Accession Number : AD0690463

Title :   THE CAPTURE AND STABILITY OF A GRAVITY-GRADIENT SATELLITE IN AN ECCENTRIC ORBIT.

Descriptive Note : Technical memo.,

Corporate Author : JOHNS HOPKINS UNIV SILVER SPRING MD APPLIED PHYSICS LAB

Personal Author(s) : Anand,D. K. ; Whisnant,J. M. ; Sturmanis,M.

Report Date : AUG 1968

Pagination or Media Count : 37

Abstract : This paper reports on the investigation of the capture and gravity-gradient stabilization of a satellite in an orbit with an eccentricity of 0.2. The satellite is called LIDOS, and its mission is to obtain geodetic information. The orbit eccentricity gives rise principally to pitch librations. The amplitude of these librations is about 0.26 radian, which represents the minimum solution to the equation of planar librations. For an optimum selection of mass distribution and adverse orbital conditions, all the perturbations combine to cause peak roll amplitudes of 0.27 radian and close to two revolutions in yaw per orbit, in addition to the above mentioned pitch librations. Owing to the large eccentricity, the region of stability, and consequently capture, is small. Furthermore, the obtaining of 1 revolution per orbit by conventional methods of inertia changes does not insure successful gravity-gradient stabilization. Therefore, an electromagnet is employed to maneuver the satellite into the stable region before capture. This is shown by phase plane representation. (Author)

Descriptors :   (*SCIENTIFIC SATELLITES, *ATTITUDE CONTROL SYSTEMS), SATELLITE ATTITUDE, STABILIZATION SYSTEMS, GRAVITY, ELLIPTICAL ORBIT TRAJECTORIES, DAMPING, HYSTERESIS, STABILITY

Subject Categories : Unmanned Spacecraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE