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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 145 records · Page 8
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NASA NTRS1990

Immunology presentation at the 1990 NASA/NSF Antarctica Biomedical Science Working Group

An overview of methodology used for determining human in vitro lymphocyte activation, proliferation and effector cell function was presented and results of previous manned space flight immunology studies from Apollo through Shuttle were reviewed. Until the Shuttle era, lymphocyte assays were not very sensitive and had such large variations among normal subjects that it was difficult to define a consistent effect of space flight. More sensitive assay, however, even with Shuttle missions as brief as 6 days indicate depressed T-cell proliferative responses are routinely observed following space flight. Using a slight modification of the Shuttle assay, five different human stress-immunology models have been studied over the last 6 years in our lab. These have included: academic examinations of medical students having blood drawn during major test periods on three separate groups of first year students and two hypoxia studies (at 25,000 feet in a 6 week chamber ascent to the equivalent of Mount Everest and twice on Pikes Peak at 14,000 feet). These studies are particularly pertinent to Antarctica, since the altitude equivalent of 11,000 feet at the South Pole may affect some of the variables that are being measured in immunology, physiology or cognitive studies. An extravehicular study was performed drawing blood from 35 individuals before and immediately following a chamber exposure study. Preliminary results from 30 Shuttle astronauts investigated immunophenotype analysis and the role of a novel monocyte population in modulating the previously observed suppressed in vitro immune function. The results of the Air Force Academy cadet stress study were also presented.

Meehan, Richard T.↗
NASA NTRS1993

Sensible and latent heat flux estimates in Antarctica

The assumption has been made that the net annual contribution of water by the processes of deposition and sublimation to the Antarctic Ice Sheet is zero. The U.S. Antarctic Program started installing reliable automatic weather stations on the Antarctic Continent in 1980. The initial units were equipped to measure wind speed, wind direction, air pressure, and air temperature. During the 1983-1984 field season in Antarctica, three units were installed that measured a vertical air temperature difference between the nominal heights of 0.5 m and 3.0 m and relative humidity at a nominal height of 3 m. The measurements of the vertical air temperature difference and the relative humidity are the minimum required to estimate the sensible and latent heat fluxes to the air, while not exceeding the available energy requirements for the weather stations. The estimates of the net annual sublimation and deposition on the Ross Ice Shelf amount to 20 to 80 percent of the annual accumulation. We conclude that the assumption that annual sublimation and deposition are zero is not valid under Antarctic conditions.

Stearns, Charles R.↗
NASA NTRS1993

Stratospheric dryness - Antiphased desiccation over Micronesia and Antarctica

HALOE observations of water vapor and methane during the period 21 September - 15 October 1992 are used to examine the role of Antarctic drying in the lower stratosphere. Zonal mean cross-sections of 2 CH4 + H2O show the probability of transport of Antarctic type dryness to latitudes as distant as 20 deg N, with major water vapor deficits evident between 10 and 100 mb to 10 deg S. Examination of monthly mean tropical 100 mb temperatures and of Antarctic temperatures suggests that the observations are consistent with stratospheric dryness being achieved by the combined effects of tropopause freeze-drying over the Micronesia region during northern winter and drying through the influence of the very low temperatures over Antarctica during southern winter. This paper presents these intriguing new results, and offers a possible explanation.

Tuck, A. F.↗
NASA NTRS1994

The controlled ecological life support system Antarctic analog project: Analysis of wastewater from the South Pole Station, Antarctica, volume 1

The Controlled Ecological Life Support system (CELSS) Antarctic Analog Project (CAAP) is a joint National Science Foundation (NSF) and NASA project for the development, deployment and operation of CELSS technologies at the Amundsen-Scott South Pole Station. NASA goals are operational testing of CELSS technologies and the conduct of scientific studies to facilitate technology selection and system design. The NSF goals are that the food production, water purification, and waste treatment capabilities which will be provided by CAAP will improve the quality of life for the South Pole inhabitants, reduce logistics dependence, and minimize environmental impacts associated with human presence on the polar plateau. This report presents an analysis of wastewater samples taken from the Amundsen-Scott South Pole Station, Antarctica. The purpose of the work is to develop a quantitative understanding of the characteristics of domestic sewage streams at the South Pole Station. This information will contribute to the design of a proposed plant growth/waste treatment system which is part of the CELSS Antarctic Analog Project (CAAP).

