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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Antarctic stratospheric chemistry of chlorine nitrate, hydrogen chloride, and ice - Release of active chlorine

The reaction rate between atmospheric hydrogen chloride (HCl) and chlorine nitrate (ClONO2) is greatly enhanced in the presence of ice particles; HCl dissolves readily into ice, and the collisional reaction probability for ClONO2 on the surface of ice with HCl in the mole fraction range from about 0.003 to 0.010 is in the range from about 0.05 to 0.1 for temperatures near 200 K. Chlorine is released into the gas phase on a time scale of at most a few milliseconds, whereas nitric acid (HNO3), the other product, remains in the condensed phase. This reaction could play an important role in explaining the observed depletion of ozone over Antarctica; it releases photolytically active chlorine from its most abundant reservoir species, and it promotes the formation of HNO3 and thus removes nitrogen dioxide from the gas phase. Hence it establishes the necessary conditions for the efficient catalytic destruction of ozone by halogenated free radicals.

Molina, Mario J.↗
NASA NTRS1988

Antarctic ozone depletion chemistry - Reactions of N2O5 with H2O and HCl on ice surfaces

In a study concerning Antarctic ozone depletion, reactions of dinitrogen pentoxide with water and hydrochloric acid were studied on ice surfaces in a Knudsen cell flow reactor. The N2O5 reacted on ice at 185 K to form condensed-phase nitric acid (HNO3). This reaction may provide a sink for odd nitrogen, NO(x), during the polar winter, a requirement in nearly all models of Antarctic ozone depletion. The reaction of N2O5 on HCl-ice surfaces at 185 K produced gaseous nitryl chloride (ClNO2) and condensed-phase HNO3 and proceeded until all of the HCl within the ice was depleted. The ClNO2 which did not react or condense on ice at 185 K, can be readily photolyzed in the Antarctic spring to form atomic chlorine for catalytic ozone destruction cycles. The other photolysis product, gaseous nitrogen dioxide may be important in the partitioning of NO(x) between gaseous and condensed phases in the Antarctic winter.

Tolbert, Margaret A.↗
NASA NTRS1988

CANOZE measurements of the Arctic ozone hole

In CANOZE 1 (Canadian Ozone Experiment), a series of 20 ozone profile measurements were made in April, 1986 from Alert at 82.5 N. CANOZE is the Canadian program for study of the Arctic winter ozone layer. In CANOZE 2, ozone profile measurements were made at Saskatoon, Edmonton, Churchill and Resolute during February and March, 1987 with ECC ozonesondes. Ground based measurements of column ozone, nitrogen dioxide and hydrochloric acid were conducted at Saskatoon. Two STRATOPROBE balloon flights were conducted on February 26 and March 19, 1987. Two aerosol flights were conducted by the University of Wyoming. The overall results of this study will be reported and compared with the NOZE findings. The results from CANOZE 3 in 1988, are also discussed. In 1988, as part of CANOZE 3, STRATOPROBE balloon flights were conducted from Saskatchewan on January 27 and February 13. A new lightweight infrared instrument was developed and test flown. A science flight was successfully conducted from Alert (82.5 N) on March 9, 1988 when the vortex was close to Alert; a good measurement of the profile of nitric acid was obtained. Overall, the Arctic spring ozone layer exhibits many of the features of the Antarctic ozone phenomenon, although there is obviously not a hole present every year. The Arctic ozone field in March, 1986 demonstrated many similarities to the Antarctic ozone hole. The TOMS imagery showed a crater structure in the ozone field similar to the Antarctic crater in October. Depleted layers of ozone were found in the profiles around 15 km, very similar to those reported from McMurdo. Enhanced levels of nitric acid were measured in air which had earlier been in the vortex. The TOMS imagery for March 1987 did not show an ozone crater, but will be examined for an ozone crater in February and March, 1988, the target date for the CANOZE 3 project.

