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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

A preliminary study of a Mars penetrator system for subsurface exobiological exploration

The earth seems to stand alone among the planets of the solar system in that its surface, atmosphere, and hydrosphere provide an environment conducive to the maintenance of life. At one time, Mars was also considered to have the potential to harbor life. However, the absence of detectable organic molecules at the two Viking landing sites and the absence of liquid water anywhere on the surface seems to indicate that life is not present on Mars now. There are, however, many indications that the surface of Mars was less hostile in the distant past and the possibility that life may have existed on primordial Mars or that prebiotic chemistry may have occurred can not be excluded. The search for the organic evidence of this prebiotic or biotic activity will require a subsurface study of possible sediments at several sites. The purpose of this paper is to propose and describe a device termed a penetrator to emplant the required instrumentation beneath the surface (2-4 m) at likely sites to search for the evidence of biogenic organic material. The paper examines, in detail, the rationale for the scientific activity, any issues of technical feasibility, and describes the associated system requirements.

Swenson, Byron L.↗
NASA NTRS1995

Secondary ion mass spectrometry (SIMS) analysis of hypervelocity microparticle impact sites on LDEF surfaces

Two dimensional elemental ion maps have been recorded for hundreds of microparticle impact sites and contamination features on LDEF surfaces. Since the majority of the analyzed surfaces were metal-oxide-silicon (MOS) impact detectors from the Interplanetary Dust Experiment, a series of 'standard' and 'blank' analyses of these surfaces are included. Hypervelocity impacts of forsterite olivine microparticles on activated flight sensors served as standards while stylus and pulsed laser simulated 'impacts' served as analytical blanks. Results showed that despite serious contamination issues, impactor residues can be identified in greater than 1/3 of the impact sites. While aluminum oxide particles could not be detected on aluminum surfaces, they were detected on germanium surfaces from row 12. Remnants of manmade debris impactors consisting of paint chips and bits of metal were identified on surfaces from LDEF Rows 3 (west or trailing side), 6 (south), 9 (ram or leading side), 12 (north) and the space end. Higher than expected ratios of manmade microparticle impacts to total microparticle impacts were found on the space end and the trailing side. These results were consistent with time-tagged and time-segregated microparticle impact data from the IDE and other LDEF experiments. A myriad of contamination interferences were identified and their effects on impactor debris identification mitigated during the course of this study. These interferences include pre-, post and inflight deposited surface contaminants as well as indigenous heterogeneous material contaminants. Non-flight contaminations traced to human origins, including spittle and skin oils, contributed significant levels of alkali-rich carbonaceous interferences. A ubiquitous layer of in-flight deposited silicaceous contamination varied in thickness with location on LDEF, even on a micro scale. In-flight deposited (low velocity) contaminants include urine droplets and bits of metal film from eroded thermal blankets.

Simon, C. G.↗
NASA NTRS1995

Ice Processes and Growth History on Arctic and Sub-Arctic Lakes Using ERS-1 SAR Data

A survey of ice growth and decay processes on a selection of shallow and deep sub-Arctic and Arctic lakes was conducted using radiometrically calibrated ERS-1 SAR images. Time series of radar backscatter data were compiled for selected sites on the lakes during the period ot ice cover (September to June) for the years 1991-1992 and 1992-1993. A variety of lake-ice processes could be observed, and significant changes in backscatter occurred from the time of initial ice formation in autumn until the onset of the spring thaw. Backscatter also varied according to the location and depth of the lakes. The spatial and temporal changes in backscatter were most constant and predictable at the shallow lakes on the North Slope of Alaska. As a consequence, they represent the most promising sites for long-term monitoring and the detection of changes related to global warming and its effects on the polar regions.

