NASA JPL/Draper Laboratories – Mars Pinpoint Landing
Estimated landing accuracy of Mars landers to date has steadily improved, from 150 km off the target for Mars Pathfinder to 90 km for Mars Polar Lander to 35 km for the Mars Exploration Rovers. Factors which contribute to these position uncertainties at landing include uncertainties in entry point, atmosphere, vehicle aerodynamics and wind drift. The improvements made to date have been in improved approach navigation. Mars Science Laboratory will advance accuracy to within 5 - 10km of the target using guided entry to correct known errors at entry as well as the uncertainties in atmospheric modelling and vehicle aerodynamics. The NASA Mars Pinpoint program sought ways to address the remaining error sources: primarily wind drift, to achieve landing within hundreds of meters of high scientific value targets.
Assess the ability of steerable parachutes to offset wind drift landing errors for Mars missions.
The Vorticity team carried out analysis of the use of subsonic parachutes to improve precision of landing on Mars within the scope of the JPL Mars Pinpoint Lander program. This effort included trajectory dispersion predictions, system sizing and control response for round and ram-air parachutes gliding in the Martian atmosphere using the Vorticity multi-body parachute flight dynamics code.
The study clearly demonstrated that parachutes that glide and can be accurately steered at low altitude on earth are unstable or too responsive in the low density Martian atmosphere. Ram-air parachutes were shown to be unsuitable for Mars. A solution was proposed based on a steerable low glide parachute.