"Since I am the mission manager and not representing the science team I won't comment on their speculations," he said. "But there is a lot of enthusiasm, probably as much enthusiasm as we've ever had by the science team and a lot of intense discussions over these last several days."

It was not certain when scientists would comment on their findings. The next formal press conference was set for Thursday at JPL in Pasadena.

"I know they're not ready to talk ... they're speculating a lot at this point," JPL spokesman Guy Webster said.

"There's a lot of things to chew on," Manning added.

"Once we got close the images are much more striking, and although the science team is very reluctant to make any decisions about what they're looking at, there's a lot of information in the pictures they've been looking at," Manning said.

Manning predicted that Opportunity would spend "a fair amount of time" at the outcrop before leaving the area to search for other sites to explore in an area known as Meridiani Planum.

"There's just too much excitement, too much to see," he said.