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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 649 records · Page 36
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NASA NTRS1984

Atmospheres of Uranus and Neptune

Current knowledge of the atmospheric compositions and structures are surveyed. Although the two planets are similar in some ways, they are strikingly different in a number of others. The similarities include mass, size, and effective temperature. There are differences in heat flow, stratospheric thermal structure and composition, and spectral appearance. Presumably these are traceable to some combination of Uranus' unusual obliquity and smaller distance from the sun, but most of the details are obscure.

Hunten, D. M.↗
NASA NTRS1984

Shuttle tethered satellite program

Features and applications of the Shuttle tethered satellite system (TSS) are outlined. The TSS would be mounted on a normal cargo pallet and used to deploy or retrieve payloads weighing up to 500 kg from the Orbiter by reeling in or unreeling a tether line extended along the gravity gradient vertical. Attaching a conducting wire to the tether would permit electrodynamic measurements of space plasma. An initial mission under development is to deploy an instruments package 20 km above the Orbiter with a conducting wire tether, thereby obtaining data on low frequency hydromagnetic waves generated by tether passage through the space plasma. An aerodynamics package could also be lowered to 130 km, where measurements can be made with magnetometers for geoscience data, atmospheric composition, and cosmic dust can be collected. Details of engineering assignments for the TSS divided up between NASA and the Italian National Research Council are discussed.

Nolan, M. B.↗
NASA NTRS1984

Space Station medical sciences concepts

Current life sciences concepts relating to Space Station are presented including the following: research, extravehicular activity, biobehavioral considerations, medical care, maintenance of dental health, maintaining health through physical conditioning and countermeasures, protection from radiation, atmospheric contamination control, atmospheric composition, noise pollution, food supply and service, clothing and furnishings, and educational program possibilities. Information on the current status of Soviet Space Stations is contained.

Mason, J. A.↗
NASA NTRS1985

Atomic nitrogen densities near the polar cusp

The neutral atmospheric composition spectrometer on board the Dynamics Explorer 2 spacecraft sampled several major and minor thermospheric gases including atomic nitrogen. A selection of passes over the polar cusp that provide a quantitative measure of N densities in this region and provide evidence of localized density increases due to soft particle precipitation is presented. Increases in N densities are frequently observed but are smaller than accompanying increases in N2 densities. The observations support earlier studies suggesting that (1) N densities increase more rapidly than O densities during periods of high solar EUV flux and (2) N densities are larger in the summer hemisphere than in the winter hemisphere. A series of passes in February 1983, late in the lifetime of DE 2, indicated N densities at 200 km altitude were a factor of 2 larger near the southern cusp than near the northern cusp.

Engebretson, M. J.↗
NASA NTRS1985

AE and DE mass spectrometer observations relevant to the shuttle glow

Recent work suggested that NO2 may be responsible for the observed continuum glow near surfaces of the space shuttle. The observations of atomic nitrogen (N) are reported at shuttle altitudes using mass spectrometers, giving special attention to the surface reactions of N relevant to the production of NO2 on spacecraft surfaces. Data from two semi-open sources mass spectrometers, the OSS instruments on the Atmosphere Explorer-C and -D satellites, and the closed source Neutral Atmospheric Composition Spectrometer (NACS) on the Dynamic Explorer-2 satellite are presented to show the similar behavior of NO in each case and the contrasting behavior of NO2. Although signals of NO and NO2 are highly dependent on surface temperature and surface composition, it appears that direct exposure of ion source surfaces to rammed gas is a necessary condition for the production of large amounts of NO2. Evidence that elevated surface temperatures can significantly reduce the production of NO2, likely by causing more rapid desorption of NO from these surfaces, is presented.

Engebretson, M. J.↗
NASA NTRS1985

Analysis of atomic thermospheric nitrogen density

A NASA grant provided support for a research project at Augsbury College, Minneapolis, Minnesota for the analysis of atomic nitrogen density data obtained by the Neutral Atmospheric Composition Spectrometer (NACS) on board the Dynamics Explorer-2 satellite. Initial funding was for an exploratory study of the feasibility of obtaining ambient densities of N from source densities of NO. Funding was continued under the Dynamics Explorer Guest Investigator Program when initial studies indicated probable success in obtaining such ambient densities. The major scientific focus of the later work was to be to characterize the behavior of N densities at high latitudes.

