Travelling at more than 10 km/s (23,000 mph), it passed Earth at a distance less than a third the distance to the moon. Had that chunk of space debris hit Moscow or London or Hong Kong instead, the devastation would have been staggering. Asteroid! The Doomsday Rock tells the story of a multi-national team of gifted scientists who believe and intend to prove that the world's largest environmental disaster is entirely preventable. The documentary follows the evolution of scientific knowledge and public attitudes about comets and asteroids, and visits scientists at NASA's Jet Propulsion Laboratory who accurately predicted the timing and size of an asteroid that crashed into Jupiter, and mathematicians and astrophysicists who calculate the exact position in space of each asteroid and comet.