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The Plan to Redirect Asteroids With Lasers and a Mothership

Getting ready for not-the-end of the world.
Dr. Richard Fork with the plan to save the world via UAH

Asteroids, man. Turns out, there’s a ton of them near the Earth and eventually one’s going to swing right into us. In fact, they swing into Earth all the time. So, let’s say you want to redirect a little asteroid, one that’s, oh I don't know, around the size of the one that blew everyone’s minds when it exploded over Chelyabinsk, Russia in February. How would you do?

Lasers. Naturally, you’d use lasers, right? That’s what Richard Fork, an electrical and computer engineering professor at University of Alabama, Huntsville proposed to NASA. And unlike other space-based, laser protection systems, Fork thinks this one could be feasible in the relatively near future. "Much of the required technology is existing stuff that is out there now. It's not too expensive," Fork said. "It's doable in a few years if the effort is well-funded."

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It works like this—one controlling “mothership” and multiple microspacecraft are sent at the asteroid. The smaller spacecraft orbit within a few kilometers of the asteroid, and at the optimal moment bombard it with trains of ultrashort optical pulses, reflected into just the right spot. The lasers heat the asteroid in those just-right spots, which cause “plumes of ejecta” that propel the asteroid off its Earth-smashing course, and off to somewhere else.

There would likely be three optical pulses at once, each about a millimeter in diameter. "We propose to use a carefully balanced thrust delivered so as to push the asteroid in an optimally efficient manner,” said Fork. “We can both choose where the asteroid will go and also verify, after an adequate number of such events have occurred, that the desired deflection is being successfully achieved.”

Right now the system is only ready to take on smaller, non-apocalyptic asteroids. “Our concept is to go out after the little guys and then as we learn more, we can take on the big guys," said Dr. Fork. "As far as we're concerned, we have identified a technically calculable and optimally efficient means of deflecting small asteroids of the Chelyabinsk class. This method can be explored, quantitatively tested and verified in the very near future and then scaled to address larger asteroids and, possibly, eventually even comets."

The trick with scale is getting that much power in the right place. “One pulse, during the brief time the propulsive force is applied, provides as much power as all three Space Shuttle main engines when they are firing together," Fork said. "The challenging technical task our group is addressing is that of delivering the required total number of these pulses to an Earth-threatening asteroid so as to apply this highly effective propulsive force efficiently with each delivered pulse.”

Fork’s group is about fifty students down in Alabama in a laser systems class and a special topics course called Cooperative Quantum Energy. They might be a ragtag bunch of misfits—and I hope to God that they are—but they’re taking on a plausible world-ending scenario with lasers. You gotta respect that.