The development of new decelerator technologies will be required as the desired payload mass for future Mars landing missions increases beyond the current state-of-the-art architecture capability. This thesis examines the potential for supersonic retropropulsion applied on entry, descent, and landing vehicles to increase the landed payload mass. Supersonic retropropulsion systems use rocket thrust directed into the free stream flow to decelerate the vehicle during descent. Under certain conditions the aerodynamic drag on the entry vehicle can be preserved or augmented using supersonic retropropulsion.
The development of a model characterizing the drag augmentation capabilities of supersonic retropropulsion flow interactions is described. The model combines results from computational fluid dynamic simulations available in literature and analytic techniques to estimate the drag coefficient of a 70° sphere-cone aeroshell. The model is designed to capture the dominant flow physics of pressure conservation through various shock cascade structures more quickly than computational fluid dynamic simulations. This allows conceptual systems analysis to be performed across a wide range of input values beyond the current parameter space evaluated in experiments or computational simulations. The drag coefficient model developed is validated against available results from wind tunnel tests and computational simulations to within 10%. In addition, the sensitivity of the computed drag coefficient to inputs estimated from computational simulation results in literature is analyzed.
A study of drag-augmented supersonic retropropulsion operation concepts for use in Mars entry, descent, and landing is presented. The feasible entry and payload masses for ballistic entries are determined for a range of supersonic retropropulsion operation intervals to illustrate the flight regimes where supersonic retropropulsion is most effective. The use of supersonic retropropulsion is shown to reduce the required propellant mass by 65% when the operation interval is focused in the region of maximum dynamic pressure. In addition, the feasibility of two concepts combining supersonic decelerator concepts is investigated: a combination of drag-augmented and high-thrust supersonic retropropulsion, and a combination of drag-augmented supersonic retropropulsion and inflatable aerodynamic decelerators. The potential for these hybrid solutions to increase the payload mass capability by up to 708% using each technology in the appropriate flight regime is demonstrated
