Deflecting an Asteroid Before It Hits Earth May Take Multiple Bumps

After years of shooting meteorites with a special gun owned by NASA, researchers highlighted challenges for a preferred method of planetary defense.

There’s probably a large space rock out there, somewhere, that has Earth in its cross hairs. Scientists have in fact spotted one candidate — Bennu, which has a small chance of banging into our planet in the year 2182. But whether it’s Bennu or another asteroid, the question will be how to avoid a very unwelcome cosmic rendezvous. For almost 20 years, a team of researchers has been preparing for such a scenario. Using a specially designed gun, they’ve repeatedly fired projectiles at meteorites and measured how the space rocks recoiled and, in some cases, shattered. These observations shed light on how an asteroid might respond to a high-velocity impact intended to deflect it away from Earth. At the 84th annual meeting of the Meteoritical Society held in Chicago this month, researchers presented findings from all of that high-powered marksmanship. Their results suggest that whether we’re able to knock an asteroid away from our planet could depend on what kind of space rock we’re faced with, and how many times we hit it.