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NASA NTRS1975

The Apollo 15 and 16 X-ray fluorescence experiment

An X-ray fluorescence spectrometer was flown aboard the Apollo 15 and 16 spacecrafts orbiting the moon. The X-ray instrument was used to produce a chemical map of that portion of the moon covered by the projected ground tracks and illuminated by the sun during the period of flight. The instrument includes three thin windowed proportional counters, two of which have selected X-ray filters. The field of view of the surface is determined by a collimator, while a detector on the opposite side of the spacecraft provides a continuous monitoring of the solar X-ray output. While the number of chemical elements determined was limited to Mg, Al, and Si, these proved to be very important diagnostic elements.

Adler, I.↗

NASA NTRS1976

New horizons for study of the cardiopulmonary and circulatory systems

The paper discusses the development of computer-controlled three-dimensional reconstruction techniques designed to determine the dynamic changes in the true shape and dimensions of the epi- and endocardial surfaces of the heart, along with variable time base (stop-action to real-time) displays of the transmural distribution of the coronary microcirculation and the three-dimensional anatomy of the macrovasculature in all regions of the body throughout individual cardiac and/or respiratory cycles. A technique for reconstructing a cross section of the heart from multiplanar videoroentgenograms is outlined. The capability of high spatial and high temporal resolution scanning videodensitometry makes possible measurement of the appearance, mean transit and clearance of roentgen opaque substances in three-dimensional space through the myocardium with a degree of simultaneous anatomic and temporal resolution not obtainable by current isotope techniques. The distribution of a variety of selected chemical elements or biologic materials within a body portion can also be determined.

Wood, E. H.↗

NASA NTRS1976

Mineral and nitrogen metabolic studies on Skylab flights and comparison with effects of earth long-term recumbency

A metabolic study of the effects of space flight on various chemical elements, particularly those with special relevance to the musculo-skeletal system, was carried out on the nine astronauts who participated in the three Skylab flights of 28, 59 and 84 days in 1973-1974. The study required of the cooperating crewmen constant dietary intake, continuous 24-hour urine collections and total fecal collections for 21-31 days before each flight, throughout each flight and for 17-18 days post-flight. Increases in urinary calcium and negative calcium balances during space flight were generally similar to those found in previous immobilization and bedrest studies. The persistence of these alterations in calcium metabolism throughout the flights suggested that calcium losses would continue in weightlessness for a very long time. Significant losses of nitrogen and phosphorus occurred, associated with observed reduction in muscle tissue. Both mineral and muscle losses occurred despite rigorous exercise regimens in flight. It was concluded that unless protective measures can be developed, capable musculo-skeletal function is likely to be impaired in space flights, ultimately to be conducted to Mars, of 1-1/2 to 3 years duration.

Whedon, G. D.↗

NASA NTRS1977

Differentiation of the matter of the moon

The following facts were uncovered in comparing the basaltic surface rocks of the moon with terrestrial tholeiitic basalts and ordinary chondrites: (1) there is an excess of the so-called refractory chemical elements, including the group of truly refractory elements, the rare earths, U, and Th, in comparison with their content in primitive terrestrial basalts and chondrites; (2) the so-called siderophilic elements have lower contents in the lunar surface rocks than in terrestrial rocks; (3) the low alkali content (Na, K, Rb) in lunar rocks is established; (4) there is a low content of H2O and the ordinary gases CO2, halides, etc.; (5) the low content of metals with high vapor pressure, (In, Tl, etc.) has been established. It is proposed that U and Th were carried from the internal areas to the peripheral rocks of the moon during magmatic activity, i.e., up to 3 billion years ago. This redistribution of U and Th lead to their concentration in surface layers of the moon, and the heat which they generated was lost into surrounding space. The conclusion is then reached that in order to understand processes on the moon, the chondritic model cannot be used.

Vinogradov, A. P.↗

NASA NTRS1977

Wear studies on aircraft brake materials

An investigation of both worn surfaces of friction pads and steel rotors which are being applied in current aircraft brakes has been carried out by employing an X-ray diffraction technique. It consists of the analysis of chemical element distribution in the surface layers. The wear particles were also examined by using the scanning electron microscope. The initiation and growth of surface cracks and the oxidation were emphasized in this investigation. A wear model was proposed for the current aircraft brake materials. Essentially this model proposed that cracks are formed in the surface layer of the brake material due to the normal and frictional stresses. It is primarily surface temperature dependent.

Ho, T. L.↗

NASA NTRS1978

Extraterrestrial materials processing and construction

Applications of available terrestrial skills to the gathering of lunar materials and the processing of raw lunar materials into industrial feed stock were investigated. The literature on lunar soils and rocks was reviewed and the chemical processes by which major oxides and chemical elements can be extracted were identified. The gathering of lunar soil by means of excavation equipment was studied in terms of terrestrial experience with strip mining operations on earth. The application of electrostatic benefication techniques was examined for use on the moon to minimize the quantity of materials requiring surface transport and to optimize the stream of raw materials to be transported off the moon for subsequent industrial use.

