May 16, 2008 -- Anything could go wrong during the May 25 descent and landing of the Phoenix probe on Mars. The braking rockets could peter out. The parachute could be a dud. The solar panels could jam, leaving the spacecraft powerless.
But one thing scientists aren't worried about is landing on a jackpot target. Where Phoenix is heading, it's all good terrain.
"Everything that we know says wherever we land we're going to see ice close to the surface," Ray Arvidson, a co-investigator on the Phoenix science team, told Discovery News. "Everyone would be very, very surprised if there's not ice and if it's more than a matter of inches beneath the soil."
The landing zone is farther north than any site previously explored; it was selected to give scientists an opportunity to analyze a bit of Martian water. Most of the planet's water has disappeared, though signs of its presence are carved into rocks and chemically locked in many of its minerals.
The Mars rover Opportunity, for example, had the good fortune to plop down into a shallow ancient lakebed along the equatorial region known as Meridiani Planum. However, its twin Spirit, located on the other side of the planet in Gusev Crater, initially found scant evidence of past water. It wasn't until the rover headed up some nearby hills that the story changed dramatically.
Unlike the rovers, Phoenix won't have to go looking for its science. That's a good thing considering the lander has no wheels. Adding mobility to the spacecraft would have exceeded the mission costs, which are about $500 million.
NASA approved the Phoenix mission in response to the 2002 discovery by the orbiting Odyssey spacecraft that the Martian poles have a layer of ice near the surface.
Rather than wheels, Phoenix has a small backhoe to dig through the soil and scoop up ice samples. It also has a variety of science instruments to test the ice and soil and determine their components.
The most pressing question on scientists' minds: Are there organics?
"The discovery of organic materials, which haven't been found on Mars yet -- in ice or in soil -- would be an amazing discovery," said Arvidson, a planetary scientist with Washington University in St. Louis. "It would probably lead to a replanning of the Mars mission architecture for the next decade."
Scientists are chipping away at one of the fundamental questions of human existence: Is life unique on Earth or does it exist elsewhere in the universe?
As far as we know, water is one of life's essential ingredients.
NASA's previous journeys to Mars have revealed water was once as plentiful on Earth's neighbor as it is on the home planet. With Phoenix, scientists hope to get a look at what was left behind after the surface liquids vanished.
Discovery News will be blogging live from the Phoenix flight control center at the Jet Propulsion Laboratory in Pasadena, Calif., beginning Thursday, May 22.
Related Links:
Irene Klotz's blog: Free Space