Mars Probe Heading for Sea of Buried Ice

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.