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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Method for retarding dye fading during archival storage of developed color photographic film

Dye fading during archival storage of developed color photographic film is retarded by placing the film in a sealed, opaque vault, introducing a dry, pressurized inert gas into the vault while the latter is vented, and sealing the vault after the air within the vault has been purged and replaced by the inert gas. Preferably, the gas is nitrogen; and the vault is stored at a temperature below room temperature to preserve the color photographic emulsions on the film contained within the vault. For short-term storage, sodium thiocyanate pads charged with water are placed within the vault. For long term storage, the interior of the vault is kept at a low relative humidity.

Hoover, R. B.↗
NASA NTRS1994

Using optical-microwave synergy for estimating surface energy fluxes over semi-arid rangeland

First results of the Walnut Gulch '92 (Arizona, U.S.) experiment concerning the combined use of radar backscattering (ERS-1) and thermal infrared (LANDSAT TM (Thematic Mapper)) data to estimate surface sensible heat flux are reported. The first step investigates the potential use of ERS-1 SAR (Synthetic Aperture Radar) images for surface soil moisture monitoring of the watershed using five calibrated images acquired during the year 1992 (dry to wet conditions). Results show that despite the typical low level of biomass of semi arid rangeland, an attenuation of the soil backscatter (up to 2 dB) can occur during the rainy season mainly due to the vegetation characteristics. A statistical relationship is then used to retrieve the volumetric surface soil moisture from ERS-1 backscattering (sensitivity of 0.23 dB/% moisture) with a resulting root mean square error of 1.3% of soil moisture. In a second step a semi empirical approach based on energy balance relates soil temperatures to this estimated surface soil moisture. Vegetation temperature is then deduced from soil temperatures and LANDSAT TM composite temperature in order to estimate sensible heat flux according to a two layer type model providing an RMSE of 29 W/sq m.

Troufleau, D.↗
NASA NTRS2013

Analysis of Water Recovery Rate from the Heat Melt Compactor

Human space missions generate trash with a substantial amount of plastic (20% or greater by mass). The trash also contains water trapped in food residue and paper products and other trash items. The Heat Melt Compactor (HMC) under development by NASA Ames Research Center (ARC) compresses the waste, dries it to recover water and melts the plastic to encapsulate the compressed trash. The resulting waste disk or puck represents an approximately ten-fold reduction in the volume of the initial trash loaded into the HMC. In the current design concept being pursued, the trash is compressed by a piston after it is loaded into the trash chamber. The piston face, the side walls of the waste processing chamber and the end surface in contact with the waste can be heated to evaporate the water and to melt the plastic. Water is recovered by the HMC in two phases. The first is a pre-process compaction without heat or with the heaters initially turned on but before the waste heats up. Tests have shown that during this step some liquid water may be expelled from the chamber. This water is believed to be free water (i.e., not bound with or absorbed in other waste constituents) that is present in the trash. This phase is herein termed Phase A of the water recovery process. During HMC operations, it is desired that liquid water recovery in Phase A be eliminated or minimized so that water-vapor processing equipment (e.g., condensers) downstream of the HMC are not fouled by liquid water and its constituents (i.e., suspended or dissolved matter) exiting the HMC. The primary water recovery process takes place next where the trash is further compacted while the heated surfaces reach their set temperatures for this step. This step will be referred to herein as Phase B of the water recovery process. During this step the waste chamber may be exposed to different selected pressures such as ambient, low pressure (e.g., 0.2 atm), or vacuum. The objective for this step is to remove both bound and any remaining free water in the trash by evaporation. The temperature settings of the heated surfaces are usually kept above the saturation temperature of water but below the melting temperature of the plastic in the waste during this step to avoid any encapsulation of wet trash which would reduce the amount of recovered water by blocking the vapor escape. In this paper, we analyze the water recovery rate during Phase B where the trash is heated and water leaves the waste chamber as vapor, for operation of the HMC in reduced gravity. We pursue a quasi-one-dimensional model with and without sidewall heating to determine the water recovery rate and the trash drying time. The influences of the trash thermal properties, the amount of water loading, and the distribution of the water in the trash on the water recovery rates are determined.

