Curiosity lands on Mars

Mars Science Laboratory arrived at its destination Sunday night at 10:31pm Pacific Time. The MSL team at NASA’s Jet Propulsion Laboratory’s control center in Pasadena was ecstatic; the mission control room was flooded with jubilant pandemonium. According to NASA Administrator Charlie Bolden, who was there along with Deputy Administrator Lori Garver and Presidential Science Advisor John Holdren, “Everybody in the morning should be sticking their chests out saying, ‘That’s MY Curiosity rover on Mars!’” The rover is checking out in perfect shape so far, and soon the science will begin.

Progress reports rolled in last night at a rate of about one per minute. Each time a milestone in the intricate system was transmitted home, the team clapped and broke out in spontaneous laughter.

Some events in the control room timeline as they arrived (14 minutes after they actually took place on Mars):

10:14 Lost telemetry, received heartbeat signals
10:15 Cruise stage separation, vehicle turns to the correct attitude, which means that the reaction control system rockets are working
10:20 5 minutes to entry, heartbeat tones still coming, spacecraft at about 5.5 km/sec
10:22 MRO began storing data for retransmission
10:24 Reentry began, signal dropped, indicating a change in antennas
10:26 Odyssey data begins flooding in, MSL decelerating at about 11 G’s
10:28 17 kilometers altitude
10:29 Down to about Mach 2, parachute will deploy at Mach 1.7
10:30 Parachute deployed!!! Spacecraft decelerating well!
10:30 Still descending, at 6.9 kilometers
10:31 86 meters/second, 4.2 kilometers and descending
10:31 Powered flight!!! yes!!! down to 500 meters altitude, 50 m/sec
10:32 10m/sec, 40 m altitude
10:32 1.5m/sec descending, skycrane is working!!!
10:32 Touchdown confirmed!!!! The skycrane worked!!!! Joy in control room. Everyone’s faces are red.
10:34 First thumbnail of Curiosity’s wheel rolls in, cameras working
10:35 Full-sized picture with Curiosity’s wheel, Martian horizon arrives to sheer joy in the control room

Touchdown time was 10:14:39pm Pacific Time, with 140.46kg of fuel remaining (out of 400kg to start) in the descent stage as it flew away. There’s no doubt we’ll visit that descent stage again some day.

Scientists and engineers at JPL will spend the next several hours sorting through data relayed from two other spacecraft in orbit around Mars. Mars Odyssey and Mars Reconnaissance Orbiter were catching the telemetry from Curiosity and sending it home to Earth.

At the press conference this morning, John Holdren said Curiosity is “the most challenging mission ever attempted in the history of robotic exploration.” Anyone who has watched the NASA JPL video Seven Minutes of Terror (the website has been knocked offline due to large amounts of traffic) knows why. The Mars Science Laboratory spacecraft weighed almost four metric tons at launch. Even after using much of its fuel, it was far too large to land using anything NASA has ever tried before.

There are basically three ways to land a spacecraft on Mars, which has an atmosphere one percent of the density of Earth’s. Reentry shields and parachutes work to slow down the spacecraft, but not nearly as well as they do on Earth.

The Viking probes used rockets to slow the spacecraft in the air and lower them gently to the Martian surface. The Mars Exploration Rovers, Spirit and Opportunity, used a similar system to suspend them 10 to 15 meters above the surface. They then popped giant airbags and fell the rest of the way.

Curiosity’s landing system worked much the same way as its predecessors’ down to a few tens of meters above the surface. To begin, a giant 4.5m aerodynamic heat shield, the largest ever flown in space, slowed the spacecraft down to about 470 meters per second. That was slow enough for Curiosity’s 16m incredibly strong, supersonic parachute to pop out and slow Curiosity down further to about 100 meters per second—better, but still pretty fast.

At that point, about 1.8 kilometers above the ground, the parachute was cut loose, and the descent stage’s rockets began firing. During this time, Curiosity began to unfold. The rockets lowered the craft down to only 7.6 meters above the surface, just a few stories. So far, very similar to previous probes, except much larger.