A six-year mission will soon bring back a few grains of soil that could explain how water arrived on our planet

In a few days, a capsule containing samples of soil from a distant asteroid will be released by a robot spaceship and dropped into Earth’s upper atmosphere. If all goes well, the container will parachute safely on to the Woomera test range in South Australia on 6 December, completing a mission that has involved a three-billion-mile journey across our solar system.

The information returned could help solve several major astronomical puzzles, say scientists – including the mystery of how water first appeared on our planet.

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