Scientists were stunned on May 30 when a rock that NASA’s Curiosity Mars rover drove over cracked open to reveal something never seen before on the Red Planet: yellow sulfur crystals.Since October 2023, the rover has been exploring a region of Mars rich with sulfates, a kind of salt that contains sulfur and forms as water evaporates. But where past detections have been of sulfur-based minerals — in other words, a mix of sulfur and other materials — the rock Curiosity recently cracked open is mad...