A new report from the National Research Council entitled, "Limiting Future Collision Risk to Spacecraft: An Assessment of NASA's Meteoroid and Orbital Debris Programs," says we've already managed to pollute Earth's orbit with enough space junk to pose a serious risk to future space flight missions.
The study actually says we've reached a "tipping point" in the amount of man-made crap floating around the planet, "with enough currently in orbit to continually collide and create even more debris, raising the risk of spacecraft failures."
Space junk has been piling up at an impressive rate in recent years. In 2007, China aimed destructive laser beams at a decommissioned weather satellite (they were testing out an anti-satellite weapon, 'cause that's how they roll), which disintegrated the device into 150,000 little pieces. Then, a couple of years later, two satellites collided in orbit, contributing even more debris. Last June, some of this floating space crap narrowly missed colliding into the International Space Station.
"Those two single events doubled the amount of fragments in Earth orbit and completely wiped out [the cleanup efforts of] the last 25 years," said Donald Kessler, who led the research.
As for concrete solutions, no one has any. (Duh. We've filled outer space with the equivalent of a million little discarded Starbucks Doubleshot cans.) But a Pentagon think tank has suggested what they call "Project Catcher's Mitt," which would somehow — harpoons? Nets? World's biggest Dyson? — "net" the space debris. Get on it, somebody!