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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Nondestructive activation analysis of sample of lunar surface material returned by Luna 16 automatic station

The composition of a sample of lunar surface material returned by the Luna 16 automatic station from the Sea of Fertility was studied, using nondestructive activation analysis. The structure of the returned surface material is inhomogeneous; the surficial material is thin, quite homogeneous, and the granularity increases with depth. Based on grain size, the sample was separated into five zones. The activation analysis was conducted on a sample taken from the friable surficial layer, zone A. The content of Al, Mn, Na, Cr, Co, Fe, and Sc was determined by nondestructive activation analysis of the sample. In determining Cr, Co, Fe, and Sc, the sample was irradiated for 24 hours and cooled for 10 days. Gamma spectra of the samples were recorded with a semiconductor Ge(Li)-detector and a multichannel analyzer, and measurement data were processed with an electronic computer.

Chayko, M.↗
NASA NTRS1975

Test evaluation of potential heatshield contamination of an outer planet probe's gas sampling system

The feasibility of retaining the heat shield for outer planet probes was investigated as a potential source of atmospheric sample contamination by outgassing. The onboard instruments which are affected by the concept are the pressure sensor, temperature sensor, IR detector, nephelometer, and gas sampling instruments. It was found that: (1) The retention of the charred heatshield and the baseline atmospheric sampling concepts are compatible with obtaining noncontaminated atmospheric samples. (2) Increasing the sampling tube length so that it extends beyond the viscous boundary layer eliminates contamination of the atmospheric sample. (3) The potential for contamination increases with angle of attack.

Kessler, W. C.↗
NASA NTRS1977

A high pressure modulated molecular beam mass spectrometric sampling system

The current state of understanding of free-jet high pressure sampling is critically reviewed and modifications of certain theoretical and empirical considerations are presented. A high pressure, free-jet expansion, modulated molecular beam, mass spectrometric sampling apparatus was constructed and this apparatus is described in detail. Experimental studies have demonstrated that the apparatus can be used to sample high temperature systems at pressures up to one atmosphere. Condensible high temperature gaseous species have been routinely sampled and the mass spectrometric detector has provided direct identification of sampled species. System sensitivity is better than one tenth of a part per million. Experimental results obtained with argon and nitrogen beams are presented and compared to theoretical predictions. These results and the respective comparison are taken to indicate acceptable performance of the sampling apparatus. Results are also given for two groups of experiments related to hot corrosion studies. The formation of gaseous sodium sulfate in doped methane-oxygen flames was characterized and the oxidative vaporization of metals was studied in an atmospheric pressure flowing gas system to which gaseous salt partial pressures were added.

Stearns, C. A.↗
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 NTRS1978

Apollo 14 rock samples

Petrographic descriptions of all Apollo 14 samples larger than 1 cm in any dimension are presented. The sample description format consists of: (1) an introductory section which includes information on lunar sample location, orientation, and return containers, (2) a section on physical characteristics, which contains the sample mass, dimensions, and a brief description; (3) surface features, including zap pits, cavities, and fractures as seen in binocular view; (4) petrographic description, consisting of a binocular description and, if possible, a thin section description; and (5) a discussion of literature relevant to sample petrology is included for samples which have previously been examined by the scientific community.

Carlson, I. C.↗
NASA NTRS1979

Determination of trace gases in learjet and U-2 whole air samples collected during the intertropical convergence zone experiment

The contribution of Washington State University (WSU) to the Intertropical Convergence Zone (ITCZ) study, conducted in the Panama Canal Zone in July 1977 is reported. The ITCZ program had the objective to study the meteorology and air chemistry to determine, if possible, the magnitude of injection of tropospheric air into the stratosphere in the ITCZ. WSU was responsible for two phases of the air chemistry program for the ITCZ study: (1) the collection of whole-air samples from ground level to 13.7 km using a Learjet as a sampling platform, and the analysis of the samples for selected halocarbons, C2 hydrocarbons, N2O, and SF6; and (2) the analysis for selected halocarbon species and N2O of low pressure whole-air samples, collected between 13.7 km and 21.3 km by a U-2 aircraft. The report is divided into separate sections describing the Learjet and the U-2 sampling methods, analytical methods, and results. Complete data tables for all samples analyzed are given.

Cronn, D. R.↗
NASA NTRS1981

Mineralogical, optical, geochemical, and particle size properties of four sediment samples for optical physics research

X-ray diffraction and spectroscopy were used to investigate the mineralogical and chemical properties of the Calvert, Ball Old Mine, Ball Martin, and Jordan Sediments. The particle size distribution and index of refraction of each sample were determined. The samples are composed primarily of quartz, kaolinite, and illite. The clay minerals are most abundant in the finer particle size fractions. The chemical properties of the four samples are similar. The Calvert sample is most notably different in that it contains a relatively high amount of iron. The dominant particle size fraction in each sample is silt, with lesser amounts of clay and sand. The indices of refraction of the sediments are the same with the exception of the Calvert sample which has a slightly higher value.