Criswell, D. R.↗

NASA NTRS1979

Lunar building materials: Some considerations on the use of inorganic polymers

The use of inorganic polymer systems synthesized from the available lunar chemical elements, viz., silicon, aluminum, and oxygen to make adhesives, binders, and sealants needed in the fabrication of lunar building materials and the assembly of structures is considered. Inorganic polymer systems, their background, status, and shortcomings, and the use of network polymers as a possible approach to synthesis are examined as well as glassy metals for unusual structural strength, and the use of cold-mold materials as well as foam-sintered lunar silicates for lightweight shielding and structural building materials.

Lee, S. M.↗

NASA NTRS1978

Glasses in the Luna 24 core and petrogenesis of ferrobasalts

Modal abundance and major- and minor-element chemical analysis of homogeneous, non-agglutinitic mare and non-mare glasses from the Luna 24 drill core show that most glasses can be related to known rock types. Mare glasses include: brown glass identical in composition to the fine-grained low-Mg VLT basalt; green glass which might be related to a coarser-grained ferrogabbro; a high-K green glass; and a high-Ti orange glass. Highland glass compositions include Highland basalt, gabbroic anorthosite, and pure anorthosite (i.e. plagioclase); minor Fra Mauro-type glass may also be present. It is apparent that fractional crystallization of some primitive basaltic magma occurred at Mare Crisium producing a chemically evolved ferrobasalt and related glasses. An early, high-Mg basin fill, as represented by the olivine vitrophyres, may be the parent magma. Subsequent near-surface fractionation produced a multiply-saturated liquid that finally erupted as the ferrobasalt flows sampled by Luna 24.

Norman, M.↗

NASA NTRS1978

The case for at least three mare basalt magmas at the Luna 24 landing site

Petrographic and electron microprobe studies have been carried out for 1230 particles from the Luna 24 drill core. At least three mare basalts were distinguished on the basis of major and minor element chemical compositions of pyroxenes. Mg-rich monomineralic particles of olivine and pyroxene defined one major type. The other two magmas were identified by the Ti/(Ti + Cr) ratio at constant Fe/(Fe + Mg) ratio in pyroxenes derived from polymineralic igneous lithic fragments. Whole rock chemical analyses for V and Cr also provided evidence for these distinct magmas.

Nielsen, R. L.↗

NASA NTRS1978

Ar-39-Ar-40 and petrologic study of Luna 24 samples 24077,13 and 24077,63

The ferrogabbro 24077,13, with pyroxene and plagioclase major and minor element chemical ranges comparable to the dominant ferrogabbro component in the Luna 24 core, has a Ar-39-Ar-40 temperature release age of 3.33 plus or minus 0.21 billion years. The metaferrobasalt 24077,63 is very fine-grained with a texture and mineralogy consistent with contact metamorphism between superimposed basalt flows or within a single flow. The Ar-39-Ar-40 plateau age of 24077,63 is 3.26 plus or minus 0.4 billion years. The basalt flows in Mare Crisium are about the same age as those of Mare Imbrium and younger than those of Mare Tranquillitatis and Mare Serenitatis.

Schaeffer, O. A.↗

NASA NTRS1979

Chemical processes involved in the initiation of hot corrosion of B-1900 and NASA-TRW VIA

Sodium sulfate induced hot corrosion of B-1900 and NASA-TRW VIA at 900 C was studied with special emphasis on the chemical reactions occurring during and immediately after the induction period. Thermogravimetric tests were run for set periods of time after which the samples were washed with water and water soluable metal salts and/or residual sulfates were analyzed chemically. Element distributions within the oxide layer were obtained from electron microprobe X-ray micrographs. A third set of samples were subjected to surface analysis by X-ray photoelectron spectroscopy. Evolution of SO2 was monitored throughout many of the hot corrosion tests. Results are interpreted in terms of acid-base fluxing mechanisms.

Fryburg, G. C.↗

NASA NTRS1980

Float zone experiments

The objectives of this work are: to determine if surface tension-driven convection in float zone experiments may be controlled by means of surface films; and if convection can be controlled, determine whether homogeneous solute distributions will be achieved in float zone solidification and whether accurate measurements of liquid diffusion coefficients may be obtained from float zone solidification experiments. Sn was chosen as a model material because it is a group IV element, chemically similar to Si and Ge and its low melting point and low vapor pressure allow Auger spectroscopy to be employed with liquid samples.

Verhoeven, J.↗

NASA NTRS1981

Planetary phase equilibria - Application to formation of earth, Venus and Mercury

Calculations of phase equilibria in a solar mixture with variable hydrogen abundance show that the major element chemical composition of the earth and Venus can be simply explained by their formation in equilibrium at 800 and 1000 K, respectively, at a pressure of 0.001 atm, provided that there is an iron loss from the region of proto-Venus relative to the solar nebula. The calculated mineralogical chemical compositions of the two planets are in excellent agreement with the available chemical and physical data. Phase equilibrium calculations at 1500 K and 0.001 atm show that nearly 96% of the silicates and 81% of metal must have been lost from the region of proto-Mercury.

