Did you watch the movie Wall-E? If so, you might remember the part where Wall-E leaves Earth and goes up to the space colony where the main part of the movie takes place. The rocket he's on, as it's leaving Earth's atmosphere, plows through a thick layer of space junk, almost so dense as to block out the sun.
That scene is there for a reason: more stuff is being launched into orbit every day, all of it at risk of slamming into each other (and thereby creating more pieces of space junk), and much of it does. And the hell of it is, nobody's ever been able to really figure out how to get it down once they're done using it before its orbit decays and it comes down on its own, possibly on someone's head. (Second pop culture reference: Dead Like Me, the events of which were kicked off when the main character was killed by a plummeting space station toilet seat.) The longer it takes us to figure out, the more stuff goes up, and the bigger risk there is that something crashes into something else, possibly something important.
For example, the International Space Station, which had to dodge a piece of junk last month.
It doesn't take much to cause havoc, given the speeds at which things typically orbit. Anything can wreak havoc if it's going fast enough. Throw a bullet at someone and they'd just be annoyed and tell you to stop it, because it's just a tiny little piece of metal, but shoot it at them and we all know what happens.
The speed of a bullet as it leaves an AK-47 (aka muzzle velocity) is 2,340 feet per second. That's 1,595.45 MPH. This article about a space junk alert from last November is talking about speeds of 17,000 MPH. Get the idea?
Currently, the closest thing anyone can come up with to an actual cleaning job is to either make a given object's orbit decay and take one's chances on where it crashes, or to have a 'graveyard orbit' far above the regular orbit in which the stuff we're actually using lies. At the end of a satellite's life, the last of its fuel is used to boost it up high out of the way of everything else. But that's not really a clean; that's just sweeping the problem under the rug. So we're in that weird 'proof of concept' part of the innovative process when you get a whole bunch of off-the-wall ideas.
You know that part. It's this part.
Eventually it's got to get done, though- it's imperative that we find a way to get that space junk down- so that in mind, Treehugger has compiled nine concepts being kicked around at the moment.
It's not exactly getting to Mars, but you can't get anywhere if there's a traffic jam.