Performance assessment of discrete-event drag modulation for mars entry with real-time guidance

Entry flight performance is assessed for single-stage discrete-event drag-modulation trajectory control on Mars with two different real-time guidance algorithms: a heuristic velocity trigger and numerical predictor–corrector. Three degree-of-freedom simulation and Monte Carlo techniques are used to determine flight performance across a range of mission and vehicle design parameters. Trends are identified in flight performance across different initial conditions, ballistic-coefficient ratios, and target ranges. Results indicate that both guidance algorithms can provide landing accuracy better than 10 km across likely vehicle properties and entry conditions. The heuristic velocity trigger performs nearly as well as the numerical predictor–corrector for low-ballistic-coefficient ratios and entry flight-path angles steeper than approximately –18 deg. The numerical predictor–corrector provides consistent flight performance across all feasible mission and vehicle parameters with accuracy better than approximately 5 km. Overall, single-stage discrete-event drag-modulation trajectory control is a feasible option for accurate landings for ballistic coefficients below approximately 140 kg∕m² and landed altitudes above 0 km.