Saxena, S. K.↗

NASA NTRS1982

Long-term thermal degradation and alloying constituent effects on five boron/aluminum composites

Thermal exposure effects on the properties of five boron/aluminum composite systems were experimentally investigated. The composite systems were 49 volume percent boron fibers (203 micron diameter) in aluminum-alloy matrices 1100 Al, 2024 Al, 3003 Al, 5052 Al, and 6061 Al. Specimens were thermally exposed up to 10,000 hours at 500 K and 590 K, up to 500 hours at 730 K, and up to 10,000 hours at 500 K and 590 K, up to 500 hours at 730 K, and up to 2000 thermal cycles between 200 K and 590 K. Composite longitudinal and transverse tensile strengths, longitudinal compression strength, and in-plane shear strength were determined. None of the systems was severely degraded by exposure at 590 K. The best performing system was B-2024 Al. Effects of matrix alloys on degradation mechanisms were experimentally investigated. Composite specimens and individual fibers were metallurgically analyzed with a scanning electron microscope and an electron microprobe to determine failure characteristics, chemical element distribution, and reaction layer morphology. Alloying constituents were found to be affect the composite degradation mechanisms as follows: alloys containing iron, but without manganese as a stabilizer, caused increased low-temperature degradation; alloys containing magnesium, iron, or manganese caused increased degradation; and alloys containing copper caused increased fiber strength.

Olsen, G. C.↗

NASA NTRS1982

VLA observations of Saturn at 1.3, 2, and 6 cm

Radio maps with a resolution of 1.5 arcsec were made of Saturn at 1.3, 2, and 6 cm. The inclination of the ring plane was -5.4 deg. A fraction of 0.49 + or - 0.08 of Saturn's emitted light is transmitted through the rings at 2 and 6 cm. This value converts to an effective head-on or normal optical depth of 0.07 + or - 0.02. The transparency at this small inclination angle must be provided entirely by the regions of very low optical depth, e.g., the Cassini and Encke's Divisions, and to achieve the desired number this requires either a relatively large fraction of gaps or a strong forward scattering by the ring particles. The planetary disk appears to be much less limb darkened in the N-S than the E-W direction, while cuts across the planet, averaged over all directions, agree with the theoretical limb-darkening curves for a planet with a uniform atmosphere and solar abundances for all chemical elements.

De Pater, I.↗

NASA NTRS1982

Chemistry of cometary meteoroids from video-tape records of meteor spectra

The chemistry of the cometary meteoroids was studied by closed circuit television observing systems. Vidicon cameras produce basic data on standard video tape and enable the recording of the spectra of faint shower meteors, consequently the chemical study is extended to smaller particles and we have a larger data bank than is available from the more conventional method of recording meteor spectra by photography. The two main problems in using video tape meteor spectrum records are: (1) the video tape recording has a much lower resolution than the photographic technique; (2) video tape is relatively new type of data storage in astronomy and the methods of quantitative photometry have not yet been fully developed in the various fields where video tape is used. The use of the most detailed photographic meteor spectra to calibrate the video tape records and to make positive identification of the more prominent chemical elements appearing in the spectra may solve the low resolution problem. Progress in the development of standard photometric techniques for the analysis of video tape records of meteor spectra is reported.

Millman, P. M.↗

NASA NTRS1984

Relic interstellar grains in Murchison meteorite

It is shown that, in the Murchison meteorite, the D/H ratios of hydrogen are unusually high in several separates and in one case up to 30 times the cosmic value of 2 x 10 to the -5th. Many phases show high C-13/C-12 ratios, up to 2.5 times the terrestrial value of 0.011. These C-13-rich and D-rich components of the two chemical elements are not correlated. They are heterogeneously distributed, suggesting that different components in the meteorite originated from different astrophysical sites and at different times. The D-rich hydrogen in the meteorite is probably due to molecules formed by ion-molecule reactions in interstellar clouds while the tiny amount of C-13-rich carbon is probably due to nucleosynthesis in red giant stars as suggested by Swart et al. (1983). Both of these heavy-isotope enriched components survived homogenization in the accumulation and subsequent history of the meteorites.

Yang, J.↗

NASA NTRS1986

In situ gas and ion measurements at comet Halley

The Giotto space probe's neutral mass spectrometer experiment has determined the abundances and the chemical, elemental and isotopic compositions of gases and low energy ions in the coma of comet Halley. Preliminary results show water predominating, at about 80 percent by volume, with a density of 4.7 x 10 to the 7th molecules/cu cm at 1000 km and a photodestruction scale length of 39,000 km. Limits on the abundances of CO2, NH3 and CH4 relative to H2O are also obtained. An ion temperature change observation indicates a contact surface location at 47,000 + or - 200 km.

Krankowsky, D.↗