NASA attempts a return to Mars tonight
Robot ship readies for six minutes 'from hell'
By Richard Stenger
CNN
Saturday, January 3, 2004 Posted: 4:21 PM EST (2121 GMT)
PASADENA, California (CNN) -- The countdown was on Saturday for the possible arrival on Mars of a new form of life from Earth -- one with chips and circuits slated to conduct unprecedented scientific and photographic surveys of the red planet.
Whether the NASA's solar-powered, six-wheeled craft survives the dangerous trip, or becomes scrap like many of its predecessors, will not be known until it sends a radio signal home -- and that could take hours or days.
It is scheduled to land Saturday night. If it succeeds, the new rover could be the first of several on Mars.
Despite the complexity of the landing, NASA scientists were upbeat and optimistic at a midafternoon press briefing.
They noted the probe has a 99 percent chance of landing within its optimal drop zone and that conditions on Mars look good for landing.
Mission Manager Mark Adler said the "spacecraft health is excellent."
There is a slight chance that the $400 million rover, named Spirit, could contact Earth minutes after it undertakes the most complicated part of its seven-month journey -- going from 12,000 mph through space to a complete rest on the surface.
"It's going to be high anxiety," said Ed Weiler, NASA associate administrator of space science. The six minutes during which the rover enters the atmosphere and lands will be "from hell," he said.
Four-story bounce
In that brief time, if all goes as planned, Spirit will endure 2,600 degrees Fahrenheit temperatures as it slams into the atmosphere, deploys parachutes and fires retro rockets to decelerate. Seconds before impact, it will inflate a protective cocoon of airbags.
A series of bounces and rolls could send the golf cart-sized robot more than a mile from its landing spot, according to mission control scientists at NASA's Jet Propulsion Laboratory in Pasadena, California.
"It will bounce about a four-story building [in] height, we believe, and roll somewhere between one and two kilometers," said Peter Theisinger, Mars exploration rover project manager at JPL.
"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 3 million-mile trip to Mars in three weeks.
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.
Stunning panoramas
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.
'Death planet'
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."
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