New Scientist has an interesting look at research into the best way to stop an asteroid on a trajectory for a deadly impact with the Earth.
To investigate the best way to deflect this and other asteroids onto a harmless path, a team led by David Dearborn of the Lawrence Livermore National Laboratory in California has modelled the impact of a nuclear explosion on an object’s trajectory. Their virtual asteroid was 1 kilometre in diameter and made of rocky rubble loosely bound together by gravity, which is considered by many planetary scientists to be the most likely composition for small asteroids.
Typically the “nuke the asteroid” scenario is ridicule on a number of grounds, but Dearborn found if you can get to the asteroid soon enough — in his model, 30 years prior to the projected impact with the Earth — a 100 kiloton nuclear blast 250 meters behind the asteroid was quite effective at altering the asteroid’s trajectory so it missed the Earth. The nuke in the model did cause about 1 percent of the asteroid to break off, but only 1 part in a million of that debris was still headed on a collision course with the Earth.
And, of course, unlike a lot of other techniques that have been proposed for steering deadly asteroids off of a collision course is that we actually have nukes sitting around and quite a bit of experience using them.
The New Scientist piece does look at some of these other proposals, including an intriguing one using satellite-based lasers to vaporize small section of an oncoming asteroid. That would create a plume of gas that would then propel the asteroid on a slightly different path, hopefully altering it enough to keep it from impacting the Earth.