Morris, K.↗
NASA NTRS1995

Implications of Gamma-Ray Transparency Constraints in Blazars: Minimum Distances and Gamma-Ray Collimation

We develop a general expression for the gamma - gamma absorption coefficient, alpha(sub gamma(gamma)) for gamma-rays propagating in an arbitrary direction at an arbitrary point in space above an X-ray-emitting accretion disk. The X-ray intensity is assumed to vary as a power law in energy and radius between the outer disk radius, R(sub 0), and the inner radius, R(sub ms) which is the radius of marginal stability for a Schwarzschild black hole. We use our result for alpha(sub gamma(gamma)) to calculate the gamma - gamma optical depth, tau(sub gamma(gamma)) for gamma - rays created at height z and propagating at angle Phi relative to the disk axis, and we show that for Phi = 0 and z greater than or approx equal to R(sub 0), tau(sub gamma(gamma)) proportional to Epsilon(sup alpha)z(sup -2(alpha) - 3), where alpha is the X-ray spectral index and Epsilon is the gamma - ray energy. As an application, we use our formalism to compute the minimum distance between the central black hole and the site of production of the gamma-rays detected by EGRET during the 1991 June flare of 3C 279. In order to obtain an upper limit, we assume that all of the X-rays observed contemporaneously by Ginga were emitted by the disk. Our results suggest that the observed gamma - rays may have originated within less than or approx equal to 45 GM/sq c from a black hole of mass greater than or approx equal to 10(exp 9) solar mass, perhaps in active plasma located above the central funnel of the accretion disk. This raises the possibility of establishing a direct connection between the production of the observed gamma - rays and the accretion of material onto the black hole. We also consider the variation of the optical depth as a function of the angle of propagation Phi. Our results indicate that the "focusing" of the gamma - rays along the disk axis due to pair production is strong enough to explain the observed degree of alignment in blazar sources. If the gamma - rays are produced isotropically in gamma - ray blazars, then these objects should appear as bright MeV sources when viewed along off-axis lines of sight.

Becker, Peter A.↗
NASA NTRS1982

Protein specific fluorescent microspheres for labelling a protein

Highly fluorescent, stable and biocompatible microspheres are obtained by copolymerizing an acrylic monomer containing a covalent bonding group such as hydroxyl, amine or carboxyl, for example, hydroxyethylmethacrylate, with an addition polymerizable fluorescent comonomer such as dansyl allyl amine. A lectin or antibody is bound to the covalent site to provide cell specificity. When the microspheres are added to a cell suspension the marked microspheres will specifically label a cell membrane by binding to a specific receptor site thereon. The labeled membrane can then be detected by fluorescence of the fluorescent monomer.

Rembaum, Alan↗
NASA NTRS2013

Possible Detection of Perchlorates by the Sample Analysis at Mars (SAM) Instrument: Comparison with Previous Missions

The first chemical analysis of soluble salts in the soil was carried out by the Phoenix Lander in the Martian Arctic [1]. Surprisingly, chlorine was present as magnesium or calcium perchlorate at 0.4 to 0.6 percent. Additional support for the identification of perchlorate came from the evolved gas analysis which detected the release of molecular oxygen at 350-550C [1]. When Mars-like soils from the Atacama Desert were spiked with magnesium perchlorate (1 percent) and heated using the Viking GC-MS protocol, nearly all the organics were combusted but a small amount was chlorinated, forming chloromethane and dichloromethane [2]. These chlorohydrocarbons were detected by the Viking GC-MS experiments when the Martian soil was analyzed but they were considered to be terrestrial contaminants [3]. Reinterpretation of the Viking results suggests <0.1 percent perchlorate and ppm levels of organic carbon at landing site 1 and 2 [2]. The suggestion of perchlorate in the Viking sites [2] has been challenged on the grounds that the detected compounds (CH3Cl and CH2Cl2) were carried from Earth [4]. Recently the Sample Analysis at Mars (SAM) instrument on board the Mars Science Laboratory (MSL) ran four samples from an aeolian bedform named Rocknest. The samples analyzed were portioned from the fifth scoop at this location. The samples were heated to 835C at 35C/min with a He flow. The SAM QMS detected a major oxygen release (300-500C) [5], coupled with the release of chlorinated hydrocarbons (chloromethane, dichloromethane, trichloromethane, and chloromethylpropene) detected both by SAM QMS and GC-MS derived from known Earth organic contaminants in the instrument [6]. Calcium perchlorate appears to be the best candidate for evolved O2 in the Rocknest samples at this time but other Cl species (e.g., chlorates) are possible and must be evaluated. The potential detection of perchlorates in Rocknest material adds weight to the argument that both Viking Landers measured signatures of perchlorates. Even if the source of the organic carbon detected is still unknown, the chlorine source was likely Martian. Two mechanisms have been hypothesized for the formation of soil perchlorate: (1) Atmospheric oxidation of chlorine; and (2) UV photooxidation of chlorides catalyzed by mineral catalysts [7]. The presence of soil perchlorates in the Martian surface has important implications for the detection of organics [2], carbonates [8] and nitrates [9] by SAM.

