The agency said Thursday that the deal with ClearSpace SA will lead to the “first active debris removal mission” in 2025, in which a custom-made spacecraft will capture and bring down part of a rocket once used to deliver a satellite into orbit.

Experts have long warned that hundreds of thousands of pieces of space debris circling the planet — including an astronaut's lost mirror — pose a threat to functioning satellites and even the International Space Station.

Several teams are working on ways to tackle the problem.