Optimization of a Martian Aero-Gravity Assist

A study is performed to investigate the available velocity increase from an aero-gravity assist maneuver about Mars. While the gravity assist uses gravitational acceleration alone to increase a spacecraft’s velocity on an interplanetary trajectory, the aero-gravity assist supplements gravitation with lift to increase the time spent in the gravity well of the transfer planet. Direct simulation of the maneuver is performed using a simple control algorithm and analytical models of hypersonic aerodynamics. An evolutionary algorithm is implemented to quantify maximum possible turning around the planet for a wide range of approach velocities and energy depletions. The effects of varying both of these mission parameters are examined on relevant trajectory parameters and performance metrics. While the potential benefits of aero-gravity assist have been demonstrated for certain specific mission profiles, this study develops a generic characterization of the problem, in order to create a database of manuevering performance applicable to a wider range of reasonable candidate missions. With a given geometry, it is shown that there is an optimal maximum turning angle that occurs at values greater than 10◦ to the parallel direction.