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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

EO-1 Hyperion Reflectance Time Series at Calibration and Validation Sites: Stability and Sensitivity to Seasonal Dynamics

This study evaluated Earth Observing 1 (EO-1) Hyperion reflectance time series at established calibration sites to assess the instrument stability and suitability for monitoring vegetation functional parameters. Our analysis using three pseudo-invariant calibration sites in North America indicated that the reflectance time series are devoid of apparent spectral trends and their stability consistently is within 2.5-5 percent throughout most of the spectral range spanning the 12-plus year data record. Using three vegetated sites instrumented with eddy covariance towers, the Hyperion reflectance time series were evaluated for their ability to determine important variables of ecosystem function. A number of narrowband and derivative vegetation indices (VI) closely described the seasonal profiles in vegetation function and ecosystem carbon exchange (e.g., net and gross ecosystem productivity) in three very different ecosystems, including a hardwood forest and tallgrass prairie in North America, and a Miombo woodland in Africa. Our results demonstrate the potential for scaling the carbon flux tower measurements to local and regional landscape levels. The VIs with stronger relationships to the CO2 parameters were derived using continuous reflectance spectra and included wavelengths associated with chlorophyll content and/or chlorophyll fluorescence. Since these indices cannot be calculated from broadband multispectral instrument data, the opportunity to exploit these spectrometer-based VIs in the future will depend on the launch of satellites such as EnMAP and HyspIRI. This study highlights the practical utility of space-borne spectrometers for characterization of the spectral stability and uniformity of the calibration sites in support of sensor cross-comparisons, and demonstrates the potential of narrowband VIs to track and spatially extend ecosystem functional status as well as carbon processes measured at flux towers.

Calibration↗
NASA NTRS1992

Petrology of basaltic sills from ocean drilling program sites 794 and 797 in the Yamato Basin of the Japan Sea

The basaltic sills from ocean drilling program sites 794 and 797 in the Yamato Basin of the Japan Sea are characterized petrographically on the basis of a detailed study of the composition of relict phenocryst and groundmass phases. The systematic variation in the rock compositions is discussed. Results of 1-atm melting experiments on a relatively primitive basalt from site 797 are reported. The sills are found to constitute two distinct groups of suites: primitive, olivine-bearing suites with low potassium and primitive olivine-bearing to evolved, olivine-free suites with relatively high potassium. A pseudoinvariant reaction relationship between olivine and augite and magnetite is inferred. Complex magmatic and tectonic evolutions in the region, perhaps reflecting a transitional stage between subduction zone activity and back arc spreading, are suggested.

Thy, P.↗
NASA NTRS1978

Martian intrusions - Possible sites and implications

Both the Moon and Mars exhibit volcanic modification of impact craters characterized by subfloor intrusions that either lift the old crater floor or result in extrusions of lava. Endogenic modification of martian craters, however, probably has involved interactions between such intrusive bodies and permafrost, as suggested by differences between lunar and martian floor-fractured craters. Such interactions raise the interesting possibility for hydrothermally concentrating ores in a manner analogous to the Sudbury structure on the Earth that may be consistent with interpretations of Viking lander results.

Schultz, P. H.↗
NASA NTRS2001

Preparation and Preliminary Characterization of Crystallizing Fluorescent Derivatives of Chicken Egg White Lysozyme

