There are 500,000 pieces of space junk orbiting the earth, many of which significantly endanger satellites and crewed space missions.
Now there's a fascinating experiment underway to test various techniques of collecting and disposing of space junk: Orbital garbage collection!
A European consortium launched the RemoveDEBRIS satellite last week, and it's already in space ready to be deployed for its tests in May. The satellite will test a couple of ways of capturing space junk, including firing a net around a junk satellite (producing enough drag so the junk begins spiraling towards Earthbound destruction), and — more dramatically — firing a harpoon at a target, to test whether space junk could be collected using space harpoons.
To repeat: Space harpoons.
In the first test, a CubeSat released from the main spacecraft will maneuver to a distance of more than 20 feet, where it will unfurl a balloon (to provide a bigger target). A net similar to the kind used in commercial fishing will then be deployed from the main spacecraft to capture the CubeSat. Atmospheric drag should cause the netted CubeSat to burn up in the atmosphere in a matter of weeks, according to Guglielmo Aglietti, Director of the Surrey Space Centre at the University of Surrey, and the principal investigator for RemoveDEBRIS.
For the second test, another CubeSat will be released to fly at a distance from the main spacecraft, where a camera and LIDAR will observe it to assess how well future trash-collecting satellites could judge the position and speed of a piece of debris.
Then, to test a different method of snaring space trash, a standoff target—made of representative satellite materials—will be shot with a harpoon connected to a tether. Finally, a large sail will be unfurled from the main satellite to increase its atmospheric drag and cause it to burn up during re-entry, about a year and a half later. The project investigators expect to have all their tests wrapped up by the end of this year, says Aglietti.
RemoveDEBRIS has produced the above video visualizing the experiment, complete with the requisite stirring space-opera soundtrack.