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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Recognition of the geologic framework of porphyry deposits on ERTS-1 imagery

The author has identified the following significant results. Three major tectonic provinces have been mapped by geologic photointerpretation of ERTS-1 imagery over the Ok Tedi test site. These areas can be characterized as follows: (1) A broad area of low relief and mature topography suggesting a history of relative tectonic stability. (2) A narrow belt of moderate to high relief, broad open folds and prominent linear features. The Mount Fubilan-type porphyry copper deposits and recent volcanic effusive centers occur in this province. (3) A heterogeneous zone of high relief and high drainage density suggestive of relative structural complexity.

Wilson, J. C.↗
NASA NTRS2005

Tribological Behavior of Nano-Onions in Krytox 143AB Evaluated

Nanoparticles have been developed over the past 10 years and have found several applications. This work presents the use of carbon nano-onions as a potential oil additive for aerospace applications. Researchers at the NASA Glenn Research Center tested lubricant lifetimes in ambient air and ultrahigh vacuum and characterized the breakdown products of the friction and wear. These carbon nanoparticles can provide adequate lubrication very similar to that of graphitic material when run in air. Soot represents one of the very first nanostructured materials, although it has rarely been considered as such. Changes in the carbon nanostructure, resulting in increased graphitic layer plane length, correlate with reactivity loss. Upon heating spherically shaped nanometer-sized carbon black in the absence of oxidant, graphene sheets form, and the initial soot particle templates the growth of a graphitic particle into what is best described as a sphere with many flat sides having a hollow interior. Because there are no edge sites, these polygonal graphitic particles, or nano-onions, are relatively resistant to oxidation. Graphite is used as a solid lubricant because of its stability at moderately high temperatures. However, the temperature at which graphite oxidizes rapidly is strongly influenced by surface area. With the size of particles typically employed in lubrication, a great amount of thermal stability is lost because of size reduction either during preparation or during lubrication of contacting parts. Therefore, we have undertaken a study of the lubricating ability of graphitic nano-onions (ref. 1).

Street, Kenneth W.↗
NASA NTRS2006

AIRS Observations of DomeC in Antarctica and Comparison with Automated Weather Stations (AWS)

We compare the surface temperatures at Dome Concordia (DomeC) deduced from AIRS data and two Automatic Weather Stations at Concordia Station: AWS8989 , which has been in operation since December 1996, and AWS.it, for which data are available between January and November 2005. The AWS8989 readings are on average 3 K warmer than the AWS.it readings, with a warmer bias in the Antarctic summer than in the winter season. Although AIRS measures the skin brightness temperature, while the AWS reports the temperature of the air at 3 meter above the surface, the AIRS measurements agree well with the AWS.it readings for all data and separately for the summer and winter seasons, if data taken in the presence of strong surface inversions are filtered out. This can be done by deducing the vertical temperature gradient above the surface directly from the AIRS temperature sounding channels or indirectly by noting that extreme vertical gradients near the surface are unlikely if the wind speed is more than a few meters per second. Since the AIRS measurements are very well calibrated, the agreement with AWS.it is very encouraging. The warmer readings of AWS8989 are likely due to thermal contamination of the AWS8989 site by the increasing activity at Concordia Station. Data from an AWS.it quality station could be used for the evaluation of radiometric accuracy and stability of polar orbiting sounders at low temperatures. Unfortunately, data from AWS.it was available only for a limited time. The thermal contamination of the AWS8989 data makes long-term trends deduced from AWS8989 and possibly results about the rapid Antarctic warming deduced from other research stations on Antarctica suspect. AIRS is the first hyperspectral infrared sounder designed in support of weather forecasting and climate research. It was launched in May 2002 on the EOS Aqua spacecraft into a 704 km altitude polar sun-synchronous orbit. The lifetime of AIRS, estimated before launch to be at least 5 years is, based on the latest evaluation, limited by the amount of attitude control gas on the EOS Aqua spacecraft, which is expected to last through 2015.