Fluorescence is one of the most versatile and powerful tools for the study of macromolecules. While most proteins are intrinsically fluorescent, working at crystallization concentrations require the use of covalently prepared derivatives added as tracers. This approach requires derivatives that do not markedly affect the crystal packing. We have prepared fluorescent derivatives of chicken egg white lysozyme with probes bound to one of two different sites on the protein molecule. Lucifer yellow and 5-(2-aminoethyl)aminonapthalene-1-sulfonic acid (EDANS) have been attached to the side chain carboxyl of Asp(sup 101) using a carbodiimide coupling procedure. Asp(sup 101) lies within the active site cleft, and it is believed that the probes are "buried" within that cleft. Lucifer yellow and MANS probes with iodoacetamide reactive groups have been bound to His(sup 15), located on the "back side" of the molecule relative to the active site. All the derivatives fluoresce in the solution and the crystalline states. Fluorescence characterization has focused on determination of binding effects on the probe quantum yield, lifetime, absorption and emission spectra, and quenching by added solutes. Quenching studies show that, as postulated, the Asp(sup 101)-bound probes are partially sheltered from the bulk solution by their location within the active site cleft. Probes bound to His(sup 15) have quenching constants about equal to those for the free probes, indicating that this site is highly exposed to the bulk solution.

Sumida, John↗
NASA NTRS2001

Preparation and Preliminary Characterization of Crystallizing Fluorescent Derivatives of Chicken Egg White Lysozyme

Fluorescence is one of the most versatile and powerful tools for the study of macromolecules. While most proteins are intrinsically fluorescent, working at crystallization concentrations require the use of covalently prepared derivatives added as tracers. This approach requires derivatives that do not markedly affect the crystal packing. We have prepared fluorescent derivatives of chicken egg white lysozyme with probes bound to one of two different sites on the protein molecule. Lucifer yellow and 5-(2-aminoethyl)aminonapthalene-i-sulfonic acid (EDANS) have been attached to the side chain carboxyl of Asp(sup 101) using a carbodiimide coupling procedure. Asp(sup 101) lies within the active site cleft, and it is believed that the probes are 'buried' within that cleft. Lucifer yellow and MANS probes with iodoacetamide reactive five groups have been bound to His(sup 15), located on the 'back side' of the molecule relative to the active site. All the derivatives fluoresce in the solution and the crystalline states. Fluorescence characterization has focused on determination of binding effects on the probe quantum yield, lifetime, absorption and emission spectra, and quenching by added solutes. Quenching studies show that, as postulated, the Asp(sup 101)-bound probes are partially sheltered from the bulk solution by their location within the active site cleft. Probes bound to His(sup 15) have quenching constants about equal to those for the free probes, indicating that this site is highly exposed to the bulk solution.

Sumida, John P.↗
NASA NTRSDate not supplied

Radioactivity of Sediments at the Atacama Rover Astrobiology Drilling Studies Field Site

Introduction: During the 2018 Atacama Rover Astrobiology Drilling Studies (ARADS) field activities, we conducted a survey of surface and subsurface sediment radioactivity. Our objective was to characterize the radiation environment of various near-surface sampling locations, as well as along the entire profile of a 2.60 m deep pit that had been dug near one of the ARADS rover drill site locations. This pit was used to collect samples that have been well characterized [2] for comparison to samples collected and analyzed by the rover.

ARADS↗
NASA NTRS1984

Wind turbine generator interaction with conventional diesel generators on Block Island, Rhode Island. Volume 1: Executive summary

Primary results are summarized for a three-part study involving the effects of connecting a MOD-OA wind turbine generator to an isolated diesel power system. The MOD-OA installation considered was the third of four experimental nominal 200 kW wind turbines connected to various utilities under the Federal Wind Energy Program and was characterized by the highest wind energy penetration levels of four sites. The study analyses address: fuel displacement, dynamic interaction, and three modes of reactive power control. These analyses all have as their basis the results of the data acquisition program conducted on Block Island, Rhode Island.

