This is the third in a series of successful space-trash cleanup tests by the RemoveDEBRIS spacecraft.

Gotcha: The RemoveDEBRIS satellite, created by a team at the University of Surrey, has pulled off its most demanding experiment yet. It fired a harpoon at 20 meters a second at a separate satellite panel that it was holding at the end of a boom. As you can see in the video above, the harpoon succeeded in stabbing and capturing the item. Last year the team also accurately fired a giant net at a satellite to capture it, and tested out a lidar- and camera-based system for identifying space junk.

The space landfill: Earth’s orbit is full of trash. Right now there are more than 7,600 tons of space junk floating around our planet. And that’s a problem, because the more things we send up there, the greater the chances they crash into each other. That creates many more, smaller bits of junk, which would pose serious danger to future space missions (while overly dramatized, see the movie Gravity).

Cleaning up the mess: The final test by RemoveDEBRIS in March will be an act of self-sacrifice. The satellite will inflate a sail designed to carry itself into Earth’s atmosphere, where it will burn up. If more satellites clean up after themselves when their job is done, we can prevent more junk piling up in orbit.

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