atmospheric↗
NASA NTRS2021

Framework for Coordinated Efforts in the Exploration of Volatiles in the South Polar Region of the Moon

The exploration of the lunar south polar region and the ground truthing of polar volatiles is one of the top priorities for several space agencies and private partners. Here we use Moon Mineralogy Mapper surficial water ice detections to investigate the location of water ice-bearing permanently shaded regions near the south pole. We extract a variety of parameters such as their temperature regime, slope, hydrogen content, number of ice detections, depth stability for water ice and dry ice, and mobility aspects. We identify 169 water ice-bearing PSRs and use their characteristics to identify sites that allow to access the highest abundances of volatiles, sites that can be visited to characterize the lateral or vertical distribution of volatiles (water ice and dry ice), and sites that allow for the fastest recovery of a scientifically interesting sample. Collectively, 37 PSRs are identified as sites of interest, including 11 that would address more than one mission objective and may be, for that reason, higher priority targets of exploration. These PSRs are found in Shoemaker, Faustini, Cabeus, Malapert, Nobile, Sverdrup, Wiechert J and Haworth craters, as well as 3 unnamed craters (PSRs 57, 120, 89). These sites are all located within 6 degrees of the south pole. We present case studies for a relatively short traverse mission (20 to 50 km) to PSR 89, a medium length traverse (~100 km) to Sverdrup 1, and a longer traverse (~300 km) to Cabeus that can serve as a guide in planning upcoming exploration missions.

Myriam Lemelin↗
NASA NTRS2021

Anaerobic Expression and Purification of Holo-CCIS, an Artificial Iron-sulfur Protein

Iron-sulfur proteins are ubiquitous among all living organisms and are indispensable for almost all metabolic pathways ranging from photosynthesis, respiration, nitrogen, and carbon dioxide cycles. The iron-sulfur clusters primarily serve as electron acceptors and donors and transfer electrons to active sites of various enzymes, thus driving the energy metabolism. Prokaryotes like E. coli have ISC and SUF pathways that help in the assembly and maturation of iron-sulfur proteins. These ironsulfur proteins, especially with [4Fe-4S] clusters, are highly sensitive to molecular oxygen, and it would be advantageous if the de novo proteins and native proteins having iron-sulfur binding sites are expressed and isolated under anaerobic conditions. Bacterially assembled iron-sulfur proteins, when isolated and purified anaerobically, exhibit improved biochemical and biophysical stabilities in comparison to the counterparts expressed and purified aerobically and reconstituted under anaerobic conditions. This protocol outlines the expression and purification of the artificial protein, Coiled-Coil IronSulfur (CCIS). It may be deployed to both natural and artificial [4Fe-4S] proteins when heterologously expressed in E. coli.

Bhanu P. Jagilinki↗
NASA NTRS1990

Stability constraints for line scanning cameras in orbit

Requirements, parameters, and constraints influencing the design of a line scanner camera system for imaging from orbit are described. The driving requirements are the area of the site to be imaged in each pass and the resolution as determined by the size of a pixel projected on the planet surface. Allowable jitter and distortion, required SNR, maximum data rate, and maximum variation of the emission angle during imaging are among the constraints. Simplified equations incorporating these requirements, constraints, and parameters are developed and presented.

Bernard, Douglas E.↗
NASA NTRS1975

Magnetochemistry of the Apollo landing sites

A coherent magnetochemical picture of lunar samples is presented which was determined from a synthesis of available magnetic-property data and corresponding chemical and petrographic data for soils and rock samples collected at the Apollo landing sites. The magnetic properties of the samples are correlated with Al/Si ratio as well as with telescope spectral reflectivity curves, and magnetochemical diagrams based on composition-sensitive magnetic parameters describing the Fe metal and Fe(2+) contents are used to classify the samples. It is shown that the relative metal-fraction size distribution and magnetic stability for different rock types and soils of varying Al/Si values are reflected in a plot of the ratio of saturation isothermal remanence to saturation magnetization vs the ratio of remanent coercive force to coercive force. It is concluded that all the Apollo landing sites have distinct telescope curves correlated with petrology, chemistry, Al/Si values, and magnetic properties. The established correlations suggest the possibility of estimating the magnetic properties of the regolith from remote-sensing observations.

