Famed for their ability to inflict Armageddon from outer space, asteroids are now revealing the secrets of how they are responsible for both life and death on our planet.
Armed with an array of powerful telescopes, scientists are finding up to 3000 new asteroids every night. And some are heading our way.
But astronomers have discovered that it’s not the giant rocks that are the greatest danger – it’s the small asteroids that pose a more immediate threat to Earth.
Researchers have explained the photon propulsion that propels these rocks across space, and have discovered that some asteroids are carrying a mysterious cargo of frost and ice across the solar system that could have helped start life on earth.

Part 7: Asteroids - Worlds that Never Were
Asteroids have a bad reputation as deadly rocks from space. They wiped out the dinosaurs and will be back for us. But that's only half the story. Ancient asteroids built the Earth. And they may have brought life to its barren surface. Asteroids will shape our future as much as our past. They are the perfect location for deep space colonies and could be the stepping stones that eventually send humans out into the cosmos. From icy worlds with more fresh water than Earth to flying mountains of pure metal, a hundred miles wide, scientists are striving to unlock their secrets. Could these enigmatic space rocks hold the key to how life in the Universe arises and is extinguished?