Rusty Schweickart (Apollo 9 astronaut) gave an interesting talk back on 2004 on "The Asteroid Threat Over the Next 100,000 Years" [1]. He said that we don't hav

Rusty Schweickart (Apollo 9 astronaut) gave an interesting talk back on 2004 on "The Asteroid Threat Over the Next 100,000 Years" [1]. He said that we don't have any technology (space capable nukes, gravity tractors, laser deflection, etc) to prevent impacts. As far as I know this is still true nine years later. He gave some useful probabilities for the likelihood of impacts with rocks of various sizes over long an short time scales, which puts the risk into context. He also explained that if you could develop the means to deflect an incoming rock away from the earth, the same technology could be weaponized to deliver impactors towards points on the planet's surface. Schweickart is involved with the B612 Foundation [2], who are doing work on impact prevention technology. He's co-chair of the NASA Task Force on Planetary Defense [3], which sounds cool. [1] http://longnow.org/seminars/02004/mar/12/the-asteroid-threat-over-the-next-100000-years/ http://longnow.org/seminars/02004/mar/12/the-asteroid-threat... [2] http://en.wikipedia.org/wiki/B612_Foundation http://en.wikipedia.org/wiki/B612_Foundation [3] http://www.nasa.gov/directorates/heo/library/nac/planetary-defense.html http://www.nasa.gov/directorates/heo/library/nac/planetary-d...