The largest, most advanced rover NASA has sent to another world touched down on Mars Thursday, after a 203-day journey traversing 293 million miles (472 million kilometers). About the size of a car, the robotic geologist and astrobiologist will undergo several weeks of testing before it begins its two-year science investigation of Mars’ Jezero Crater. A fundamental part of its mission is astrobiology, including the search for signs of ancient microbial life.