|
Organizers |
Optimizing the Earth to Mars Trajectory
by
Bill Clark
University of Texas at Austin
The Earth-to-Mars flight path is set up in a computer simulation with the planets in two body motion and the spacecraft (s/c) in motion about a central body, perturbed by the other two. The trajectory is continuously integrated, accurate to 14 significant digits throughout. The simulation provides for a mid-course correction, approximately at conjunction; plus several variations in the Earth escape and Mars capture geometries. There are five possible flight path corrections (ten degrees of freedom), similar to a typical NASA Mars mission flight plan. Given an input of magnitude and direction of the mid course thrust, the trajectory is then optimized for total energy usage and transit time for all the other parameters. The complete analysis takes less than 30 seconds on a 300 mHz PC. The optimization is done without benefit of any traditional nonlinear programming methods, so the code is compact and the results are obtained quickly - without loss of accuracy. The program is able to do this because it takes maximum advantage of the geometry of the problem, the underlying principles of orbital mechanics, and it uses the variable step integrator to help determine where the best neighboring optimal paths lie. Many more degrees of freedom will be possible using nonlinear programming tools, greatly extending the accuracy with which interplanetary trajectories can be calculated.
Date received: February 2, 2002
Copyright © 2002 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cago-35.