October 21, 2013
The growing problem of space junk around Earth could be cleaned up in part using the same forces that give you a static shock when you touch a doorknob on a windy day. By shooting space debris with an electron beam, a charged spacecraft could tug them to higher orbit and then fling them away.
This solution relies on what are known as electrostatic forces, which occur whenever electrons build up on something. Bombarding a piece of space junk with electrons could give it a modest negative charge of a few tens of kilovolts, roughly the equivalent charge stored in a car spark plug. An unmanned space probe with a positive charge could then tow it in a tractor-beam-like fashion.
Orbital debris is a well-known problem of the Space Age. In the early days of space travel, it was assumed that the area around Earth could absorb a near-limitless amount of junk. We figured that if we simply left our defunct satellites, spent rocket stages, and any pieces of garbage emerging from spacecraft for long enough, they would take care of themselves. The truth was rather different, and now we might be nearing a situation called the Kessler Syndrome where space debris is so prevalent that it increasingly collides with other orbital trash, fragmenting into thousands of new pieces of junk and rendering the orbits around Earth useless.