Flynn, Michael T.↗
NASA NTRS1994

Ozone profiles over McMurdo Station, Antarctica, during August, September, and October of 1986 - 1991

Vertical profiles of ozone and temperature have been measured at McMurdo Station, Antarctica, during the springs of 1986 to 1991, roughly every two days from 25 August to 31 October. Comparisons of temporal histories and average vertical structure for these years reveals some striking consistency in the ozone depletion process. Ozone depletion generally begins in early September, and with a half-life of 20-30 days, reaches its maximum in mid-October. The depletion occurs almost exclusively between 12 and 20 km. At the time of maximum depletion total ozone has been decreased roughly 40 percent while ozone between 12 and 20 km has been reduced 80 percent. Recovery generally begins in late October with the influx, above 20 km, of ozone rich air from the lower latitudes. From this record the worst years for ozone depletion were 1987, 1989, and 1990. A new region of ozone depletion, below 12 km, was observed in 1991, coinciding with the entrainment of a volcanic cloud into the polar vortex.

Deshler, Terry↗
NASA NTRS1994

Long-term ozone and temperature correlations above SANAE, Antarctica

A significant decline in Antarctic total column ozone and upper air temperatures has been observed in recent years. Furthermore, high correlations between monthly mean values of ozone and stratospheric temperature have been measured above Syowa, Antarctica. For the observations reported here, data from TOMS (Total Ozone Mapping Spectrometer) aboard the Nimbus 7 satellite have been used to examine the 1980 to 1990 decrease in total column ozone above the South African Antarctic base of SANAE (70 deg 18 min S, 2 deg 21 min W). The cooling of the Antarctic stratosphere above SANAE during this period has been investigated by examining upper air temperatures at the 150, 100, 70, 50, and 30 hPa levels obtained from daily radiosonde balloon launches. Furthermore, these two data sets have been used to examine long-term, medium-term, and short-term correlations between total column ozone and the temperatures at each of the five levels. The trend in SANAE total column ozone has been found to be -4.9 DU/year, while upper air temperatures have been found to decrease at around 0.3 C/year. An analysis of monthly average SANAE total column ozone has shown the decrease to be most severe during the month of September with a trend of -7.7 DU/year. A strong correlation (r(exp 2) = 0.92) has been found between yearly average total column ozone and temperature at the 100 hPa level. Daily ozone and temperature correlations show high values from September to November, at a time when the polar vortex is breaking down.

Bodeker, Gregory E.↗
NASA NTRS1994

Measurements of stratospheric odd nitrogen at Arrival Heights, Antarctica, in 1991

An FTIR spectrometer was installed at Arrival Heights, Antarctica (78 deg S, 167 deg E) in February 1991 to measure the evolution of stratospheric HNO3 during the year. In particular, it was the intention to make the first observations of HNO3 trends during autumn, concurrently with ongoing measurements of column NO2 made with a grating spectrometer. The time-series of NO2 in the Antarctic shows a rapid decline in the column amount during autumn, and a slow recovery in spring, as the photochemical conditions move the species to and from higher storage reservoirs. The new nitric acid data show for the first time that during autumn the vertical column increases from approximately 1.9 x 10(exp 16) molecule cm(exp -2) at day 30 to approximately 3.1 x 10(exp 16) molecule cm(exp -2) by day 100. When the sun returns in spring, it is found that the column amount has fallen to about half the value at the end of autumn. Spring amounts are variable, but as found in the data from previous years remain low inside the vortex. The autumn increase is attributed to the heterogeneous conversion of N2O5 to gas-phase HNO3 on background aerosols. Low nitric acid column amounts at the start of spring suggest that the HNO3 has moved from the gas to the condensed phase on polar stratospheric clouds with the advent of low temperatures during the polar night.

Keys, J. Gordon↗
NASA NTRS1994

The use of visible-channel data from NOAA satellites to measure total ozone amount over Antarctica

