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At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Pressurized Lunar Rover (PLR)

The objective of this project was to design a manned pressurized lunar rover (PLR) for long-range transportation and for exploration of the lunar surface. The vehicle must be capable of operating on a 14-day mission, traveling within a radius of 500 km during a lunar day or within a 50-km radius during a lunar night. The vehicle must accommodate a nominal crew of four, support two 28-hour EVA's, and in case of emergency, support a crew of six when near the lunar base. A nominal speed of ten km/hr and capability of towing a trailer with a mass of two mt are required. Two preliminary designs have been developed by two independent student teams. The PLR 1 design proposes a seven meter long cylindrical main vehicle and a trailer which houses the power and heat rejection systems. The main vehicle carries the astronauts, life support systems, navigation and communication systems, lighting, robotic arms, tools, and equipment for exploratory experiments. The rover uses a simple mobility system with six wheels on the main vehicle and two on the trailer. The nonpressurized trailer contains a modular radioisotope thermoelectric generator (RTG) supplying 6.5 kW continuous power. A secondary energy storage for short-term peak power needs is provided by a bank of lithium-sulfur dioxide batteries. The life support system is partly a regenerative system with air and hygiene water being recycled. A layer of water inside the composite shell surrounds the command center allowing the center to be used as a safe haven during solar flares. The PLR 1 has a total mass of 6197 kg. It has a top speed of 18 km/hr and is capable of towing three metric tons, in addition to the RTG trailer. The PLR 2 configuration consists of two four-meter diameter, cylindrical hulls which are passively connected by a flexible passageway, resulting in the overall vehicle length of 11 m. The vehicle is driven by eight independently suspended wheels. The dual-cylinder concept allows articulated as well as double Ackermann steering. The primary power of 8 kW is supplied by a dynamic isotope system using a closed Brayton cycle with a xenon-hydrogen mixture as the working fluid. A sodium-sulfur battery serves as the secondary power source. Excess heat produced by the primary power system and other rover systems is rejected by radiators located on the top of the rear cylinder. The total mass of the PLR 2 is 7015 kg. Simplicity and low total weight have been the driving principles behind the design of PLR 1. The overall configuration consists of a 7-m-long, 3-m-diameter cylindrical main vehicle and a two-wheeled trailer. The cylinder of the main body is capped by eight-section, faceted, semi-hemispherical ends. The trailer contains the RTG power source and is not pressurized. The shell of the main body is constructed of a layered carbon fiber/foam/Kevlar sandwich structure. Included in the shell is a layer of water for radiation protection. The layer of water extends from the front of the rover over the crew compartment and creates a safe haven for the crew during a solar flare-up. The carbon fiber provides the majority of the strength and stiffness and the Kevlar provides protection from micrometeoroids. The Kevlar is covered with a gold foil and multi-layer insulation (MLI) to reduce radiation degradation and heat transfer through the wall. A thin thermoplastic layer seals the fiber and provides additional strength.

Creel, Kenneth↗
NASA NTRS1985

New Life for Miss Liberty

Corrosion protection for the Statue of Liberty's interior structure is provided by a coating called IC 531, manufactured by Inorganic Coatings, Inc. The coating was developed by Goddard to protect structures at KSC. Inorganic Coatings has an exclusive to this high ratio potassium silicate formula. The coating is water based, nontoxic, nonflammable, and bonds to steel in 30 minutes. Tests on a variety of coated structures have been very positive.

Source record↗
NASA NTRS1984

Mixed Layers and Satellite Retrievals

As part of the process to determine whether it is possible to retrieve boundary layer structure with the current sounding techniques, temperature retievals were performed for radiosonde profiles that showed temperature inversions. It was found that when temperature inversions exceed 8 to 10 C a retrieval will indeed show a temperature increase with height over a limited vertical distance. For weaker inversions retrieved temperatures are generally smoothly decreasing with height. It is, however, impossible to determine the actual mixed layer height from the retrievals. Whether the water vapor channels could be used in observing mixed layer structure was investigated. Temperature inversions are accompanied by significant drops in relative humidity. While this effect is very pronounced in parts of the trade wind regimes with relative humidity drops of up to 60%, it is widespread in other areas of the ocean as well. A simulation experiment was performed in which brightness temperatures were computed for smooth temperature and humidity profiles and compared with those computed from inversion profiles.

