It sounds like a Hollywood thriller, but the phrase describes the anxiety NASA is expecting as its car-sized robotic rover tries a tricky landing on Mars late Sunday.
Skimming the top of the Martian atmosphere at 13,000 mph, the Curiosity rover needs to brake to a stop
-- in seven minutes.
The rover is headed for a two-year mission to study whether Mars ever had the elements needed for microbial life. Because of its heft, the 2,000-pound robot can't land the way previous spacecraft did. They relied on air bags to cushion a bouncy touchdown. This time NASA is testing a brand new landing that involves gingerly setting down the rover similar to the way heavy-lift helicopters lower huge loads at the end of a cable. How hard is it? "The degree of difficulty is above a 10," says Adam Steltzner, an engineer at NASA's Jet Propulsion Laboratory, which manages the mission.
And American University space policy analyst Howard McCurdy says: "It would be a major technological step forward if it works. It's a big gamble."
A communication time delay between Mars and Earth means Curiosity will have to nail the landing by itself, following the half-million lines of computer code that engineers uploaded to direct its every move.
After an 8 1/2-month, 352-million-mile journey, here's a step-by-step look at how Curiosity will land:
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Ten minutes before entering the Martian atmosphere, Curiosity separates from the capsule that carried it to Mars.
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Turning its protective heat shield forward, it streaks through the atmosphere at 13,200 mph, slowing itself with a series of S-curves.
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Seven miles from the ground at 900 mph, Curiosity unfurls its enormous parachute.
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Next it sheds its heat shield and turns on radar to scope out the landing site. Now it's 5 miles from touchdown and closing in at 280 mph.
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A video camera aboard Curiosity starts to record the descent.
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A mile from landing, the parachute is jettisoned.
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Curiosity is still attached to a rocket-powered backpack, and those rockets are used to slow it to less than 2 mph.
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Twelve seconds before landing, nylon cables release and lower Curiosity. Once it senses six wheels on the ground, it cuts the cords. The hovering rocket-powered backpack flies out of the way, crashing some distance away.
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Online:
NASA's Mars site: http://mars.jpl.nasa.gov/
NASA's YouTube video "Seven Minutes of Terror":
http://www.youtube.com/watch?vKi-Af-o9Q9s
[Associated
Press; By ALICIA CHANG]
Follow Alicia Chang's Mars coverage at
http://twitter.com/SciWriAlicia.
Copyright 2012 The Associated
Press. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed.
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