Curiosity, the $2.5 billion rover formerly known as the Mars Science Laboratory, is heading to Gale Crater, NASA announced today at a press conference at the National Air & Space Museum.

The site, a 5-kilometre deep crater with an intriguing central mound that rises above the crater’s rim, won out over three other finalist sites in a contentious process that began about 5 years ago with 60 potential sites, and ended with just one. Project scientist John Grotzinger said that Gale, which may have been partially or even fully filled with water, offered the best opportunities. “In the end we picked the one that felt best,” he says.

The 900 kilogram, truck-sized rover, powered by a radioisotope source, is a major leap over the 2004 Mars Exploration Rovers Spirit and Opportunity, not just in size, but in scientific capability. It will carry a suite of 10 instruments, including trace gas sniffers and spectrometers that can identify minerals created in the presence of water. Nine months after Curiosity is launched later this year, it will fire reverse thrusters and land near the Mars equator via a new “sky crane” technology, which NASA engineers say offer more precision and safety than the giant air bags that cushioned the fall of Spirit and Opportunity.

Curiosity will have science to perform right at the start. At the the landing ellipse, just within the crater walls, lies an alluvial fan — deposits which could have been brought tumbling down by water, through a small breach in the crater rim. But the main meal will be the long track to the five-kilometre high mound in the middle, and the climb up it. Geologists are intrigued by the spectroscopic signatures for sulfates and clays that have been detected in the mound from orbiting satellites. But they are more excited by the stacked, layered mound, which offers the chance for an orderly narrative through several hundred million years of ancient Mars history. Parts of this mound are also heavily eroded into canyons, suggesting that water may have played a role not just on the crater floor. Grotzinger notes that the mound — a gently sloping mountain, really — is as tall as Mount Whitney in California. “This might be the tallest mountain in the Solar System that we can climb with a rover,” he says.