Space debris consists of millions of pieces of man-made material orbiting the Earth. Debris poses a growing threat to satellites and could prevent the use of valuable orbits in the future. Many pieces of debris are too small to monitor but too large to shield satellites against. This POSTnote looks at measures to protect satellites and international agreements and guidelines to reduce the amount of debris generated. In the long term, experts agree that it will be necessary to remove debris from orbit, but this is technically and politically challenging.