Arden Albee, the Mars Global Surveyor project scientist, said the new data could throw open a window on that ancient Mars by revealing precise locations that future missions could target. The work will be published in Friday’s issue of the journal Science.

"The impact is more is we have the potential for understanding an early wet period than it is a discovery, because people have long hypothesized an early warm and wet Mars," Albee said.

As such, the literally hundreds of outcroppings that show evidence of layering are sure to be considered as destinations for future robotic missions to Mars.

"The finding of layered sedimentary deposits is something that biologists have been hoping for," said Ken Nealson, director of the Center for Life Detection on JPL’s Pasadena, California campus. "Perhaps the favorite sites for biologists to search for fossils or evidence of past life on Earth are layered lake or oceanic sediments such as in these sites."

Huntress said what’s needed now is a surface investigation of the sites in question.

Accessing any of the features detailed by Malin and Edgett may prove difficult to do. Most of the outcroppings lie in craters and chasms – precisely the type of terrain conservative engineers are loath to steer even the most robust spacecraft.

Even though either of the twin rovers NASA will send to Mars in 2003 could land within the confines of one of the larger craters that contains evidence of layered rock, Malin said he doubted the space agency would take such a gamble.