Accurate, detailed maps of total ozone were not available until the launch of the Total Ozone Mapping Spectrometer (TOMS) in late 1978. However, the Scanning Radiometer (SR), an instrument on board the NOAA series satellites during the 1970s, had a visible channel that overlapped closely with the Chappuis absorption band of ozone. We are investigating whether data from the SR can be used to map Antarctic ozone prior to 1978. The method is being developed with 1980s data from the Advanced Very High Resolution Radiometer (AVHRR), which succeeded the SR on the NOAA polar-orbiting satellites. Visible-derived total ozone maps can then be compared able on the NOAA satellites, which precludes the use of a differential absorption technique to measure ozone. Consequently, our method works exclusively over scenes whose albedos are large and unvarying, i.e. scenes that contain ice sheets and/or uniform cloud-cover. Initial comparisons of time series for October-December 1987 at locations in East Antarctica show that the visible absorption by ozone in measurable and that the technique may be usable for the 1970s, but with much less accuracy than TOMS. This initial test assumes that clouds, snow, and ice all reflect the same percentage of visible light towards the satellite, regardless of satellite position or environmental conditions. This assumption is our greatest source of error. To improve the accuracy of ozone retrievals, realistic anisotropic reflectance factors are needed, which are strongly influenced by cloud and snow surface features.

Boime, Robert D.↗
NASA NTRS1994

From Antarctica to space: Use of telepresence and virtual reality in control of remote vehicles

In the Fall of 1993, NASA Ames deployed a modified Phantom S2 Remotely-Operated underwater Vehicle (ROV) into an ice-covered sea environment near McMurdo Science Station, Antarctica. This deployment was part of the antarctic Space Analog Program, a joint program between NASA and the National Science Foundation to demonstrate technologies relevant for space exploration in realistic field setting in the Antarctic. The goal of the mission was to operationally test the use of telepresence and virtual reality technology in the operator interface to a remote vehicle, while performing a benthic ecology study. The vehicle was operated both locally, from above a dive hole in the ice through which it was launched, and remotely over a satellite communications link from a control room at NASA's Ames Research Center. Local control of the vehicle was accomplished using the standard Phantom control box containing joysticks and switches, with the operator viewing stereo video camera images on a stereo display monitor. Remote control of the vehicle over the satellite link was accomplished using the Virtual Environment Vehicle Interface (VEVI) control software developed at NASA Ames. The remote operator interface included either a stereo display monitor similar to that used locally or a stereo head-mounted head-tracked display. The compressed video signal from the vehicle was transmitted to NASA Ames over a 768 Kbps satellite channel. Another channel was used to provide a bi-directional Internet link to the vehicle control computer through which the command and telemetry signals traveled, along with a bi-directional telephone service. In addition to the live stereo video from the satellite link, the operator could view a computer-generated graphic representation of the underwater terrain, modeled from the vehicle's sensors. The virtual environment contained an animate graphic model of the vehicle which reflected the state of the actual vehicle, along with ancillary information such as the vehicle track, science markers, and locations of video snapshots. The actual vehicle was driven either from within the virtual environment or through a telepresence interface. All vehicle functions could be controlled remotely over the satellite link.

Stoker, Carol↗
NASA NTRS1994

The natural thermoluminescence of meteorites. 7: Ordinary chondrites from the Elephant Moraine region, Antarctica

We report natural and induced thermoluminescence (TL) measurements for meteorites from the Elephant Moraine region (76 deg 17 min S, 157 deg 20 min E) of Antarctica. We use our data to identify fragmented meteorites (i.e., 'pairings'); our dataset of 107 samples represents at most 73 separate meteorite falls. Pairing groups are generally confined to single icefields, or to adjacent icefields, but a small proportion cross widely separated icefields in the region, suggesting that the fields can be considered as a single unit. Meteorites from this region have high natural TL levels, which indicates that they have small terrestrial surface exposure ages (less than 12,500 years). There do not appear to be significant differences in natural TL levels (and hence surface exposure ages) between individual blue icefields in the region. The proportion of reheated meteorites from the Elephant Moraine region is similar to that of other Antarctic sites and modern falls, consistent with the uniformity of the meteoritic flux in this regard. An unusual subset of H-chondrites, with high induced TL peak temperatures, is absent among the data for meteorites collected in the Elephant Moraine region, which stresses their similarity to modern falls. We suggest that the Elephant Moraine region, which stresses their similarity to modern falls. We suggest that the Elephant Moraine icefields formed through shallow ablation of the ice. Unlike the Allan Hills sites to the south, lateral transport is probably less important relative to the infall of meteorites in concentrating meteorites on these icefields.