Navarro-Gonzalex, Rafael↗
NASA NTRS2013

Ten Years of Vegetation Change in Northern California Marshlands Detected using Landsat Satellite Image Analysis

The Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS) methodology was applied to detected changes in perennial vegetation cover at marshland sites in Northern California reported to have undergone restoration between 1999 and 2009. Results showed extensive contiguous areas of restored marshland plant cover at 10 of the 14 sites selected. Gains in either woody shrub cover and/or from recovery of herbaceous cover that remains productive and evergreen on a year-round basis could be mapped out from the image results. However, LEDAPS may not be highly sensitive changes in wetlands that have been restored mainly with seasonal herbaceous cover (e.g., vernal pools), due to the ephemeral nature of the plant greenness signal. Based on this evaluation, the LEDAPS methodology would be capable of fulfilling a pressing need for consistent, continual, low-cost monitoring of changes in marshland ecosystems of the Pacific Flyway.

Marshland↗
NASA NTRS2015

Mineralogical Indicators for Climate Change on Mars: Evidence from Landed Missions

Mineralogical and geochemical data returned by a flotilla of Mars orbiters and landers over the past 10 years has substantially enhanced our understanding on the evolution of the atmosphere and climate. Instruments onboard Mars Express and MRO discovered widespread deposits of phyllosilicates that formed during the Noachian followed by formation of sulfates into the Hesperian. The formation of extensive valley networks along with these layered deposits of phyllosilicates and sulfates during the late Noachian/ early Hesperian indicate a past martian climate that was capable of maintaining liquid water at the surface. The planet's climate changed substantially after these early 'episodes' of water and very little aqueous alteration has occurred over the past 3.5 Gyrs . A key to understanding Mars past climate is to identify, characterize, and age date secondary minerals that have formed by reaction with volatile compounds, e.g., H2O, CO2, SO2. Here, we summarize the detection of secondary minerals at the four landing sites visited over the past 10 years. We also provide potential pathways for their formation and implications for past climate change on Mars.

Ming, D. W.↗
NASA NTRSDate not supplied

Trajectory Shaping of Lunar Descent Approach Phase for Human Landing Systems

NASA’s Artemis program will have many mission phases but perhaps the most dangerous and dynamic is the powered descent and landing phase. NASA’s HLS Program has developed a candidate lunar approach concept of operations to address the needs of both hazard detection sensors and crew visibility of the landing site. The descent trajectory is shaped such that the approach phase is initiated at a steep trajectory path angle for hazard map generation then transitions to a shallow trajectory path angle to facilitate crew landing site visibility. The results show this tailored approach concept is a viable option to reduce risk during landing with minimal performance impacts.

Trajectory Optimization↗
NASA NTRS2014

Nanophase Carbonates on Mars: Implications for Carbonate Formation and Habitability

