Mechanical component screening for scanner

The critical mechanical components of the scan mirror mechanism are described and their evaluation and screening procedures are discussed. A bumper/damper unit is used in the design to reverse motion of the mirror and effect scan and retrace cycles. A wear evaluation was conducted on the bumper impact surfaces that established nylon 6-10 as an acceptable material. The elastomeric dampers were subjected to thermal vacuum tests for condensables and outgassing as well as parametric life tests. The flexure pivots that support the mirror were tested to establish a curve of stress plotted as a function of cycles to failure for rotational operation. The pivots met the life requirement of 150,000,000 cycles at a + or - 2.9 deg amplitude during fatigue testing. Screening procedures were established for dampers and flexure pivots to obtain flight quality components

The Mountain Pass Rare-Earth Deposits

Rare-earth minerals were discovered near Mountain Pass in northeastern San Bernardino County, Calif., in April 1949, and in the following year the Sulphide Queen carbonate body was found. This body is the world's greatest known concentration of rare-earth metals with a tonnage larger than the total of all rare earths used in the world prior to 1950. The rare earths in the Mountain Pass district are chiefly cerium, lanthanum, and neodymium. These elements occur principally in bastnaesite, a rare-earth fluocarbonate, heretofore reported from only about 10 localities in the world. The bastnaesite was discovered in samples from Mountain Pass obtained by H. E. Woodward and Clarence Watkins of Goodsprings, Nev., and its identity was established in laboratory studies by E . T. Schenk of the U. S. Bureau of Mines and D. F. Hewett of the U. S. Geological Survey. Subsequent prospecting by individuals and geologic investigations by the U. S. Geological Survey resulted in the discovery of bastnaesite in the Sulphide Queen carbonate body and numerous other deposits in a belt 6 miles long. Investigations by the U. S. Geological Survey since 1949 (Olson et al., in preparation) include detailed mapping of the site of the initial discovery-the Birthday claims-by L. C. Pray and W. N. Sharp; geologic mapping of the district by J. C. Olson; detailed mapping of the Sulphide Queen carbonate body and several smaller deposits by D. R. Shawe and W. N. Sharp; and laboratory mineralogic investigations by H. W. Jaffe

Emissivity coatings for low-temperature space radiators Quarterly progress report no. 1, 1 Jul. - 30 Sep. 1965

Emissivity coatings for low temperature spacecraft radiator

Jamming in Granular Polymers

We examine the jamming transition in a two-dimensional granular polymer system using compressional simulations. The jamming density \phi_c decreases with increasing length of the granular chain due to the formation of loop structures, in excellent agreement with recent experiments. The jamming density can be further reduced in mixtures of granular chains and granular rings, also as observed in experiment. We show that the nature of the jamming in granular polymer systems has pronounced differences from the jamming behavior observed for polydisperse two-dimensional disk systems at Point J. This result provides further evidence that there is more than one type of jamming transition.Comment: 5 pages, 7 postscript figures, version to appear in PR

CELSS Transportation Analysis

Regenerative life support systems based on the use of biological material was considered for inclusion in manned spacecraft. Biological life support systems are developed in the controlled ecological life support system (CELSS) program. Because of the progress achieved in the CELSS program, it is determined which space missions may profit from use of the developing technology. Potential transportation cost savings by using CELSS technology for selected future manned space missions was evaluated. Six representative missions were selected which ranged from a low Earth orbit mission to those associated with asteroids and a Mars sortie. The crew sizes considered varied from four persons to five thousand. Other study parameters included mission duration and life support closure percentages, with the latter ranging from complete resupply of consumable life support materials to 97% closure of the life support system. The analytical study approach and the missions and systems considered, together with the benefits derived from CELSS when applicable are described

Plasma Sterilization Technology for Spacecraft Applications

The application of plasma gas technology to sterilization and decontamination of spacecraft components is considered. Areas investigated include: effective sterilizing ranges of four separate gases; lethal constituents of a plasma environment; effectiveness of plasma against a diverse group of microorganisms; penetrating efficiency of plasmas for sterilization; and compatibility of spacecraft materials with plasma environments. Results demonstrated that plasma gas, specifically helium plasma, is a highly effective sterilant and is compatible with spacecraft materials

Leading-edge slat optimization for maximum airfoil lift

A numerical procedure for determining the position (horizontal location, vertical location, and deflection) of a leading edge slat that maximizes the lift of multielement airfoils is presented. The structure of the flow field is calculated by iteratively coupling potential flow and boundary layer analysis. This aerodynamic calculation is combined with a constrained function minimization analysis to determine the position of a leading edge slat so that the suction peak on the nose of the main airfoil is minized. The slat position is constrained by the numerical procedure to ensure an attached boundary layer on the upper surface of the slat and to ensure negligible interaction between the slat wake and the boundary layer on the upper surface of the main airfoil. The highest angle attack at which this optimized slat position can maintain attached flow on the main airfoil defines the optimum slat position for maximum lift. The design method is demonstrated for an airfoil equipped with a leading-edge slat and a trailing edge, single-slotted flap. The theoretical results are compared with experimental data, obtained in the Ames 40 by 80 Foot Wind Tunnel, to verify experimentally the predicted slat position for maximum lift. The experimentally optimized slat position is in good agreement with the theoretical prediction, indicating that the theoretical procedure is a feasible design method

Packing Fractions and Maximum Angles of Stability of Granular Materials

In two-dimensional rotating drum experiments, we find two separate influences of the packing fraction of a granular heap on its stability. For a fixed grain shape, the stability increases with packing fraction. However, in determining the relative stability of different grain shapes, those with the lowest average packing fractions tend to form the most stable heaps. We also show that only the configuration close to the surface of the pile figures prominently.Comment: 4 pages, 4 figure