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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Pluto - Evidence for methane frost

Results are presented for infrared photometry of Pluto in the wavelength range from 1.2 to 2.2 microns, which includes the diagnostic absorption bands of water and methane frosts (designated as H1 and H2, respectively). Based on Pluto's observed J-H color and H1/H2 reflectance ratio as well as restrictions imposed by other observational and theoretical studies, it is concluded that methane frost is probably the dominant reflecting material on the planet's surface. It is suggested that this frost may be mixed with other materials, and some variation of the frost cover is indicated. Two plausible sources for the methane on Pluto are discussed, the average geometric albedo of the planet is assumed to be 0.4, and its diameter is estimated to be 3300 km.

Cruikshank, D. P.↗
NASA NTRS1978

Laboratory studies of the diffuse reflectance spectra of frosts and minerals occurring on astronomical objects

A vacuum monochromator was integrated into the system and optics chosen to increase data collection in the infrared spectral region. Using a InSb detector, good reflectance data was obtained to 5.5 micron from a variety of samples including magnesium oxide, barium sulfate, water frost and Bloedite. Magnesium oxide was found to be a poorer reflector than the barium sulfate throughout the visible and near infrared region. The barium sulfate material was shown to be a Lambert reflector in the visible region and over an angular range of 60 deg. Several samples of water frost were prepared and in reflectance measured from 0.3 micron to 5.5 microm. The fine grained frosts were better reflectors than the coarse grained frosts, usually by 20 percent or more, over the entire spectral range. The minerals Bloedite and sulfur were also investigated further.

Glaser, F. M.↗
NASA NTRS1981

Water frost and ice - The near-infrared spectral reflectance 0.65-2.5 microns

The spectral reflectance of water frost and frost on ice as a function of temperature and grain size is presented with 1-1/2% spectral resolution in the 0.65- to 2.5-micron wavelength region. The well-known 2.0-, 1.65-, and 1.5-micron solid water absorption bands are precisely defined along with the little studied 1.25-micron band and the previously unidentified (in reflectance) 1.04-, 0.90-, and 0.81-micron absorption bands. The 1.5-microns band complex is quantitatively analyzed using a nonlinear least squares algorithm to resolve the band into four Gaussian components as a function of grain size and temperature. It is found that the 1.65-micron component, which was thought to be a good temperature sensor, is highly grain-size dependent and poorly suited to temperature sensing. Another Gaussian component appears to show a dependence of width on grain size while being independent of temperature. The relative apparent band depths are different for frost layers on ice than for thick layers of frost and may explain the apparent band depths seen in many planetary reflectance spectra.

Clark, R. N.↗
NASA NTRS1983

Device for determining frost depth and density

A hand held device having a forward open window portion adapted to be pushed downwardly into the frost on a surface, and a rear container portion adapted to receive the frost removed from the window area are described. A graph on a side of the container enables an observer to determine the density of the frost from certain measurements noted. The depth of the frost is noted from calibrated lines on the sides of the open window portion.

Huneidi, F.↗
NASA NTRS1990

Mariner 9 observations of the south polar cap of Mars - Evidence for residual CO2 frost

The first spacecraft observations of the south residual polar cap of Mars were obtained by the Mariner 9 orbiter during the Martian southern summer season, 1971-1972. Analyses of Viking orbiter observations obtained 3 Mars years later have shown that residual carbon dioxide frost was present at the south polar cap in 1977. In this study, Mariner 9 infrared interferometer spectrometer spectra and television camera images are used in conjuction with multispectral thermal emission models to constrain the temperatures of dark bare ground and bright frost regions within the south residual cap. The results provide strong evidence that carbon dioxide frost was present throughout the summer season despite the fact that the residual frost deposits observed by Mariner 9 were less extensive than those observed by Viking.

Paige, D. A.↗
NASA NTRS1992

Sunlight penetration through the Martian polar caps: Effects on the thermal and frost budgets

An energy balance model of the seasonal polar caps on Mars is modified to include penetration of solar radiation into and through the ice. Penetration of solar radiation has no effect on subsurface temperature or total frost sublimation if seasonal ice overlies a dust surface. An effect is noted for seasonal ice which overlies the residual polar caps. For the case of an exposed water-ice residual polar cap, the temperature at depth is calculated to be up to several degrees warmer and the calculated lifetime of seasonal CO2 frost is slightly lower when penetration of sunlight is properly treated in the model. For the case of a residual polar cap which is perennially covered by CO2 frost, the calculated lifetime of seasonal CO2 frost is very slightly increased as a result of sunlight penetration through the ice. Hence, penetration of sunlight into the ice helps to stabilize the observed dichotomy in the residual polar caps on Mars, although it is a small effect.

