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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 91 records · Page 5
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NASA NTRS1981

Some new worldwide cloud-cover models

Using daily measurements of day and night infrared, and incoming and absorbed solar radiation obtained from a Tiros satellite over a period of approximately 45 months, and integrated over 2.5 deg latitude-longitude grids, the proportion of cloud cover over each grid each day was derived for the entire period. For each of four 3-month periods, for each grid location, estimates a and b of the two parameters of the best-fit beta distribution were obtained. The (a, b) plane was divided into a number of regions. All the geographical locations whose (a, b) estimates were in the same region in the (a, b) plane were said to have the same cloud cover type for that season. For each season, the world is thus divided into separate cloud-cover types.

Bean, S. J.↗
NASA NTRS1981

Albedo, internal heat, and energy balance of Jupiter - Preliminary results of the Voyager infrared investigation

Full disk measurements recorded by the 0.4-1.7 micron radiometer on Voyager 1 indicate a geometric albedo of 0.274 + or - 0.013. This measurement and the Pioneer-based phase integral of 1.25 yield a Jovian Bond albedo of 0.343 + or - 0.032. Infrared spectra yield a thermal emission of 1.359 + or - 0.014 x .001 W/sq cm, which corresponds to an equivalent blackbody temperature of 124.4 + or - 0.3 K. In addition, the internal heat flux of Jupiter is estimated to be 5.444 + or - 0.425 x .0001 W/sq cm, and the energy balance defined as the ratio of emitted thermal to absorbed solar energy is 1.668 + or - 0.085.

Hanel, R. A.↗
NASA NTRS1981

Liquid water on Mars - An energy balance climate model for CO2/H2O atmospheres

A simple climatic model is developed for a Mars atmosphere containing CO2 and sufficient liquid water to account for the observed hydrologic surface features by the existence of a CO2/H2O greenhouse effect. A latitude-resolved climate model originally devised for terrestrial climate studies is applied to Martian conditions, with the difference between absorbed solar flux and emitted long-wave flux to space per unit area attributed to the divergence of the meridional heat flux and the poleward heat flux assumed to equal the atmospheric eddy heat flux. The global mean energy balance is calculated as a function of atmospheric pressure to assess the CO2/H2O greenhouse liquid water hypothesis, and some latitude-resolved cases are examined in detail in order to clarify the role of atmospheric transport and temperature-albedo feedback. It is shown that the combined CO2/H2O greenhouse at plausible early surface pressures may account for climates hot enough to support a hydrological cycle and running water at present-day insolation and visible albedo levels.

Hoffert, M. I.↗
NASA NTRS1983

High-Absorptance Radiative Heat Sink

Absorptance of black-painted open-cell aluminum honeycomb improved by cutting honeycomb at angle or bias rather than straight across. This ensures honeycomb cavities escapes. At each reflection radiation attenuated by absorption. Applications include space-background simulators, space radiators, solar absorbers, and passive coolers for terrestrial use.

Cafferty, T.↗
NASA NTRS1984

Thermal control coatings experiment (A0138-6)

The objectives of this LDEF experiment are to verify the validity of space environment simulation performed in the laboratory in order to measure the stability of the thermo-optical properties of thermal control coatings, and to compare the behavior in space of some materials for which the available ultraviolet solar simulation is inadequate (especially in the far ultraviolet). The experimental approach is to passively expose samples of the thermal coatings of interest. These coatings include black paint, aluminum paint, white paint, a solar absorber, an optical surface reflector, second surface mirrors, metal coatings, and silica fabrics. Preflight and postflight measurements of thermo-optical properties will be compared to determine the effects of space environment exposure.

Paillous, A.↗
NASA NTRS1984

The atmospheric effects of El Chichon

The eruption of the Mexican volcano El Chichon in late March and early April of 1982 injected an unusually large amount of volcanic material into the stratosphere. This event demonstrates for the first time that a relatively small but sulfur-rich volcanic eruption can produce a dense, widespread stratospheric cloud. Sulfuric acid aerosol is formed by the photochemical reaction of sulfur gases released by a volcano with water vapor in the atmosphere. The aerosol causes a decrease in the mean global temperature because the droplets both absorb solar radiation and scatter it back into space. Attention is given to details concerning the volcanic eruption, the relation of El Chichon to the Mexican and Guatemalan volcanic belts, sources for the sulfur erupted by the volcano, and the mechanisms involved in the formation of sulfuric acid.

Rampino, M. R.↗
NASA NTRS1984

Determining soil moisture from geosynchronous satellite infrared data - A feasibility study

Numerical modelling results are reported from a pilot study investigating the feasibility of developing a technique for daily soil moisture measurement throughout the world, based on GOES infrared data. A detailed one-dimensional boundary layer-surface-soil model was used in order to determine which physical parameters observable from GOES are most sensitive to soil moisture, and which are most effected by seasonal changes, atmospheric effects and vegetation cover. The results of the sensitivity test show that the mid-morning differential of surface temperature with respect to absorbed solar radiation is optimally sensitive to soil moisture. A case study comparing model results with GOES infrared data confirms the sensitivity of this parameter to soil moisture and also confirms the applicability of the model to predicting area-averaged surface temperature changes. Model measurements of soil moisture are expected to be most accurate for dry or marginal agricultural areas where drought is common. Sources of error, including the advection of clouds, are examined and methods of minimizing error are discussed.