Wasilewski, P. J.↗
NASA NTRS2001

Further Studies of Materials Compatibility in High-Test Hydrogen Peroxide

Assessment of the compatibility of high-test hydrogen peroxide (HTP) with materials, in particular new materials such as composites, is critical to the development of new propulsion systems meeting requirements of reduced cost and environmental impact. While compatibility with HTP has been addressed previously, newer materials were not considered. The focus of this project was to develop a scheme for evaluation of HTP with all materials. In the previous summer, methods were developed for production of HTP on site, and preliminary steps were taken to evaluate materials. Methods investigated this summer have included accelerated aging by heating, coupled with assay of concentration and stabilization loss, observation of reactivity by means of Isothermal Microcalorimetry, and evaluation of changes to the materials by Short Beam Shear testing and by Photoacoustic-Fourier Transform Infrared Spectroscopy. Various metals, polymers, and composites were examined in this study.

Gostowski, R.↗
NASA NTRS1993

B-DNA to Z-DNA structural transitions in the SV40 enhancer: stabilization of Z-DNA in negatively supercoiled DNA minicircles

During replication and transcription, the SV40 control region is subjected to significant levels of DNA unwinding. There are three, alternating purine-pyrimidine tracts within this region that can adopt the Z-DNA conformation in response to negative superhelix density: a single copy of ACACACAT and two copies of ATGCATGC. Since the control region is essential for both efficient transcription and replication, B-DNA to Z-DNA transitions in these vital sequence tracts may have significant biological consequences. We have synthesized DNA minicircles to detect B-DNA to Z-DNA transitions in the SV40 enhancer, and to determine the negative superhelix density required to stabilize the Z-DNA. A variety of DNA sequences, including the entire SV40 enhancer and the two segments of the enhancer with alternating purine-pyrimidine tracts, were incorporated into topologically relaxed minicircles. Negative supercoils were generated, and the resulting topoisomers were resolved by electrophoresis. Using an anti-Z-DNA Fab and an electrophoretic mobility shift assay, Z-DNA was detected in the enhancer-containing minicircles at a superhelix density of -0.05. Fab saturation binding experiments demonstrated that three, independent Z-DNA tracts were stabilized in the supercoiled minicircles. Two other minicircles, each with one of the two alternating purine-pyrimidine tracts, also contained single Z-DNA sites. These results confirm the identities of the Z-DNA-forming sequences within the control region. Moreover, the B-DNA to Z-DNA transitions were detected at superhelix densities observed during normal replication and transcription processes in the SV40 life cycle.