Benoit, P. H.↗
NASA NTRS1995

A preliminary comparison of two perennially ice-covered lakes in Antarctica: Analogs of past martian lacustrine environments

Perennially ice-covered lakes in the Antarctic have been suggested as analogs to lakes which may have existed on the surface of Mars 3.5 billion years ago. During the 1991-1992 austral summer, a joint Russian/American research effort was directed at studies of ice-covered lakes in the Bunger Hills Oasis, Antarctica (66 deg S, 100 deg E). The primary objective of the expedition was to investigate this ice-free area for features analogous to ancient martian environments that may have been capable of supporting life and to compare the ice-covered lakes of the Bunger Hills with those in the McMurdo Dry Valleys of southern Victoria Land (77 deg S, 166 deg E) as part of the continuing studies of Antarctic-Mars analogs.

Andersen, D. T.↗
NASA NTRS1994

Light transmission and reflection in perennially ice-covered Lake Hoare, Antarctica

We have investigated the transmission and albedo of the perennial ice cover on Lake Hoare, Antarctica. Our database consists of year-round measurements of the photosynthetically active radiation (400-700 nm) under the ice, measurements of the spatial variation of the under-ice light in midsummer, and spectrally resolved measurements from 400 to 700 nm of the albedo and transmission of the ice cover in early (November) and in midsummer (January). Our results show that the transmission decreases in the first part of summer, dropping by a factor of approximately 4 from November to January. We suggest that this is due to heating in the upper layers of the ice cover and the formation of Tyndall figures. Later in the summer when a significant liquid water fraction occurs within the ice cover, the transmission increases. In the fall when the ice cover freezes solid the transmission drops markedly. The spectrally resolved measurements from 400 to 700 nm show that approximately 2-5% of the incident light in this spectral region penetrates the 3.5-m thick ice cover. We have analyzed the spectral data using a two-stream scattering solution to the radiative transfer equation with three vertical layers in the ice cover. A surficial glaze of scattering ice 1 cm thick overlies a layer of sandy, bubbly ice about a meter thick, and below this is a thick layer of sand-free ice with bubbles. We find that the ice cover is virtually opaque at wavelengths longer than 800 nm. The net transmission of solar energy is approximately 2%. Significant changes in the thickness of the ice cover have been reported at Lake Hoare. These are due primarily to changes in the thickness of the bottom layer only. Because this layer is relatively clear, the effect on the transmission through the ice cover from these changes is less than would be predicted assuming a homogeneous ice cover.

Mckay, C. P.↗
NASA NTRS1995

Stratospheric ClO profiles from McMurdo Station, Antarctica, spring 1992

We describe ground-based measurements of ClO made at McMurdo Station, Antarctica, during September and October 1992. Vertical profiles were retrieved from molecular rotational emission spectra at 278 GHz. Peak mixing ratios of 1.6 +/- 0.3 ppbv were seen in mid-September at approximately 18 km altitude, suggestive of somewhat larger quantities than were measured at the same site and season in 1987. As the core of the polar vortex moved away from McMurdo by early October, the ClO mixing ratio at this altitude dropped to less than 0.2 ppbv, coincident with increasing temperature, ozone, and NO2. The diurnal variation of ClO was also observed. The lower stratospheric layer from 15 to 27 km was found to reach approximately midday abundance by 2 - 3 hours after sunrise. The column abundance in this layer began to decrease by the period 4 - 2 hours before sunset and had declined to approximately one quarter of its midday value by 2 - 0 hours before sunset. In contrast, the ClO column in the upper stratosphere, from 28 to 50 km, built up slowly until midday and remained large while sunlight persisted.

Emmons, L. K.↗
NASA NTRS1995

The Center for Astrophysics in Antarctica

Nowhere on Earth are the infrared skies clearer, darker, or more stable than on the high Antarctic Plateau. At some wavelengths, Antarctic telescopes may be more than one to two orders of magnitude more efficient than at other sites. However, exploiting these advantages requires first addressing the formidable practical difficulties of working in the remote and frigid polar environment. This was the motivation for the Center for Astrophysical Research in Antarctica (CARA), one of twenty-five National Science Foundation Science and Technology Centers. At its inception, the Center organized its research into four projects. Three - AST/RO, COBRA, and SPIREX - address key problems in star formation, evolution of galaxies, and the distribution of matter in the early universe. They feature surveys which can be conducted effectively with moderate-size telescopes operated in a highly automated mode. They also explore the potential of the Antarctic Plateau for a broad range of astrophysical research over a spectral range extending from the near-infrared to millimeter wavelengths. A fourth, ATP, was created to obtain quantitative data on the qualities of the South Pole site and to plan for future scientific projects. During the next five years, AST/RO, COBRA, and SPIREX will become operational, and the Center will begin to build a second generation of telescopes which can address a broader range of problems and accommodate a larger community of users.