Heat Melt Compactor↗
NASA NTRS2015

Design and Test of a Liquid Oxygen / Liquid Methane Thruster with Cold Helium Pressurization Heat Exchanger

A liquid oxygen / liquid methane 2,000 lbf thruster was designed and tested in conjuction with a nozzle heat exchanger for cold helium pressurization. Cold helium pressurization systems offer significant spacecraft vehicle dry mass savings since the pressurant tank size can be reduced as the pressurant density is increased. A heat exchanger can be incorporated into the main engine design to provide expansion of the pressurant supply to the propellant tanks. In order to study the systems integration of a cold-helium pressurization system, a 2,000 lbf thruster with a nozzle heat exchanger was designed for integration into the Project Morpheus vehicle at NASA Johnson Space Center. The testing goals were to demonstrate helium loading and initial conditioning to low temperatures, high-pressure/low temperature storage, expansion through the main engine heat exchanger, and propellant tank injection/pressurization. The helium pressurant tank was an existing 19 inch diameter composite-overwrap tank, and the targert conditions were 4500 psi and -250 F, providing a 2:1 density advantage compared to room tempatrue storage. The thruster design uses like-on-like doublets in the injector pattern largely based on Project Morpheus main engine hertiage data, and the combustion chamber was designed for an ablative chamber. The heat exchanger was installed at the ablative nozzle exit plane. Stand-alone engine testing was conducted at NASA Stennis Space Center, including copper heat-sink chambers and highly-instrumented spoolpieces in order to study engine performance, stability, and wall heat flux. A one-dimensional thermal model of the integrated system was completed. System integration into the Project Morpheus vehicle is complete, and systems demonstrations will follow.

Melcher, John C.↗
NASA NTRS1973

Electrical properties of dry rocks

The mechanism by which atmospheric moisture affects the conductivity and dielectric constant of rock specimens was studied in time and frequency domains. It is suggested that adsorbed water molecules alter the surface conductivity in a manner similar to that observed in semiconductors and insulators. Powdered basalts show a low-frequency dispersion produced by the atmospheric moisture remaining in the pore system of the sample in a high vacuum; this effect is attributed to isolated adsorption centers. Simulated lunar permafrost at 100 K and a vacuum of 10 to the -8th power torr together with data on lunar samples contaminated with atmospheric moisture and the dielectric properties of ice at various temperatures indicate that, if permafrost exists in the moon it should present a relaxation peak at approximately 300 Hz; for temperatures up to 263 K it may go up to 20 KHz. It is concluded that in order to have electrical steady state conditions in rock samples it is necessary to have volume charge accumulations at interfaces within the sample and at the electrode sample interface. A method for measuring heterogeneous dielectrics with non-negligible ohmic and dielectric conductivities is proposed and experimentally verified.

Morrison, H.↗
NASA NTRS1997

Passive Microwave Observation of Diurnal Surface Soil Moisture

Microwave radiometers operating at low frequencies are sensitive to surface soil moisture changes. Few studies have been conducted that have involved multifrequency observations at frequencies low enough to measure a significant soil depth and not be attenuated by the vegetation cover. Another unexplored aspect of microwave observations at low frequencies has been the impact of diurnal variations of the soil moisture and temperature on brightness temperature. In this investigation, observations were made using a dual frequency radiometer (1.4 and 2.65 GHz) over bare soil and corn for extended periods in 1994. Comparisons of emissivity and volumetric soil moisture at four depths for bare soils showed that there was a clear correspondence between the 1 cm soil moisture and the 2.65-GHz emissivity and between the 3-5 cm soil moisture and the 1.4-GHZ emissivity, which confirms previous studies. Observations during drying and rainfall demonstrate that new and unique information for hydrologic and energy balance studies can be extracted from these data.

