The space agency said Wednesday that the project team and outside scientists have narrowed the options to two landing sites.
The nuclear-powered rover nicknamed Curiosity will touch down either in Gale Crater near the Martian equator or Eberswalde crater in the southern hemisphere.
Scientists are intrigued by a mountain inside Gale that contains rich minerals. They're also interested in Eberswalde because it's thought to be the site of a former river delta.
NASA will make a final decision later this month.
Engineers are prepping the rover for launch from Florida in November. It's scheduled to arrive on the red planet next summer and will study whether the site ever had an environment favorable for life to emerge.