Upper stages and satellites that are not passivated at the end of their life have the potential to break-up.

The main cause of on-orbit explosions is related to residual fuel that remains in tanks or fuel lines once a rocket stage or satellite is discarded in Earth orbit. Over time, the harsh space environment can deteriorate the mechanical integrity of external and internal parts, leading to leaks and/or mixing of fuel components, which could trigger self-ignition. The resulting explosion can destroy the source object and spread its mass across numerous fragments with a wide spectrum of masses and imparted velocities. Besides such accidental break-ups, spacecraft interceptions by surface-launched missiles, have been a major contributor in the recent past. The Chinese Feng-Yun 1C engagement in January 2007 alone increased the trackable space object population by 25 percent.