Non-NASA Center↗
NASA NTRS2006

Repairing Fractured Bones by Use of Bioabsorbable Composites

A proposed method of surgical repair of fractured bones would incorporate recent and future advances in the art of composite materials. The composite materials used in this method would be biocompatible and at least partly bioabsorbable: that is, during the healing process following surgery, they would be wholly or at least partly absorbed into the bones and other tissues in which they were implanted. Relative to the traditional method, the proposed method would involve less surgery, pose less of a risk of infection, provide for better transfer of loads across fracture sites, and thereby promote better healing while reducing the need for immobilization by casts and other external devices. One requirement that both the traditional and proposed methods must satisfy is to fix the multiple segments of a broken bone in the correct relative positions. Mechanical fixing techniques used in the traditional method include the use of plates spanning the fracture site and secured to the bone by screws, serving of wire along the bone across the fracture site, insertion of metallic intramedullary rods through the hollow portion of the fractured bone, and/or inserting transverse rods through the bone, muscle, and skin to stabilize the fractured members. After the bone heals, a second surgical operation is needed to remove the mechanical fixture(s). In the proposed method, there would be no need for a second surgical operation. The proposed method is based partly on the observation that in the fabrication of a structural member, it is generally more efficient and reliable to use multiple small fasteners to transfer load across a joint than to use a single or smaller number of larger fasteners, provided that the stress fields of neighboring small fasteners do not overlap or interact. Also, multiple smaller fasteners are more reliable than are larger and fewer fasteners. However, there is a trade-off between structural efficiency and the cost of insertion time and materials. The proposed method is further based partly on the conjecture that through-the-thickness reinforcements could be excellent for fixing bone segments for surgical repair. The through-the-thickness reinforcements would superficially resemble nails in both form and function. Denoted small-diameter rods (SDRs) to distinguish them from other narrow rods, these reinforcements would be shot or otherwise inserted through adjacent segments of fractured bone to fix them in their correct relative positions (see figure). Shot insertion would be effected by use an applicator that would amount to a miniaturized and highly refined version of the pneumatic guns often used in carpentry to drive nails and brads. The applicator, envisioned to be about the size of a ball-point-pen, would be driven by pressurized carbon dioxide. To further promote stabilization of the segments, layers of bone glue could be applied to the fracture surfaces prior to insertion of the SDRs. The bone glue could be therapeutically loaded with chemicals to promote growth of bone and fight infection

Farley, Gary L.↗
NASA NTRS2010

Fabrication and Modification of Nanoporous Silicon Particles

Silicon-based nanoporous particles as biodegradable drug carriers are advantageous in permeation, controlled release, and targeting. The use of biodegradable nanoporous silicon and silicon dioxide, with proper surface treatments, allows sustained drug release within the target site over a period of days, or even weeks, due to selective surface coating. A variety of surface treatment protocols are available for silicon-based particles to be stabilized, functionalized, or modified as required. Coated polyethylene glycol (PEG) chains showed the effective depression of both plasma protein adsorption and cell attachment to the modified surfaces, as well as the advantage of long circulating. Porous silicon particles are micromachined by lithography. Compared to the synthesis route of the nanomaterials, the advantages include: (1) the capability to make different shapes, not only spherical particles but also square, rectangular, or ellipse cross sections, etc.; (2) the capability for very precise dimension control; (3) the capacity for porosity and pore profile control; and (4) allowance of complex surface modification. The particle patterns as small as 60 nm can be fabricated using the state-of-the-art photolithography. The pores in silicon can be fabricated by exposing the silicon in an HF/ethanol solution and then subjecting the pores to an electrical current. The size and shape of the pores inside silicon can be adjusted by the doping of the silicon, electrical current application, the composition of the electrolyte solution, and etching time. The surface of the silicon particles can be modified by many means to provide targeted delivery and on-site permanence for extended release. Multiple active agents can be co-loaded into the particles. Because the surface modification of particles can be done on wafers before the mechanical release, asymmetrical surface modification is feasible. Starting from silicon wafers, a treatment, such as KOH dipping or reactive ion etching (RIE), may be applied to make the surface rough. This helps remove the nucleation layer. A protective layer is then deposited on the wafer. The protective layer, such as silicon nitride film or photoresist film, protects the wafer from electrochemical etching in an HF-based solution. A lithography technique is applied to pattern the particles onto the protective film. The undesired area of the protective film is removed, and the protective film on the back side of the wafer is also removed. Then the pattern is exposed to HF/surfactant solution, and a larger DC electrical current is applied to the wafers for a selected time. This step removes the nucleation layer. Then a DC current is applied to generate the nanopores. Next, a large electrical current is applied to generate a release layer. The particles are mechanically suspended in the solvent and collected by filtration or centrifuge.

