After years of debating where on Mars the next NASA rover should land, it comes down to the final four.
Scientists meeting this week in California get their final chance to make a case for the place that they want the rover Curiosity to go.
The candidates include: Gale crater, Mawrth Vallis, Eberswalde crater and Holden crater.
Curiosity is slated to launch in late November and arrive at the red planet next summer.
After the meeting, members of the project will meet to weigh the pros and cons and come up with a recommendation to NASA.
The space agency has the final say. A decision is not expected until late June or July.
Explore further: NASA head views progress on asteroid lasso mission