Wilreker, V. F.↗
NASA NTRS2003

Molecular characterization of sulfate-reducing bacteria in the Guaymas Basin

The Guaymas Basin (Gulf of California) is a hydrothermal vent site where thermal alteration of deposited planktonic and terrestrial organic matter forms petroliferous material which supports diverse sulfate-reducing bacteria. We explored the phylogenetic and functional diversity of the sulfate-reducing bacteria by characterizing PCR-amplified dissimilatory sulfite reductase (dsrAB) and 16S rRNA genes from the upper 4 cm of the Guaymas sediment. The dsrAB sequences revealed that there was a major clade closely related to the acetate-oxidizing delta-proteobacterial genus Desulfobacter and a clade of novel, deeply branching dsr sequences related to environmental dsr sequences from marine sediments in Aarhus Bay and Kysing Fjord (Denmark). Other dsr clones were affiliated with gram-positive thermophilic sulfate reducers (genus Desulfotomaculum) and the delta-proteobacterial species Desulforhabdus amnigena and Thermodesulforhabdus norvegica. Phylogenetic analysis of 16S rRNAs from the same environmental samples resulted in identification of four clones affiliated with Desulfobacterium niacini, a member of the acetate-oxidizing, nutritionally versatile genus Desulfobacterium, and one clone related to Desulfobacula toluolica and Desulfotignum balticum. Other bacterial 16S rRNA bacterial phylotypes were represented by non-sulfate reducers and uncultured lineages with unknown physiology, like OP9, OP8, as well as a group with no clear affiliation. In summary, analyses of both 16S rRNA and dsrAB clone libraries resulted in identification of members of the Desulfobacteriales in the Guaymas sediments. In addition, the dsrAB sequencing approach revealed a novel group of sulfate-reducing prokaryotes that could not be identified by 16S rRNA sequencing.

Non-programmatic↗
NASA NTRS2005

Large Multispectral and Albedo Panoramas Acquired by the Pancam Instruments on the Mars Exploration Rovers Spirit and Opportunity

Introduction. The panoramic camera (Pancam) multispectral, stereoscopic imaging systems on the Mars Exploration Rovers Spirit and Opportunity [1] have acquired and downlinked more than 45,000 images (~35 Gbits of data) over more than 700 combined sols of operation on Mars as of early January 2005. A large subset of these images were acquired as part of 26 large multispectral and/or broadband "albedo" panoramas (15 on Spirit, 11 on Opportunity) covering large ranges of azimuth (12 spanning 360 ) and designed to characterize major regional color and albedo characteristics of the landing sites and various points along both rover traverses.

Bell, J. F., III↗
NASA NTRS1999

Validation of Airborne Visible-Infrared Imaging Spectrometer Data at Ray Mine, AZ

We validate 1997 Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) reflectance spectra covering 0.4 meu - 2.4 meu from a stable, flat mineralogically characterized man-made target at Ray Mine, AZ, the site for an EPA/NASA assessment of the utility of remote sensing for monitoring acid drainage from an active open pit mine.

AVIRIS visible-infrared spectrometer imaging↗
NASA NTRS2014

Effects of Dopant on Depoling Temperature in Modified BiScO3 - PbTiO3

In recent years there has been a renewed interest for high temperature piezoelectrics for both terrestrial and aerospace applications. These applications are limited in part by the operating temperature, which is usually taken as one half of the Curie temperature (Tc), and is 200C for one of the most widely used commercial piezoelectrics, Pb(Zr,Ti)O3 (PZT). In an effort to increase Tc, subsequent research into high temperature Bi(BB)O3 PbTiO3 piezoelectrics led to the discovery of the morphotropic phase boundary (MPB) in the high-Tc BiScO3 PbTiO3 (BS-PT) system with a Tc of 460C and a d33 of 460 pmV. The Tc marks the ferroelectric to paraelectric phase transformation and while, in general, a phase transformation leads to thermal depoling in piezoelectrics with low or moderate Tcs, for high Tc piezoelectrics thermally assisted dipole rotation can lead to randomization of domains at temperatures below Tc. It becomes necessary to determine the depoling temperature (Td) which dictates the actual working temperature range. By doping for Sc and Ti the Td can be shifted while maintaining similar electromechanical properties as a function of temperature. The effect of this B-site doping on depoling temperature has been explored through the characterization of microstructure and weakhigh field measurements.

