Curiosity, a one-ton geochemistry lab on wheels, landed on Mars in August. Its goal is to see if the crater at one time could have been hospitable for simple forms of organic life. Curiosity has spent the past six months exercising its suite of 10 instruments and its seven-foot robotic arm in a series of tests aimed at ensuring all the hardware is working well before the rover heads for Mt. Sharp, its ultimate destination.
The rover probably won't begin to explore Mt. Sharp for another year.
Curiosity has traveled slightly more than a quarter of a mile, as the crow flies, since landing. Along the way, however, scientists have chosen targets for instrument tests that have already provided insights into the crater's geologic past – including evidence for an ancient stream bed.
Yellowknife Bay, a portion of a larger feature the team dubbed Glenelg, is the lowest, hence oldest, formation the rover has explored. It hosts a number of clues that point to a watery past. [Editor's note: The original version of this paragraph gave an incorrect relative age for the Yellowknife Bay formation.]