Engebretson, M. J.↗
NASA NTRS1985

Middle Atmosphere Program. Handbook for MAP. Volume 15: Balloon techniques

Some techniques employed by investigators using balloons to obtain data on the properties of the middle atmosphere are discussed. Much effort has gone into developing instruments which could be used on small balloons to measure temperature and variable species. These efforts are discussed. Remote sensing techniques used to obtain data on atmospheric composition are described. Measurement of stratospheric ions and stratospheric aerosols are also discussed.

Murcray, D. G.↗
NASA NTRS1986

Atomic nitrogen densities near the polar cusp

The neutral atmospheric composition spectrometer on board the Dynamics Explorer 2 spacecraft sampled several major and minor thermospheric gases including atomic nitrogen. A selection of passes over the polar cusp that provide a quantitative measure of N densities in this region and provide evidence of localized density increases due to soft particle precipitation is presented. Increases in N densities are frequently observed but are smaller than accompanying increases in N2 densities. The observations support earlier studies suggesting that N densities increase more rapidly than O densities during periods of high solar EUV flux and N densities are larger in the summer hemisphere than in the winter hemisphere. A series of passes in February 1983, late in the lifetime of DE 2, indicated N densities at 200 km altitude were a factor of 2 larger near the southern cusp than near the northern cusp.

Engebretson, M. J.↗
NASA NTRS1985

Nitric oxide profile from 7 to 32 km

An analysis is given of some results of the LIMS experiment, launched on the Nimbus 7 satellite on October 24, 1978 for the purpose of sounding the middle atmosphere composition and structure. One of the LIMS channels was centered spectrally in the 6 micron region to measure vertical profiles and the global distribution of NO2 mixing ratio. The data reveal that NO2 is highly variable with altitude, latitude, longitude and time. Steep latitudinal gradients are observed in high latitude winter ('the NO2 cliff') when a wave number one pattern exists in the geopotential height field. The daytime gradient under these conditions is less than that for the night. The summer hemisphere column amount is considerably greater (by a factor of about 2) than in the winter hemisphere. The largest mixing ratios occur at 4 mb at night (about 20 ppbv) and 9 mb in the day (about 7 ppbv) and the latitude region of the peak mixing ratio is skewed toward the Southern Hemisphere. The mixing ratio variability is greater at night (by a factor of about 2 to 3) than in the day and there are significant long-term changes revealed by mixing ratio time series analyses on a pressure vs time grid.

Matthews, W. A.↗
NASA NTRS1986

Vertical cloud structure models for the NTRZ EQZ, SEB and STRZ of Jupiter

Latitude-dependent models of the vertically inhomogeneous Jovian cloud structure are presented. The models assume an atmospheric composition with (CH4)/(H2) = 2.0 x .003, (He)/(H2) = 0.11 and (NH3)/(H2) = 2.0 x .0004 consistent with the Voyager IRIS measurements and employ refractive indices appropriate for ammonia ice particles and a photochemical stratospheric aerosol layer. The free parameters of the models are determined by fitting the results of multiple, scratching calculations to the near-infrared center and limb spectra of Clark and McCord and the center-to-limb 6190, 6350, 7250, 7500, 8900 and 9500 A photometric measurements of West. The resulting synthetic center-to-limb profiles are in excellent agreement with the observations. Of the regions studied the tropical zones are the most similar, with the observed differences explained by variations in the vertical extent of the cloudy layers. The Equatorial Zone is a unique region with denser NH3 clouds than either of the tropical zones. At visible and near-infrared wavelengths the belt-zone contrasts can be explained by opacity differences. The optical depth of the stratospheric aerosol layer is larger in a belt, while the tropospheric clouds are deeper and thinner.

