Planetary scientists studying the images relayed home by the Mars Pathfinder are finding signs that a great ancient flood on the Red Planet deposited rocks at the landing site, the Ares Valles region. But not all experts are convinced by the evidence, presented at a press conference today.
Images from the Viking orbiter in 1976 made plain that something had flowed across Ares Valles billions of years ago. Pathfinder project scientist Matthew Golombek of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, which is running the show, says the latest images suggest that a great catastrophe swept the region for weeks with a flood of a billion cubic meters per second, carrying a variety of rocks from distant highlands.
At the press conference, Pathfinder team member Michael Malin of Malin Space Science Systems Inc., in San Diego, pointed out 4-meter-high ripples in the nearby terrain, spaced 20 meters apart--the sort left by the late stages of a catastrophic flood. The flow direction suggested by the ripples matches the orientation of a stack of boulders piled up against each other, as if by a flood. It also matches the direction that orbiter images suggest the flood took. The coincidence of all three directions is "one piece of evidence that water flowed through here," says Malin. Once he gets some sleep after 24 hours of watching images come down from Pathfinder and planning the next round of activities, he expects to calculate just how catastrophic a flood it would have been.
Other experts have expressed doubts about this scenario. For example, planetary scientist Kenneth Tanaka of the U.S. Geological Survey in Flagstaff, Arizona, has trouble imagining that rocks like meter-size boulders near the landing site could have been carried that far by a flood of water. A water-rich slurry of rock, sand, and mud seems more likely to him.
The latest images and data from Pathfinder and the Sojourner rover can be seen at JPL's Web site.