It’s a familiar disaster film scenario that was put on-screen twice in 1998’s Deep Impact and Armageddon: an asteroid (or comet) is on a collision course with Earth. All options have been exhausted, so a plucky team of astronauts and engineers must fly out and destroy it via nuclear warheads. It makes for a dramatic film (and plenty of technobabble), but could it actually work? Signs point to “probably”.
According to computer simulations done at a US Department of Energy lab in Los Alamos, New Mexico, a 1-megaton nuclear weapon could successfully “disrupt” the rocks in 1,650-foot-long asteroid and “fully mitigate” the danger it poses to the planet. One would hope the blast of such a warhead would do the job, seeing as it would be about 50 times more powerful than the 1945 US attack on Nagasaki, Japan. In Armageddon, Bruce Willis and Ben Affleck’s team of oil riggers-turned-astronauts had to deposit the warhead in a deep crevice to successfully break up the dangerous space rock, but these new simulations suggest that isn’t so. The simulations were successful with a blast at the asteroids surface, which would make the added danger and complication of actually placing a nuclear device deep within an asteroid unnecessary.
That doesn’t mean going nuclear is the best first option, though. Like in many of those disaster flicks, shattering an asteroid could cause sizable chunks of rock to rain down on the planet. Instead of busting it up, we could just alter its path to a less dangerous one. There are a couple of ways to carry this out. The more dramatic (but less elegant and precise) way is to simply hurtle a spacecraft at the asteroid with enough force to knock it into a new course. Preferable to this “impactor approach” would be the evocatively titled “gravity tractor technique,” in which a robotic probe is sent out to ride along with the asteroid for months or years. The additional gravity exerted by the probe would gradually pull the asteroid into a new orbit.
While we’ve never put any of these options into practice in an situation with a potentially destructive asteroid, other excursions and experiments along these lines prove that we have the technology and skill to implement them as defensive measures. That’s good, seeing as “it’s just a matter of time before another big space rock lines Earth up in its sights“.