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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1969

Lunar Surface Material - Spacecraft Measurements of Density and Strength

The relation of the density of the lunar surface layer to depth is probably best determined from spacecraft measurements of the bearing capacity as a function of depth. A comparison of these values with laboratory measurements of the bearing capacity of low-cohesion particulate materials as a function of the percentage of solid indicates that the bulk density at the lunar surface is about 1.1 grams per cubic centimeter and that it increases nearly linearly to about 1.6 grams per cubic centimeter at a depth of 5 centimeters.

Jaffe, L. D.↗
NASA NTRS1969

Lunar soil coefficient of friction determined from Surveyor data and laboratory tests

A series of laboratory tests on simulated soils was conducted to evaluate some of these physical properties. Using soils similar to lunar soil composition, particle size distribution, and cohesion as determined from the Surveyor mission, the coefficient of friction and bulk density were evaluated by reproducing soils with the same force vs penetration characteristics as demonstrated at the Surveyor landing sites. The determination of soil coefficient of friction is presented in this paper; the soil density is treated separately in the previous paper’ of this report.

Choate, R.↗
NASA NTRS1970

Apollo 11 soil mechanics investigation

Apollo 11 lunar rock and soil mechanical behavior and physical characteristics, discussing color, specific gravity, density, shapes and adhesive and cohesive properties

Costes, N. C.↗
NASA NTRS1971

Improved reflective coating for integrating spheres

Inorganic salts or oxide material is transparent in single-crystal form, has high refractive index, smooth cleavage, and chemical stability, is stable to radiations of interest, partially soluble and easily dispersed in liquid for spraying, and readily dried /cured/ with reasonable cohesion and adhesion, and has good mechanical stability.

Stuart, J. W.↗
NASA NTRS1971

Lunar Surface Closeup Stereoscopic Photography on the Ocean of Storms (Apollo 12 Landing Site)

To obtain information about in-place lunar rocks and soil, a closeup stereoscopic camera capable of photographing small scale surface features was used at the Apollo 12 landing site on the Ocean of Storms. Fifteen stereoscopic photograph pairs were obtained. The stereoscopic pairs were of excellent quality and showed the in-place lunar material in detail. The photographs were analyzed and the results compared with the results of the Apollo 12 core sample analysis and other investigations. Significant information about the physical composition and genesis of the lunar soil at the Apollo 12 landing site was obtained. The cohesive soil on the Ocean of Storms probably results from repetitive bombardment of basalt flows by meteorites over long periods of time.

Heiken, G.↗
NASA NTRS1972

Metallic transfer between metals in sliding contact examined by auger emission spectroscopy

Metallic transfer between polycrystalline metals in sliding contact was examined. Hemispherical riders of iron, nickel, and cobalt were slid on tungsten, tantalum, niobium, and molybdenum disks in ultrahigh vacuum. Auger emission spectroscopy was used to monitor the elemental composition of the disk surfaces. Iron, nickel, and cobalt transferred to tungsten, whereas only cobalt transferred to tantalum, niobium, and molybdenum. The results of this investigation are discussed in terms of the cohesive energy and strain hardening characteristics of the specimen materials.

Pepper, S. V.↗
NASA NTRS1972

Liquid-phase mixing of bipropellant doublets

Experimental results of unlike doublet mixing are correlated with an analytically derived equation predicting fluid cavitation. The correlation relates the minimum orifice pressure drop required to initiate cavitation, with the system back pressure, cold flow simulant vapor pressure, and the orifice flow discharge and contraction coefficients. Stream flow instabilities are also visually correlated with the onset of cavitation and orifice discharge coefficient measurements. The influence of cavitation on the characteristic phenomenon of hydraulic flip is observed for both circular and noncircular shaped orifices. For certain intermediate orifice lengths, some noncircular shapes are shown to produce more fully developed flows (shorter recovery lengths) and therefore a more cohesive jet, which in turn yields slightly higher cold flow mixing uniformities than circular shaped orifices of equal absolute length. The particular noncircular shaped elements evaluated are shown to be more sensitive to liquid stream misimpingement than the corresponding circular orifices.

