SEARCH · Search NASA

Results for “surface samples”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27

All sources NASA NTRS DOE OSTI

NASA NTRS1976

The surface chemical composition of lunar samples and its significance for optical properties

The surface Fe, Ti, Ca, and Si concentrations in a variety of soil and rock samples from all the Apollo sites are determined using an Auger spectrometer plus a single-pass cylindrical-mirror analyzer with a standard 15-stage BeCu electron multiplier. It is found that there are no great differences between the surface and bulk concentrations of any of the four elements in the rock samples, but the surface Fe and Ti concentrations in soil samples are higher than the bulk concentrations. Results are also reported for solar-wind simulation experiments in which a pulverized rock sample was bombarded with 2-keV alpha-particles corresponding to about a 30,000-yr dose of the solar-wind proton component. These results indicate that the chemical change induced on the surface of a rock powder by positive-ion bombardment is similar to the change from bulk to surface chemical composition in lunar soil samples. A clear correlation is observed between the surface Fe concentration and albedo of the soil samples.

Gold, T.↗

NASA NTRS2022

Assessing the Sampleability of Bennu’s Surface for the OSIRIS-REx Asteroid Sample Return Mission

NASA’s first asteroid sample return mission, OSIRIS-REx, collected a sample from the surface of near-Earth asteroid Bennu in October 2020 and will deliver it to Earth in September 2023. Selecting a sample collection site on Bennu’s surface was challenging due to the surprising lack of large ponded deposits of regolith particles exclusively fine enough (≤ 2 cm diameter) to be ingested by the spacecraft’s Touch-and-Go Sample Acquisition Mechanism (TAGSAM). Here we describe the Sampleability Map of Bennu, which was constructed to aid in the selection of candidate sampling sites and to estimate the probability of collecting sufficient sample. “Sampleability” is a numeric score that expresses the compatibility of a given area’s surface properties with the sampling mechanism. The algorithm that determines sampleability is a best fit functional form to an extensive suite of laboratory testing outcomes tracking the TAGSAM performance as a function of four observable properties of the target asteroid. The algorithm and testing were designed to measure and subsequently predict TAGSAM collection amounts as a function of the minimum particle size, maximum particle size, particle size frequency distribution, and the tilt of the TAGSAM head off the surface. The sampleability algorithm operated at two general scales, consistent with the resolution and coverage of data collected during the mission. The first scale was global and evaluated nearly the full surface. Due to Bennu’s unexpected boulder coverage and lack of ponded regolith deposits, the global sampleability efforts relied heavily on additional strategies to find and characterize regions of interest based on quantifying and avoiding areas heavily covered by material too large to be collected. The second scale was site-specific and used higher-resolution data to predict collected mass at a given contact location. The rigorous sampleability assessments gave the mission confidence to select the best possible sample collection site and directly enabled successful collection of hundreds of grams of material.

Asteroid exploration↗

NASA NTRS1972

Laboratory and airborne techniques for measuring fluoresence of natural surfaces

Techniques are described for obtaining fluorescence spectra from samples of natural surfaces that can be used to predict spectral regions in which these surfaces would emit solar-stimulated or laser-stimulated fluorescence detectable by remote sensor. Scattered or reflected stray light caused large errors in spectrofluorometer analysis or natural sample surfaces. Most spurious light components can be eliminated by recording successive fluorescence spectra for each sample, using identical instrument settings, first with an appropriate glass or gelatin filter on the excitation side of the sample, and subsequently with the same filter on the emission side of the sample. This technique appears more accurate than any alternative technique for testing the fluorescence of natural surfaces.

Stoertz, G. E.↗

NASA NTRS1974

Radiation damage and structure recorded at high resolution in grains from fine fractions of Luna 16 surface material

Samples returned to earth by Luna 16, were studied with a high voltage electron microscope for ultramicroscopic features. The following amazing features were noted in particles of surface material returned in all the lunar trips: A very high density of tracks of nuclear particles, ultrathin amorphous shells, highly rounded forms, and amazingly good ordering of crystal lattice. These features were used along with calibration experiments in solving the following problems: (1) determining the energy spectrum and chemical abundances of the very heavy nuclei in the solar wind and in the solar cosmic rays; (2) studying the past activity of the sun; (3) obtaining data on lunar dynamic processes affecting dust particles; (4) analyzing composite effects caused by penetration of solar wind into the lunar surface material; and (5) establishing the existence of the ancient lunar atmosphere and magnetic field.

