Baker: Engineers don't believe in superstition. We believe in the laws of physics. But when it comes to things like this, you have a sense you'd better do what you've always done before.
Chen: You know the saying—"There are no atheists in a foxhole."
Baker: Late afternoon, things started happening. My Twitter feed started buzzing like mad. Then this radio show in Australia wants to interview me. That's when I realize the whole world is watching.
Chen: My job is to explain to the world what's going on. That was the first time anyone had ever put makeup on me. Not many people get to have their life's work play out before the whole world and also do the play-by-play of it. It was nerve-racking.
Devereaux: We see that people are watching in Times Square. There's a landing party at a bar in Seattle.
Chen: TV goes live with programming at eight thirty. The girl who named Curiosity is outside getting interviewed. There are sound checks. It's surreal.
Devereaux: My job was to be the fire extinguisher behind the glass. Hypothetically, something goes wrong, I'm expected to break the glass and leap into action. But really there was nothing I could do. There was nothing anyone in that room could do.
Steve Sell (war-room chief): We're just monitoring the data as it comes in. We've got engineers monitoring specific events, giving a thumbs-up if we're nominal. We make that call on the network and let Allen know.
Baker: A big milestone is forty minutes before atmosphere, a signal called EDL main. It's basically "Okay, no kidding, we're doing EDL now." I'm a snowboarder, so it's like you've gotten off the ski lift, you've edged over, and you're looking down that double black diamond.
Chen: Ten minutes before cruise-stage separation, Adam selects "All or Nothing at All" by Sinatra, plays it over the network.
Sell: There's a fourteen-minute speed-of-light delay. When we learn we're hitting the top of the atmosphere, in reality Curiosity has been sitting on the surface for seven minutes. Or she's dead. Either way, it was all over seven minutes ago.
Steltzner: But you don't live it that way. You're in the moment.
Chen: We separate from cruise and switch to an omnidirectional antenna. Our data stream slows significantly. We've suddenly got the speed of a dial-up modem, a blip of data every ten seconds.
Baker: If you want to make an engineer nervous, take away his data.
Chen: We watch the spacecraft turn off the fault-protection software. That keeps it from doing anything dangerous during cruise. It's about to start doing lots of dangerous things.
Sell: You can feel the anxiety level starting to rise.
Steltzner: I'm not sitting. I can't sit.
Devereaux: I'm seated next to the chief engineer, Rob Manning. He and Adam are pacers. The two of them are doing cycles around the room. They've got their own little orbits.
Davis: We had run millions of simulations. Now we had one chance to get it right.
Steltzner: When you get close to Mars, Mars starts sucking you in.
Baker: We hit the atmosphere doing 13,000 mph.
Chen: We pressurize the engines, start flying towards the target.
Baker: We've got eight rockets producing sixty pounds of thrust.
Chen: We're doing bank reversals, steering from left to right.
Baker: We're carving S's in the upper atmosphere.
Chen: In seventy seconds we hit our peak temperature, 1,300 degrees Celsius [2,372 Fahrenheit], and peak deceleration. The spacecraft is pulling twelve Earth g's.
Baker: For thirteen minutes we're getting this really low data rate, which means we're doing some critical things in the dark—cruise separation, de-spinning, pressurizing. Then boom! All our screens light up. We've got our data back. The Mars Odyssey satellite is now close enough to the spacecraft to give us a faster rate.
Baker: We do a maneuver called "straighten up and fly right" just before the parachute deploys. The parachute is going to yank us with 60,000 pounds of force.
Sengupta: Parachute deployment is particularly violent and chaotic.
Chen: We lose communication briefly when violent things happen to the spacecraft. Things are tense.
Sengupta: It's the largest parachute ever used on Mars, and it's deployed at the largest Mach number a parachute has ever been deployed, 950 mph, two times the speed of sound on Mars. It's unpredictable. It acts like a big jellyfish, collapsing and reinflating. It's just spewing everywhere.
Baker: We slow dramatically with the parachute.
Chen: The parachute deploys; the heat shield drops; our radar picks up the ground. We're nine kilometers up. You can hear some excitement in people's voices. But this is a place that has killed us in tests.
Baker: At back-shell separation, we sever the parachute, and the descent stage and rover fall out and free-fall for one second.
Chen: We activate the descent-stage thrusters. We do some pretty gnarly maneuvers to fly away from the back shell and parachute.
Baker: We're falling at 200 mph one minute before impact. The engines throttle up to slow us to 64 mph. I've never been more stressed-out.
Chen: Now we're hovering twenty meters above the surface, moving less than 2 mph.
Steltzner: I hear Al say, "Sky crane start." That was the part I was frankly most nervous about.
Davis: I'm the one who has to tell everyone that we've touched down, but you can't say, "Touchdown." There are two more confirmation steps after that.
Davis: So we came up with "Tango delta nominal." Only the core people knew what that meant.
Steltzner: I hear Jody say, "Tango delta nominal."
Davis: I want to scream it, but you have to remain cool and collected.
Steltzner: I'm like, "This could be pretty cool," but I'm still listening, listening...
Sell: There's an inertial sensor in Curiosity. When we learn that the rover is no longer moving, someone will say, "RIMU stable."
Steltzner: I hear, "RIMU stable..."
Sengupta: You've still got those high-velocity supersonic jets hovering twenty feet over the rover. You don't want that.
Baker: Curiosity tells the descent stage to fly away. Then it's got .7 seconds to fire pyrotechnic devices that cut the cables or it's going for a ride.
Davis: Everyone's bubbling with anticipation. I start this clock in the back of my head. We have to wait ten seconds after "RIMU stable" to make sure the fly-away has happened.
Baker: The descent stage flies 625 meters away and crashes into the surface going 100 mph.
Chen: Adam pokes me in the shoulder. I say, "Touchdown confirmed. We are safe on Mars."
Sell: The room erupts.
Steltzner: Almost immediately we get the thumbnail images. For me, that was it. That was the human existential proof that we did it.
Baker: [In the satellite photos] you could see this little plume. That was all my hardware and engines going up in a cloud of debris and vapor. Sometimes I think of someone finding that stuff one day, the stuff some nameless engineer spent eleven years of his life on. It would be like finding one of Columbus's ships.
Devereaux: The data is great, but you see pictures and you think, That is fucking Mars!
Davis: "Tango delta nominal" has become its own thing. I get tweets from people taking trips, and when their plane lands, they'll say, "Tango delta nominal Paris" or "Tango delta nominal L.A."
Devereaux: I walked around in a trance for a week.
Steltzner: So, um, it was a great night. Inspirational.
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