The Change Mariner

Mars Rock Offers Hint of Ancient Water

New York Times:

"We are about to embark on what is arguably going to be the coolest geologic field trip in human history," Dr. Squyres said. At first glance, the outcrop looks huge, like the rock formations of Yosemite National Park.

"It's actually really tiny," Dr. Squyres said.

The semicircle of rock, part of the rim of the small, shallow crater where the Opportunity landed, is about 30 yards long, but only a foot and a half high at most. The rover, when it gets there, will tower over the rocks.

"The rover drivers, when they first saw this, they went `yikes!' " Dr. Squyres said. "But when they realized the scale of those things, it was not quite the imposing obstacle it appeared to be."

The scientists also realized how small the layers are, each perhaps half an inch thick. "So that really places some constraints on what it could be," Dr. Squyres said. "These aren't lava flows."

The light-colored bedrock is believed to underlie the whole region where the Opportunity landed, known as Meridiani Planum and spanning tens of thousands of square miles. Dr. Knoll said the vast expanse of rock led him to discount the possibility that the rocks formed out of sediment blown in by wind.