Durrieu, L.↗

NASA NTRS1986

Quantitative flaw characterization with scanning laser acoustic microscopy

Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. In accuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. The relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness is investigated. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw.

Generazio, E. R.↗

NASA NTRS1986

Quantitative flaw characterization with scanning laser acoustic microscopy

Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. Inaccuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. The relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness is investigated. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw.

Generazio, E. R.↗

NASA NTRS2010

GeoLab in NASA's Pressurized Excursion Module: First Results from the 2010 Field Trials

Before humans explore other planets, NASA must develop advanced techniques for collection, preservation and return of unique extraterrestrial samples. To help evaluate hardware requirements and operational concepts for future sample-return missions, we designed and built GeoLab our first generation lab for geological samples into NASA s Habitat Demonstration Unit in the Pressurized Excursion Module (HDU1-PEM). The center of GeoLab is a glovebox for the examination of samples in a shirt-sleeve environment. As part of a deployable habitat, GeoLab can participate in NASA s analog missions that simulate planetary exploration activities and support the testing of relevant technologies for collecting and handling geological samples. Over time, these tests will evaluate sample handling environments (field and lab), sampling tools and analytical instruments, and different scenarios involving both robotic and human procedures. The GeoLab design supports evolving tests and configurations. The glovebox is mounted on the habitat bulkhead, with three sample pass-though chambers that allow for direct sample transfer into the glovebox from the outside. The glovebox design and construction (low-particle shedding, minimally off-gassing materials) provides a clean environment to reduce sample contamination; in the future, we will integrate a positive pressure, enriched nitrogen atmosphere. The glovebox is equipped with configurable instrument ports. The 2010 test included a mass balance, a stereomicroscope with a HD camera for detailed imaging of samples, and a handheld XRF analyzer for preliminary geochemical characterization of samples. Network cameras provided context imagery and sample handling activities. We present early results from the initial field trial of GeoLab during the 2010 Desert Research and Technology Studies (D-RATS) planetary analog test near Flagstaff AZ. The 2010 D-RATS mission involved two rovers, the habitat with GeoLab, four crew members, and a team of scientists and flight controllers. The crewed rovers conducted geological traverses and collected samples on the planetary surface. Selected samples were transferred into GeoLab for detailed examination and initial analysis, providing critical data to the science team for evaluation and prioritization of samples.

Evans, Cynthia A.↗

NASA NTRS1979

Lunar sample analysis

The surface composition of two samples from the highly shocked, glass-coated lunar basalt (12054) and from four glass-coated fragments from the 1-2 mm (14161) fines were examined by X-ray photoemission spectroscopy to determine whether the agglutination process itself is responsible for the difference between their surface and bulk compositions. Auger electron spectroscopy of glass balls from the 15425 and 74001 fines were analyzed to understand the nature, extent, and behavior of volatile phases associated with lunar volcanism. Initial results indicate that (1) volatiles, in the outer few atomic layers sampled, vary considerably from ball to ball; (2) variability over the surface of individual balls is smaller; (3) the dominant volatiles on the balls are S and Zn; and (4) other volatiles commonly observed are P, Cl, and K.

Housley, R. M.↗

NASA NTRS1977

The search for organic substances and inorganic volatile compounds in the surface of Mars

A total of four Martian samples, one surface and one subsurface sample at each of the two Viking landing sites, Chryse Planitia and Utopia Planitia, have been analyzed for organic compounds by a gas chromatograph-mass spectrometer. In none of these experiments could organic material of Martian origin be detected at detection limits generally of the order of parts per billion and for a few substances closer to parts per million. The evolution of water and carbon dioxide, but not of other inorganic gases, was observed upon heating the sample to temperatures of up to 500 C. The absence of organic compounds seems to preclude their production on the planet at rates that exceed the rate of their destruction. It also makes it unlikely that living systems that behave in a manner similar to terrestrial biota exist, at least at the two Viking landing sites.

