Estimation of Unmodeled Forces on a Lunar Satellite
TEXAS UNIV AT AUSTIN DEPT OF AEROSPACE ENGINEERING AND ENGINEERING MECHANICS
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In previous investigations, a sequential estimation procedure for estimating the state of a lunar orbiting space vehicle acted upon by unmodeled terms in the lunar potential and unmodeled mechanical forces such as those due to venting has been developed. The unmodeled accelerations are approximated by a first-order Gauss-Markov process. The estimation algorithm gives an estimate of the position and velocity of the space vehicle as well as the components of the unmodeled acceleration at each observation epoch. The results obtained by processing real-time tracking data from the Apollo 10, 11, and 15 missions have indicated that the algorithm provides more precise estimates of the vehicle state than conventional orbit determination procedures and, hence, provides accurate input for navigation or guidance purposes. The question of the usefulness of the unmodeled accelerations for scientific experiments has not been established.
- Spacecraft Trajectories and Reentry