Lindner, Bernhard Lee↗
NASA NTRS1992

Sunlight penetration through the Martian polar caps - Effects on the thermal and frost budgets

An energy balance model of the seasonal polar caps on Mars is modified to include penetration of solar radiation into and through the ice. Penetration of solar radiation has no effect on subsurface temperature or total frost sublimation if seasonal ice overlies a dust surface. An effect is noted for seasonal ice which overlies the residual polar caps. For the case of an exposed water-ice residual polar cap, the temperature at depth is calculated to be up to several degrees warmer, and the calculated lifetime of seasonal CO2 frost is slightly lower when penetration of sunlight is properly treated in the model. For the case of a residual polar cap which is perennially covered by CO2 frost, the calculated lifetime of seasonal CO2 frost is very slightly increased as a result of sunlight penetration through the ice. Hence, penetration of sunlight into the ice helps to stabilize the observed dichotomy in the residual polar caps on Mars, although it is a small effect.

Lindner, Bernhard L.↗
NASA NTRS2014

Frost Monitoring and Forecasting Using MODIS Land Surface Temperature Data and a Numerical Weather Prediction Model Forecasts for Eastern Africa

Frost is a major challenge across Eastern Africa, severely impacting agricultural farms. Frost damages have wide ranging economic implications on tea and coffee farms, which represent a major economic sector. Early monitoring and forecasting will enable farmers to take preventive actions to minimize the losses. Although clearly important, timely information on when to protect crops from freezing is relatively limited. MODIS Land Surface Temperature (LST) data, derived from NASA's Terra and Aqua satellites, and 72‐hr weather forecasts from the Kenya Meteorological Service's operational Weather Research Forecast model are enabling the Regional Center for Mapping of Resources for Development (RCMRD) and the Tea Research Foundation of Kenya to provide timely information to farmers in the region. This presentation will highlight an ongoing collaboration among the Kenya Meteorological Service, RCMRD, and the Tea Research Foundation of Kenya to identify frost events and provide farmers with potential frost forecasts in Eastern Africa.

Kabuchanga, Eric↗
NASA NTRS1970

Frost as an insulator

Insulating qualities of frost and mechanisms for using frost in specific applications in controlled experiments are discussed. With available supply of moist air, frost possesses inherent advantage of easy insulation of cryogenic lines and improvement of overall system efficiency.

Bronson, J. C.↗
NASA NTRS1973

Low frost-point humidity generator

A low frost-point humidity generator has been developed at NBS to provide a capability for calibration, testing, and research at very low levels of water vapor content in such gases as atmospheric air, carbon dioxide and nitrogen. The generator produces frost points from -30 to -100 C at ambient pressures from 500 to 200,000 pascals (0.005 to 2 atm.). This is equivalent to mixing ratios of 4 micrograms to 51 grams of water vapor per kilogram of dry air and to vapor pressures of .0014 to 38 pascals. The generated test gas can be fed to a test chamber with independent temperature control between +25 and -100 C. The uncertainty of the frost point in the test chamber is estimated not to exceed 0.05 deg C.

Greenspan, L.↗
NASA NTRS1975

Performance of a hypersonic hot fuselage structure with a carbon dioxide frost projected, nonintegral cryogenic tank

A model which consisted of a hot structure and a nonintegral tank protected by a carbon dioxide frost thermal protection system was tested under the following conditions: (1) room temperature loading and (2) heating and loading corresponding to the Mach 8 flight of an air-breathing launch vehicle. In the simulated flight tests, liquid nitrogen inside the tank was withdrawn at the rate fuel would be consumed. Prior to each simulated flight test, carbon dioxide was cryodeposited in the insulation surrounding the tank; during the tests, subliming CO2 frost absorbed heat and provided a purge gas for the space between the tank and the structure. A method of flame spraying the joints between panels with a nickel-aluminum material was developed to prevent excessive leakage of the purge gas through the outer structure. The tests indicated that the hot structure (with a joint repaired by riveting), the nonintegral tank and suspension system, and the carbon dioxide frost thermal protection system provide a workable concept with predictable performance.

Sharpe, E. L.↗
NASA NTRS1978

Reflectance spectra for sodium and potassium doped ammonia frosts - Implications for Io's surface

This paper reports measurements of the reflection spectra of sodium- and potassium-doped ammonia frosts as a function of alkali metal concentration for the wavelength range 0.35-2.5 microns. The purpose of the measurements was to determine whether or not the reflection spectra for such a solid was compatible with the spectra albedo of Io. The data show that, with a sufficiently large alkali metal concentration, the reflection spectra of the doped ammonia frosts do not display the characteristic ammonia features at 2.0 and 2.25 micron. The high reflectance of the more concentrated samples and the character of the observed reflection spectrum make it difficult to rule out sodium-doped ammonia frost as a surface constituent on Io on the basis of existing data.