Jackson, Thomas J.↗
NASA NTRS1992

The Martian polar caps: Stability and water transport at low obliquities

The seasonal cycle of water on Mars is regulated by the two polar caps. In the winter hemisphere, the seasonal CO2 deposits at a temperature near 150 K acts as a cold trap to remove water vapor from the atmosphere. When summer returns, water is pumped back into the atmosphere by a number of mechanisms, including release from the receding CO2 frost, diffusion from the polar regolith, and sublimation from a water-ice residual cap. These processes drive an exchange of water vapor between the polar caps that helps shape the Martian climate. Thus, understanding the behavior of the polar caps is important for interpreting the Martian climate both now and at other epochs. Mars' obliquity undergoes large variations over large time scales. As the obliquity decreases, the poles receive less solar energy so that more CO2 condenses from the atmosphere onto the poles. It has been suggested that permanent CO2 condenses from the atmosphere onto the poles. It has been suggested that permanent CO2 caps might form at the poles in response to a feedback mechanism existing between the polar cap albedo, the CO2 pressure, and the dust storm frequency. The year-round presence of the CO2 deposits would effectively dry out the atmosphere, while diffusion of water from the regolith would be the only source of water vapor to the atmosphere. We have reviewed the CO2 balance at low obliquity taking into account the asymmetries which make the north and south hemispheres different. Our analysis linked with a numerical model of the polar caps leads us to believe that one summertime cap will always lose its CO2 cover during a Martian year, although we cannot predict which cap this will be. We conclude that significant amounts of water vapor will sublime from the exposed cap during summer, and the Martian atmosphere will support an active water cycle even at low obliquity.

Henderson, B. G.↗
NASA NTRS1994

Surface-induced brightness temperature variations and their effects on detecting thin cirrus clouds using IR emission channels in the 8-12 microns region

A method for detecting cirrus clouds in terms of brightness temperature differences between narrowbands at 8, 11, and 12 microns has been proposed by Ackerman et al. In this method, the variation of emissivity with wavelength for different surface targets was not taken into consideration. Based on state-of-the-art laboratory measurements of reflectance spectra of terrestrial materials by Salisbury and D'Aria, it is found that the brightness temperature differences between the 8- and 11-microns bands for soils, rocks, and minerals, and dry vegetation can vary between approximately -8 and +8 K due solely to surface emissivity variations. The large brightness temperature differences are sufficient to cause false detection of cirrus clouds from remote sensing data acquired over certain surface targets using the 8-11-12-microns method directly. It is suggested that the 8-11-12-microns method should be improved to include the surface emissivity effects. In addition, it is recommended that in the future the variation of surface emissivity with wavelength should be taken into account in algorithms for retrieving surface temperatures and low-level atmospheric temperature and water vapor profiles.

Gao, Bo-Cai↗
NASA NTRS1995

Metamorphism and aqueous alteration in low petrographic type ordinary chondrites

In order to investigate the relative importance of dry metamorphism and aqueous alteration in the history of chondruies, chondruies were hand-picked from the Semarkona (petrographic type 3.0), Bishunpur (3. 1), Chainpur (3.4), Dhajala (3.8) and Allegan (5) chondrites, and matrix samples were extracted from the first three ordinary chondrites. The thermoluminescence (TL) properties of all the samples were measured, and appropriate subsets of the samples were analyzed by electron-microprobe and radiochemical neutron activation and the water and H-isotopic composition determined. The TL data for chondrules from Semarkona and Bishunpur scatter widely showing no unambiguous trends, although group B1 chondrules tend to have lower sensitivities and lower peak temperatures compared with group A5 chondrules. It is argued that these data reflect the variety of processes accompanying chondrule formation. The chondrules show remarkably uniform contents of the highly labile elements, indicating mineralogical control on abundance and volatile loss from silicates and loss and recondensation of mobile chalcophiles and siderophiles in some cases. Very high D/H values (up to approx. 8000% SMOW) are observed in certain Semarkona chondrules, a confirmation of earlier work. With increasing petrographic type, mean TL sensitivities of the chondrules increase, the spread of values within an individual meteorite decreases, and peak temperatures and peak widths show trends indicating that the TL is mainly produced by feldspar and that dry, thermal metamorphism is the dominant secondary process experienced by the chondrules. The TL sensitivities of matrix samples also increase with petrographic type. Chainpur matrix samples show the same spread of peak temperatures and peak widths as Chainpur chondruies, indicating metamorphism-related changes in the feldspar are responsible for the TL of the matrix. The TL data for the Semarkona and Bishunpur matrix samples provide, at best, only weak evidence for aqueous alteration, but the matrix contains H with approximately terrestrial D/H values, even though it contains much water. Secondary processes (probably aqueous alteration) presumably lowered the D/H of the matrix and certain chondrules. While chondrule properties appear to be governed primarily by formation processes and subsequent metamorphism, the matrix of Semarkona has a more complex history involving aqueous alteration as a meteorite-wide process.

