After a seven-month journey, NASA's Perseverance rover prepares to touch down on Mars on Thursday after first negotiating a risky landing procedure that will mark the start of its multi-year search for signs of ancient microbial life. "We know Mars had water at one point, we know that it was habitable, it could have had life at one point. That's why we're going back and looking for it," Perseverance deputy project manager, Jennifer Trosper, tells AFPTV.