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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Odor test

To prevent the use of spacecraft material that would outgas objectionable or nauseating odors, an odor test was developed. This test provided a means whereby candidate spacecraft materials were subjected to a particular environment and the outgassed products were evaluated by an odor panel. This panel was comprised of individuals with acute olfactory senses. The test results of the odor panel provided design engineers with data regarding potential material-odor problems. The odor-test procedure, panel-member selection, and odor scoring methods are described and typical test results are presented.

Schluter, L. A.↗
NASA NTRS1971

Toxicology of spacecraft materials

The procedures for determining the toxicity of products outgassed from spacecraft structures are discussed. The test equipment involved in the tests and the criteria for acceptability are described. The use of animals as the final step in determining toxicity of a spacecraft environment is explained.

Harris, E. S.↗
NASA NTRS1972

Investigations of high power problems in space shuttle antenna designs

A study program is discussed which includes a survey of industry and government laboratories and was undertaken to determine the state of the art in dealing with problems of high power levels in reentry antenna design. A laboratory program to develop techniques for testing dielectric materials for effects on RF transmission is also considered, with emphasis on high power applications in space and reentry flights. The study program resulted in a set of guidelines for avoiding breakdown in antenna design. A discussion of temperature effects on dielectric breakdown is also given. From the laboratory program, a description is presented of techniques for (1) heating with a carbon arc image furnace, (2) temperature measurement (using thermocouples and an infrared pyrometer), (3) mass spectrometric monitoring of outgassing, (4) testing for RF breakdown in both heated dielectrics and the dielectric/air and dielectric/plasma interfaces. Data and observations are reported from technique development using candidate shuttle materials falling into three categories: (1) lightweight refractory foams, (2) dense RF window materials, and (3) ablative materials.

Taylor, W. C.↗
NASA NTRS1971

Multilayer high performance insulation materials

A number of tests are required to evaluate both multilayer high performance insulation samples and the materials that comprise them. Some of the techniques and tests being employed for these evaluations and some of the results obtained from thermal conductivity tests, outgassing studies, effect of pressure on layer density tests, hypervelocity impact tests, and a multilayer high performance insulation ambient storage program at the Kennedy Space Center are presented.

Stuckey, J. M.↗
NASA NTRS1972

A study of the frictional and stick-slip behavior of magnetic recording tapes

Methods were developed to determine the coefficient of friction and the extent of stick-slip of magnetic recording tapes. After a preliminary phase during which experimental procedures were established and screening of candidate tapes was carried out, the frictional and stick-slip behavior of four selected tapes, using four different kinds of magnetic heads, was studied at various temperatures, under dry and humid conditions, and in various gaseous atmospheres, such as argon, helium, nitrogen and air. The effects of tape speed and outgassing on the drag properties of the tapes were also studied. A rank was assigned to each tape and magnetic head as a result of these tests. This study helped in the selection of a magnetic tape in a flight project, and will be useful in the consideration of tapes and magnetic heads for future spacecraft applications.

Kalfayan, S. H.↗
NASA NTRS1972

Changes in some physical properties induced by vacuum heat treatment

A method is proposed for reducing or eliminating outgassing of materials by heat treating them in vacuum prior to use. This may be performed on the raw material prior to manufacturing and installation or after fabrication of parts. Processing of a fabricated part can be performed only on relatively small parts and on assemblies containing no components which are affected by the required temperatures and pressures. Processing conditions of temperature and time are dependent on the particular application and the materials involved. Silicone-coated fiber glass cloth was vacuum-heat treated for 100 hrs at 400 + or - 25 F at pressures of 0.001 torr or less. The materials were tested in terms of tensile strength and tear properties in both the smooth and several creased configurations. Data obtained on one side silicone coated fiber glass showed large reductions in these properties as a result of the vacuum-heat treatment. The problem was alleviated by coating both sides of the fiber glass.