Xie, T.↗
NASA NTRS2015

Sample Acquisition and Analytical Chemistry Challenges to Verifying Compliance to Aviators Breathing Oxygen (ABO) Purity Specification

NASA has been developing and testing two different types of oxygen separation systems. One type of oxygen separation system uses pressure swing technology, the other type uses a solid electrolyte electrochemical oxygen separation cell. Both development systems have been subjected to long term testing, and performance testing under a variety of environmental and operational conditions. Testing these two systems revealed that measuring the product purity of oxygen, and determining if an oxygen separation device meets Aviator's Breathing Oxygen (ABO) specifications is a subtle and sometimes difficult analytical chemistry job. Verifying product purity of cryogenically produced oxygen presents a different set of analytical chemistry challenges. This presentation will describe some of the sample acquisition and analytical chemistry challenges presented by verifying oxygen produced by an oxygen separator - and verifying oxygen produced by cryogenic separation processes. The primary contaminant that causes gas samples to fail to meet ABO requirements is water. The maximum amount of water vapor allowed is 7 ppmv. The principal challenge of verifying oxygen produced by an oxygen separator is that it is produced relatively slowly, and at comparatively low temperatures. A short term failure that occurs for just a few minutes in the course of a 1 week run could cause an entire tank to be rejected. Continuous monitoring of oxygen purity and water vapor could identify problems as soon as they occur. Long term oxygen separator tests were instrumented with an oxygen analyzer and with an hygrometer: a GE Moisture Monitor Series 35. This hygrometer uses an aluminum oxide sensor. The user's manual does not report this, but long term exposure to pure oxygen causes the aluminum oxide sensor head to bias dry. Oxygen product that exceeded the 7 ppm specification was improperly accepted, because the sensor had biased. The bias is permanent - exposure to air does not cause the sensor to return to its original response - but the bias can be accounted for by recalibrating the sensor. After this issue was found, continuous measurements of water vapor in the oxygen product were made using an FTIR. The FTIR cell is relatively large, so response time is slow - but moisture measurements were repeatable and accurate. Verifying ABO compliance for oxygen produced by commercial cryogenic processes has a different set of sample acquisition and analytical chemistry challenges. Customers want analytical chemists to conserve as much as possible. Hygrometers are not exposed to hours of continuous flow of oxygen, so they don't bias, but small amounts of contamination in valves can cause a "fail". K bottles are periodically cleaned and recertified - after cleaning residual moisture can cause a "fail". Operators let bottle pressure drop to room pressure, introduce outside air into the bottle, and the subsequent fill will "fail". Outside storage of K‐bottles has allowed enough in‐leakage, so contents will "fail".

Graf, John↗
NASA NTRS2022

Rapid Radiolytic Degradation of Amino Acids in the Martian Shallow Subsurface: Implications for the Search for Extinct Life

Amino acids are fundamental to life as we know them as the monomers of proteins and enzymes. They are also readily synthesized under a variety of plausible prebiotic conditions and are common in carbon-rich meteorites. Thus, they represent a reasonable class of organics to target in the search for prebiotic chemistry or chemical evidence of life on Mars. However, regardless of their origin, amino acids and other organic molecules present in near-surface regolith and rocks on Mars can be degraded by exposure to cosmic rays that can penetrate to a depth of a few meters. We exposed several pure amino acids in dry and hydrated silicate mixtures and in mixtures of silicates with perchlorate salts to gamma radiation at various temperatures and radiation doses representative of the martian near-subsurface. We found that irradiation of amino acids mixed with dry silica powder increased the rate of amino acid radiolysis, with the radiolysis constants of amino acids in silicate mixtures at least a factor of 10 larger compared with the radiolysis constants of amino acids alone. The addition of perchlorate salts to the silicate samples or hydration of silicate samples further accelerated the rate of amino acid destruction during irradiation and increased the radiolysis constants by a factor of *1.5. Our results suggest that even low-molecular-weight amino acids could degrade in just *20 million years in the top 10 cm of the martian surface regolith and rock, and even faster if the material contains elevated abundances of hydrated silicate minerals or perchlorates. We did not detect evidence of amino acid racemization after gamma radiation exposure of the samples, which indicates that the chirality of some surviving amino acids may still be preserved. Our experimental results suggest serious challenges for the search of ancient amino acids and other potential organic biosignatures in the top 2 m of the martian surface.

