A mysterious 3-mile-high (5 kilometer) mountain called Mount Sharp rises from Gale's center. Mount Sharp's many layers preserve a record of Mars' environmental conditions going back perhaps 1 billion years or more, scientists say. Curiosity will read these layers like a book to gain insights about how the Red Planet has changed over time.
Mars-orbiting spacecraft have spotted signs of clays and sulfates — materials known to form in the presence of water — in Mount Sharp's lower reaches. Since all life on Earth is intimately tied to water, Curiosity will doubtless spend a lot of time poking around the mound's base.
But the MSL team also wants the rover to climb high enough to reach the mountain's drier layers, so it can help investigate why Mars transitioned from a relatively warm and wet planet to the frigid and dry world we know today.
"Something happened on Mars, and it went dry, and that's what we have today," MSL chief scientist John Grotzinger, of Caltech in Pasadena, told SPACE.com. "The question is, what was that event? What was that trigger? What happened environmentally? My hope is that we'll get some insight into this Great Desiccation Event." [7 Biggest Mysteries of Mars]
To cross the wet-dry threshold, Curiosity will likely have to climb about 2,300 feet (700 meters) up Mount Sharp. But that shouldn't be too difficult, as the mountain has relatively gentle slopes, like the huge volcanoes of Hawaii, Grotzinger said.