Hultquist, A. E.↗
NASA NTRS1972

Alpha-particle spectrometer experiment

Mapping the radon emanation of the moon was studied to find potential areas of high activity by detection of radon isotopes and their daughter products. It was felt that based on observation of regions overflown by Apollo spacecraft and within the field of view of the alpha-particle spectrometer, a radon map could be constructed, identifying and locating lunar areas of outgassing. The basic theory of radon migration from natural concentrations of uranium and thorium is discussed in terms of radon decay and the production of alpha particles. The preliminary analysis of the results indicates no significant alpha emission.

Gorenstein, P.↗
NASA NTRS1972

Organic contamination analysis: High resolution mass spectrometric analysis of surface organics on selected areas of Surveyor 3

The mirror and middle shroud were extracted for organics by washing the surfaces with solvents. The techniques are discussed. Ion microprobe analyses of the primarily atomic species are presented. The sources of the organic contaminants are: (1) hydrocarbons from lubricating oils and general terrestrial contamination, (2) dioctyl phthalate, probably from polyethylene bagging material (the plasticizer), (3) carboxylic acids from decomposition of grease and general terrestrial contamination, (4) silicones from sources such as lubricating oil, (5) outgassing of electronics and plasticizer, (6) vinyl alcohol and styrene copolymer, probably from electronic insulation, and (7) nitrogenous compounds from the lunar module and possibly Surveyor 3 engine exhaust.

Simoneit, B. R.↗
NASA NTRS1972

An etiological study of phthalate self-contamination of spacecraft and contamination from their earthly environs

Phthalates are very objectionable contaminants in space experiments because of their strong absorption in the UV and IR regions of the spectrum. Thus, even minute amounts of these compounds migrating to optical equipment, in test or space flight conditions, can seriously compromise the results of experiments by altering the sensitivity of the functional equipment. Volatility data of the phthalates and other plasticizers are presented in addition to UV spectra of ultrathin films of these same types of compounds. Sources of plasticizer contamination are revealed with special recognition given to di-2-ethylhexyl phthalate (DEHP), the single most ubiquitous plasticizer in use. A surprisingly large percentage of the outgassing condensates from vacuum testing of spacecraft contain DEHP as well as other plasticizers. IR and gas chromatography/mass spectroscopy methods were used to analyze samples from spacecraft. Methods for successful reduction of plasticizers and other contaminants are mentioned.

Gross, F. C.↗
NASA NTRS1972

Experimental Investigation of the Mechanical Behavior of a Filled Elastomer at Pressures Below 10 to the -6th Power Torr

The mechanical behavior of a filled elastomer was studied with emphasis on understanding the vacuum-material interactions occurring, and to develop analytical techniques for predicting the vacuum behavior. The test results indicate that two separate mechanisms are involved in the observed property changes: the first controls the time response to applied stress; the second determines the initial internal state of the materials as the result of stresses. It is concluded that the mechanical property changes are attributable to changes in the relaxation processes occurring in the material. These changes are brought about by outgassing of water. Recommendations for future investigations are included.

Gregory, G. L.↗
NASA NTRS1972

Development and evaluation of vacuum pressure gauge components from carbon and graphite

A prototype all carbon triode ultrahigh vacuum gage was fabricated and tested. The gage exhibited a sensitivity of 3.7 per torr for nitrogen and an X-ray background approximately 0.1 as large as would be expected of a metal gage of the same design. The gage made from these materials, showed good sensitivity and durability. A practical technique was developed for bonding carbon components together without metal fasteners. The bond is made with a cross-linked phenolic resin which is converted to vitreous carbon by a careful pyrolysis procedure. The resulting bonds are strong, electrically conductive, and can withstand repeated excursions to 2500 K in vacuum. Measurements of adsorption and outgassing characteristics of four refractory carbons have confirmed that such materials are suitable for use in ultrahigh vacuum and that some are superior refractory metals in man respects.

