Planetary Mission Design and Analysis Using Aeroassist Maneuvers

2019-08-14T18:07:11Z (GMT) by Ye Lu
Mission designs have been focused on using proven orbital maneuvers (i.e., propulsive maneuvers and gravity-assist) to deliver spacecraft to planetary destinations. Aeroassist maneuvers, despite their potential benefits, have not been given serious considerations due to the perceived risk and complexity. As entry technologies mature, aeroassist maneuvers need to be considered more extensively. Currently, there is no tool available that can perform rapid preliminary mission designs using aeroassist maneuvers. In this dissertation, integrated design methodologies for aerocapture and aerogravity-assist are developed, which can be readily converted to design tools that enable rapid mission concept formulations.
The aerocapture design methodology is used to develop extensive design rules and relations for aerocapture missions to Titan, Venus, and Uranus, considering a wide range of vehicle parameters and interplanetary trajectories. These design rules and relations are intended as a convenient resource for mission designers and system engineers to evaluate the feasibility of aerocapture (e.g., effects of V-infinity on aerocapture missions) and the relevant design requirements, such as choices for vehicle characteristics and TPS materials. In addition, potentials for inclination change for Titan aerocapture are also quantified, presenting additional benefits of using aerocapture. Given the unusual orientation of Uranus, the changes in inclination and shift of line of apsides are also quantified for Uranus aerocapture.
A novel design methodology is developed for Saturn system missions using nontraditional aerogravity-assist maneuvers at Titan. Compared with the existing literature, the novel methodology explores a comprehensive design space by integrating design considerations for interplanetary trajectories, atmospheric trajectories, arrival geometries at Titan, and vehicle designs. The methodology enables preliminary design trades and allows the mission designer to assess the feasibility of Titan aerogravity-assist and quickly develop requirements for trajectory designs and vehicle designs. The methodology also identifies potential Saturn and Titan arrival conditions. Results for an example Enceladus mission and Saturn system mission are presented, showing that a Saturn arrival V-infinity of 7 km/s renders Titan aerogravity-assist feasible for an Enceladus mission, while using the current entry technology.
Bank modulation and drag modulation have been considered separately for aeroassist vehicles in the literature. The investigation combines bank modulation and drag modulation to improve the control authorities for aeroassist vehicles and such improvements are quantified using numerical simulations for a wide range of vehicle design configurations. The results show the potential of using a low-L/D vehicle for aerocapture at Uranus using combined bank and drag modulation.