Orbital maintenance of endoatmospheric low earth-orbiting satellites

Abstract

The optimization of spacecraft trajectories in vacuum has received extensive consideration since the inception of space flight, yet the effects of atmosphere have been largely neglected. The advent of low Earth-orbiting, large satellites and platforms necessitates that atmosphere be included in the optimization process. A practical means of studying this topic is as a problem in minimum-fuel orbital maintenance is optimized through periodic thrusting as opposed to forcing Keplarian motion by nullifying the effects of drag with thrust. Further, this must be optimized by primary vectoring. This thesis examined the efficiency of a simple method of orbital maintenance using fixed-angle transverse thrusting. Results show that for the purpose of fuel-minimization, the width of the radial band in which the satellite is to be maintained, is dependent upon thruster size. in nearly all cases, a thrust-angle of 70 degrees maximized the fuel saved. This thesis shows that fixed-angle transverse thrusting does not improve on forced Keplarian motion and hence thrust vectoring must be optimized.