Asteroid warning system in the pipeline
NASA, universities and private groups in the US are working on asteroid warning systems that can detect objects from space like the one that struck Russia last week.
But the US space agency reiterated that events like the one in the Urals, which shattered windows and injured nearly 1,000 people, are rare.
NASA estimates that before entering the Earth's atmosphere above Russia, the asteroid measured 56 feet in diameter and weighed 10 tons.
