SPACE JUNK The white dots in this computer-generated graphic show the location of space debris that lie within 2,000 kilometers of Earth’s surface, the most concentrated area for debris. Two large satellites — a functioning U.S. device and a nonoperating Russian instrument — collided in Earth orbit about 800 kilometers over Siberia on February 10, creating a swarm of some 600 chunks of debris. In 1991, a nonfunctioning Russian navigation satellite hit debris from another Russian satellite.