On-orbit servicing is any work done on a spacecraft after it has reached space. That can include inspection, refueling, repositioning, repairs, software updates, or docking with another vehicle to extend mission life. It matters because once a satellite or probe is in orbit, operators have only a narrow window to interact with it, and every command must be precise.
In cyber security, on-orbit servicing is a high-trust operation. The spacecraft may accept remote commands, new firmware, or navigation changes over a communications link that attackers would love to intercept or impersonate. If command authentication, telemetry integrity, or update signing fails, an adversary could spoof maintenance actions, disrupt control, or alter mission data. Defenders protect these systems with strong encryption, key management, access control, anomaly detection, and signed software loads. In real operations, on-orbit servicing appears in satellite life-extension missions, rescue attempts, and defensive upkeep of critical space assets.