The history of exploration on Mars reads like a good book with twists and turns and unexpected findings. None of these findings, though, have turned up evidence of life. After decades of searching, scientists are hopeful a NASA rover called Perseverance, which touched down on Mars in February, will reveal ancient, long-dead, fossilized life. Sarah Stewart Johnson, planetary scientist and author of The Sirens of Mars, says Perseverance is scouring the surface of a crater and producing rock samples. She says finding signs of life on the Red Planet would be an inspiration to humankind and make us think differently about our place in the cosmos. She speaks with Marina Koren, staff writer for The Atlantic.