This month, a drilling platform will rise in the Gulf of Mexico, but it won’t be aiming for oil. Scientists will try to sink a diamond-tipped bit into the heart of Chicxulub crater—the buried remnant of the asteroid impact 66 million years ago that killed off the dinosaurs, along with most other life on the planet. They hope that the retrieved rock cores will contain clues to how life came back in the wake of the cataclysm, and whether the crater itself could have been a home for novel microbial life. And by drilling into a circular ridge inside the...