184,587 research outputs found
Development of an Orbital Receiver for Low-Frequency Radio Energy from the Planet Jupiter Final Report
Development of radio receiver for Pioneer F/G Asteroid-Jupiter spacecraf
Low cost uniform heat source
Electrically powered heat source was developed for ground simulation of isotope heat-source assembly in Brayton power system. Heat source, which operates on ordinary 110 vac power, consists of tungsten filament heating element wound onto a spirally grooved boron nitride core and inserted in a hollowed-out graphite hexahedron
No evidence of dark matter in the solar neighborhood
We measured the surface mass density of the Galactic disk at the solar
position, up to 4 kpc from the plane,by means of the kinematics of ~400 thick
disk stars. The results match the expectations for the visible mass only, and
no dark matter is detected in the volume under analysis. The current models of
dark matter halo are excluded with a significance higher than 5sigma, unless a
highly prolate halo is assumed, very atypical in cold dark matter simulations.
The resulting lack of dark matter at the solar position challenges the current
models.Comment: Proceeding of the first binational Sochias-AAA meeting, held in San
Juan, Argentin
Thermal insulation protection means
A system for providing thermal insulation for portions of a spacecraft which do not exceed 900 F during ascent or reentry relative to the earth's atmosphere is described. The thermal insulation is formed of relatively large flexible sheets of needled Nomex felt having a flexible waterproof coating. The thickness of the felt is sized to protect against projected temperatures and is attached to the structure by a resin adhesive. Vent holes in the sheets allow ventilation while maintaining waterproofing. The system is heat treated to provide thermal stability
Analysis of aerothermal loads on spherical dome protuberances
Hypersonic flow over spherical dome protuberances was investigated to determine increased pressure and heating loads to the surface. The configuration was mathematically modeled in a time-dependent three-dimensional analysis of the conservation of mass, momentum (Navier-Stokes), and energy equations. A boundary mapping technique was used to obtain a rectangular parallelepiped computational domain, a MacCormack explicit time-split predictor-corrector finite difference algorithm was used to obtain solutions. Results show local pressures and heating rates for domes one-half, one, and two boundary layer thicknesses high were increased by factors on the order of 1.4, 2, and 6, respectively. Flow over the lower dome was everywhere attached while flow over the intermediate dome had small windward and leeside separations. The higher dome had an unsteady windward separation region and a large leeside separation region. Trailing vortices form on all domes with intensity increasing with dome height. Discussion of applying the results to a thermally bowed thermal protection system are presented
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