The team that landed Curiosity on Mars takes home a trophy.
- By Paul Hoversten
- AirSpaceMag.com, March 22, 2013
(Page 2 of 3)
What was it like during the Seven Minutes of Terror it took for the rover to reach the surface?
I had the better part of a decade of my life invested in something that would all go down in the span of seven minutes. The number of things that had to go right to see the fruits of my decade ripen is remarkable. Thousands of lines of code, hundreds of devices, almost all of them being mission-critical, so it is terrifying. There was an interesting numerology for us when we were landing, because Mars was far enough away from the Earth that it took about 14 minutes for the signal to get from Mars to Earth. So it’s not only seven minutes of terror from the top of the atmosphere down to the surface, but it’s also true that when we first see that first signal, the rover’s been alive or dead for seven minutes on the surface. So seven was rolling all around there. When you’re actually in the event, on landing night, everybody in the control room is just a spectator. The vehicle is flying itself and we’re along for the ride.
Which part of the landing sequence was most worrisome?
The thing that we felt, mathematically, was the single lowest reliability element was probably the parachute, and that’s just [because of] the intrinsic uncertainties associated with parachutes. We throw more than 10,000 troops out of airplanes each year, and largely it’s into a very controlled environment, and we have parachutes designed exactly for those conditions. But we still give them a second parachute because even with all those controls, the odds just aren’t good enough. That’s not the case when you’re moving supersonically in an uncertain atmosphere 10 kilometers above the surface of Mars. So when you do the numbers, you end up convincing yourself that the single highest device risk is the parachute.
But that’s not the thing I was worried about. I was worried we could have missed something on the Sky Crane. It was so new and different. It was the unknown unknowns I was most concerned about, some unappreciated feature of this new landing system that we did not absorb and was waiting to bite us. So on landing night, as the data clicked by, I became more and more anxious. I said ‘Oh my God, is it really going to happen just this easily?’ I was pretty wound up for those last 20 or 40 seconds.
And your reaction afterward?
Tremendous relief, tremendous exhilaration, and, frankly, a slight sense of surrealness. To work on something for the better part of a decade, and then to have it done. Regardless of the outcome. It’s awesome that it was done successfully, but, I mean, all of a sudden it’s over. It was such a build-up, so much of my life was invested, and then it’s now, well, it just happened, now we move on.
The Sky Crane will also be used to land a rover similar to Curiosity in 2020. Are you studying any improvements to the system?