Despite having an atmosphere composed primarily of CO2 and evidence for abundant water in the past, carbonate minerals have only been discovered in small amounts in martian dust [1], in outcrops of very limited extent [2, 3], in soils in the Northern Plains (the landing site of the 2007 Phoenix Mars Scout Mission) [4] and may have recently been detected in aeolian material and drilled and powdered sedimentary rock in Gale Crater (the Mars Science Laboratory [MSL] landing site) [5]. Thermal analysis of martian soils by instruments on Phoenix and MSL has demonstrated a release of CO2 at temperatures as low as 250-300 degC, much lower than the traditional decomposition temperatures of calcium or magnesium carbonates. Thermal decomposition temperature can depend on a number of factors such as instrument pressure and ramp rate, and sample particle size [6]. However, if the CO2 released at low temperatures is from carbonates, small particle size is the only effect that could have such a large impact on decomposition temperature, implying the presence of extremely fine-grained (i.e., "nanophase" or clay-sized) carbonates. We hypothesize that this lower temperature release is the signature of small particle-sized (clay-sized) carbonates formed by the weathering of primary minerals in dust or soils through interactions with atmospheric water and carbon dioxide and that this process may persist under current martian conditions. Preliminary work has shown that clay-sized carbonate grains can decompose at much lower temperatures than previously thought. The first work took carbonate, decomposed it to CaO, then flowed CO2 over these samples held at temperatures >100 degC to reform carbonates. Thermal analysis confirmed that carbonates were indeed formed and transmission electron microsopy was used to determine crystal sized were on the order of 10 nm. The next step used minerals such as diopside and wollastonite that were sealed in a glass tube with a CO2 and H2O source. After reacting these materials for a number of hours, thermal analysis demonstrated the formations of carbonates that decomposed at temperatures as low as 500 degC [7]. Further work is underway to carry out the weathering process under more Mars-like conditions (low pressure and low temperature) to determine if the carbonate decomposition temperature can be shifted to even lower temperatures, consistent with what has been detected by thermal analysis instruments on Mars.

Archer, P. Douglas, Jr.↗
NASA NTRS2009

Thermal and Evolved Gas Analysis of Magnesium Perchlorate: Implications for Perchlorates in Soils at the Mars Phoenix Landing Site

Perchlorate salts were discovered in the soils around the Phoenix landing site on the northern plains of Mars [1]. Perchlorate was detected by an ion selective electrode that is part of the MECA Wet Chemistry Laboratory (WCL). The discovery of a mass 32 fragment (likely 02) by the Thermal and Evolved-Gas Analyzer (TEGA) provided additional confirmation of a strong oxidizer in the soils around the landing site. The purpose of this paper is to evaluate the thermal and evolved gas behavior of perchlorate salts using TEGA-like laboratory testbed instruments. TEGA ovens were fabricated from high purity Ni. Hence, an additional objective of this paper is to determine the effects that Ni might have on the evolved gas behavior of perchlorate salts.

Ming, Douglas W.↗
NASA NTRS2001

Derivative Analysis of AVIRIS Hyperspectral Data for the Detection of Plant Stress

A remote sensing campaign was conducted over a U.S. Department of Agriculture test site at Shelton, Nebraska. The test field was set off in blocks that were differentially treated with nitrogen. Four replicates of 0-kg/ha to 200-kg/ha, in 50-kg/ha increments, were present. Low-altitude AVIRIS hyperspectral data were collected over the site in 224 spectral bands. Simultaneously, ground data were collected to support the airborne imagery. In an effort to evaluate published, derivative-based algorithms for the detection of plant stress, different derivative-based approaches were applied to the collected AVIRIS image cube. The results indicate that, given good quality hyperspectral imagery, derivative techniques compare favorably with simple, well known band ratio algorithms for detection of plant stress.

Estep, Lee↗
NASA NTRS1990

Identification of lunar rock types and search for polar ice by gamma ray spectroscopy

This paper examines the possibility of mapping the surface composition of the moon from an orbiting spin-stabilized spacecraft, using gamma ray spectroscopy and a cooled germanium solid-state device as a detector. A design for accommodating the germanium detector gamma ray spectrometer was devised, and the detection sensitivity was applied to typical lunar-rock compositions. For sets comprising nine highland and 16 mare types, the most useful elements were found to be Mg, Al, K, Ti, Fe, U, and Th. An analysis of the expected instrument response to the gamma ray and neutron fluxes of water ice indicated that a neutron mode added to the spectrometer will be more sensitive than the gamma ray mode to the possible presence of polar ice. It was calculated that, with a pair of selected neutron absorbers and a model which provides that 2.5 percent of the area above 75-deg latitude is occupied by trapping sites, the instrument will provide a 1-yr mission detection limit of 0.056 percent H2O by weight for each polar region.

