Accession Number : AD0663710

Title :   OPTIMUM THREE-DIMENSIONAL DEORBIT FOR SPECIFIC REENTRY ANGLE FROM CIRCULAR ORBITS,

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF EL SEGUNDO TECHNICAL OPERATIONS

Personal Author(s) : Chu,S. T.

Report Date : OCT 1967

Pagination or Media Count : 53

Abstract : The minimum impulsive velocity requirements for three-dimensional deorbits from circular orbits to achieve any specified reentry angle are analyzed. The investigation treats two cases: the first case determines the optimum impulsive velocity for a given reentry angle and a given heading angle change; the second treats the problem of a given reentry angle and a given earth central cross-range angle. Comparisons are made between a solution based on superposition and the analytical optimum solution developed for the case of constant heading change. The method of superposition treats separately the velocity required for in-plane deorbit and the velocity required for heading change. The results are summed algebraically or vectorially to give the combined velocity requirement. It is shown that large savings may be realized by combining the deorbit impulse and the impulse necessary to change the heading angle. Moreover, the three-dimensional optimum solution may be approximated very closely by superposition provided that the corresponding two-dimensional optimum solution is used and that it is summed vectorially with correct angular relation to the out-of-plane velocity component. Finally, the parametric results of the optimum solutions for deorbit from altitudes of 75, 100, 200, and 300 n mi and reentry angles between -1 and -25 deg are presented.

Descriptors :   (*REENTRY VEHICLES, *DESCENT TRAJECTORIES), (*ATMOSPHERE ENTRY, OPTIMIZATION), FLIGHT PATHS, LOW ORBIT TRAJECTORIES, CIRCULAR ORBITS, INCLINED ORBIT TRAJECTORIES, MANEUVERABILITY, MATHEMATICAL ANALYSIS, MISSION PROFILES, THEORY

Subject Categories : Unmanned Spacecraft
      Spacecraft Trajectories and Reentry

Distribution Statement : APPROVED FOR PUBLIC RELEASE