Evans, W. F. J.↗
NASA NTRS1989

Performance characterization and transient investigation of multipropellant resistojets

The multipropellant resistojet thruster design initially was characterized for performance in a vacuum tank using argon, carbon dioxide, nitrogen, and hydrogen, with gas inlet pressures ranging from 13.7 to 310 kPa (2 to 45 psia) over a heat exchanger temperature range of ambient to 1200 C (2200 F). Specific impulse, the measure of performance, had values ranging from 120 to 600 seconds for argon and hydrogen respectively, with a constant heat exchanger temperature of 1200 C (2200 F). When operated under ambient conditions typical specific impulse values obtained for argon and hydrogen ranged from 55 to 290 seconds, respectively. Performance measured with several mixtures of argon and nitrogen showed no significant deviation from predictions obtained by directly weighting the argon and nitrogen individual performance results. Another aspect of the program investigating transient behavior, showed responses depended heavily on the start-up scenario used. Steady state heater temperatures were achieved in 20 to 75 minutes for argon, and in 10 to 90 minutes for hydrogen. Steady state specific impulses were achieved in 25 to 60, and 20 to 60 minutes respectively.

Braunscheidel, Edward P.↗
NASA NTRS1988

Observations of atmospheric water vapor with the SAGE 2 instrument

The Stratospheric Aerosol and Gas Experiment 2 (SAGE 2) is discussed. The SAGE 2 instrument was a multichannel spectrometer that inferred the vertical distribution of water vapor, aerosols, nitrogen dioxide, and ozone by measuring the extinction of solar radiation at spacecraft sunrise/sunset. At altitudes above 20 km, the SAGE 2 and LIMS (Limb Infrared Monitor of the Stratosphere) data are in close agreement. The discrepancies below this altitude may be attributed to differences in the instruments' field of view and time of data acquisition.

Larsen, Jack C.↗
NASA NTRS1989

Performance characterization and transient investigation of multipropellant resistojets

The multipropellant resistojet thruster design initially was characterized for performance in a vacuum tank using argon, carbon dioxide, nitrogen, and hydrogen, with gas inlet pressures ranging from 13.7 to 310 kPa (2 to 45 psia) over a heat exchanger temperature range of ambient to 1200 C (2200 F). Specific impulse, the measure of performance, had values ranging from 120 to 600 seconds for argon and hydrogen respectively, with a constant heat exchanger temperature of 1200 C (2200 F). When operated under ambient conditions typical specific impulse values obtained for argon and hydrogen ranged from 55 to 290 seconds, respectively. Performance measured with several mixtures of argon and nitrogen showed no significant deviation from predictions obtained by directly weighting the argon and nitrogen individual performance results. Another aspect of the program investigating transient behavior, showed responses depended heavily on the start-up scenario used. Steady state heater temperatures were achieved in 20 to 75 minutes for argon, and in 10 to 90 minutes for hydrogen. Steady state specific impulses were achieved in 25 to 60, and 20 to 60 minutes, respectively.

Braunscheidel, Edward P.↗
NASA NTRS1990

SAGE 3: A visible wavelength limb sounder

A brief description is presented for the SAGE 3 (Stratospheric Aerosol and Gas Experiment 3) instrument that has been selected to fly onboard the National Polar Platform 1 (NPOP 1) for the Earth Observational System (Eos) in 1996. The SAGE 3 instrument will perform earth limb sounding with the solar occultation technique measuring the ultraviolet (UV), the visible, and the near infrared (IR) wavelength solar radiation. The instrument will produce atmospheric data for the vertical distribution of aerosol, ozone, nitrogen dioxide, water vapor, and oxygen. The details of the instrument design, data flow, and processing requirements are discussed.

Chu, W. P.↗
NASA NTRS1989

Electrochemical incineration of wastes

A low temperature electrolysis process has been developed for the treatment of solid waste material and urine. Experiments are described in which organic materials are oxidized directly at the surface of an electrode. Also, hypochlorite is generated electrochemically from chloride component of urine. Hypochlorite can act as a strong oxidizing agent in solution. The oxidation takes place at 30-60 C and the gaseous products from the anodic reaction are carbon dioxide, nitrogen, oxygen. Hydrogen is formed at the cathode. Carbon monoxide, and nitrogen oxides and methane were not detected in the off gases. Chlorine was evolved at the anode in relatively low amounts.

Kaba, L.↗
NASA NTRS1989

The Stratospheric Aerosol and Gas Experiment III instrument proposed for EOS - A conceptual design

This paper describes the Stratospheric Aerosol and Gas Experiment III (SAGE III) instrument proposed for the Earth Observing System (EOS), which is designed to monitor the vertical distribution of stratospheric aerosols, ozone, water vapor, nitrogen dioxide, and temperature by measuring the extinction and scattering of solar radiation in the 03 to 1.6 micron range through the atmosphere. The SAGE III employs proven concepts which have evolved from the SAM II, SAGE, and SAGE II programs. The launch is scheduled for the summer of 1996. The SAGE II block diagram is included.

Mauldin, L. E.↗
NASA NTRS1990

Kelvin wave-induced trace constituent oscillations in the equatorial stratosphere

Kelvin wave induced oscillations in ozone (O3), water vapor (H2O), nitric acid (HNO3) and nitrogen dioxide (NO2) in the equatorial stratosphere are analyzed using Limb Infrared Monitor of the Stratosphere (LIMS) data. Power and cross-spectrum analyses reveal coherent eastward propagating zonal wave 1 and 2 constituent fluctuations, due to the influence of Kelvin waves previously documented in the LIMS data. Comparison is made between a preliminary and the archival versions of the LIMS data; significant differences are found, demonstrating the sensitivity of constituent retrievals to derived temperature profiles. Because Kelvin waves have vanishing meridional velocity, analysis of tracer transport in the meridional plane is substantially simplified. Kelvin wave vertical advection is demonstrated by coherent, in-phase temperature-tracer oscillations, co-located near regions of strong background vertical gradients.

Randel, William J.↗
NASA NTRS1991

SAGE III capabilities and global change

The science objectives of the satellite-borne SAGE III are presented as they pertain to detecting global change. SAGE III is the proposed follow on and improved version of SAM II, SAGE I and SAGE II which have measured stratospheric and, in some cases, tropospheric species since late 1978. Specifically, SAGE III will measure profiles of aerosols, ozone, water vapor, nitrogen dioxide and trioxide, neutral density, temperature, clouds, and chlorine dioxide using the solar and lunar occultation techniques. These techniques are inherently self-calibrating, provide high vertical resolution, and use well-behaved data retrievals making them ideal for trend detection and global change studies. The potential capabilities of SAGE III are illustrated by using data and results from SAM II, SAGE I and SAGE II.

Mccormick, M. Patrick↗
NASA NTRS1992

SAGE II stratospheric density and temperature retrieval experiment

This paper describes a stratospheric density and temperature retrieval experiment based on the solar occultation measurement of the Stratospheric Aerosol and Gas Experiment (SAGE II). The entire retrieval analysis involves two inversion steps: the vertical structure inversion, which derives the profile of local atmospheric extinction from SAGE II limb optical depth data, and the species inversion, which inverts the concentration of air molecules, aerosols, ozone, and nitrogen dioxide from the derived atmospheric extinction at five SAGE II short wavelengths (0.385, 0.448, 0.453, 0.525, and 0.600 microns). The derived density profile is then used to infer the temperature distribution, assuming that the atmosphere is in hydrostatic equilibrium and obeys the ideal gas law. The temperature profiles retrieved from the SAGE II observations are compared with near-coincident, in both time and space, French Rayleigh lidar and NASA Wallops Flight Facility rocket datasonde soundings as well as the National Meteorological Center (NMC) data analyses. The results indicate that the mean SAGE II temperature agrees with the mean lidar measurements to within 2 C at altitudes from 30.5 to 52.5 km. The SAGE II and datasonde observations agree to within about 4 C in approximately the same altitude region.

Wang, Pi-Huan↗
NASA NTRS1991

Improved Limb Atmospheric Spectrometer (ILAS) for polar stratospheric trace gas measurements

The Improved Limb Atmospheric Spectrometer (ILAS) is a grating spectrometer designed to measure vertical profiles of high latitude stratospheric constituents in a solar occultation mode. ILAS measurement gases are ozone (03), methane (CH4), nitrous oxide (N2O), nitric acid (HNO3), water vapor (H2O), nitrogen dioxide (NO2), and CFC-11 using an IR channel. Temperature, pressure, and aerosol are also measured using a visible channel. The IR channel consists of 44 detector elements which cover the spectral range 6.2 to 11.8 microns, and the visible channel is composed of 1024 pixels that cover 753 to 784 nm. ILAS will be installed on the Advanced Earth Observing Satellite (ADEOS) which will be launched in 1995. Instrument design data are outlined.

