| With the explosion of commercial space in the past 30 years and the end of the Cold War, the space agencies are very concerned about this issue and there is a lot of tracking and cooperation. The regulatory process for launch is quite lengthy, and debris concerns are absolutely addressed industry-wide. Generally as part of the permitting process you have to file an Orbital Debris Assessment Report that contains predictions for orbital lifetime, what will happen to the satellite at EOL, systems for putting the satellite in a safe orbit in case of in-service failure, launch failure etc, risk of collision with other orbital objects and so on. The details differ depending what orbital regime. Things at ISS altitude (~400km) or below will deorbit very quickly (days to months). Terra Bella and other earth observation satellites are typically in slightly altitude, sun-synchronous, near-polar orbits. They will need to carry propellant to drop the vehicle down to a lower orbit when they are taken out of service, otherwise the orbital lifetime will be 5-50 years. Geosynchronous satellites are basically going to be up there forever, so they are placed into a slightly lower (but still extremely high) parking orbit after their useful life ends. This keeps them out of the way of the active satellites, and the orbit there is so large that collisions are unlikely. Finally, the US maintains radar tracking, and will notify operators if a collision is possible so they can make a maneuver. Generally a small adjustment, if performed ahead of time, is sufficient to reduce the probability of collision significantly. The scary things are debris that are too small to track but large enough to cause damage, and situations where non-operational satellites conjuct. Fun fact: if the conjunction probability is high enough, the Air Force will call you in the middle of the night. |