric SO2.

Pearl, J.↗
NASA NTRS1979

The mean Jovian temperature structure derived from spectral observations from 105 to 630 cm kaysers

Far infrared observations of the thermal emission of Jupiter are used to determine the temperature at 1 bar. High-altitude observations of the whole-disk brightness temperature of Jupiter in the range of 100 to 347 kaysers were inverted to obtain a P-T profile between 1.5 and 0.06 atm, assuming as opacity sources the H2 collisionally induced continuum and the rotation inversion bands of ammonia. The P-T profile derived from the spectrum reproduces the main features of the observed spectrum, with a slightly improved fit if the effects of ammonia haze opacity or NH3 supersaturation in the saturated region are taken into account. The Jovian temperature is found to be 160 + or - 7 K at 1 bar, and 105 + or - 3 K at the inversion level at 0.15 bar. The 1-bar temperature is shown to be consistent with Jovian interior models which match the observed gravitational moment.

Goorvitch, D.↗
NASA NTRS1979

Water quality monitor

The preprototype water quality monitor (WQM) subsystem was designed based on a breadboard monitor for pH, specific conductance, and total organic carbon (TOC). The breadboard equipment demonstrated the feasibility of continuous on-line analysis of potable water for a spacecraft. The WQM subsystem incorporated these breadboard features and, in addition, measures ammonia and includes a failure detection system. The sample, reagent, and standard solutions are delivered to the WQM sensing manifold where chemical operations and measurements are performed using flow through sensors for conductance, pH, TOC, and NH3. Fault monitoring flow detection is also accomplished in this manifold assembly. The WQM is designed to operate automatically using a hardwired electronic controller. In addition, automatic shutdown is incorporated which is keyed to four flow sensors strategically located within the fluid system.

West, S.↗
NASA NTRS1979

Phosphine absorption in the 5-micron window of Jupiter

Since the original suggestion by Gillett et al. (1969) it has generally been assumed that the region of partial transparency near 5 micron in Jupiter's atmosphere (the 5-micron window) is bounded by the nu sub 4 NH3 at 6.1 micron and the nu sub 3 CH4 band at 3.3 micron. New measurements of Jupiter and of laboratory phosphine (PH3) samples show that PH3 is a significant contributor to the continuum opacity in the window and in fact defines its short-wavelength limit. This has important implications for the use of 5-micron observations as a means to probe the deep atmospheric structure of Jupiter. The abundance of PH3 which results from a comparison of Jovian and laboratory spectra is about 3 to 5 cm-am. This is five to eight times less than that found by Larson et al. (1977) in the same spectral region, but is in good agreement with the result of Tokunaga et al. (1979) from 10-micron observations.

Beer, R.↗
NASA NTRS1979

On the clouds of Uranus

Several models for the atmosphere of Uranus are considered. If the H2 abundance is less than 250 km-am and the internal heat source is only a few percent of the total emitted energy then the cloud at the base of the atmosphere may be composed of solid CH4 particles, while if the H2 abundance is greater than 250 km-am or if the internal heat source is near the current upper limit of 35% of the total emitted energy the cloud at the base of the atmosphere may be composed of either solid NH3 or H2S particles.

Macy, W., Jr.↗
NASA NTRS1979

Nitrogen isotope fractionations in the Fischer-Tropsch synthesis and in the Miller-Urey reaction

Nitrogen isotope fractionations have been measured in Fischer-Tropsch and Miller-Urey reactions in order to determine whether these processes can account for the large N-15/N-14 ratios found in organic matter in carbonaceous chondrites. Polymeric material formed in the Fischer-Tropsch reaction was enriched in N-15 by only 3 per mil relative to the starting material (NH3). The N-15 enrichment in polymers from the Miller-Urey reaction was 10-12 per mil. Both of these fractionations are small compared to the 80-90 per mil differences observed between enstatite chondrites and carbonaceous chondrites. These large differences are apparently due to temporal or spatial variations in the isotopic composition of nitrogen in the solar nebula, rather than to fractionation during the production of organic compounds.

King, C.-C.↗
NASA NTRS1979

Organic chemistry on Titan

Features taken from various models of Titan's atmosphere are combined in a working composite model that provides environmental constraints within which different pathways for organic chemical synthesis are determined. Experimental results and theoretical modeling suggest that the organic chemistry of the satellite is dominated by two processes: photochemistry and energetic particle bombardment. Photochemical reactions of CH4 in the upper atmosphere can account for the presence of C2 hydrocarbons. Reactions initiated at various levels of the atmosphere by cosmic rays, Saturn 'wind', and solar wind particle bombardment of a CH4-N2 atmospheric mixture can account for the UV-visible absorbing stratospheric haze, the reddish appearance of the satellite, and some of the C2 hydrocarbons. In the lower atmosphere photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. It is concluded that the surface of Titan may contain ancient or recent organic matter (or both) produced in the atmosphere.

Chang, S.↗
NASA NTRS1980

Observations of the spectrum of Jupiter from 1500 to 2000 A with the IUE

The paper examines the far-UV spectrum of Jupiter recorded by observations with the International Ultraviolet Explorer, noting that only the upper levels of the plant's atmosphere are sampled. It is shown that there are several absorptions caused by C2H2 and indications that NH3 may also be present at these altitudes. In addition, it is suggested that PH3 may also play a role as a continuum absorber, and a new upper limit of 5 x 10 to the -9 on H2S/H2 forbidden line ratio. It is concluded that these results are consistent with existing models for Jovian photochemistry and atmospheric structure.

Owen, T.↗
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 NTRS1980

Nitridation of silicon /111/ - Auger and LEED results

Clean silicon (111) (7x7) surfaces at up to 1050 C have been reacted with nitrogen ions and neutrals produced by a low energy ion gun. The LEED patterns observed are similar to those previously reported for reaction of silicon (111) (7x7) with NH3. The nitrogen KLL peak exhibits no shift or change in shape with nitride growth. At the same time the magnitude of the elemental silicon LVV peak at 92 eV decreases progressively as a new peak at 84 eV increases. The position of both peaks appears to be independent of the degree of nitridation. Since the Auger spectra are free of oxygen and other impurities, these features can be attributed only to silicon, nitrogen, and their reaction products. Characteristic features of the Auger spectra are related to LEED observations and to the growth of microcrystals of Si3N4.

Delord, J. F.↗