Asteroids aren't something to be concerned about on a day to day basis, but once every couple hundred years or so, we get hit with a doozy. The last one hit Siberia in 1908, so it's about time to start to come up with a defense plan, and one new idea involves a bunch of tiny satellites with solar-powered lasers.
The idea with using lasers to deflect asteroids is not as cool as you might be thinking: there won't be any slicing and dicing of space rocks. Aww. That said, it is pretty clever. The idea is that a laser is used to vaporize bits of rock on the surface of an asteroid, and doing so generates tiny little puffs of thrust. Enough puffs over enough time will start to measurably alter the orbit of a space rock, no matter how large, and with enough lasers cooperating, it could even be accomplished on short notice.
Instead of relying on one giant laser to do this, the same objective can be accomplished with lots of little lasers working together. The advantages of using a swarm of mini satellites, instead of a Death Star, are numerous: they're simpler to design, cheaper to manufacture, if you need more power you can just launch more of 'em, it doesn't matter if you lose a couple, and their thermal exhaust ports are significantly smaller than a womp rat. And, if they're rigged up to power their lasers with solar energy, they can keep on firing for a couple billion years.
Engineers at the University of Strathclyde in Glasgow, who have been developing this idea, also suggest that micro laser sats could be handy in Earth orbit, zapping some of that dangerous orbital debris. And totally not zapping anything else. Nope, nothing else at all.