What's Nasa doing about Killer Asteroids? Other than telling us to, well, 'pray'?
Actually, quite a bit. While we aren't yet able to send up cosmic heroes to drill into asteroids and blow them up with nukes, we are better able than ever to track and learn about potential threats before they happen.
In the video below Nasa says that its current plans revolve mainly around learning as much as we can about asteroids, what they're made of, how they move and where they come from.
Several spacecraft are currently scanning and rescanning the skies to build a better map of near-Earth asteroids, and to identify potentially hazardous ones.
So far we have discovered about 95% of the Earth-crossing asteroids bigger than a kilometre, Nasa said. But asteroids smaller than that are still capable of causing large amounts of damage.
Nasa's operation is coordinated by the Jet Propulsion Laboratory, while the European Space Agency and other space agencies have their own efforts too.
Nasa is also looking further afield to try and understand asteroids. Its Dawn mission will orbit the large asteroid Ceres in 2015.
More recently, Nasa announced a new plan to send a craft to an asteroid, capture it and then redirect it into a lunar orbit. The idea is then to go back to the asteroid and bring back samples.
"We can do these things, it's just a question of will," one Nasa engineer says in the video below. Check out the full clip to learn more about Nasa's plan.