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For a planet so close to ours, Mars has proved strangely inhospitable to earthly visitors. Of the 33 missions to the Red Planet since 1960, 22 have crashed, broken up en route or otherwise failed before they could complete their research. Undaunted, earthlings are launching yet another assault on Mars this month, when no fewer than three spacecraft — two from NASA, one from the European Space Agency (ESA)--will take flight. If they deliver on even part of their promise, the missions could go a long way toward explaining the history, geology and — most intriguing — biology of Mars.
The trio of ships will take about seven months to reach Mars (the moon, by contrast, is just a quick three-day hop) and will follow flight plans that are in many respects quite similar. All are traveling to deep basins or other formations on Mars that look as if they were once flooded with water, a key requirement for life. All will also reach the surface in the Rube Goldbergian fashion pioneered by NASA's Mars Pathfinder in the summer of 1997, slowing their fall with a combination of heat shields, parachutes and, in the case of the U.S. landers, braking rockets. All will come to a bouncing landing swaddled in air bags.
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The ESA mission, set for launch on Monday of this week, was scheduled to be the first off the blocks, but it is the U.S. missions, scheduled for lift-off on Sunday, June 8, and Wednesday, June 25, that are likely to generate the most buzz — and not just because NASA has had 45 years to master the media spin cycle. What will make these expeditions stand out is that each will set loose on the Martian surface a remote-controlled rover even smarter and more photogenic than the miniature robot that captured the world's attention during the Pathfinder mission.
Pathfinder's rover was a toy-size machine. Barely 1 ft. high and 2 ft. long and weighing 24 lbs., it operated for three months and in all that time toddled across a stretch of Martian terrain little bigger than a football field. The new rovers are much closer to true space cars. Measuring 5 ft. tall from their wheels to the top of their camera masts, the 2003 models weigh about 400 lbs. each and should be able to cover up to 3,000 ft. in their 90 days of life — including many days they will spend standing around studying rocks. Each has a robot arm crowded with instruments: a rock-abrasion tool for boring into samples, a pair of spectrometers for analyzing mineral composition and measuring radioactive and electromagnetic radiation, and a microscopic imager. "The rovers are like field geologists going out to a new place," says Steve Squyres of Cornell University, NASA's principal investigator for the missions.
When they go, they will take 6 billion earthlings with them — after a fashion. Each rover carries an array of eight cameras, including one perched atop the mast for a you-are-there view. On the 1997 mission, the rover's camera was barely 10 in. off the ground. "It was like crawling around on your belly," says project scientist Joy Crisp of NASA's Jet Propulsion Laboratory.
For all their sophistication, the rovers won't be especially good at addressing the question people ask most: Is there now, or might there ever have been, life on Mars? The devices can make inferences, looking for evidence of water or iron. And if the microscopic imager sent back a picture of a microbial fossil, that would settle the question. But even NASA acknowledges that when it comes to searching for life, the Europeans have the edge this time.
The ESA probe comes in two parts: an orbiter that will stay aloft to conduct atmospheric studies and a lander that will descend to the surface. Dubbed Beagle 2, after Charles Darwin's famous specimen-collecting ship, the lander is only 3 ft. wide when packed for flight, but on the ground it will open like a flower and deploy an impressive array of equipment. Among the instruments are a drill capable of digging 5 ft. below the surface, 12 ovens that can heat samples to some 1,600ºF to generate carbon dioxide and a mass spectrometer to identify carbon isotopes, along with other elements. The lander can also measure ultraviolet radiation, temperature and atmospheric pressure, all variables that play a key role in biology. "If there is one mission capable of detecting past and present life, it will be ours," says planetary scientist Colin Pillinger, a professor at Britain's Open University and the man who dreamed up the project.
Whatever discoveries the trio of missions make, they are almost certain to rekindle some of the thrill of space exploration for a world that has seen precious little of it lately. Says Squyres: "Hey, if you can't have fun building spacecraft and sending them to Mars, give it up, man!"
- Jeffrey Kluger