Wetzel, P. J.↗
NASA NTRS1984

Far Infrared and Submillimeter Observations of the Giant Planets

Far infrared measurements of the effective temperatures of Jupiter, Saturn, Uranus and Neptune were made. The measurements presented here cover the range from 35-1000 micrometers in relatively narrow bands. The observations at lambda 350 micrometers were made at the 3m NASA Infrared Telescope Facility (IRTF) of the Mauna Kea Observatory; those at lambda 350 micrometer were made on the Kuiper Airborne Observatory (KAO). All observations of Saturn were made when the ring inclination to Earth was 1.7 deg assuring an unambiguous measurement of the flux from the disk itself. Mars was used as the calibration reference. The results represent a consistent set of calibration standards. In these measurements, it is assumed that sub b(lambda = 350 micrometers) = T sub (lambda 350 micrometers). Measurements have been made of roughly 50% of the total flux emitted by Jupiter, 65% by Saturn, and 92% by Uranus and Neptune. These measurements therefore permit a considerable reduction in the uncertainties associated with the bolometric thermal outputs of the planets. The effective temperatures (T sub e) and the ratios of emitted to absorbed solar radiation were calculated.

Loewenstein, R. F.↗
NASA NTRS1984

IRAS observations of cometary dust

It is pointed out that solid material present in the coma and tail of a comet is revealed by the scattering of sunlight and thermal emission of absorbed solar radiation. The large beam size and low background of the cold Infrared Astronomy Satellite (IRAS) telescope make it extremely well suited to the measurement of faint diffuse thermal emission from solid grains associated with comets. The IRAS project was conducted jointly by the Netherlands, the United Kingdom, and the U.S. Its basic objective involved a survey of the sky in four wavelength regions centered on 12, 25, 60, and 100 microns. The present paper is mainly concerned with IRAS observations of the coma-nucleus regions as defined by the maximum in the intensity distribution. Attention is given to circumstances of comet observations, dust production rates, and a discussion of the results.

Walker, R. G.↗
NASA NTRS1984

Method for estimating errors for radiation budget based on a scanning radiometer

The conduction of the Earth Radiation Budget Experiment (ERBE) will involve the utilization of three sets of instruments. Each set consists of a nonscanning package and a scanning radiometer. The instruments will fly on the NOAA F and G operational satellites and on a dedicated spacecraft, the Earth Radiation Budget Satellite (ERBS). The ERBS will be in a 57 deg inclination orbit and will precess around the earth to provide sampling of the diurnal cycle of regions between + or - 57 deg latitude. The primary function of the scanning radiometer is to provide measurements for the calculation of the earth-emitted and absorbed solar radiation at the top of the earth-atmosphere system, averaged over 250 x 250 km regions. The present paper is concerned with errors found in these regional averages. Attention is given to details regarding the problem, scene identification probabilities, scene identification error effects, total pixel error, and errors due to regional averaging.

Smith, G. L.↗
NASA NTRS1985

On the structure and dynamics of the thermosphere

Thermospheric temperature, composition and wind measurements from the Dynamics Explorer satellite (DE-2) are interpreted using a three dimensional, multiconstituent spectral model. The analysis accounts for tides driven by the absorbed solar radiation as well as energy and momentum coupling involving the magnetosphere and lower atmosphere. Phenomena associated with the annual tide, polar circulation, magnetic storms and substorms are discussed.

Mayr, H. G.↗
NASA NTRS1986

Space station common module thermal management: Design and construction of a test bed

In this project, a thermal test bed was designed, simulated, and planned for construction. The thermal system features interior and exterior thermal loads and interfacing with the central-radiator thermal bus. Components of the test bed include body mounted radiator loop with interface heat exchangers (600 Btu/hr); an internal loop with cabin air-conditioning and cold plates (3400 Btu/hr); interface heat exchangers to the central bus (13,000 Btu/hr); and provisions for new technology including advanced radiators, thermal storage, and refrigeration. The apparatus will be mounted in a chamber, heated with lamps, and tested in a vacuum chamber with LN2-cooled walls. Simulation of the test bed was accomplished using a DEC PRO 350 computer and the software package TK! olver. Key input variables were absorbed solar radiation and cold plate loads. The results indicate temperatures on the two loops will be nominal when the radiation and cold plate loads are in the range of 25% to 75% of peak loads. If all loads fall to zero, except the cabin air system which was fixed, the radiator fluid will drop below -100 F and may cause excessive pressure drop. If all loads reach 100%, the cabin air temperature could rise to 96 F.

