One other advanced EDL technology under study by STMD is a 33.5-meter-dia. supersonic parachute with a ring sail configuration instead of the disk band gap approach used as part of Curiosity's landing. It is the largest supersonic parachute ever designed, Gazarik says, and is being considered for the Curiosity 2.0 mission under development for a 2020 launch.
While the sky crane will not scale up to the payload size that will be needed for human landings, it will remain the state of the art for landing robotic explorers for the foreseeable future. A science definition team already is at work on the instrument suite for the follow-on version of Curiosity NASA plans to launch in 2020, and the list is likely to include hardware for collecting and storing samples for eventual return to Earth (AW&ST Dec. 10, 2012, p. 32).
“I think we will see, after the science definition team comes back from their consideration on the 2020 mission, an absolutely fabulous array of measurements that need to be made on samples, decision processes on whether we keep those or not, how we keep those,” says James Green, director of NASA's Planetary Science Div. and acting director of the Mars program. “And then, of course, how we would return those is an element [in that] next decade.”
One concept just gaining public attention is using the Orion multi-purpose crew vehicle NASA is developing to bring the samples back to Earth, after picking them up in the deep retrograde lunar orbit under study for Orion's first deep space mission to a captured asteroid (AW&ST April 29, p. 36). But beyond the $100 million NASA is seeking as a down payment on the asteroid-capture mission, the agency has very little to say about its actual plans to send humans to Mars. Overall, the latest DRMs estimate a human Mars mission will require launching about 800 tons of payload with the heavy-lift Space Launch System. But estimates of just how much of that mass actually will touch down on Mars range from 20-60 tons, and the most recent DRMs NASA has developed are being held so closely that the National Academies of Science panel studying the future of human spaceflight cannot access them.
“Bottom line, as I understand it, is that the design reference missions are internal, pre-decisional studies that help inform our decision-making process,” says David S. Weaver, the agency's associate administrator for communications.