Actuator↗
NASA NTRS2015

OSIRIS-REx Touch-And-Go (TAG) Navigation Performance

The Origins Spectral Interpretation Resource identification Security Regolith Explorer (OSIRIS-REx) mission is a NASA New Frontiers mission launching in 2016 to rendezvous with the near-Earth asteroid (101955) Bennu in late 2018. Following an extensive campaign of proximity operations activities to characterize the properties of Bennu and select a suitable sample site, OSIRIES-REx will fly a Touch-And-Go (TAG) trajectory to the asteroid's surface to obtain a regolith sample. The paper summarizes the mission design of the TAG sequence, the propulsive required to achieve the trajectory, and the sequence of events leading up to the TAG event. The paper will summarize the Monte-Carlo simulation of the TAG sequence and present analysis results that demonstrate the ability to conduct the TAG within 25 meters of the selected sample site and +-2 cms of the targeted contact velocity. The paper will describe some of the challenges associated with conducting precision navigation operations and ultimately contacting a very small asteroid.

Spectral↗
NASA NTRS2015

OSIRI-REx Touch and Go (TAG) Navigation Performance

The Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) mission is a NASA New Frontiers mission launching in 2016 to rendezvous with the near-Earth asteroid (101955) Bennu in late 2018. Following an extensive campaign of proximity operations activities to characterize the properties of Bennu and select a suitable sample site, OSIRIS-REx will fly a Touch-And-Go (TAG) trajectory to the asteroid's surface to obtain a regolith sample. The paper summarizes the mission design of the TAG sequence, the propulsive maneuvers required to achieve the trajectory, and the sequence of events leading up to the TAG event. The paper also summarizes the Monte-Carlo simulation of the TAG sequence and presents analysis results that demonstrate the ability to conduct the TAG within 25 meters of the selected sample site and 2 cm/s of the targeted contact velocity. The paper describes some of the challenges associated with conducting precision navigation operations and ultimately contacting a very small asteroid.

Security Regolith Explorer↗
NASA NTRS2016

OSIRIS-REx Orbit Determination Covariance Studies at Bennu

The Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) mission is a NASA New Frontiers mission launching in 2016 to rendezvous with the small, Earth-crossing asteroid (101955) Bennu in late 2018, ultimately returning a sample of regolith to Earth. Approximately three months before the encounter with Bennu, the asteroid becomes detectable in the narrow field PolyCam imager. The spacecraft's rendezvous with Bennu begins with a series of four Asteroid Approach Maneuvers, slowing the spacecraft's speed relative to Bennu beginning two and a half months prior to closest approach, ultimately delivering the spacecraft to a point 18 km from Bennu in Nov, 2018. An extensive campaign of proximity operations activities to characterize the properties of Bennu and select a suitable sample site will follow. This paper will discuss the challenges of navigating near a small 500-m diameter asteroid. The navigation at close proximity is dependent on the accurate mathematical model or digital terrain map of the asteroid's shape. Predictions of the spacecraft state are very sensitive to spacecraft small forces, solar radiation pressure, and mis-modeling of Bennu's gravity field. Uncertainties in the physical parameters of the central body Bennu create additional challenges. The navigation errors are discussed and their impact on science planning will be presented.