Rosen, M. D. A.↗
NASA NTRS1979

Frost-weathering on Mars - Experimental evidence for peroxide formation

The weathering of silicates by frost is investigated in relation to the formation of surface peroxides to which Viking biology experiment results have been attributed. Samples of the minerals olivine and pyroxene were exposed to water vapor at -11 to -22 C and resultant gas evolution and pH were monitored. Experiments reveal the formation of an acidic oxidant upon interaction of the mineral and H2O frost at subfreezing temperatures, which chemical indicators have suggested to be chemisorbed hydrogen peroxide. A model for the formation of chemisorbed peroxide based on the chemical reduction of the mineral by surface frost is proposed, and it is predicted that the perioxide would decay at high temperatures to H2O and adsorbed O, consistent with the long-term storage and sterilization behavior of the soil oxidants observed in the Viking Gas Exchange and Labeled Release experiments.

Huguenin, R. L.↗
NASA NTRS1980

Io - Longtudinal distribution of sulfur dioxide frost

A longitudinal variation in the distribution of SO2 frost on Io is examined. Twenty spectra of Io (0.26 to 0.33 micrometer) are presented and a strong ultraviolet absorption is found shortward of 0.33 micrometer. The abundance of frost is greatest at orbital longitudes 72 to 137 degrees. Longitudes 250 to 323 degrees are least abundant in SO2. Comparisons are made with a Voyager color relief map, which suggest that SO2 frost is in greatest concentration in the white areas of Io and other sulfurous materials are in greatest concentration in the red areas.

Nelson, R. M.↗
NASA NTRS1981

Far-UV, visible, and near-IR reflectance spectra of frosts of H2O, CO2, NH3 and SO2

Measurements in the 0.1-2.5 micron range are presented for the reflectance spectra of the frosts of several volatiles pertinent to the study of comet nuclei. The frost spectra have distinctive features permitting their identification by spectroscopic reflectance remote sensing, notably in the far UV. It is found that: (1) H2O has a minimum at 0.16 microns and a maximum at 0.13 microns; (2) CO2 has minima near 0.21, 0.18 and 0.125 microns, with maxima at 0.19, 0.135 and 0.120 microns; (3) NH3 is bright at wavelengths longer than 0.21 microns, where reflectance drops to a value of only a few per cent at shorter wavelengths; (4) SO2 has a sharp drop at 0.32 microns, with a minimum at 0.18 microns and a maximum at 0.13 microns. The features in the frost spectra largely correspond to absorption line bands in the gas phase.

Hapke, B.↗
NASA NTRS1988

Balloon borne Antarctic frost point measurements and their impact on polar stratospheric cloud theories

The first balloon-borne frost point measurements over Antarctica were made during September and October, 1987 as part of the NOZE 2 effort at McMurdo. The results indicate water vapor mixing ratios on the order of 2 ppmv in the 15 to 20 km region which is somewhat smaller than the typical values currently being used significantly smaller than the typical values currently being used in polar stratospheric cloud (PSC) theories. The observed water vapor mixing ratio would correspond to saturated conditions for what is thought to be the lowest stratospheric temperatures encountered over the Antarctic. Through the use of available lidar observations there appears to be significant evidence that some PSCs form at temperatures higher than the local frost point (with respect to water) in the 10 to 20 km region thus supporting the nitric acid theory of PSC composition. Clouds near 15 km and below appear to form in regions saturated with respect to water and thus are probably mostly ice water clouds although they could contain relatively small amounts of other constituents. Photographic evidence suggests that the clouds forming above the frost point probably have an appearance quite different from the lower altitude iridescent, colored nacreous clouds.

Rosen, James M.↗
NASA NTRS1990

Winter frost at Viking Lander 2 site

This paper presents quantitative evidence for cold trapping (frost redeposition) at the Viking Lander 2 site. This evidence consists of the frost surface coverage and color transition, the timing of this transition, and the limited vertical mixing and horizontal water transport. It is argued that cold trapping must be a general property of seasonal frost and, therefore, must be considered in order to understand the evolution of the surface environment of Mars.

Svitek, Thomas↗
NASA NTRS1990

Backscattering from frost on icy satellites in the outer solar system

Two extreme models are presented of how frost and ice might be intermixed on a typical satellite surface: areal and intimate mixing. Applying such models to selected representative satellite data, it is found that the frost component of the surfaces of these outer satellites must itself be backscattering, unlike its terrestrial counterpart. The difference may arise because frost particles can have much more complex internal textures under the low-temperature and low-gravity conditions of the outer satellites than is the case on earth.

Verbiscer, Anne↗