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Dirt Digger Rocketing Toward Mars
Even if organic molecules pop up, they could be from incoming meteorites, Boynton noted. "It is important, I think, to keep in mind that we are just looking for organic molecules to see if the conditions are right that they could survive," he said, "and that we aren't really going to be making any inference about whether these molecules are indicative of life."
Mars landings are especially risky. Only five of the 15 U.S., Russian and European attempts have worked, all of them American successes beginning with the 1976 Viking touchdowns. Given those odds, the Phoenix team said it did everything possible to test for failures and will continue to do so as the spacecraft flies to Mars. The entire mission costs $420 million.
  This artist rendering released by NASA shows the Phoenix Mars Lander's powered landing on Mars. The Phoenix Mars Lander, managed by the Jet Propulsion Lab in Pasadena, was scheduled to blast off before sunrise Saturday, Aug. 4, 2007, aboard an unmanned rocket. Its journey to Mars will take nearly 10 months and cover 422 million miles. (AP Photo/NASA, Corby Waste) (Corby Waste, Artist - AP) 
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NASA has never attempted to land a spacecraft on Mars at such a high northern latitude. A lander intended for the red planet's South Pole went silent immediately upon arrival in 1999. That failure, combined with the loss of the companion Mars orbiter, prompted NASA to cancel a 2001 lander mission. The parts from that scrapped mission were used for Phoenix, thus its name, which alludes to the mythological bird that rises from its own ashes.
Mars' North Pole would have been too cold for Phoenix to operate, and so scientists opted for a little lower latitude for touchdown. Phoenix will be shooting for 68.35 degrees north latitude, comparable to Greenland or northern Alaska, and 233 degrees east longitude. The lander will parachute down, with pulse thrusters easing its final descent.
Scientists chose the flattest, rock-free zone they could to ensure success. The target landing area is "Kansas flat," according to the spacecraft team, with few if any big rocks that could overturn the stationary three-legged lander or bump against its circular solar panels and jam them. The 772-pound lander will stretch 18 feet across once its solar panels are deployed on Mars, and its weather mast will tower 7 feet.
Phoenix should help pave the way for human visitors, especially if it confirms the presence of water ice in large amounts near the pole, said Michael Meyer, NASA's lead Mars scientist. That would be a tremendous resource, he noted. But if organic matter is indeed found, it could pose a dichotomy: "As Mars gets more interesting, you may not want to send humans right away until you learn out a little bit more about the red planet and find out whether or not life ever got started there."
Science fiction writer Kim Stanley Robinson is thrilled to see another robot headed to Mars and is confident humans will follow. His novel "Green Mars" is one of dozens of writings going up on a disk aboard Phoenix.
"When people get there, they'll be able to do on the ground what maybe 100 robotic missions would have been able to do," Robinson said.
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