The Earth was hit by 26 asteroids that exploded with a force of between one and 600 kilotons between 2000 and 2013. And no one knew they were coming.

A study was carried out by the B612 Foundation, a group set up by three former astronauts, who are worried about the threat of asteroids to life on Earth.


Dr. Ed Lu, the foundations CEO, said: "While most large asteroids with the potential to destroy an entire country or continent have been detected, less than 10,000 of the more than a million dangerous asteroids with the potential to destroy an entire major metropolitan area have been found by all existing space or terrestrially operated observatories. Because we don't know where or when the next major impact will occur, the only thing preventing a catastrophe from a 'city-killer' sized asteroid has been blind luck."

In 2013, over a thousand people were injured when an asteroid exploded over Chelyabinsk.

NASA's Spaceguard project has kept track of larger clumps of space junk but is missing a lot of the smaller debris that could just wipe out a city or cause a tsunami.

The B612 Foundation wants to build and launch a privately funded orbital asteroid detector, dubbed the Sentinel Space Telescope Mission, that could conceivably find 200,000 smaller asteroids a year after its planned 2018 launch.

The study has found that most of the asteroids burn up in earth’s atmosphere and cause little harm, but sooner or later, probability suggests, one will hit and cause major damage.