By David L. Brown
If you didn’t watch the live feed from the Jet Propulsion Lab last night as the new Mars Rover, Curiosity, made its entry and landing, you missed one of the great moments in space exploration history. The landing took place about 11:30 p.m. here in Mountain time, so it was pretty late for those in the East and Central time zones. But it was definitely a dramatic two hours I spent watching the action in the control room as the team followed the approach and landing.
Because it takes fourteen minutes for radio waves (and light) to travel from Mars in its present location, the rover’s landing had already taken place, either for good or bad, when the team saw it happening. But there was telemetry from the craft throughout the approach, which slowed the vehicle carrying the rover from about 13,000 miles per hour to a gentle set down at 2 m.p.h. seven minutes later. The entire process was pre-programmed—the complex system did it all by itself—using radar and other input to steer to the final landing place with incredible accuracy.
The process was amazing. First, the vehicle used atmospheric slowing such as the Space Shuttle does, using a heat shield. Since the Martian atmosphere is 100 times thinner than earth’s, that was sufficient only to slow the capsule to about 1000 m.p.h. Next a huge supersonic parachute was deployed, slowing it further to about 200 m.p.h. Again, due to Mars’s thin atmosphere, the parachute could only do so much, so a final third phase was deployed. In this case, a rocket powered module that flew the capsule sideways to clear the parachute, then as it approached the ground, lowered Curiosity on a cable “sky crane” to a gentle touchdown before flying away to crash at safe distance. It was an engineering achievement of almost unbelievable complexity and with zero margin for error. If any single thing had gone wrong, and there were many crucial details during the descent and landing the scientists called “Seven Minutes of Terror,” the $2.5 billion project would have been a loss.
To really put the achievement into perspective, Curiosity is believed to have touched down just 262 meters from the planned landing spot, after traveling for about 350 million miles from earth. (For the metrically challenged, that’s less than three football fields away from the target.) As someone said, it’s like hitting a golf ball halfway around the world for a hole-in-one.
The scene in the control center at the JPL when Curiosity reported its safe landing was emotional to say the least. Hugs and high fives went on for about a half hour among the ecstatic scientists and engineers. As icing on the cake, within minutes Curiosity’s first pictures arrived from the surface of Mars. It was a night to remember, and a huge achievement for the U.S. space program. No other nation could even come close to achieving what NASA and JPL achieved yesterday with the landing of this huge and sophisticated rover on the Red Planet.