NASA’s Perseverance rover landed on Mars in 2021 to search for signs of ancient microbial life and to help scientists understand the planet’s climate and geography. But another key objective is to pave the way for human exploration of Mars, and as part of that effort, the rover carries a set of five spacesuit material samples. Now, after those samples have endured four years of exposure on Mars’ dusty, radiation-soaked surface, scientists are beginning the next phase of studying them.