Alexander A. Pavlov↗
NASA NTRS1977

The effect of outgassing upon the closure of cracks and the strength of lunar analogues

The effect of an ultrahigh vacuum and low water vapor pressure on the stress-strain relation in rocks was studied in order to understand geologic and tectonic processes of the moon. Terrestrial basaltic rocks carefully outgassed in high vacuum provided the sample material for the compression tests reported here. The tests were conducted either under 1 atm air saturated with moisture, or under high vacuum. Results of the stress-strain determinations indicated that the dry rocks could show as much as twice the strength of the wet rocks. The data may also provide a means of reconciling the high strength and high temperature exhibited by the lunar interior.

Mizutani, H.↗
NASA NTRS2012

Spark Ignition Characteristics of a LO2/LCH4 Engine at Altitude Conditions

The use of non-toxic propellants in future exploration vehicles would enable safer, more cost effective mission scenarios. One promising "green" alternative to existing hypergols is liquid methane/liquid oxygen. To demonstrate performance and prove feasibility of this propellant combination, a 100lbf LO2/LCH4 engine was developed and tested under the NASA Propulsion and Cryogenic Advanced Development (PCAD) project. Since high ignition energy is a perceived drawback of this propellant combination, a test program was performed to explore ignition performance and reliability versus delivered spark energy. The sensitivity of ignition to spark timing and repetition rate was also examined. Three different exciter units were used with the engine's augmented (torch) igniter. Propellant temperature was also varied within the liquid range. Captured waveforms indicated spark behavior in hot fire conditions was inconsistent compared to the well-behaved dry sparks (in quiescent, room air). The escalating pressure and flow environment increases spark impedance and may at some point compromise an exciter.s ability to deliver a spark. Reduced spark energies of these sparks result in more erratic ignitions and adversely affect ignition probability. The timing of the sparks relative to the pressure/flow conditions also impacted the probability of ignition. Sparks occurring early in the flow could trigger ignition with energies as low as 1-6mJ, though multiple, similarly timed sparks of 55-75mJ were required for reliable ignition. An optimum time interval for spark application and ignition coincided with propellant introduction to the igniter and engine. Shifts of ignition timing were manifested by changes in the characteristics of the resulting ignition.

Kleinhenz, Julie↗
NASA NTRS1981

Development of Advanced Czochralski Growth Process to produce low cost 150 KG silicon ingots from a single crucible for technology readiness

The modified CG2000 crystal grower construction, installation, and machine check-out was completed. The process development check-out proceeded with several dry runs and one growth run. Several machine calibrations and functional problems were discovered and corrected. Several exhaust gas analysis system alternatives were evaluated and an integrated system approved and ordered. A contract presentation was made at the Project Integration Meeting at JPL, including cost-projections using contract projected throughput and machine parameters. Several growth runs on a development CG200 RC grower show that complete neck, crown, and body automated growth can be achieved with only one operator input. Work continued for melt level, melt temperature, and diameter sensor development.