Boers, R.↗
NASA NTRS1993

Discovery Venera surface: Atmosphere geochemistry experiments mission concept

The phenomenal increase in our understanding of Venus provided by the Magellan Mission has raised a series of focused, fundamental scientific questions about the geochemistry of the surface of Venus, the nature of the lower atmosphere, and the relationship of the lower atmosphere and surface. First, surface geochemical measurements from the Venera/Vega spacecraft showed that widely spaced regions of the venusian plains are made of basalts; thus basalts are significant and may be the only component of the venusian crust. But we lack information on the composition of several key elements of Venus geology: (1) Tessera terrain (which may be outcrops of continental-like non-basaltic crustal material) and steep-sided domes/festoons are promising candidates for non-basaltic geochemically evolved material. The composition of the lower part of the Venusian crust is unknown: however, ejecta from large venusian craters provides us with the possibility of sampling this material on the surface; (2) bulk chemistry (structure and dynamics) of the venusian atmosphere are known. The altitude profiles of water vapor content and minor admixtures relevant to redox conditions in the lower atmosphere (less than 20 km altitude) remain uncertain. Lack of that knowledge means that we do not understand the fine chemical structure of the main mass of the Venusian atmosphere; and (3) thermodynamic models predict that igneous materials on the surface of Venus should react with gases of the venusian atmosphere. But because the water vapor content and redox conditions in the lower atmosphere are not well known, we do not understand the nature of venusian weathering: oxidation, sulfatization, carbonatization, and hydration. The answers to these questions are critical to the understanding of Venus, the most Earth-like of the terrestrial planets.

Surkov, Yuri A.↗
NASA NTRS1989

Thermographic detection of disbonds

The presence of disbonds significantly decreases the integrity of many laminated structures used in aerospace applications. A thermographic technique is presented which is able to detect subsurface delamination. The technique uses one of several heat sources (such as hot water, hot air, IR lamps, etc.) to increase the surface temperature of the structure. The subsequent temperature profiles of the surface are detected with an IR camera. A novel spatial filter developed at NASA-Langley eliminates the effects of uneven heating to give clear images of the subsurface delaminations. Defects are detectable in samples as diverse as solid rocket motor samples and laminated wood for wind tunnel blades. Numerical simulations are presented for comparison with experiment results.

Winfree, William P.↗
NASA NTRS1984

Studies of Atmospheric Water in Storms with the Nimbus 7 Scanning Multichannel Microwave Radiometer

The new tools for the study of midlattitude cyclones by atmospheric water channels of the scanning multichannel microwave radiometer (SMMR) on Nimbus 7, were discussed. The integrated atmospheric water vapor, total cloud liquid water and rain data were obtained from the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR). The frontal structure of several midlattitude cyclones over the North Pacific Ocean as they approached the West Coast of North America were studied. It is found that fronts are consistently located at the leading edge of the strongest gradient in integrated water vapor. The cloud liquid water content has patterns which are consistent with the structure seen in visible and infrared imagery. The rain distribution is a good indicator of frontal location. It is concluded that the onset of rain on the coast can be forecast accurately by simple advection of the SMMR observed rain areas.

Katsaros, K. B.↗
NASA NTRS1994

Archean geochemistry of formaldehyde and cyanide and the oligomerization of cyanohydrin

The sources and speciation of reduced carbon and nitrogen inferred for the early Archean are reviewed in terms of current observations and models, and known chemical reactions. Within this framework hydrogen cyanide and cyanide ion in significant concentration would have been eliminated by reaction with excess formaldehyde to form cyanohydrin (glycolonitrile), and with ferrous ion to formferrocyanide. Natural reactions of these molecules would under such conditions deserve special consideration in modeling of primordial organochemical processes. As a step in this direction, transformation reactions have been investigated involving glycolonitrile in the presence of water. We find that glycolonitrile, formed from formaldehyde and hydrogen cyanide or cyanide ion, spontaneously cyclodimerizes to 4-amino-2-hydroxymethyloxazole. The crystalline dimer is the major product at low temperatue (approximately 0 C); the yield diminishes with increasing temperature at the expense of polymerization and hydrolysis products. Hydrolysis of glycolamide and of oxazole yields a number of simpler organic molecules, including ammonia and glycolamide. The spontaneous polymerization of glycolonitrile and its dimer gives rise to soluble, cationic oligomers of as yet unknown structure, and, unless arrested, to a viscous liquid, insoluble in water. A loss of cyanide by reaction with formaldehyde, inferred for the early terrestrial hydrosphere and cryosphere would present a dilemma for hypotheses invoking cyanide and related compounds as concentrated reactants capable of forming biomolecular precursor species. Attempts to escape from its horns may take advantage of the efficient concentration and separation of cyanide as solid ferriferrocyanide, and most directly of reactions of glycolonitrile and its derivatives.