Metzger, Albert E.↗
NASA NTRS1972

Geographic applications of ERTS-A imagery to rural landscape change

There are no author-identified significant results in this report. The study area, centered on Knoxville, Tennessee, encompasses nearly 20,000 square miles. The Knoxville Test Site, an 11 x 21 mile area over the city of Knoxville and the western portion of Knox County, has been chosen for the analysis of landscape change detection associated with urban growth. The second area, the Cumberland Plateau Test Site, exhibits landscape change through forest alterations and landform disturbances associated with strip mining in the area and was so chosen for its sharp contrasts in physical and human phenomena as well as its change dynamics. Accomplishments since reception of ERTS-1 imagery include: (1) basic cataloging and classifying of the data into a filling system; (2) a densitometer analysis; (3) first look analysis; and (4) preparation of results from the project. Examples of all four bands of the MSS have been received and analyses reveal distinctive positive and negative reactions. Band 5 has been found to be best for landscape analysis of contrasts between urban and rural landscapes, and band 7 for topographic features and water surfaces. Preliminary results are summarized.

Rehder, J. B.↗
NASA NTRS1978

Activities of the US Geological Survey in Applications of Remote Sensing in the Chesapeake Bay Region

The application of remote sensing in the Chesapeake Bay region has been a central concern of three project activities of the U.S. Geological Survey: two are developmental, and one is operational. The two developmental activities were experiments in land-use and land-cover inventory and change detection using remotely sensed data from aircraft and from the LANDSAT and Skylab satellites. One of these is CARETS (Central Atlantic Regional Ecological Test Site). The other developmental task is the Census Cities Experiment in Urban Change Detection. The present major concern is an operational land-use and land-cover data-analysis program, including a supporting geographical information system.

Wray, J. R.↗
NASA NTRS1973

Evaluate the application of ERTS-A data for detecting and mapping snow cover

The author has identified the following significant results. Analysis of ERTS-1 data covering the test sites in the western United States indicate that the MSS-4 and 5 spectral bands are the most useful for detecting and mapping snow cover. Of these two bands, the MSS-5 is the most consistently useful, as snow-covered areas in some MSS-4 images are nearly saturated causing some loss of detail. Snow can be readily detected and can be distinguished from clouds through a number of interpretive keys. At the ERTS-1 resolution, numerous terrestrial features not visible in lower resolution meteorological satellite data can be detected. In addition to various natural features, man-made features such as roads, electric power lines, cultivated fields, and timber cuts are visible. In two cases analyzed for the Salt-Verde Watershed in Arizona, good agreement is observed between the location of the snowline as mapped from the ERTS-1 data and as depicted on aerial snow survey charts compiled within a few days of the ERTS-1 passage. Results indicate that the snowline can be mapped in more detail from ERTS-1 imagery than can be achieved by current aerial survey methods.

Barnes, J. C.↗
NASA NTRS2018

Field Exploration and Life Detection Sampling for Planetary Analogue Research (FELDSPAR): Variability and Correlation in Biomarker and Mineralogy Measurements from Icelandic Mars Analogues

In situ exploration of planetary environments allows biochemical analysis of sub-centimeter-scale samples; however, landing sites are selected a priori based on measurable meter- to kilometer-scale geological features. Optimizing life detection mission science return requires both understanding the expected biomarker distributions across sample sites at different scales and efficiently using first-stage in situ geochemical instruments to justify later-stage biological or chemical analysis. Icelandic volcanic regions have an extensive history as Mars analogue sites due to desiccation, low nutrient availability, and temperature extremes, in addition to the advantages of geological youth and isolation from anthropogenic contamination. Many Icelandic analogue sites are also rugged and remote enough to create the same type of instrumentation and sampling constraints typically faced by robotic exploration.

Planetary↗