Deadly Asteroids: Can We Spot Them in Time? - NASA's Lindley Johnson and Ed Lu (Full Session)

The relatively small asteroid that exploded in the skies over Siberia last February, injuring over 1,000 people, was a shocking reminder that our planet is a target in a cosmic shooting range. Larger asteroids, from the width of a football field to the size of a small city, have the potential to be killers on a massive scale: in previous collisions with Earth, they have set off deadly blast waves, raging fires, and colossal tidal waves. Fortunately, space rocks like these can be deflected----if we have enough warning. But whose responsibility is it to survey for, and protect against, these potential doomsday bringers? Leaders of governmental and private organizations discuss the defense against the next strike.

Featuring Lindley Johnson, Ed Lu, and Paula Apsell

[robertgraybeard]

The "giggle factor" is a problem - "Are you serious?"  The very small probability of an astronomically catastrophic event is still something warranting concern.  Statistically,   events like the Chelyabinsk meteor (see the excellent Wikipedia article) occur several times a century.  Another informative read is  the "Introduction to Impact Craters" article at the Canadian Planetary and Space Science Centre, especially the illustration "Frequency of impact plotted against energy". Also, their website has the Earth Impact Data Base.  There is most likely a large crater near you but the odds are that it is so old that it's buried under mega-years of sediment.  Fortunately, the really big impacts are rare.  The "small" ones, the "city busters" happen on a century time scale.

I applaud the B612 Foundation's efforts.  The human race need not risk another Tungusta class event.