Carlson, B. E.↗
NASA NTRS1987

Limitations to modeling the thermosphere and exosphere

Correlations were noted between solar 10cm radio flux, the indices of geomagnetic activity, and what happens in the atmosphere. There are also correlations between events in the troposphere and density in the thermosphere. Gravity waves in the thermosphere are not handled in existing models. A reasonable estimate is that they contribute perhaps ten percent to the deviation between model density values and the effective density as it influences satellite orbital motion. Another factor is atmospheric composition which influences density through the different scale heights of components of different molecular weight in this regime.

Slowey, John↗
NASA NTRS1987

Hypersonic aerodynamic coefficients and convection flow estimation in a HERMES type project

An analysis of all the experimental and computation requirements of the HERMES project is presented. The discussion includes the influence of the upper atmosphere composition and possible chemical reactions, the information collected in Orbiter experiments, the possibility of utilizing plasma generators and CF4 in wind tunnel tests, the development of parabolized Navier-Stokes models and solutions, and the computing capacity requirements.

Pollak, C.↗
NASA NTRS1986

Atmospheres and ionospheres of the outer planets and their satellites

Essential aspects of physical and chemical processes in the atmospheres and ionospheres of the outer planets are examined in an introductory overview of current knowledge, intended both for graduate students of planetary science and for practicing scientists. Chapters are devoted to bulk atmospheric compositions, thermal structures, cloud structures, vertical mixing, photochemistry, the ionospheres, and the satellites. Measurement data are compiled in tables, and extensive graphs and diagrams are provided.

Atreya, Sushil K.↗
NASA NTRS1988

Advanced EVA system design requirements study

The results are presented of a study to identify specific criteria regarding space station extravehicular activity system (EVAS) hardware requirements. Key EVA design issues include maintainability, technology readiness, LSS volume vs. EVA time available, suit pressure/cabin pressure relationship and productivity effects, crew autonomy, integration of EVA as a program resource, and standardization of task interfaces. A variety of DOD EVA systems issues were taken into consideration. Recommendations include: (1) crew limitations, not hardware limitations; (2) capability to perform all of 15 generic missions; (3) 90 days on-orbit maintainability with 50 percent duty cycle as minimum; and (4) use by payload sponsors of JSC document 10615A plus a Generic Tool Kit and Specialized Tool Kit description. EVA baseline design requirements and criteria, including requirements of various subsystems, are outlined. Space station/EVA system interface requirements and EVA accommodations are discussed in the areas of atmosphere composition and pressure, communications, data management, logistics, safe haven, SS exterior and interior requirements, and SS airlock.

Woods, T. G.↗
NASA NTRS1987

Laboratory measurements of the microwave opacity of gaseous ammonia (NH3) under simulated conditions for the Jovian atmosphere

Microwave opacity measurements have been conducted for gaseous ammonia simulating Jovian atmosphere conditions at five frequencies from 18.5 to 1.38 cm, at temperatures from 178 to 300 K and 1-6 atm pressures. The atmospheric composition is 90-percent H/10-percent He. In the 1.38-18.5 cm wavelength range, ammonia absorption is well expressed by Berge and Gulkis' (1976) lineshape. The results obtained suggest that either an ammonia abundance 1.5-2.0 times greater than solar must be present at less than 1-2 bar, or some other microwave absorber is present.

Steffes, Paul G.↗
NASA NTRS1988

The earth observing system - A mission for lidar remote sensing technology

NASA plans an earth observing system (EOS) to address low earth orbit remote sensing satellite requirements. EOS will incorporate three active remote-sensing instruments employing some form of lidar: (1) the Lidar Atmospheric Sounder and Altimeter (LASA), the Laser Atmospheric Wind Sounder (LAWS), and the Geodynamics Laser Ranging System (GLRS). LASA will deepen understanding of atmospheric composition and structure; LAWS will measure winds using Doppler lidar technology; GLRS will be used to ascertain the position of strategically placed retroreflectors to an accuracy of several cm.

Sokoloski, Martin M.↗