The rover is expected to reach a richer slice of Martian history next year when it begins examining layers of sediment in a mountain rising from the floor of the crater.

“We’re starting to find the spices that make a stew tasty. There are the basic ingredients that you expect to be there, but it’s how you combine them and the minor ingredients that really turn out to be interesting,” Grotzinger said.

“What this mission is about is integrated science. There is not going to be one single moment where we all stand up and, on the basis of a single measurement, have a hallelujah moment.”

The $2 billion Curiosity mission, which is slated to last two years, is NASA’s first astrobiology mission since the 1970s Viking probes.