The Chelyabinsk meteor was a small asteroid approximately the size of a six-story building that without warning broke up over the Siberia city of Chelyabinsk in February 2013.
The resulting blast was 30 to 40 times more powerful than the atomic bomb dropped on Hiroshima, shattering glass and injuring about 1,200 people.
Professor Harris believes the technology remains incapable of detecting such rogue space rocks.
He said: “And anything like that, I’d say up to 50 metres or so these days, could slip through defences, and hit the Earth without any warning at all, as Chelyabinsk did.
source: express.co.uk