Barile, R. G.↗
NASA NTRS1986

Thermal balance of the atmospheres of Jupiter and Uranus

Two-dimensional, radiative-convective-dynamical models of the visible atmospheres of Jupiter and Uranus are presented. Zonally-averaged temperatures and heat fluxes are calculated numerically as functions of pressure and latitude. In addition to radiative heat fluxes, the dynamical heat flux due to large-scale baroclinic eddies is included and is parametrized using a mixing length theory which gives heat fluxes similar to those of Stone. The results for Jupiter indicate that the internal heat flow is non-uniform in latitude and nearly balances the net radiative flux leaving the atmosphere. The thermal emission is found to be uniform in latitude in agreement with Pioneer and Voyager observations. Baroclinic eddies are calculated to transport only a small amount of the meridional heat flow necessary to account for the uniformity of thermal emission with latitude. The bulk of the meridional heat transfer is found to occur very deep in the stable interior of Jupiter as originally proposed by Ingersoll and Porco. The relative importance of baroclinic eddies vs. internal heat flow in the thermal balance of Uranus depends on the ratio of emitted thermal power to absorbed solar power. The thermal balance of Uranus is compared to that of Jupiter for different values of this ratio.

Friedson, A. J.↗
NASA NTRS1989

Global distribution of moisture, evaporation-precipitation, and diabatic heating rates

Global archives were established for ECMWF 12-hour, multilevel analysis beginning 1 January 1985; day and night IR temperatures, and solar incoming and solar absorbed. Routines were written to access these data conveniently from NASA/MSFC MASSTOR facility for diagnostic analysis. Calculations of diabatic heating rates were performed from the ECMWF data using 4-day intervals. Calculations of precipitable water (W) from 1 May 1985 were carried out using the ECMWF data. Because a major operational change on 1 May 1985 had a significant impact on the moisture field, values prior to that date are incompatible with subsequent analyses.

Christy, John R.↗
NASA NTRS1990

Spacecraft attitude impacts on COLD-SAT non-vacuum jacketed LH2 supply tank thermal performance

The Cryogenic On-Orbit Liquid Depot - Storage, Acquisition and Transfer (COLD-SAT) spacecraft will be launched into low earth orbit to perform fluid management experiments on the behavior of subcritical liquid hydrogen (LH2). For determining the optimum on-orbit attitude for the COLD-SAT satellite, a comparative analytical study was performed to determine the thermal impacts of spacecraft attitude on the performance of the COLD-SAT non-vacuum jacketed LH2 supply tank. Tank thermal performance was quantified by total conductive and radiative heat leakage into the pressure vessel due to the absorbed solar, earth albedo and infra-red on-orbit fluxes, and also by the uniformity of the variation of this leakage on the vessel surface area. Geometric and thermal analysis math models were developed for the spacecraft and the tank as part of this analysis, based on their individual thermal/structural designs. Two quasi-inertial spacecraft attitudes were investigated and their effects on the tank performance compared. The results are one of the criteria by which the spacecraft orientation in orbit was selected for the in-house NASA Lewis Research Center design.

Arif, Hugh↗
NASA NTRS1990

Spacecraft attitude impacts on COLD-SAT non-vacuum jacketed LH2 supply tank thermal performance

The Cryogenic On-Orbit Liquid Depot - Storage, Acquisition and Transfer (COLD-SAT) spacecraft will be launched into low earth orbit to perform fluid management experiments on the behavior of subcritical liquid hydrogen (LH2). For determining the optimum on-orbit attitude for the COLD-SAT satellite, a comparative analytical study was performed to determine the thermal impacts of spacecraft attitude on the performance of the COLD-SAT non-vacuum jacketed LH2 supply tank. Tank thermal performance was quantitied by total conductive and radiative heat leakage into the pressure vessel due to the absorbed solar, earth albedo and infra-red on-orbit fluxes, and also by the uniformity of the variation of this leakage on the vessel surface area. Geometric and thermal analysis math models were developed for the spacecraft and the tank as part of this analysis, based on their individual thermal/structural designs. Two quasi-inertial spacecraft attitudes were investigated and their effects on the tank performance compared. The results are one of the criteria by which the spacecraft orientation in orbit was selected for the in-house NASA Lewis Research Center design.

Arif, Hugh↗
NASA NTRS1992

Selected results for LDEF thermal control coatings

The investigation of space environmental effects on LDEF thermal control coatings by the Materials Special Investigation Group is continuing. Analyses of chromic acid anodize, A276 white paint, and Z306 black paint were conducted, assessing performance as functions of environmental exposure. Test results from additional coatings, such as on scuff plates, M003, and the black chromium plate solar absorber, were obtained. Guidelines for the use of these materials and comparisons to ground based test data will be presented.

Golden, Johnny L.↗
NASA NTRS1992

Numerical simulation of the circulation of the atmosphere of Titan

A three dimensional General Circulation Model (GCM) of Titan's atmosphere is described. Initial results obtained with an economical two dimensional (2D) axisymmetric version of the model presented a strong superrotation in the upper stratosphere. Because of this result, a more general numerical study of superrotation was started with a somewhat different version of the GCM. It appears that for a slowly rotating planet which strongly absorbs solar radiation, circulation is dominated by global equator to pole Hadley circulation and strong superrotation. The theoretical study of this superrotation is discussed. It is also shown that 2D simulations systemically lead to instabilities which make 2D models poorly adapted to numerical simulation of Titan's (or Venus) atmosphere.

Hourdin, F.↗