93-170
NEAR-OPTIMAL AEROCAPTURE TRAJECTORIES WITH FULL ORBITAL ELEMENT CONTROL*
Gordon R. Woodcock**
Abstract
Mars aerocapture trajectories were designed for capture into elliptic orbits with control of all orbital elements (semimajor axis, eccentricity inclination, line of nodes, and line of apsides). The nominal L/D was 0.5 one case was investigated with L/D 1.0. A gradient optimization scheme was used. The optimization criterion was the impulsive delta V to reach the target orbit (with the defined target orbital elements) after aeropass exit. The paper presents the formulation of the optimization criterion in detail and presents results of aerocapture simulations. Two types of aerocapture trajectories, a "slalom" roll program and a "rollover" roll program, were found to enable control of all element with minimal correction delta V. sensitivities were run on atmosphere density, entry speed, and other parameters of interest. Results are presented to show how these sensitivities affect the roll program and the trajectory. Certain persistent (i.e. present in all cases) features of optimal capture trajectories are discussed. A correction delta V budget of 100 m/sec appears more than adequate for Mars aerocapture.
*This paper appears in full in the microfiche supplement to this volume, AAS Microfiche Series, Volume 68.Copyright1993 The Boeing Company, All Rights Reserved. Reprinted by the AAS with permission.
**Boeing Defense and Space Group, Advanced Civil Space Systems, P.O. Box 240002, Huntsville Alabama 35824-6402