UPDATED: June 10, 2021 11:59 IST The SUV-sized rover is the most advanced laboratory on wheels to have landed on Mars. (Photo: Nasa) The Perseverance rover trundling the surface of Mars began its most critical mission phase — looking for ancient microbial life. This phase of the mission began on June 1, the Joint Propulsion Laboratory said in a statement as the rover left the “Octavia E. Butler” landing site. During the first few weeks of the science operations phase, the rover will drive up to a low-lying scenic overlook in the Jazero crater, from where it will survey some of the oldest geological features using its auto-navigation and sampling systems. "The goal is to find four spots to collect samples," JPL said.