Mars rover discovers ancient sea’s remains

The surf was up on ancient Mars.

It probably didn’t look like Cocoa Beach. It may have flowed and evaporated and flowed again, as deep as a puddle or a backyard pool. But there was almost certainly a sea, as revealed by ancient sediments identified by the robotic rover Opportunity, NASA announced Tuesday.

“This is a profound discovery,” said Ed Weiler, NASA’s associate administrator for space science. “It has profound implications for astrobiology. And, I would like to say, if you have an interest in searching for fossils on Mars, this is the first place you want to go.”

The discovery makes Meridiani Planum the No. 1 candidate for a 2009 mission better suited to look for evidence of past life, he said.

The Mars team announced a few weeks ago that the rocks at Opportunity’s landing site formed in either groundwater or flowing water. The scientists subjected their results to outside review before revealing Tuesday that a sea likely existed at Meridiani Planum.

The prime evidence for the body of water is twofold. One is the rocks’ composition — for instance, they hold a lot of bromine. “It’s characteristic of what you see in rocks on Earth that were formed by evaporation of sea water,” principal investigator Steve Squyres said.

The other clues were visual. The rover’s microscopic imager produced an elaborate mosaic of the sediments, showing layers at different angles that suggest the action of rippling water.

“There is still a lot we don’t know,” Squyres said, such as how big the sea was and how long it was there.

The $820 million twin rovers landed in January on opposite sides of the planet. Originally projected to roam for 90 days, the robotic geologists now are expected to drive into or beyond the summer, Weiler said.

Spirit is roaming in the 100-mile-wide Gusev Crater, thought to be an ancient lake, though Spirit hasn’t found anything akin to Opportunity’s catch. Water-formed sediments may exist below the volcanic rock in Gusev, Squyres said, or in the Columbia Hills, a mile and a half away from the rover. Spirit is undertaking a months- long journey to get there.

“I’ve still got a lot of hope and a lot of interest in what Spirit can find,” Squyres said.