Benson, D. K.↗
NASA NTRS1972

The effect of ambient pressure on the evaporation rate of materials

A simple expression is obtained using a diffusion model for the effect of ambient pressure on the outgassing or evaporation rate of materials. The correctness of the expression is demonstrated by comparing the estimates from this expression with actual weight loss measurements. It is shown that the rate of mass loss is governed by the ratio of mean free path to the characteristic dimension of the surface in question.

Naumann, R. J.↗
NASA NTRS1971

Mars - Has nitrogen escaped.

Discussion of the implications of low concentration of Martian nitrogen as reflected in the apparent failure of the ultraviolet spectrometers on Mariner 6 and Mariner 7 to detect molecular nitrogen. If eddy mixing is about as effective on Mars as it is on earth, then there seems to be less nitrogen present on Mars than would be expected if terrestrial-type outgassing were operating. It is shown that, in this case, a nonthermal escape mechanism involving the predissociation of exospheric nitrogen can be used to explain the low nitrogen concentration.

Brinkmann, R. T.↗
NASA NTRS1971

Organic analyses of selected areas of Surveyor III recovered on the Apollo 12 mission.

Results of organic analyses of certain parts of the Surveyor 3 television camera retrieved from the moon by the Apollo 12 astronauts. Organic contamination of the mirror surface and camera exterior (shroud) is reported and is attributed to spacecraft outgassing, Lunar Module descent engine blasting, possible Surveyor 3 engine exhaust products, and unknown sources.

Simoneit, B. R.↗
NASA NTRS1971

Xe and Kr analyses of silicate inclusions from iron meteorites.

Measurements have been conducted of the amounts and isotopic composition of Xe and Kr in silicate inclusions of several iron meteorites. It is shown that the Xe and Kr contents are comparable to chondritic values. The isotopic compositions show trapped gas of both chondritic and atmospheric composition. Large spallation effects occur in some of the meteorites; the spallation spectra in some instances differ from those reported for stone meteorites. In several meteorites, very large neutron capture effects on Br and I occur. All samples have pronounced Xe129 excesses which apparently indicate differences in the formation times from chondrites of less than about 100 million years; however, the presence of trapped Xe132 in silicates which were enclosed in molten Fe-Ni and cooled slowly proves that they were not entirely outgassed, so that some of the Xe129 excess may also be trapped.

Bogard, D. D.↗
NASA NTRS1972

The evolution of water vapor in the atmosphere of Venus.

Examination of the feasibility of loss of water vapor from the Venus atmosphere, assuming H2O as the sole initial constituent. A steady-state model is constructed, and the photochemistry establishes the distribution of important products in the upper atmosphere. Calculations of exospheric temperatures yield values as high as 100,000 K. Such large temperatures result from the large abundance of atomic hydrogen in the exosphere, and imply a dynamic outflow of all constituents from the upper region of the atmosphere. Such an outflow would cause the escape of all hydrogen and some of the oxygen resulting from dissociation of H2O. Little loss of CO2 would result, due to its low abundance in the upper region, permitting its accumulation to the present observed value. It is concluded that if Venus formed from the same mix of materials as the earth, much tectonic activity and fairly rapid outgassing must have occurred during the early phase of its history to account for the loss of water vapor.

Smith, L. L.↗
NASA NTRS1972

On the possible detection of H2 in Titan's atmosphere.

Review of the weak absorption features in Titan's spectrum detected at the wavelengths of the 3-0S(1)H2 quadrupole line and, with less certainty, the S(0) line of the same band. The probable reality of these features is discussed in terms of a statistical analysis of the photometric data, and evidence is presented that they are not scattered from Saturn by the sky or the telescope. Based on the assumption that this absorption arises from H2, implied abundances are estimated, and the implications this has for escape and outgassing rates are discussed.

Trafton, L.↗
NASA NTRS1973

Vacuum-stripped silicone binder for thermal-control paint

Silicone elastomer is placed in evacuating system, heated to 160 C and held at this temperature for 24 hours. Elastomer is then cooled to room temperature in vacuum, producing upgraded, low outgassing polymer of increased molecular weight.

Gilligan, J. E.↗