Rover touches down on Mars
By Richard Stenger
A NASA drawing of the Mars rover
CNN's Miles O'Brien has more on the Spirit rover as it gets closer to landing.
PASADENA, California (CNN) -- A NASA robotic explorer touched down on the red planet Saturday night, sending a signal home that it survived the risky descent through the Martian atmosphere and bouncing landing.
The $400 million rover Spirit, designed to conduct unprecedented geologic and photographic surveys on the Martian surface, transmitted a simple hello to Earth within minutes after landing, which took place just after 11:30 p.m. ET.
The golf cart-sized Spirit went through what NASA assistant administrator Ed Weiler characterized as "six minutes from hell" -- the time it took to enter the Martian atmosphere, descend and land in Gusev Crater.
During the descent, Spirit deployed parachutes and fire retrorockets to decelerate. Seconds before impact, it inflated a protective cocoon of airbags.
A series of bounces and rolls probably sent the robot about four stories high and more than a mile from its landing spot, according to mission control scientists at the Jet Propulsion Laboratory in Pasadena.
"It sounds like a crazy way to land on Mars, but it's actually tried and tested," said Steven Squyres, a Cornell University geologist in charge of the scientific instruments on Spirit and its identical twin, Opportunity, which will complete the 300 million-mile trip to Mars in the next three weeks.
Spirit launched June 10 and Opportunity took off July 7.
The airbag bounce method worked well with Pathfinder, NASA's last success on Martian soil.
The 1997 mission included a lander, which beamed back thousands of images, and Sojourner, a toy-sized test rover that scurried around the rocks and boulders littering the landing site.
The new 400-pound rovers like Spirit and Opportunity, packed with a slew of geology instruments and cameras, have much more mobility and capability than previous missions.
Each is built to explore nearly as much territory in one day as Sojourner covered in three months, about 100 yards.
Their eight cameras should provide stunning panoramas of the Martian surface, with resolutions so sharp they retain crisp detail when blown up to the size of a movie screen, according to NASA. And their microscopes, spectrometers and drills could uncover history from long, long ago.
"It's a cold, dry miserable place today. But we have got these tantalizing clues that, in the past, it used to be warmer and wetter," said Squyres, who exudes a passion for planets like his one-time teacher at Cornell, the late astronomer Carl Sagan.
"You can think of these vehicles as being robot field geologists. A field geologist is like a detective at the scene of a crime. They go to a place where something happened long ago and they try to read the clues," he told CNN.
But this scene of the crime could easily include Spirit's corpse, NASA scientists acknowledge.
Mars has proven a deadly place to visit. Two-thirds of the more than 30 spacecraft that have attempted to reach or orbit Mars have met with disaster, including two NASA attempts in 1999.
The most recent casualties include Japan's Nozomi, a satellite zapped by lethal solar radiation during its four-year odyssey to Mars. Mission engineers abandoned their attempts to steer the ailing craft as it neared the red planet last month.
Another possible victim is the Beagle 2, an ambitious life-searching lander from Britain, which has remained silent since its presumed touchdown December 25.
"A lot of people have had bad days on Mars," Weiler quipped last year. "They don't call it the death planet for nothing."
CNN's Miles O'Brien and David Santucci contributed to this report.