Michael E. Ash

The Case for the Radar Radius of Venus

The Venus radius of 6085 � 10 kilometers, deduced from combining observations made with the Venera 4 and Mariner V space probes is incompatible with the value of 6050 � kilometers determined from Earth-based radar mesurements.

Radar observations of Icarus

Abstract The minor planet Icarus was observed with the 3.8-cm Haystack radar from 12 to 15 June 1968. Weak but significant echoes were detected indicating a radar cross section of about 0.1 km2, a radius of about 1 km, and an effective reflectivity of about 0.05. These results have an uncertainty of about a factor of 2.

Doubly averaged effect of the Moon and Sun on a high altitude Earth satellite orbit

Infinite series expansions are obtained for the doubly averaged effects of the Moon and Sun on a high altitude Earth satellite, and the results used to interpret numerically integrated examples. New in this paper are: (1) both sublunar and translunar satellites are considered; (2) analytic expansions include all powers in the satellite and perturbing body semi-major axes; (3) the fact that retrograde orbits have more benign eccentricity behavior than direct orbits should be exploited for high altitude satellite systems; and (4) near circular orbits can be maintained with small expenditures of fuel in the face of an exponential driving force one forIa<I<Ib, whereIb=180°−Ia andIa is somewhat less than 39.2° for sublunar orbits and somewhat greater than 39.2° for translunar orbits.