Jon D. Strizzi, Joshua M. Kutrieb, Paul E. Damphousse,
Department of Aeronautics & Astronautics
US Naval Postgraduate School
Monterey, CA
and
John P. Carrico
Analytical Graphics, Inc
Malvern, Pennsylvania
ABSTRACT
The equilibrium points of the Sun-Mars system bring some unique characteristics to the discussion of future inner solar system exploration missions, particularly an expedition to Mars itself. Existing research has identified potential utility for Sun-Mars libration point missions, particularly for satellites orbiting each of the co-linear, near-Mars, Sun-Mars libration points (the L1 and L2 points) serving as Earth-Mars communication relays. Regarding these Lissajous orbits, we address questions of ÒWhy go there?Ó ÒHow to get there?Ó and ÒHow to stay there?Ó Namely, we address utility and usefulness, transfer and injection, and stationkeeping. The restricted 3-body problem involving a spacecraft in that system is reviewed; and past and present research and proposals involving the use of these orbits are summarized and discussed. We use commercial, desktop tools (Satellite Tool Kit (STK)/Astrogator) for simulation and analysis of Earth-Mars transfers, Lissajous orbit insertions, and station-keeping trajectories. On-going, successful collaboration between military and industry researchers in a virtual environment is demonstrated. Much of this study focuses on 2016 Earth-Mars transfers to these mission orbits with their trajectory characteristics and sensitivities. This includes analysis of using a mid-course correction as well as a braking maneuver at close approach to Mars to control Lissajous orbit insertion and the critical parameter of the phasing of the two-vehicle relay system. Stationkeeping sensitivities are investigated via a Monte Carlo technique. The resulting data provides confirmation and insight for existing research and proposals, as well as new information on Mars transfer and Lissajous orbit insertion strategies, communications coverage, and stationkeeping sensitivities. The data provides new information on these trajectories to future researchers and mission planners