93-149
Optimal Parking Orbits For Manned Mars Missions*
Michael L. Cupples and Jill A. Nordwall**
Abstract
The paper summarizes a Mars parking orbit optimization effort. This parking orbit study includes the selection of optimal elliptic Mars parking orbits that meet mission constraints and that include pertinent apsidal misalignment losses. Mars missions examined are for the opportunity years of 2014, 2016, and 2018. For these mission opportunities, R is shown that the optimal parking orbits depend on the year that the mission occurs and are coupled with the outbound, Mars stay, and return phases of the mission. Constraints included in the parking orbits optimization process are periapsis lighting angle (related to a daylight landing requirement), periapsis latitude (related to a landing latitude range requirement) and the vehicle Trans-Earth-lnjection stage mass. Also, effects of mission abort requirements on optimal parking orbits are investigated. Off-periapsis maneuvers for Mars orbits capture were found to be cost effective in reducing the mission delta-V for the 2016 abort from Mars capture scenario. The total capture and departure delta-V was split" between the capture maneuver and the departure maneuver to reduce the 2016 Mars departure delta-V to below the level of the corresponding stage of the 2014 baseline mission. Landing results are provided that show Mars landing site access from the optimal elliptic parking orbits for Mars excursion vehicles with low (0.2) and high (1.3) and 1 6) lift to drag ratio.
*This paper appears in full in the microfiche supplement to this volume, AAS MicroficheSeries, Volume 68.1992 The Boeing company. All rights reserved. Based on work originally performed under NASA contract NAS8-378s7 Published by the AAS with permission.
**Engineers,Boeing Defense & space Group, M/S JW-21, P 0. Box 240002, Huntsville, Alabama 35824.