Source record↗
NASA NTRS2012

Spark Ignition Characteristics of a L02/LCH4 Engine at Altitude Conditions

The use of non-toxic propellants in future exploration vehicles would enable safer, more cost effective mission scenarios. One promising "green" alternative to existing hypergols is liquid methane/liquid oxygen. To demonstrate performance and prove feasibility of this propellant combination, a 100lbf LO2/LCH4 engine was developed and tested under the NASA Propulsion and Cryogenic Advanced Development (PCAD) project. Since high ignition energy is a perceived drawback of this propellant combination, a test program was performed to explore ignition performance and reliability versus delivered spark energy. The sensitivity of ignition to spark timing and repetition rate was also examined. Three different exciter units were used with the engine s augmented (torch) igniter. Propellant temperature was also varied within the liquid range. Captured waveforms indicated spark behavior in hot fire conditions was inconsistent compared to the well-behaved dry sparks (in quiescent, room air). The escalating pressure and flow environment increases spark impedance and may at some point compromise an exciter s ability to deliver a spark. Reduced spark energies of these sparks result in more erratic ignitions and adversely affect ignition probability. The timing of the sparks relative to the pressure/flow conditions also impacted the probability of ignition. Sparks occurring early in the flow could trigger ignition with energies as low as 1-6mJ, though multiple, similarly timed sparks of 55-75mJ were required for reliable ignition. An optimum time interval for spark application and ignition coincided with propellant introduction to the igniter and engine. Shifts of ignition timing were manifested by changes in the characteristics of the resulting ignition.

Kleinhenz, Julie↗
NASA NTRS2016

Sorbent Structural Testing on Carbon Dioxide Removal Sorbents for Advanced Exploration Systems

Long term space missions require carbon dioxide removal systems that can function with minimal downtime required for maintenance, low power consumption and maximum efficiency for CO2 removal. A major component of such a system are the sorbents used for the CO2 and desiccant beds. Sorbents must not only have adequate CO2 and H2O removal properties, but they must have the mechanical strength to prevent structural breakdown due to pressure and temperature changes during operation and regeneration, as well as resistance to breakdown due to moisture in the system from cabin air. As part of the studies used to select future CO2 sorbent materials, mechanical tests are performed on various zeolite sorbents to determine mechanical performance while dry and at various humidified states. Tests include single pellet crush, bulk crush and attrition tests. We have established a protocol for testing sorbents under dry and humid conditions, and previously tested the sorbents used on the International Space Station carbon dioxide removal assembly. This paper reports on the testing of a series of commercial sorbents considered as candidates for use on future exploration missions.

Watson, David↗
NASA NTRS1992

The gabbro-eclogite phase transition and the elevation of mountain belts on Venus

Among the four mountain belts surrounding Lakshmi Planum, Maxwell Montes is the highest and stands up to 11 km above the mean planetary radius and 7 km above Lakshmi Planum. The bulk composition and radioactive heat production of the crust on Venus, where measured, are similar to those of terrestrial tholeiitic basalt. Because the thickness of the low-density crust may be limited by the gabbro-garnet granulite-eclogite phase transitions, the 7-11 km maximum elevation of Maxwell Montes is difficult to understand except in the unlikely situation that the crust contains a large volume of magma. A possible explanation is that the base of the crust is not in phase equilibrium. It has been suggested that under completely dry conditions, the gabbro-eclogite phase transition takes place by solid-state diffusion and may require a geologically significant time to run to completion. Solid-state diffusion is a strongly temperature-dependent process. In this paper we solve the thermal evolution of the mountain belt to attempt to constrain the depth of the gabbro-eclogite transition and thus to assess this hypothesis quantitatively. The one-dimensional heat equation is solved numerically by a finite difference approximation. The deformation of the horizontally shortening crustal and mantle portions of the thermal boundary layer is assumed to occur by pure shear, and therefore the vertical velocity is given by the product of the horizontal strain rate and depth.

Namiki, Noriyuki↗
NASA NTRS1995

Growth of single crystals of organic salts with large second-order optical nonlinearities by solution processes for devices

Data obtained from the electric field induced second harmonic generation (EFISH) and Kurtz Powder Methods will be provided to MSFC for further refinement of their method. A theoretical model for predicting the second-order nonlinearities of organic salts is being worked on. Another task is the synthesis of a number of salts with various counterions. Several salts with promising SHG activities and new salts will be tested for the presence of two crystalline forms. The materials will be recrystallized from dry and wet solvents and compared for SHG efficiency. Salts that have a high SHG efficiency and no tendency to form hydrates will be documented. The synthesis of these materials are included in this report. A third task involves method to aid in the growth of large, high quality single crystals by solution processes. These crystals will be characterized for their applicability in the fabrication of devices that will be incorporated into optical computers in future programs. Single crystals of optimum quality may be obtained by crystal growth in low-gravity. The final task is the design of a temperature lowering single crystal growth apparatus for ground based work. At least one prototype will be built.

Leslie, Thomas M.↗