The 1-ton Curiosity rover is the centerpiece of NASA's $2.5 billion Mars Science Laboratory (MSL) mission, which launched in late November. MSL's main goal is to determine if the Gale Crater area is, or ever was, capable of supporting microbial life.
To get at this question, Curiosity will investigate the different layers of Mount Sharp, which is taller than any peak in the continental United States.
Life as we know it depends on liquid water. So the rover will probably spend a lot of time poking around Mount Sharp's lower reaches, where Mars-orbiting spacecraft have spotted signs of minerals that form in the presence of water, such as clays and sulfates.
But there are reasons to climb higher. If Curiosity gets about 2,300 feet (700 meters) up the mountain, for example, it will cross a boundary, encountering layers that don't show signs of hydrated minerals. Higher still are strata that appear to have been deposited by the wind in a rhythmic pattern, perhaps indicating climate cycles, Grotzinger said.
Studying these higher layers could help scientists better understand why Mars shifted from a relatively wet world billions of years ago to the dry and desolate planet we know today — a transition marked by what Grotzinger dubbed the "Great Desiccation Event."