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'7 minutes of terror' for next Mars probe
George Leopold
6/25/2012 10:54 AM EDT
WASHINGTON – On Aug. 5, 2012, after completing a nine-month, 354 million mile journey, mission controllers at NASA’s Jet Propulsion Laboratory will attempt to break the fall of a rover-carrying spacecraft traveling at about 13,000 miles per hour to zero and set down the rover in a Martian crater.
The landing sequence for the Mars rover Curiosity is called the “Seven Minutes of Terror.”
For the first time, NASA will use an untried descent and landing technique to lower Curiosity to the surface near Gale Crater using a sky crane. The entire landing sequence will be controlled by computers relying about 500,000 lines of code that will control no less than 76 rockets and thrusters.Mission managers won’t know whether it worked for 14 minutes, the time it takes a signal from Mars to travel back to Earth.
To the casual observer, using a sky crane to land on Mars may look crazy, but “it is the result of reasoned engineering thought,” argues JPL’s Adam Steltzner, chief engineer for the Mars Science Laboratory.
“If any one thing doesn’t work just right, it’s game over,” adds JPL’s Tom Rivellini.
Previous Martian landings used what amounted to air bags to break the fall of rovers. Curiosity is too big and heavy – about the size of an SUV – to use that landing method. Hence, JPL engineers came up with a system of breaking rockets, a huge parachute and the sky crane to slow Curiosity’s fiery entry into the faint Martian atmosphere and gently deposit it in Gale Crater, which is suspected of harboring signs of Martian life.
The JPL engineers and scientists are sticking their necks way out on this mission, and that’s precisely the type of technological risk-taking that is needed to explore the solar system with our marvelous machines.
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