Bice, K.↗
NASA NTRS1982

Distribution and evolution of Zn, Cd, and Pb in Apollo 16 regolith samples and the average U-Pb ages of the parent rocks

The concentration of surface (low temperature site) and interior (high temperature site) Cd, Zn, and Pb in 13 Apollo 16 highland fines samples, pristine rock 65325, and mare fines sample 75081 were analyzed directly from the thermal release profiles obtained by flameless atomic absorption technique (FLAA). Cd and Zn in pristine ferroan anothosite 65325, anorthositic grains of the most mature fines 65701, and basaltic rock fragments of mare fines 75081 were almost all surface Cd and Zn indicating that most volatiles were deposited on the surfaces of vugs, vesicles and microcracks during the initial cooling process. A considerable amount of interior Cd and Zn was observed in agglutinates. This result suggests that high temperature site interior volatiles originate from entrapment during the lunar maturation processes. Interior Cd found in the most mature fines sample 65701 was only about 15% of the total Cd in the sample. Interior Pb present in Apollo 16 fines samples went up to 60%. From our Cd studies we can assume that this interior Pb in highland fines samples is largely due to the radiogenic decay which occurred after the redistribution of the volatiles took place. We obtained an average age of 4.0 b.y. for the parent rocks of Apollo 16 highland regolith from our interior Pb analyses.

Cirlin, E. H.↗
NASA NTRS1984

Case study of sample spacing in planar near-field measurement of high gain antennas

Far field antenna patterns can be reconstructed from planar near field measurements acquired at a sample spacing of lambda/2 or less. For electrically large antennas, sampling at the Nyquist rate may result in errors due to system electronic drift over long acquisition times. The computer capacity may limit the largest size of the near field data set. The requirement to sample at the Nyquist rate is relaxed for high gain antennas which concentrate most of the radiated energy into a small angular region of the far field. The criteria for sample spacing at greater than lambda/e through the use of a priori information of the antenna radiation characteristics are presented. Far field patterns of a 30 GHz dual offset reflector system with a 2.7 m parabolic main reflector are computed from near field data obtained at sample spacings ranging from 0.1 lambda to 10 lambda. The effects of sampling interval and spectrum cutoff on the far field patterns are discussed.

Acosta, R. J.↗
NASA NTRS1985

Spline methods for approximating quantile functions and generating random samples

Two cubic spline formulations are presented for representing the quantile function (inverse cumulative distribution function) of a random sample of data. Both B-spline and rational spline approximations are compared with analytic representations of the quantile function. It is also shown how these representations can be used to generate random samples for use in simulation studies. Comparisons are made on samples generated from known distributions and a sample of experimental data. The spline representations are more accurate for multimodal and skewed samples and to require much less time to generate samples than the analytic representation.

Schiess, J. R.↗
NASA NTRS1987

A potpourri of regolith breccias - 'New' samples from the Apollo 14, 16, and 17 landing sites

Compositional (by INAA) and petrographic studies were performed among the smaller rocks (not analyzed previously) from the Apollo 14, 16, and 17 sites as part of a search for regolith samples exotic to the small traverse areas associated with these missions. Of the 40 samples studied, 31 were regolith breccias. Among these, three of the Apollo 14 samples proved to be compositionally unique, particularly the 14315 sample, which is radically different from all other Apollo 14 regolith materials (lower Mg and Fe, far higher Al and far lower REE abundances), and is probably exotic to the Apollo 14 traverse area. Among 10 samples from Apollo 17, all but one proved to be typical Apollo 17 regolith breccia. However, the 72504,10 sample is more than 99 percent pure pyroclastic glass, compositionally identical to the Apollo 17 orange glass obtained at a location 4 km away, attesting to the widespread distribution of orange glass deposits.

Jerde, Eric A.↗
NASA NTRS1987

Detection of signals by the digital integrate-and-dump filter with offset sampling

The Integrate and Dump Filter (IDF) is used as a matched filter for the detection of signals in additive white Gaussian noise. The performance of the digital integrate and dump filter is evaluated. The case considered is when symbol times are known and the sampling clock is free running at a constant rate, i.e., the sampling clock is not phase locked to the symbol clock. Degradations in the output signal to noise ratio of the digital implementation due to sampling rate, sampling offset, and finite bandwidth, resulting from the anti-aliasing low pass prefilter, are computed and compared with those of the analog counterpart. It is shown that the digital IDF performs within 0.6 dB of the ideal analog IDF whenever the prefilter bandwidth exceeds four times the symbol rate and when sampling is performed at the Nyquist rate. The loss can be reduced to 0.3 dB by doubling the sampling rate, where 0.2 dB loss results from finite bandwidth and 0.1 dB results from the digital IDF.