Pernic, Robert J.↗
NASA NTRS1993

Geostatistical evaluation of satellite radar altimetry for high-resolution mapping of Lambert Glacier, Antarctica

The potential of satellite radar altimetry for high-resolution mapping of Antarctic ice streams is evaluated, using retracked and slope-corrected data from the Lambert Glacier and Amery Ice Shelf area, East Antarctica, acquired by Geosat during the Exact Repeat Mission (ERM), 1986-89. The map area includes lower Lambert Glacier north of 72.18 deg S, the southern Amery Ice Shelf, and the grounded inland ice sheet on both sides. The Geosat ERM altimetry is found to provide substantially more complete coverage than the 1978 Seasat altimetry, due to improved tracking. Variogram methods are used to estimate the noise levels in the data as a function of position throughout the map area. The spatial structure in the data is quantified by constructing experimental variograms using altimetry from the area of the grounding zone of Lambert Glacier, which is the area chiefly of interest in this topographically complex region. Kriging is employed to invert the along-track height measurements onto a fine-scale 3 km grid. The unsmoothed along-track Geosat ERM altimetry yields spatially continuous maps showing the main topographic features of lower Lambert Glacier, upper Amery Ice Shelf and the adjacent inland ice sheet. The probable position of the grounding line of Lambert Glacier is identified from a break in slope at the grounded ice/floating ice transition. The approximate standard error of the kriged map is inferred from the data noise levels.

Herzfeld, Ute C.↗
NASA NTRS1996

New results from mapping Antarctica at high resolution from radar altimeter data

The limits of the altimeter data evaluation were analyzed using geostatistical methods. It is often argued that satellite radar altimeter data over ice can not be used to map ice surfaces with a slope exceeding 0.5 deg. The maps presented, obtained from the Geosat satellite geodetic mission, concern the Antarctica north of 72.1 deg South. The grids constructed from other satellite observations facilitate the analysis of the changes in the Antarctic ice stream/ice shelf systems. The evaluation was applied to the Lambert Glacier/Amery Ice Shelf system.

Matassa, Michael↗
NASA NTRS1998

Curation of US Martian Meteorites Collected in Antarctica

To date the ANSMET field team has collected five martian meteorites (see below) in Antarctica and returned them for curation at the Johnson Space Center (JSC) Meteorite Processing Laboratory (MPL). ne meteorites were collected with the clean procedures used by ANSMET in collecting all meteorites: They were handled with JSC-cleaned tools, packaged in clean bags, and shipped frozen to JSC. The five martian meteorites vary significantly in size (12-7942 g) and rock type (basalts, lherzolites, and orthopyroxenite). Detailed descriptions are provided in the Mars Meteorite compendium, which describes classification, curation and research results. A table gives the names, classifications and original and curatorial masses of the martian meteorites. The MPL and measures for contamination control are described.

Lindstrom, M.↗
NASA NTRS1998

Carbon-Isotopic Dynamics of Streams, Taylor Valley, Antarctica: Biological Effects

We have investigated the role of biological processes in the C-isotopic dynamics of the aquatic ecosystems in Taylor Valley, Antarctica. This cold desert ecosystem is characterized by the complete lack of vascular plants, and the presence of algal mats in ephemeral streams and perennially ice covered lakes. Streams having abundant algal mats and mosses have very low sigma CO2 concentrations, as well as the most depleted delta C-13 values (-4%). Previous work has shown that algal mats in these streams have delta C-13 values averaging -7.01%. These values are similar to those observed in the algal mats in shallow areas of the lakes in Taylor Valley, where CO2 is thought to be colimiting to growth. These low Sigma CO2 concentrations, and delta C(13) signatures heavier than the algal mats, suggest that CO2 may be colimiting in the streams, as well. Streams with little algal growth, especially the longer ones in Fryxell Basin, have higher Sigma CO2 concentrations and much more enriched isotopic signatures (as high as +8%). In these streams, the dissolution of isotopically enriched, cryogenic CaCO3 is probably the major source of dissolved carbonate. The delta C(13) geochemistry of Antarctic streams is radically different from the geochemistry of more temperate streams, as it is not affected by terrestrially produced, isotopically depleted Sigma CO2. These results have important implications for the understanding of "biogenic" carbonate that might have been produced from aquatic ecosystems in the past on Mars.

Neumann, K.↗