J. W. Williams’s research while affiliated with University of Illinois Urbana-Champaign and other places

Small satellites may provide a low-cost platform for targeted science investigations in the Mars system. With current technology, small satellites require ride shares with larger orbiters to capture into orbit, limiting the range of orbits available to small satellite mission designers. Successful development of an independent orbit insertion capability for small satellites, using aerocapture, would allow small satellite mission designers to choose the orbit most appropriate for a science investigation while enabling small satellite ride shares on any mission to Mars. A generic small satellite drag-modulation aerocapture system is assessed for use at Mars across a range of approach trajectories and destinations in the Mars system. Analyses include assessment of the sensitivity of the entry corridor size over different atmospheric conditions, a comparison of velocity-trigger and numerical predictor-corrector guidance schemes for drag modulation, and aerocapture flight performance assessment via Monte Carlo techniques. A special focus is placed on four baseline missions: a low-altitude Mars mapping orbit, Phobos and Deimos flyby/rendezvous, and areosynchronous orbit. Results indicate that aerocapture may decrease the orbit insertion system mass fraction by 30% or more with respect to fully propulsive options.

Small satellites may provide a low-cost platform for targeted science investigations in the Mars system. With current technology, small satellites require ride shares with larger orbiters to capture into orbit, limiting the range of orbits available to small satellite mission designers. Successful development of a small satellite aerocapture capability would allow small satellite mission designers to choose the orbit most appropriate for a science investigation while enabling small satellite ride shares on any mission to Mars. A generic small satellite aerocapture system is assessed for use at Mars across a range of small satellite payloads, approach trajectories, and destinations in the Mars system. The aerocapture system uses drag modulation for trajectory control to ensure successful orbit insertion. Analyses include assessment of the sensitivity of the entry corridor size to the ballistic-coefficient ratio, the effectiveness of real-time aerocapture guidance and control algorithms, aerocapture system-level impacts of different target orbits, and development of requirements and recommendations for the development of a small satellite aerocapture system. Results indicate that a discrete drag-modulation aerocapture system may provide an orbit-insertion capability for small satellites with modest propulsion requirements.