Jezero crater and its fossil river delta is a favored landing site for NASA’s Mars 2020 rover. 

NASA/JPL/JHUAPL/MSSS/BROWN UNIVERSITY

Scientists home in on landing site for the next Mars rover

After 3 days of intense debate, a nonbinding vote by planetary scientists meeting in Glendale, California, resulted in a virtual tie between several candidate landing sites for NASA’s next $2.5 billion Mars rover, due for launch in 2020.

The straw poll is the culmination of years of scientific and engineering analysis of three NASA-approved sites: Jezero, a fossilized delta that spills into an impact crater; Northeast Syrtis, a stretch of ancient crust that may have been created by underground mineral springs; and Columbia Hills, a potential former hot springs previously visited by the Spirit rover. Earlier this year, the team added to the mix a fourth site, nearly identical in composition to Northeast Syrtis, called Midway, with the potential that a mission could visit Jezero and then Midway, or vice versa.

All four sites were evaluated both for their suitability as the primary landing site and as an area for continued exploration following the rover’s first couple of years. In turn, each site was rated for the value of the science the rover could conduct itself, with its fleet of instruments, and the value of the samples that it will drill for return to Earth.

With 158 votes tallied, Jezero and Northeast Syrtis rated in a near tie for their value as a primary destination, with Midway close behind. Jezero and Midway, in turn, rated higher as destinations for an extended mission. Across both categories, only Columbia Hills was rated much lower. Although the method of the vote—rating candidates—did not lead to a clear recommendation, the combined ratings do seem to endorse the Midway-Jezero pairing. As Ryan Anderson, a planetary scientist at the U.S. Geological Survey’s Astrogeology Science Center in Flagstaff, Arizona, put it, “A mega-mission in either direction looks pretty likely.”

What the vote means will be up to the Mars 2020 team and, ultimately, NASA’s science chief, Thomas Zurbuchen, who made a brief appearance at the workshop. Although a plan to return the rover’s samples is not finalized, Zurbuchen noted, a mission should come into view by early 2020, after Europe, a vital potential contributor, finalizes its next round of science funding. “Make no mistake,” Zurbuchen told the scientists, “we want those samples back.”

Read our in-depth preview of the landing sites, including the rise of Midway here.