In the early twenty-first century, there are approximately 5000 commercial and private airplanes in the air at any one moment. The task of the U.S. Air Traffic Control System is to ensure the safe operation of these commercial and private aircraft. Air traffic controllers coordinate the movements of these planes, keep them at safe distances from each other, direct them during take-off and landing from airports, reroute them around bad weather, and ensure that air traffic flows smoothly. Other nations around the world maintain and operate similar air traffic control systems.

As space travel becomes a more common activity, it may become essential to institute a similar traffic control system for spacecraft. However, a more urgent problem is presented by the number of individual objects that are in orbit around Earth. The Space Surveillance Network (SSN) is currently tracking around 7,000 artificial objects circling Earth. The risk...