I don't know when you were in space last, but it's pretty messy up there. Even the smallest piece of debris is dangerous to the operational satellites, spacecraft and the International Space Station. So, how do we clean it up? With balloons, according to Dr. Kristen Gates.
The "GOLD" envelope she's proposing — or the Gossamer Orbit Lowering Device — is basically the toughest balloon in the world. It's sent up to orbit in a box no larger than a suitcase, and then it's fastened to a dead satellite or a piece of space junk. After that? It inflates into a massive balloon, enveloping whatever it's designed to lower.
Lower into the atmosphere, that is, where the piece of debris will burn up and trouble the Earth's orbit no more. The balloon's size amplifies the amount of drag acting on the space junk already, which slowly decays an object's orbit.
Best of all, Dr. Gates's GOLD system would be cheap to make, and if something went wrong — say, the balloon popped — there's a chance all that another GOLD balloon would do the trick.