Talk about seeing a world in a grain of sand. A sprinkling of asteroid dust that slipped into Japan’s Hayabusa probe when it touched down on the asteroid Itokawa six years ago has revealed surprising ...

Asteroids come in a broad range of sizes and sorts. Some, like Psyche, are rich in metal and likely cores from bygone planetesimals. Others are like Vesta, hefty round bodies covered with craters and ...