An estimated 170 million pieces of debris are orbiting Earth, from old rocket parts to dead satellites. And some of that space garbage is moving faster than a bullet, making it dangerous to spacecraft. That’s why the European Space Agency (ESA) is launching its first cleanup mission. This year, scientists are starting work on a robotic junk collector that, when launched in 2025, will grab a piece of abandoned debris and drag it out of orbit. Both the robot and the debris will burn up in Earth’s atmosphere. Similar robots have been tested before, but this will be the first  mission to remove an actual piece of space debris. If all goes well, scientists hope eventually to be able to tackle multiple pieces at once. But even a small cleanup, they say, is crucial. “Imagine how dangerous sailing the high seas would be if all the ships ever lost in history were still drifting on top of the water,” says Jan Wörner, director general of the ESA. “That is the current situation in orbit, and it cannot be allowed to continue.”