COVARIANCE↗
NASA NTRS2016

OSIRIS-REx Orbit Determination Covariance Studies at Bennu

The Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) mission is a NASA New Frontiers mission launching in 2016 to rendezvous with the small, Earth-crossing asteroid (101955) Bennu in late 2018, and ultimately return a sample of regolith to Earth. Approximately 3 months before the encounter with Bennu, the asteroid finally becomes detectable in the narrow field PolyCam imager. The spacecraft's rendezvous with Bennu begins with a series of four Asteroid Approach Maneuvers, which slow the spacecraft's speed relative to Bennu beginning two and a half months prior to closest approach, ultimately delivering the spacecraft to a point 18 km from Bennu on Nov 18, 2018. An extensive campaign of proximity operations activities to characterize the properties of Bennu and select a suitable sample site will follow. This paper will discuss the challenges of navigating near a small 500-m diameter asteroid. The navigation at close proximity is dependent on the accurate mathematical model or digital terrain map of the asteroids shape. Predictions of the spacecraft state are very sensitive to spacecraft small forces, solar radiation pressure, and mis-modeling of Bennu's gravity field. Uncertainties in the physical parameters of the central body Bennu create additional challenges. The navigation errors are discussed and their impact on science planning will be presented.

Covariance↗
NASA NTRS2014

First Results from the Mojave Volatiles Prospector (MVP) Field Campaign, a Lunar Polar Rover Mission Analog

The Mojave Volatiles Prospector (MVP) project is a science-driven field program with the goal to produce critical knowledge for conducting robotic exploration of the Moon. MVP will feed science, payload, and operational lessons learned to the development of a real-time, short-duration lunar polar volatiles prospecting mission. MVP achieves these goals through a simulated lunar rover mission to investigate the composition and distribution of surface and subsurface volatiles in a natural and a priori unknown environment within the Mojave Desert, improving our understanding of how to find, characterize, and access volatiles on the Moon. The MVP field site is the Mojave Desert, selected for its low, naturally occurring water abundance. The Mojave typically has on the order of 2-6% water, making it a suitable lunar analog for this field test. MVP uses the Near Infrared and Visible Spectrometer Subsystem (NIRVSS), Neutron Spectrometer Subsystem (NSS), and a downward facing GroundCam camera on the KREX-2 rover to investigate the relationship between the distribution of volatiles and soil crust variation. Through this investigation, we mature robotic in situ instruments and concepts of instrument operations, improve ground software tools for real time science, and carry out publishable research on the water cycle and its connection to geomorphology and mineralogy in desert environments. A lunar polar rover mission is unlike prior space missions and requires a new concept of operations. The rover must navigate 3-5 km of terrain and examine multiple sites in in just ~6 days. Operational decisions must be made in real time, requiring constant situational awareness, data analysis and rapid turnaround decision support tools. This presentation will focus on the first science results and operational architecture findings from the MVP field deployment relevant to a lunar polar rover mission.

Heldmann, Jennifer L.↗
NASA NTRS2019

LCF Life of As-Deposited and Annealed NiCr-Y Coatings for Oxidation and Hot Corrosion Protection of Disk Alloys

Increasing temperatures in aero gas turbines is resulting in oxidation and hot corrosion attack of turbine disks. Since disks are sensitive to low cycle fatigue (LCF), any environmental attack, and especially hot corrosion pitting, can seriously degrade the life of the disk. Application of metallic coatings is one means of protecting disk alloys from this environmental attack. However, the presence of a metallic coating can degrade the LCF life of a disk alloy. Therefore, coatings must be designed which are not only resistant to oxidation and corrosion attack, but do not significantly degrade the LCF life of the alloy.Three different NiCr-Y coating compositions (29, 35.5, 44 wt.% Cr, all with 0.1 wt.% Y) were applied at two thicknesses by Plasma Enhanced Magnetron Sputtering (PEMS) to two similar Ni-based disk alloys. One Ni-35.5Cr-0.1Y coating also received a thin ZrO2 overcoat. The coated samples were also given a short thermal anneal in a low PO2 environment to encourage bonding of the coating and substrate as well as initiating formation of a chromia scale. Without further environmental exposure, the LCF life of coated and uncoated samples was evaluated at 760°C in air. The LCF lifetime of all coated samples was less than that of uncoated samples. The LCF life scaled with the Cr content and the high-Cr, thin coating showed the highest LCF life. Pre and post-test characterization of the various coatings, including identification of crack initiation sites, will be presented and the effect of the coating on the LCF life discussed.

low cycle fatigue↗