Hoehn, F. W.↗
NASA NTRS1972

Sputtering: A vacuum deposition method for coating material

The sputtering process is described in terms of its features: versatility, momentum transfer, configuration of target, precise controls and the relatively slow deposition rate. Sputtered films are evaluated in terms of adherence, coherence, and internal stresses. The strong adherence is attributed to the high kinetic energies of the sputtered material, sputter etched (cleaned) surface, and the submicroscopic particle size. An illustration is a sputtered solid film lubricant such as MoS2. Friction tests were conducted on a thin, 2000 A deg thick MoS2 film. These films are very dense and without observable pinholes, and the particle to particle cohesion is strong. Tolerances (film thickness) can be controlled to a millionth of a centimeter. Very adherent films of sputtered Teflon can be deposited in a single operation on any type of material (metal, glass, paper) and on any geometrical configuration with a dense adherent film.

Spalvins, T.↗
NASA NTRS1972

Five year magnetic tape for unattended satellite tape recorders

The development and fabrication of a quantity of long life magnetic tape with properties selected specifically for unattended operation in spacecraft tape recorders was studied. A detailed analytical consideration of various binder systems was undertaken. This included the chemical aspects of the binders, cohesion and adhesion effects, stability and the mechanical and physical properties. The ability to form free films of these polymers and their combination with various oxide loadings and other additives allowed a rapid selection of four polymer candidates for a five year magnetic tape. Samples were evaluated under actual running conditions which included physical, magnetic, and extensive life testing. These sample tapes withstood 50,000 bidirectional tape passes under fairly harsh operating conditions.

Benn, G. S. L.↗
NASA NTRS1972

Cracking of the lunar soil

Rather than a pattern of cracks in an apparently flat surface, the Apollo 12 photographs suggest an irregular surface that consists of clods or fragments. The impression of flat tiles and crusting, obtained by monoscopic viewing, is an illusion. Instead, the lunar soil deforms and cracks in the same manner as homogeneous isotropic terrestrial soils of moderate bulk density, having a small amount of cohesion.

Jaffe, L. D.↗
NASA NTRS1971

Performance of Boeing LRV wheels in a lunar soil simulant. Report 1: Effect of wheel design and soil

Six versions of the wire mesh wheel were laboratory tested in a lunar soil simulant, consisting of a crushed basalt with a grainsize distribution similar to that of samples collected during Apollo 11 and 12 flights, to determine their relative performance. The consistency of the soil was varied to cover a range of cohesive and frictional properties to simulate soil conditions assumed to exist on the moon. Programmed-slip and constant-slip tests conducted with the single wheel dynamometer system showed that the performance of the wheel covered with a metal chevron tread over 50 percent of its contact surface was slightly superior to that of other tread designs.

Green, A. J.↗
NASA NTRS1971

Lubrication with sputtered MoS2 films.

Sputtered MoS2 films (2000-6500 A) were deposited on highly polished metal surfaces. These films have a low coefficient of friction (0.03-0.04) at speeds of 40-80 rpm and loads of 250-1000 grams. At loads of 250 grams the wear lives are over 0.5 million cycles, but at 1000 gram loads, it decreases to 38,000 cycles. Friction experiments and tensile tests have indicated that sputtered films have a strong adherence to metal surfaces. Electron transmission, diffraction and scanning electron microscopy show that these films have an extremely small particle size, less than 30 A in diameter, and are very dense and free from observable pinholes. The high kinetic energy of these sputtered species, the submicroscopic particle size and the sputter-etched substrate surface is responsible for strong adhesion and cohesion of the sputtered film.

Spalvins, T.↗
NASA NTRS1971

Cracking of lunar mare soil.

Demonstration that lunar soil deforms and cracks in the same manner as homogeneous isotropic terrestrial soil s of moderate bulk density with a small amount of cohesion. This conclusion is made from an analysis of Surveyor 3 TV pictures and of Apollo 11 closeup picture of lunar surface disturbances by bearing tests and instrument pressure.

Jaffe, L. D.↗
NASA NTRS1972

Manufacturing in space.

Space, in contrast to earth, offers total gravity control and unequaled vacuum, temperature, pressure, and radiation characteristics. In zero-g molecular forces such as cohesion and adhesion become controlling factors even in the largest bulk processes. The absence of relative mass accelerations eliminates the need for support of solid matter. Stability in liquid-solid, liquid-liquid, or liquid-gas mixtures, and the absence of thermal convection is obtained because there is no relative motion in fluids due to differences in density. Applications of these characteristics include liquid-matrix preparation of composites, fine-grain castings, supersaturated alloys, combinations which exhibit liquid-phase immiscibility, the containerless free suspension of materials, surface-tension casting, surface-tension drawing, adhesion casting, and controlled density casting.

Wuenscher, H. F.↗