Biemann, K.↗

NASA NTRS1980

Tissue response to peritoneal implants

Peritoneal implants were fabricated from poly 2-OH, ethyl methacrylate (HEMA), polyetherurethane (polytetramethylene glycol 1000 MW, 1,4 methylene disocynate, and ethyl diamine), and untreated and sputter treated polytetrafluoroethylene (PTFE). The sputter treated PTFE implants were produced by an 8 cm diameter argon ion source. The treated samples consisted of ion beam sputter polished samples, sputter etched samples (to produce a microscopic surface cone texture) and surface pitted samples (produced by ion beam sputtering to result in 50 microns wide by 100 microns deep square pits). These materials were implanted in rats for periods ranging from 30 minutes to 14 days. The results were evaluated with regard to cell type and attachment kinetics onto the different materials. Scanning electron microscopy and histological sections were also evaluated. In general the smooth hydrophobic surfaces attracted less cells than the ion etched PTFE or the HEMA samples. The ion etching was observed to enhance cell attachment, multinucleated giant cell (MNGC) formation, cell to cell contact, and fibrous capsule formation. The cell responsed in the case of ion etched PTFE to an altered surface morphology. However, equally interesting was the similar attachment kinetics of HEMA verses the ion etched PTFE. However, HEMA resulted in a markedly different response with no MNGC's formation, minimal to no capsule formation, and sample coverage by a uniform cell layer.

Picha, G. J.↗

NASA NTRS1991

Measurement of the O18 to O16 isotope ratio for characterizing oxide surface layers on LDEF samples

Calculations indicate that measurement of the O-16 to O-18 isotope ratio in oxide layers formed on the surfaces of the Long Duration Exposure Facility (LDEF) samples would provide a powerful tool for distinguishing between layers formed at high altitudes and layers formed at low altitudes, as for example during the retrieval of a satellite. In principle, this ratio may be used to date the formation of the oxide layers.

Sagalyn, Paul L.↗

NASA NTRS1976

The Surface Chemical Composition of Lunar Samples and Its Significance for Optical Properties

The surface iron, titanium, calcium, and silicon concentration in numerous lunar soil and rock samples was determined by Auger electron spectroscopy. All soil samples show a large increase in the iron to oxygen ratio compared with samples of pulverized rock or with results of the bulk chemical analysis. A solar wind simulation experiment using 2 keV energy alpha -particles showed that an ion dose corresponding to approximately 30,000 years of solar wind increased the iron concentration on the surface of the pulverized Apollo 14 rock sample 14310 to the concentration measured in the Apollo 14 soil sample 14163, and the albedo of the pulverized rock decreased from 0.36 to 0.07. The low albedo of the lunar soil is related to the iron + titanium concentration on its surface. A solar wind sputter reduction mechanism is discussed as a possible cause for both the surface chemical and optical properties of the soil.

Gold, T.↗

NASA NTRS1973

Grain size analysis and high frequency electrical properties of Apollo 15 and 16 samples

The particle size distribution of eleven surface fines samples collected by Apollo 15 and 16 was determined by the method of measuring the sedimentation rate in a column of water. The fact that the grain size distribution in the core samples shows significant differences within a few centimeters variation of depth is important for the understanding of the surface transportation processes which are responsible for the deposition of thin layers of different physical and/or chemical origin. The variation with density of the absorption length is plotted, and results would indicate that for the case of meter wavelength radar waves, reflections from depths of more than 100 meters generally contribute significantly to the radar echoes obtained.

Gold, T.↗

NASA NTRS1992

Measurement of the O-18 to O-16 isotope ratio for characterizing oxide surface layers on LDEF samples

The ratio of the density of the oxygen 18 isotope (O-18) to the density of the oxygen 16 isotope (O-16) is a strong function of altitude in the atmosphere because of the stronger gravitational attraction on the heavier isotope. It is proposed that the measurement of this ratio for oxide surface layers on LDEF samples can easily distinguish oxides formed in orbit from contaminative oxides formed during retrieval procedures. Since the satellite altitude is known as a function of time, it may be possible to use the measured ratio to determine the time of formation of oxide layers, the accuracy depending upon the stability of the atmosphere.

