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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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Observation of an apparent posteclipse brightening of the Galilean satellite Io from two different observatories on June 25, 1971, employing the technique of area scanning in the ultraviolet. An apparent brightening was observed which amounted to about 0.2 mag at 3500 A and 0.15 mag at 4000 A. It is suggested that the brightening was a transient partial covering of high-albedo material where the contrast is by far greatest in the ultraviolet.
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A highly accurate reflection model has been developed which emphasizes efficiency of computer calculation. It is assumed that the heating of the irradiated star must depend upon the following properties of the irradiating star: (1) effective temperature; (2) apparent area as seen from a point on the surface of the irradiated star; (3) limb darkening; and (4) zenith distance of the apparent centre as seen from a point on the surface of the irradiated star. The algorithm eliminates the need to integrate over the irradiating star while providing a highly accurate representation of the integrated bolometric flux, even for gravitationally distorted stars.
This paper describes an analytic solution for the solar electric low thrust orbit raising problem derived by application of the two-variable asymptotic expansion method. Included in the formulation are the effects of (1) high initial eccentricity, (2) large change of inclination, (3) variable mass, and (4) earth shadow penalty including the rotation of the shadow axis relative to the osculating orbit. An advantage of this mathematical strategy is that the effects of various steering policies can be evaluated readily from a physical point of view.
The probable chemistry of the Saturn rings is reviewed. Reflectance spectra for H20 and NH3 frosts and Saturn's rings are compared, along with temperature dependence of 1.6 microns water frost feature. The reflection spectra of Galilean satellite J2 and water frost are also reviewed.
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Results of three-color photoelectric observations of CW Eridani are presented which were made with a 30-inch telescope over the three-year period from 1970 to 1973. The times of minima are computed, solutions of the light curves are obtained, and theoretical light curves are computed from the solutions. The period is determined to be 2.72837 days, and the orbital and photoelectric elements are derived from solutions based on the idealized Russell model.