Ferrari, Mauro↗
NASA NTRS2021

Normalization Method and Application for MODIS TEB Assessments using Earth Scene Measurements

Selected Earth targets are commonly used for satellite sensor calibration assessments (e.g. sensor stability and inter-comparisons). Moreover, typical scenes used for the calibration assessment of the thermal emissive bands (TEBs) includeDome Concordia (Dome-C), ocean, desert, and deep convective clouds (DCC). Reference data used for these calibration assessments can come from another band, another instrument, or ground measurements. The Dome-C site, covered with uniformly-distributed permanent snow, is normally used for the assessment of the TEBsat cold temperatures. Furthermore, ocean and desert measurements prove useful for scenes with higher temperatures. The DCC, one of the most consistent and coldest targets, can be used for the TEBs calibration and product stability assessments. MODIS band 31 (~ 11 m) can be used as a reference for these scenes. However, measurements over these scenes have seasonal variations, and the DCC brightness temperatures (BTs) have asymmetrical distributions. These features can introduce additional uncertainty to the stability assessments. A normalization method is applied by using an empirical model to derive reference-dependent BTs. Using the developed empirical model, measurements can be normalized to a reference BT in order to enhance the calibration assessment’s accuracy. This method is evaluated using all four scene types (i.e. ocean, desert, snow (Dome-C), and DCC) and applied to all the Terra and Aqua MODIS TEBs. Stability assessments over the instruments’ entire data records are presented and discussed. The technique can be applied in future efforts to support MODIS TEBs calibration assessments.

MODIS TEB↗
NASA NTRS1993

Research and development of high thermal stability fuels

Increases in aircraft performance are leading to increases in the thermal stress on the primary aircraft coolant--the fuel. Fuel thermal stability limitations may offset future aircraft performance gains. The Air Force's Wright Laboratory is sponsoring several research programs to address this problem. The development of an additive package for JP-8 to improve its thermal stability is the primary focus of this paper. This program involves extensive testing of fuels and additives in a variety of test devices, culminating in tests in a fuel system simulator and engine tests. These tests involve Air Force personnel, on-site contractors (University of Dayton Research Institute, Systems Research Laboratories), Pratt and Whitney Aircraft Co., additive manufacturers, and Sandia National Laboratory. The test devices include several flowing and static tests, where the behavior of a fuel is investigated in a wide variety of environments. The study of several baseline fuels in these devices has led to some new insights into the mechanisms of fuel thermal (in)stability. It is becoming clear that a fuel's tendency to oxidize (to form peroxides, for example) is often inversely proportional to its tendency to form insoluble deposits.

T Edwards↗
NASA NTRS1983

Satellite time and frequency transfer (STIFT)

The concept of placing a hydrogen maser high stability clock in Earth orbit to provide accurate time and frequency comparisons worldwide to major timing centers and to a large number of radio observatory antenna sites involved in VLBI measurements was studied. The proposal was chiefly directed toward studies and initial hardware designs for time comparisons between hydrogen maser frequency standards and to modifications of the hydrogen maser for long-term use in space.

Vessot, R. F. C.↗
NASA NTRS1982

A Temporal Approach to Monitor Surface Mine Reclamation Progress via LANDSAT

Using LANDSAT satellite imagery, the mine reclamation process can be studied on a temporal and continuing basis. Not only can the progress of reclamation be readily monitored, but also a breakdown in the mining reclamation process can be detected. In viewing reclamation, it is important to monitor the mined site well past initial revegation stages. With present mining law and bonding procedures, fast revegetational growth is encouraged, often leading to poor soil fertilizing and inappropriate stabilizing species. As a result, the initial reclamation may exhibit good qualities for one or two years but then may experience vegetational deterioration after the state has relinquished the mining company from it's responsibility. It is this small-scale breakdown in the reclamation process that was detected using an unsupervised classification technique with eight-year temporal LANDSAT imagery coverage.

Davis, A. L.↗
NASA NTRS1991

Shuttle abort landing site emergency medical services

NASA and DOD studies of medical-planning and logistical problems are reviewed as applicable to providing emergency medical care at remote transoceanic abort landing (TAL) sites. Two options are analyzed including a modified surgical response team and a combination physician/medical technician team. The two concepts are examined in terms of cost-effectiveness, specific types of medical support such as blood procurement, and search-and-rescue requirements. It is found that the physician/technician team is more economically efficient, and the description of the concept permits the development of an effective TAL-site astronaut medical-support system. A balance is struck between the competing problems of cost and medical capability by planning for on-scene medical stabilization and air evacuation to DOD tertiary medical centers.

