The European Space Agency (ESA) has tested a giant net to clean up space debris for a planned 2021 mission. The net will ensnare large pieces of space junk such as dead satellites or abandoned rocket parts and remove them from orbit.

ESA researchers on a weightless aircraft flight tested a compressed air powered net to capture a model satellite. The results were good. “The good news is they worked extremely well—so much so that the nets usually had to be cut away with a knife before we could shoot again,” ESA engineer Kjetil Wormnes said in a press ​release.

Space debris, of which there are over 500,000 pieces, are a serious threat to objects in Earth orbit. A toned down version of Gravity’s disaster happened in 2009 when a former Russian military satellite, Kosmos 2251, collided with an active communications satellite, Iridium 33, at the speed of over 26,000 mph (46,000 km/h). The collision destroyed both satellites, made the crew of the International Space Station take cover, and set off a weather alert for space debris in Kentucky.