The Earth orbits the Sun among a swarm of asteroids whose orbits cross Earth’s orbit. These are not the asteroids that make up the asteroid belt between Mars and Jupiter, but rather the Near Earth Asteroids whose orbits take them much closer to the Sun, and who regularly approach the orbit of Earth. These asteroids are remnants of the formation of our solar system, and range in size from pebbles to many miles across.
More than a million of these Near Earth Asteroids are larger than the asteroid that struck Tunguska in 1908, and about 1,000 times more powerful than the atomic bomb dropped on Hiroshima. That asteroid was only about 40 meter across (less than the length of an Olympic swimming pool), yet destroyed an area roughly the size of the San Francisco Bay area, destroying 80 million trees over 1000 square miles.
Currently there is no comprehensive dynamic map of our inner solar system showing the positions and trajectories of these asteroids that might threaten Earth. The citizens of Earth are essentially flying around the Solar System with our eyes closed. Asteroids have struck Earth before, and they will again – unless we do something about it. The probability of a 100 Megaton impact somewhere on Earth each and every year is the same as the probability of an individual being killed in an automobile accident each year – about .01%. These odds are small, yet few among us would drive around each day without wearing a seat belt. What precautions are we taking with our planet?
We as a civilization have the capability to change the odds, and it is our mission to ensure that such impacts do not happen again. Less than 1% of the over one million asteroids greater than 40 meters have been identified to date. B612 will discover the other 99% – or 50 times more asteroids than have been found by all other telescopes combined.
Defending Planet Earth – report of the National Academies on asteroid surveys and deflection
Report of the NASA Advisory Council on Planetary Defense
A Brief Note on the Economic History of Space Exploration in America, by Alexander MacDonald
Asteroid Threats: A Call for Global Response, Association of Space Explorers, October 2008,