Yokota, Tatsuya↗
NASA NTRS1992

Effect of inert propellant injection on Mars ascent vehicle performance

A Mars ascent vehicle is limited in performance by the propellant which can be brought from Earth. In some cases the vehicle performance can be improved by injecting inert gas into the engine, if the inert gas is available as an in-situ resource and does not have to be brought from Earth. Carbon dioxide, nitrogen, and argon are constituents of the Martian atmosphere which could be separated by compressing the atmosphere, without any chemical processing step. The effect of inert gas injection on rocket engine performance was analyzed with a numerical combustion code that calculated chemical equilibrium for engines of varying combustion chamber pressure, expansion ratio, oxidizer/fuel ratio, and inert injection fraction. Results of this analysis were applied to several candidate missions to determine how the required mass of return propellant needed in low Earth orbit could be decreased using inert propellant injection.

Colvin, James E.↗
NASA NTRS1993

A global analysis of the ozone deficit in the upper stratosphere and lower mesosphere

The global measurements of temperature, ozone, water vapor, and nitrogen dioxide acquired by the Limb Infrared Monitor of the Stratosphere (LIMS), supplemented by a precomputed distribution of chlorine monoxide, are used to test the balance between odd oxygen production and loss in the upper stratosphere and lower mesosphere. An efficient photochemical equilibrium model, whose validity is ascertained by comparison with the results from a fully time-dependent one-dimensional model at selected latitudes, is used in the calculations. The computed ozone abundances are systematically lower than observations for May 1-7, 1979, which suggests, contrary to the conclusions of other recent studies, a real problem in model simulations of stratospheric ozone.

Eluszkiewicz, Janusz↗
NASA NTRS1954

Investigation of effect of fluoride on corrosion of 2S-0 aluminum and 347 stainless steel in fuming nitric acid at 170 F

The effect of small additions of fluoride on the corrosion of 2S-0 aluminum and 347 stainless steel by fuming nitric acid at 170 degrees F has been evaluated quantitatively by the determination of the weight loss of metal specimens immersed in the acid. The ratio of metal surface area to volume of acid was approximately 7.5 inch (superscript)-1 in all cases. It was found that for acids containing no fluorides the weight loss of aluminum was approximately 1/5 that of stainless steel. Addition of 1 percent fluoride ion to the acid reduced the weight loss of both metals to practically zero even after 26 days of exposure to the acid at 170 degrees F. The minimum quantity of fluoride ion required to inhibit corrosion was found to be approximately 0.25 and 0.5 percent for aluminum and stainless steel, respectively, in white fuming nitric acid and 0.5 and 1 percent in red fuming nitric acid (18 percent nitrogen dioxide). These fluoride percentages were based on the total weight of acid. Provided the concentration of fluoride ion was sufficient to inhibit corrosion, the source of these ions was immaterial. Additional information concerning the effect of fluorides on corrosion was obtained by measuring the electrode potentials of the metals against a platinum reference electrode.

Feiler, Charles E↗
NASA NTRS1993

The seasonal evolution of reactive chlorine in the Northern Hemisphere stratosphere

In situ measurements of chlorine monoxide (ClO) at mid- and high northern latitudes are reported for the period October 1991 to February 1992. As early as mid-December and throughout the winter, significant enhancements of this ozone-destroying radical were observed within the polar vortex shortly after temperatures dropped below 195 K. Decreases in ClO observed in February were consistent with the rapid formation of chlorine nitrate (ClONO2) by recombination of ClO with nitrogen dioxide (NO2) released photochemically from nitric acid (HNO3). Outside the vortex, ClO abundances were higher than in previous years as a result of NO(x) suppression by heterogeneous reactions on sulfate aerosols enhanced by the eruption of Mount Pinatubo.

Toohey, D. W.↗
NASA NTRS1994

Annual variability of ozone along alpine hillsides

Over a period of more than two years (March 1989 till June 1991) ozone and nitrogen dioxide have been monitored along twelve alpine hillsides in the Austrian alps. The profiles had a height-resolution of 100 m and cover a range between 400 m and 1800 m asl, that is 100 m to 1100 m above the bottom of the valleys. They were situated in remote rural areas as well as in the vicinity of polluted urban and industrial areas. Both trace gases were monitored by means of integral chemical (SAM-surface active monitor) methods with a measuring cycle of two weeks. The concentration of ozone exhibits a substantial annual variation over the entire height range. In summer, highest ozone levels are observed near the ground and at the top of the mountains, whereas in winter the maxima are found mainly in the crest regions. The overall ozone burden shows a relative maximum near the temperature inversion layer in the valleys and an absolute maximum at the crest.

Putz, Erich↗