Little OSCaR (Obsolete Spacecraft Capture and Removal) is just about to be tested this year.  It is called a 3U CubeSat thus it's quite small, about 12 inches long by 4 inches wide by 4 inches high (30 centimeters by 10 cm by 10 cm).  It is designed specifically to clean up space debris by its onboard nets and tethers, and this it will do autonomously, with little guidance from ground controllers.

"We tell OSCaR what to do and then we have to trust it," project leader Kurt Anderson, a professor of mechanical, aerospace and nuclear engineering at Rensselaer Polytechnic Institute in New York, said in a statement. "That's why this problem actually gets very hard because we are doing things that a big, expensive satellite would do, but in a CubeSat platform," Anderson added.

Space junk is now considered by many a huge problem and it's just getting worse.  We are generating more debris than putting things up in space.  Millions of debris are flying around our planet at this very moment; about 34,000 of which are at least 4 inches (10 centimeters) wide, according to the European Space Agency.  The downside of having these objects around, is that they move too fast - 17,500 mph (28,200 kilometers/h) in low-Earth orbit, for example - that even a very small one could damage a satellite.

What Anderson was referring to was the devastating cascade of collisions that could occur if the debris that's orbiting is dense enough.  From each collision, more debris will be generated and the cycle just continues on, and this could potentially make large spaces around Earth unusable.

The space junk problem is beginning to get noticed in the spaceflight community.  It's just getting enough attention that scientists and engineers are talking and trying to think of ways to bring satellites down after their missions so as not to add to the already growing number of space debris.

OSCaR is designed to remove dangerous junk on the Earth's orbit and will be decommissioned after it fulfil it's mission.

"There's an informal agreement that's been in place for a few years that people who put space objects up there should be practicing good citizenship," Anderson said. "We envision a day where we could send up an entire flock, or squadron, of OSCaRs to work jointly going after large collections of debris."