The launch of satellites that began as part of the Cold War space race, and later included business, civil services and commercial operations, means that decades' worth of "space junk" flies above the sky.

What's easy to put up, though, isn't always as easy to bring back down. Scientists continue to work on ideas that will clean up 7,000 tons of debris and counting. Some of the debris is exceedingly large, such as solar panels for example, but space junk also comes in small chunks of simple bolts and tiny paint flecks. The NASA Orbital Debris Program office says there are more than 21,000 pieces larger than 10 centimeters, and an estimated half-million pieces between 1 and 10 centimeters. It seems to contradict our earthbound sense of awe when we see a starry night, but there are 100 million particles smaller than a centimeter.

The solutions for clearing up this space debris will not easy. While NASA minimizes the risk of debris impact both in space and on Earth, it is still true that, on average one piece of space junk has fallen back every day for the past 50 years.

At JAXA, the Japanese Aerospace Exploration Energy, they have now built a kind of space junk vacuum cleaner. The experimental vehicle has a 700-meter-long tether, made of thin strands of aluminium and stainless steel wire, that generates electricity as it swings through Earth's magnetic field.

Since the wire tether carries current, the hypothesis is that it will disrupt space debris enough to knock low-orbit objects into the sea below.

"The motion of the long charged cable through the Earth's magnetic field will create a force pushing other objects down towards the Earth – hopefully tossing some small pieces of metal down towards the atmosphere," explains Forbes author Jillian Scudder. "In its final form, the tether will have a grappling hook attached to its other end, which can be attached to a dead satellite and then used to tug the defunct satellite down to Earth."

Called KITE, the Kounotori Integrated Tether Experiment arrived at the International Space Station on December 13 and is currently undergoing trials. If KITE works as designed, it will be able to remove one large object and lots of tiny magnetic objects per mission. The ideal range for targets will be objects weighing a few hundred kilos, up to about two tons. There is no real need to physically "capture" an object since they are not being retrieved. Rather, they are being hurled into a kind of re-entry incineration.

Representatives at JAXA told Space.com that the real challenge will be how to refine control of the tether, and attach it to an uncontrolled piece of space debris. Operators will be able to position the tether, in part using the current in the tether itself, they said, but once the device identifies a target it will initially be controlled by GPS. As it gets closer, operators will use optical cameras to guide it.

Japan, along with countries that include France, Russia and the European Space Agency, all are cooperating on ways to reduce the hazards of space debris.