How to Defend Earth From Asteroids

Kill 'em

Suppose that NEOCam or Sentinel, or some ground-based survey, finds an asteroid with our number on it. What do we do?

One idea I'm fond of is the "kinetic impactor plus gravity tug," which I outline in the video. Basically, a space probe is sent to the killer asteroid at full speed, and slams into it. The force of the impact changes the velocity of the rock slightly, hopefully enough so that it will miss the Earth.

Just to make sure -- and also to make sure the asteroid doesn't simply circle the Sun a few more times and hit us at some later date -- a second probe is sent along, hitchhiking with the impactor. It can move into a station-keeping position near the rock, using its own gravity to very gently tug the rock into a safe orbit. This takes a lot of time, so the more lead-time we have, the better. In fact, it takes a lot of lead-time to build and launch the probes, as well as get to the asteroid. That's why finding all these asteroids as quickly as possible is so important.

Unfortunately, we don't have missions like these built and ready to go. We don't even have them designed! B612 is working on that, but NASA has not seriously investigated this kind of mission. Of course, NASA has a finite budget, so trying to find the money necessary to do this -- hundreds of millions if not billions of dollars -- is just not possible for them unless Congress and the president take it seriously and raise NASA's budget to do it.