EDL: Seven Minutes of Terror – A “tweeps” view while Curiosity was landing
Written By: Ben Lachman – PR and Marketing Assistant
Curiosity and her mission objectives are phenomenal; however the most suspenseful part was the MSL entry, descent and landing (EDL) which was a very complex process. The challenge of landing a 1,080 lb rover with approximately 4,000 lbs of landing apparatuses in a 15-mile X 14-mile ellipse, 350 million miles away from Earth took years of planning. A 14 minute round trip communication delay forced the scientists to pre-program the entire procedure. By the time word reached the command center that Curiosity had entered the Mars’ atmosphere, Curiosity would actually be on the ground. The landing was fully automated.
To be successful many processes had to work seamlessly; the parachute had to deploy to slow the craft down, the heat shield would have to detach for the radar to scan the ground, the rocket pack would have to detach from the shell and the parachute and perform an evasive maneuver to avoid a collision. After all of the above processes took place, the rocket pack would hover over the Martian surface while it lowered Curiosity to the ground. The complexity of this landing was unprecedented, and because the conditions on Mars and Earth are so different, all the systems were tested numerous times in different environments, but never together.
Earlier that day, I had overheard two engineers chatting about a controversy having to do with the parachute. The parachute wasn’t like any that I could imagine, at fifty-one feet, it was the largest supersonic parachute ever constructed. When testing the design, it fluttered like a jellyfish with the bow shock, which was not ideal. Dr. Anita Sengupta, EDL and advanced technology engineer, showed a video of tests and computer models, it became clear why the engineers were concerned; but Dr. Sengupta sounded confident in her research.
Adam Steltzner, EDL Phase Lead, was responsible to declare if Curiosity had touched down. He emphasized that rationally the plan was sound, but if you looked at it, it was crazy. He explained all the things that could go wrong, and how they planned for, but he said that there might be an unexpected issue. Throughout the discussion they were managing our expectations. It’s going be an amazing event if it lands, but if it doesn’t there was nothing to worry about they would figure out what went wrong and do it better the next time. Dr. Steltzner said that he would wait for three conditions to verify that Curiosity safely touched down: First, he would wait for an electronic ‘postcard’ that would tell him the final velocity, second, he would wait for Curiosity to send a signal that it wasn’t moving so he would know that it wasn’t sliding down a hill, and lastly he would wait for a steady telemetry signal. After all those conditions were met, he would declare touchdown.