Mckenas, David K.↗
NASA NTRS2016

Using Ground Targets to Validate S-NPP VIIRS Day-Night Band Calibration

In this study, the observations from S-NPP VIIRS Day-Night band (DNB) and Moderate resolution bands (M bands) of Libya 4 and Dome C over the first four years of the mission are used to assess the DNB low gain calibration stability. The Sensor Data Records produced by NASA Land Product Evaluation and Algorithm Testing Element (PEATE) are acquired from nearly nadir overpasses for Libya 4 desert and Dome C snow surfaces. A kernel-driven bidirectional reflectance distribution function (BRDF) correction model is used for both Libya 4 and Dome C sites to correct the surface BRDF influence. At both sites, the simulated top-of-atmosphere (TOA) DNB reflectances based on SCIAMACHY spectral data are compared with Land PEATE TOA reflectances based on modulated Relative Spectral Response (RSR). In the Libya 4 site, the results indicate a decrease of 1.03% in Land PEATE TOA reflectance and a decrease of 1.01% in SCIAMACHY derived TOA reflectance over the period from April 2012 to January 2016. In the Dome C site, the decreases are 0.29% and 0.14%, respectively. The consistency between SCIAMACHY and Land PEATE data trends is good. The small difference between SCIAMACHY and Land PEATE derived TOA reflectances could be caused by changes in the surface targets, atmosphere status, and on-orbit calibration. The reflectances and radiances of Land PEATE DNB are also compared with matching M bands and the integral M bands based on M4, M5, and M7. The fitting trends of the DNB to integral M bands ratios indicate a 0.75% decrease at the Libya 4 site and a 1.89% decrease at the Dome C site. Part of the difference is due to an insufficient number of sampled bands available within the DNB wavelength range. The above results indicate that the Land PEATE VIIRS DNB product is accurate and stable. The methods used in this study can be used on other satellite instruments to provide quantitative assessments for calibration stability.

Chen, Xuexia↗
NASA NTRS1994

Three-dimensional structure of Schistosoma japonicum glutathione S-transferase fused with a six-amino acid conserved neutralizing epitope of gp41 from HIV

The 3-dimensional crystal structure of glutathione S-transferase (GST) of Schistosoma japonicum (Sj) fused with a conserved neutralizing epitope on gp41 (glycoprotein, 41 kDa) of human immunodeficiency virus type 1 (HIV-1) (Muster T et al., 1993, J Virol 67:6642-6647) was determined at 2.5 A resolution. The structure of the 3-3 isozyme rat GST of the mu gene class (Ji X, Zhang P, Armstrong RN, Gilliland GL, 1992, Biochemistry 31:10169-10184) was used as a molecular replacement model. The structure consists of a 4-stranded beta-sheet and 3 alpha-helices in domain 1 and 5 alpha-helices in domain 2. The space group of the Sj GST crystal is P4(3)2(1)2, with unit cell dimensions of a = b = 94.7 A, and c = 58.1 A. The crystal has 1 GST monomer per asymmetric unit, and 2 monomers that form an active dimer are related by crystallographic 2-fold symmetry. In the binding site, the ordered structure of reduced glutathione is observed. The gp41 peptide (Glu-Leu-Asp-Lys-Trp-Ala) fused to the C-terminus of Sj GST forms a loop stabilized by symmetry-related GSTs. The Sj GST structure is compared with previously determined GST structures of mammalian gene classes mu, alpha, and pi. Conserved amino acid residues among the 4 GSTs that are important for hydrophobic and hydrophilic interactions for dimer association and glutathione binding are discussed.

Schistosoma japonicum/enzymology/genetics/immunolo↗