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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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Automatic star horizontal angle measuring aid for general navigational use incorporates an Apollo type sextant. The eyepiece of the sextant is replaced with two light detectors and appropriate circuitry. The device automatically determines the angle between a navigational star and a unique point on the earths horizon as seen on a spacecraft.
Infrared horizon radiance profiles for winter conditions based on Scanner project flight test
Horizon radiance profile analysis for determining atmospheric temperature
Computer program used to infer atmospheric water-vapor mixing ratio from measured horizon radiance profiles
Stratospheric and mesospheric temperature and moisture profiles determined from infrared horizon observations
Meteorological data interpolation techniques for computing horizon radiance profiles evaluated for possible error introductions
Engineering design of spacecraft earth horizon sensors
Low altitude atmospheric effects on IR beam horizon sensors in carbon dioxide band, noting corrections for spacecraft attitude measurement
Lunar postsunset horizon afterglow observed by Surveyor 7, discussing small particle diffraction on surface
Algorithm for converting polar stereographic projection to stereographic horizon projection
Clamped amplifier circuit for horizon scanner enabling amplification and accurate measurement of specified parameters
Horizon sensor design with digital sampling of spaced radiation-compensated thermopile infrared detectors
Brightness ratio near solar horizon from Ly alpha predawn and postdawn rocket observations consistent with radiation multiple scattering geocoronal model
Meteorological uses of stereographic horizon map projection, permitting placement of map center at any point on earth
The night airglow, which lies in a thin layer 70 to 100 kilometers above the earth, was studied. Although the surface brightness is low when observed through this layer from below, brightness of the airglow is augmented by a factor of approximately 35 when the airglow is viewed tangentially from the vantage point of the Gemini orbit. This augmentation phenomenon is an effective means of synoptic airglow study. The objective was to extend and refine the photographic method. The following techniques were used to achieve this goal: (1) The camera was equipped with a filter to photograph the two prominent line emissions at 5577 and 5893 A; (2) An illuminated camera sight and an aiming camera mount were used in an attempt to reduce the number of blurred photographs; (3) The number of photographs taken and the amount of the earth photographed were as large as possible; and (4) The photograph of the twilight horizon revealed a sunlit dayglow layer.
From the linear wave equation for small-amplitude sound waves in a curved space-time, there is derived a geodesiclike differential equation for sound rays to describe the motion of wave packets. These equations are applied in the generic, nonrotating, homogeneous closed-model universe (the 'mixmaster universe,' Bianchi type IX). As for light rays described by Doroshkevich and Novikov (DN), these sound rays can circumnavigate the universe near the singularity to remove particle horizons only for a small class of these models and in special directions. Although these results parallel those of DN, different Hamiltonian methods are used for treating the Einstein equations.
Each of the Surveyor 7, 6, and 5 spacecraft observed a line of light along its western lunar horizont following local sunset. This horizon-glow (HG) is sunlight, which is forward scattered by dust grains present in a tenuous cloud formed temporarily (less than 3 hrs duration) just above sharp sunlight/shadow boundaries in the terminator zone. Electrically charged grains are levitated into the cloud by intense electrostatic fields (above 500 volts per centimeter) extending across the sunlight/shadow boundaries. Detailed analysis of the HG absolute luminance, temporal decay, and morphology confirm the cloud-model. This electrostatic mechanism ejects 10 million more particles per unit time into the cloud than could micro-meteorites. Electrostatic transport is probably the dominant local transport mechanism of lunar surface fines.