Arrhenius, T.↗
NASA NTRS1972

Development of advanced fuel cell system

Weight, life and performance characteristics optimization of hydrogen-oxygen fuel cell power systems were considered. A promising gold alloy cathode catalyst was identified and tested in a cell for 5,000 hours. The compatibility characteristics of candidate polymer structural materials were measured after exposure to electrolyte and water vapor for 8,000 hours. Lightweight cell designs were prepared and fabrication techniques to produce them were developed. Testing demonstrated that predicted performance was achieved. Lightweight components for passive product water removal and evaporative cooling of cells were demonstrated. Systems studies identified fuel cell powerplant concepts for meeting the requirements of advanced spacecraft.

Grevstad, P. E.↗
NASA NTRS1973

Liquid rocket propellant feedline dynamics

An analytical and experimental study of liquid rocket propellant feedline dynamics has been performed. The analytical model, which includes the effects of turbulent flow, distributed and local compliances, bellows, side branches, and structural mounting stiffness, was verified by an experimental program. Water was used as the internal fluid and the dynamic perturbations in pressure and flow were created by a piston pulser. Measurements were made to determine the pressure perturbation amplitude and phase at the line terminal due to a sinusoidal pulser excitation. The frequency response of the various line configurations tested were compared with the computed theoretical results.

Holster, J. L.↗
NASA NTRS1974

The remote-sensing program of the Geological Survey of Alabama

Some areas of remote-sensing research in Alabama are reviewed, showing how remote sensing technology can provide data that cannot be obtained by other methods. Applications of this technology to structural and stratigraphic research and to the search for water, mineral, and energy sources are discussed, and some results of these applications are illustrated.

Drahovzal, J. A.↗
NASA NTRS1980

Environmental impacts of the satellite power system (SPS) on the middle atmosphere

The heavy lift launch vehicles (HLLV) proposed for use in constructing satellite power systems (SPS) would deposit various contaminants in the middle atmosphere, contaminants that would conceivable have adverse effects on climate and upper air structure. These contaminants consist of the major constitutents of water vapor, hydrogen, carbon dioxide, and carbon monoxide, and the minor constituents of sulfur dioxide and nitric oxide in the rocket effluent, as well as nitric oxide formed during reentry. To assess the magnitudes of the effects, new models or modified existing models were constructed.

Source record↗
NASA NTRS1985

A cool anomaly off northern California - An investigation using IR imagery and in situ data

The OPTOMA (Ocean Prediction Through Observation, Modeling and Analysis) program is developing an ocean descriptive-predictive system for four-dimensional data assimilation. It is presently concerned with the mesoscale variability in the California Current System (CCS). The present paper has the objective to assess the relationship of surface temperature structure to subsurface temperature structure and flow fields. Surface temperature anomalies are related to the mesoscale horizontal advective and subsurface mass fields. The cool anomaly off northern California in summer 1982 is discussed, taking into account the temperature structure along transects, T-S variations and inferred water masses, variation of horizontal temperature patterns with depth, and synoptic information from IR data.

Rienecker, M. M.↗
NASA NTRS1985

Cooperative VAS program with NASA Marshall Space Flight Center

The importance of mesoscale moisture information in the forecasting of weather events is discussed. A test is being prepared with the March 6, 1982 Vertical Atmospheric Sounder/Atmospheric Variability Experiment (VAS/AVE) case study to be run on the sub-synoptic scale model (SSM). Model intracomparison of three carefully designed simulations should isolate the role of mesoscale information in the initial conditions for both mositure and vertical motion. Three simulations will be made for the period 1200Z 6 March to 0000Z 7 March starting with the regular synoptic time data of 1200Z. The distinction between the three cases arises from data manipulation at 1800Z midway through the forecast period: (1) Control Case: no alterations at 1800Z. (2) Moisture Information Suppression: at 1800Z the model simulation field for water vapor, which by this time contains considerable mesoscale structure, is replaced by a smoothed version from which the mesoscale structure has been eliminated. No other variables are structure altered. (3) Vertical Motion Information Suppression: at 1800Z the model is subjected to a dead start procedure which primarily imposes a nondivergent constraint of the horizontal motion field field suppressing vertical motion. The main effect is to eliminate the mesoscale component. Comparison of results for the 1800Z to 0000Z time period will give the information desired.

Houghton, D. D.↗
NASA NTRS1998

Mars Secular Obliquity Change Due to Water Ice Caps

Mars may have substantially changed its average axial tilt over geologic time due to the waxing and waning of water ice caps. Depending upon Mars' climate and internal structure, the average obliquity could have increased or decreased through climate friction by tens of degrees. A decrease could account for the apparent youthfulness of the polar layered terrain. Alternatively, Mars' average obliquity may have changed until it became "stuck" at its present value of 24.4 deg.

