The InSight mission will settle a lander on the surface to study Mars' interior, rather than surface features, to advance understanding of the processes that formed and shaped the rocky planets of the inner solar system, including Earth, NASA's Jet Propulsion Laboratory in Pasadena, Calif., reported Wednesday.
Unlike previous Mars landings, what is on the surface in the touchdown area matters little in the choice of a site except for safety considerations, scientists said.
"We picked four sites that look safest," JPL geologist Matt Golombek, leader of the site-selection process, said. "They have mostly smooth terrain, few rocks and very little slope."
Cameras on NASA's Mars Reconnaissance Orbiter will focus on the semifinalists in the coming months to gather data to help select the safest of the four sites, JPL said.
"This mission's science goals are not related to any specific location on Mars because we're studying the planet as a whole, down to its core," Bruce Banerdt, InSight principal investigator at JPL, said. "Mission safety and survival are what drive our criteria for a landing site."