Sagalyn, Paul L.↗

NASA NTRS1977

Reusable Surface Insulation (RSI) Material Samples

Test specimen data sheets are presented for 48 high temperature and 40 low temperature reusable surface insulation tiles. Tabular data show dimensions, density, coating weight, and final tile weight. Codes indicate basic material, surface coating, and hydrophobic treatment.

Banas, R. P.↗

NASA NTRS1992

Mass spectrometer-pyrolysis experiment for atmospheric and soil sample analysis on the surface of Mars

Results from the Viking mission will form the foundation for future in-depth investigations of atmosphere-surface interactions on Mars. The two Viking landers carried impressive instrumentation to obtain and analyze soil samples: the sites were observed by cameras, and the collector head was located on a long boom and allowed the collection of large samples at various depths. A selection of grain sizes was possible and a distribution system supplied a number of experiments with soil material. Despite stationary vehicles, a wide sampling field was reachable. The GCMS system, responsible for atmospheric as well as surface soil analysis, worked well on both landers. Atmospheric measurements resulted in the determination of the abundance of noble gases as well as of other molecular species. Isotopic composition measurements included the important ratios of C-13/C-12, N-15/N-14, and Ar-36/Ar-40. To verify these past results and to advance detailed studies of noble gas isotope ratios and minor constituents, better instrument sensitivities, higher precision, and lower background contributions are required in future Mars missions. Soil analysis during the Viking mission concentrated on organic material. Heating cycles were performed to 500 C and only water and carbon dioxide were identified. Higher pyrolysis temperatures are of primary importance to advance our understanding of the mineralogy and gas loading of surface material and atmospheric exchange.

Mauersberger, Konrad↗

NASA NTRS2012

An Automated Algorithm to Screen Massive Training Samples for a Global Impervious Surface Classification

An algorithm is developed to automatically screen the outliers from massive training samples for Global Land Survey - Imperviousness Mapping Project (GLS-IMP). GLS-IMP is to produce a global 30 m spatial resolution impervious cover data set for years 2000 and 2010 based on the Landsat Global Land Survey (GLS) data set. This unprecedented high resolution impervious cover data set is not only significant to the urbanization studies but also desired by the global carbon, hydrology, and energy balance researches. A supervised classification method, regression tree, is applied in this project. A set of accurate training samples is the key to the supervised classifications. Here we developed the global scale training samples from 1 m or so resolution fine resolution satellite data (Quickbird and Worldview2), and then aggregate the fine resolution impervious cover map to 30 m resolution. In order to improve the classification accuracy, the training samples should be screened before used to train the regression tree. It is impossible to manually screen 30 m resolution training samples collected globally. For example, in Europe only, there are 174 training sites. The size of the sites ranges from 4.5 km by 4.5 km to 8.1 km by 3.6 km. The amount training samples are over six millions. Therefore, we develop this automated statistic based algorithm to screen the training samples in two levels: site and scene level. At the site level, all the training samples are divided to 10 groups according to the percentage of the impervious surface within a sample pixel. The samples following in each 10% forms one group. For each group, both univariate and multivariate outliers are detected and removed. Then the screen process escalates to the scene level. A similar screen process but with a looser threshold is applied on the scene level considering the possible variance due to the site difference. We do not perform the screen process across the scenes because the scenes might vary due to the phenology, solar-view geometry, and atmospheric condition etc. factors but not actual landcover difference. Finally, we will compare the classification results from screened and unscreened training samples to assess the improvement achieved by cleaning up the training samples. Keywords:

Tan, Bin↗

NASA NTRS1991

Ion beam textured and coated surfaces experiment (IBEX)

The IBEX, with 36 samples of various materials, was placed aboard the LDEF. Twenty-seven of the samples had surfaces modified using ion beam technology, and nine were made up of commercially available materials. The materials are in some way useful in space power systems. The various types of materials tested included six categories: (1) ion beam structured surfaces suitable for solar thermal (concentrator) or space radiators; (2) ion beam sputtered conductive coatings for thermal and space charge control; (3) solar reflector surfaces; (4) flexible thin film coatings and solar array blanket material for protection of spacecraft polymers; (5) painted and/or state-of-the-art solar thermal materials; and (6) micrometeoroid sensitive detector. Data analysis presented include the optical properties of each surface before and after exposure to the space environment and the respective backup surfaces.

Mirtich, Michael J.↗