Rubincam, David P.↗
NASA NTRS1999

X-Ray Fingerprinting Techniques for Recognizing A Hydrological Role in the Formation of Minerals on the Surface of Mars

Previous work has demonstrated the ability of a miniaturized XRD-XRF instrument to perform in-situ analyses without sample preparation or acquisition. Deployment of this instrument on a Martian rover will allow a large number of rapid qualitative analyses, which will maximize the diversity of samples studied and selected for possible return. As a first step in designing a decision tree for recognizing minerals in complex mixtures, d spacings were plotted against intensity for several mineral groups comprising rock and soil types inferred for the surface of Mars (weathered basalt, playa and hydrothermal deposits, clay-rich soils). In all groups, d spacings cluster in a range from about 1-4 angstroms, which can under certain circumstances obscure patterns for individual phases. However, within the silicate family, minerals containing either bound OH- or molecules of H20 (clays, micas, amphiboles, zeolites) are characterized by a shift of peaks to higher d spacings. Large d spacings (greater than about 7 angstroms) thus act as a first-order filter for distinguishing hydrous from anhydrous silicates. The ability to quickly verify the presence of silicates that have interacted with water has important implications for using mineral chemistry and structure to help decipher the hydrologic and atmospheric history of Mars. This represents a beginning for developing more sophisticated methods of pattern recognition. These will combine XRD and XRF analyses with optical data to rapidly7 discern environmentally diagnostic assemblages without the necessity of identifying every peak individual mineral phase.

Metzger, Ellen P.↗
NASA NTRS2001

Waterproofing Nanostructured Aerogel-Ceramic Fiber Composites

Aerogels are nanoporous materials which can be used to enhance the transport properties of ceramic fiber materials, to exploit their unique properties such as high porosity, large surface area, low density and low thermal conductivity. Numerous applications have been investigated. major obstacle to commercialization is that the structure of aerogels collapses due to the adsorption of water. simple and relatively cheap process has been developed to waterproof silica, alumina and alumina-silica and carbon aerogels and composites incorporating them. Previous waterproofing methods are short lived or expensive and time consuming.

White, Susan↗
NASA NTRS2004

X-Ray Crystallography Reagent

Microcapsules prepared by encapsulating an aqueous solution of a protein, drug or other bioactive substance inside a semi-permeable membrane by are disclosed. The microcapsules are formed by interfacial coacervation under conditions where the shear forces are limited to 0-100 dynes per square centimeter at the interface. By placing the microcapsules in a high osmotic dewatering solution. the protein solution is gradually made saturated and then supersaturated. and the controlled nucleation and crystallization of the protein is achieved. The crystal-filled microcapsules prepared by this method can be conveniently harvested and stored while keeping the encapsulated crystals in essentially pristine condition due to the rugged. protective membrane. Because the membrane components themselves are x-ray transparent, large crystal-containing microcapsules can be individually selected, mounted in x-ray capillary tubes and subjected to high energy x-ray diffraction studies to determine the 3-D smucture of the protein molecules. Certain embodiments of the microcapsules of the invention have composite polymeric outer membranes which are somewhat elastic, water insoluble, permeable only to water, salts, and low molecular weight molecules and are structurally stable in fluid shear forces typically encountered in the human vascular system.

Dennis R Morrison↗
NASA NTRS2005

RIO Tinto Faulted Volcanosedimentary Deposits as Analog Habitats for Extant Subsurface Biospheres on Mars: A Synthesis of the MARTE Drilling Project Geobiology Results

Geochemistry and mineralogy on Mars surface characterized by the MER Opportunity Rover suggest that early Mars hosted acidic environments in the Meridiani Planum region [1, 2]. Such extreme paleoenvironments have been suggested to be a regional expression of the global Mars geological cycle that induced acidic conditions by sulfur complexation and iron buffering of aqueous solutions [3]. Under these assumptions, underground reservoirs of acidic brines and, thereby, putative acidic cryptobiospheres, may be expected. The MARTE project [4, 5] has performed a drilling campaign to search for acidic and anaerobic biospheres in R o Tinto basement [6] that may be analogs of these hypothetical communities occurring in cryptic habitats of Mars. This Rio Tinto geological region is characterized by the occurrence of huge metallic deposits of iron sulfides [7]. Late intensive diagenesis of rocks driven by a compressive regimen [8] largely reduced the porosity of rocks and induced a cortical thickening through thrusting and inverse faulting and folding. Such structures play an essential role in transporting and storing water underground as any other aquifers do in the Earth. Once the underground water reservoirs of the Ro Tinto basement contact the hydrothermal pyrite deposits, acidic brines are produced by the release of sulfates and iron through the oxidation of sulfides [9].

Fernandez-Remolar, D. C.↗