Removing Orbital Debris with Lasers. How's that for a great research paper title?
Most of you are probably aware of the existence of space trash—that collection of disused satellites, lost tools, spent rocket boosters, and various other flotsam that is starting to become a physical hazard to the objects we actually want circling the globe in Low Earth Orbit. Currently, we get around the problem (mostly) by attaching bumpers to spacecraft and to the ISS. But there are lots of different ideas for how we could deal with the problem of space junk in a more proactive way.
The team of private and government scientists who wrote this paper want to aim lasers at space junk. But not like you're thinking. Instead of blowing up our trash in a life-size game of Asteroid (something that would really only succeed in creating a lot more, smaller pieces of space junk) the team wants to use laser pulses to alter the momentum of large pieces of junk, slowing those pieces enough that they fall out of orbit and back to Earth.
Such a system could be used to precisely time the reentry of dead satellites and other junk, ensuring that when chunks of metal fall out of the sky they won't be falling on any densely populated regions. That's one of the major benefits to this proposal.
The major detriment: Politics. How do you build a laser big enough to knock space junk out of orbit without convincing half the world that what you've really built is a giant death ray? That's something the authors hope to avoid through international cooperation.
Image: Goddard Celebrates International Observe the Moon Night with Laser Show, a Creative Commons Attribution (2.0) image from gsfc's photostream