Decades of space exploration have left an estimated 170 million pieces of debris orbiting Earth, from old rocket parts to dead . 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 on a mission to tidy up outer space. Scientists recently started work on a robotic trash collector that will attempt to grab a piece of debris and drag it out of Earth’s orbit. (Both the debris and the robot will eventually burn up in Earth’s atmosphere.) The ESA plans to launch the robot in 2025. If the mission is successful, scientists hope to tackle multiple pieces of trash at once.