Sadr, R.↗
NASA NTRS1989

Probe Samples And Cools Hot Gas

Simple concentric-tube gas-sampling probe, developed to sample hot gas streams. Includes straight outer tube and inner tube, bent to be concentric to outer tube at one end and tangent to outer tube in sampling region at other end. Two tubes brazed together along sampling region and at end to prevent sampled gas and cooling stream from mixing. Inner tube contains sampled gas, and space outside inner tube but inside outer tube path for cooling stream.

Schultz, Donald F.↗
NASA NTRS1988

Sampling strategies on Mars: Remote and not-so-remote observations from a surface rover

The mobility and speed of a semi-autonomous Mars rover are of necessity limited by the need to think and stay out of trouble. This consideration makes it essential that the rover's travels be carefully directed to likely targets of interest for sampling and in situ study. Short range remote sensing conducted from the rover, based on existing technology, can provide significant information about the chemistry and mineralogy of surrounding rocks and soils in support of sampling efforts. These observations are of course of direct scientific importance as well. Because of the small number of samples actually to be returned to Earth, it is also important that candidate samples be analyzed aboard the rover so that diversity can be maximized. It is essential to perform certain types of analyses, such as those involving volatiles, prior to the thermal and physical shocks of the return trip to Earth. In addition, whatever measurements can be made of nonreturned samples will be important to enlarge the context of the detailed analyses to be performed later on the few returned samples. Some considerations related to these objectives are discussed.

Singer, R. B.↗
NASA NTRS1988

Mars orbital tethered sample return: The feasibility and uses of obtaining entrained particulates from the atmosphere

By employing technology developed for the Tethered Satellite Program, it appears feasible to obtain Martian dust samples from the atmosphere using an orbiting spacecraft. If collected during an annual dust storm, such a sample would contain a global selection of windborne materials. Atmospheric dust sampling is of importance to the study of Martian surface geochemistry, soil mechanics, atmospheric dynamics, and atmospheric and radiative transfer. Tethered sample return offers two key advantages over a lander sample return: relative simplicity and low spacecraft weight. In another vein, the collection of atmospheric dust by a lander sample return mission is itself of scientific merit. By employing a mast and collection plate aboard a lander mission, it is possible to obtain dust from distant locations transported as entrained material in the local aeolian environment.

Stern, S. A.↗
NASA NTRS1989

The search for and identification of amino acids, nucleobases and nucleosides in samples returned from Mars

An investigation of the returned Mars samples for biologically important organic compounds, with emphasis on amino acid, the puring and pyrimidine bases, and nucleosides is proposed. These studies would be conducted on subsurface samples obtained by drilling past the surface oxidizing layer with emphasis on samples containing the larges quantities of organic carbon as determined by the rover gas chromatographic mass spectrometer (GCMS). Extraction of these molecules from the returned samples will be performed using the hydrothermal extraction technique described by Cheng and Ponnamperuma. More rigorous extraction methods will be developed and evaluated. For analysis of the extract for free amino acids or amino acids present in a bound or peptidic form, aliquots will be analyzed by capillary GCMS both before and after hydrolysis with 6N hydrochloric acid. Establishment of the presence of amino acids would then lead to the next logical step which would be the use of chiral stationary gas chromatography phases to determine the enatiomeic composition of the amino acids present, and thus potentially establish their biotic or abiotic origin. Confirmational analyses for amino acids would include ion-exchange and reversed-phase liquid chromatographic analysis. For analyses of the returned Mars samples for nucleobases and nucleosides, affinity and reversed-phase liquid chromatography would be utilized. This technology coupled with scanning UV detection for identification, presents a powerful tool for nucleobase and nucleoside analysis. Mass spectrometric analysis of these compounds would confirm their presence in samples returned form Mars.

Gehrke, Charles W.↗
NASA NTRS1988

Mars sample return - Science

The possible scientific goals of a Mars sample return mission are reviewed, including the value of samples and the selection of sampling sites. The fundamental questions about Mars which could be studied using samples are examined, including planetary formation, differentiation, volcanism and petrogenesis, weathering, and erosion. Scenarios are presented for sample acquisition and analysis. Possible sampling methods and tools are discussed, including drilling techniques, types of rovers, and processing instruments. In addition, the possibility of aerocapture out of elliptical or circular orbit is considered.

Blanchard, Douglas P.↗
NASA NTRS1989

Mars Rover Sample Return ascent, rendezvous, and return to earth

Ascent, rendezvous and earth return are three operational mission sequences in the sample return phase of the Mars Rover Sample Return (MRSR) mission. In the conduct of the current study, several vehicles have been identified to enable the sample return phase of the mission. These elements are the Mars Ascent Vehicle (MAV), the Earth Return Vehicle (ERV), the rendezvous and docking module (RDM), and the sample return capsule (SRC). The sample return elements, when combined with other elements performing the launch and delivery functions, form the basis of the MRSR system. This paper summarizes the significant mission aspects of the sample return phase, describes the Mars ascent and earth return scenario, illustrates the conceptual designs developed for the MAV, ERV, RDM, and SRC, and discusses the results of significant trade studies conducted.

Lance, Nick↗