Northeast Syrtis, which got the second highest number of votes, used to have hot water circulating under its crust. Finally, there's Columbia Hills -- the group's third and most controversial choice where the Spirit rover used to roam. Spirit found silica rocks in the site resembling hydrothermal mineral deposits on Earth. Some of the people who attended the workshop didn't think Mars 2020 would be able to shed light on whether the rocks could truly be linked to life.

Mars 2020 will spend two years drilling for samples from the final site NASA picks. Whether or not those samples make it back to Earth depends on a follow-up mission, though. The rover won't be coming back home, so the agency has to figure out a way to retrieve them. If NASA succeeds, they'll be the first Martian rocks we'll ever examine that aren't meteorites, which don't have the samples' geologic context.