Onboard autonomy is the ability of a spacecraft to make limited decisions and carry out actions without real-time human control. Instead of waiting for every command from Earth, the vehicle can monitor its own state, react to faults, schedule tasks, or switch modes when communication is delayed or unavailable.
In cyber security, this matters because autonomy expands the attack surface from simple command handling to onboard logic, sensor inputs, and update paths. If an adversary can spoof telemetry, tamper with software, or abuse a trusted command channel, the spacecraft may take unsafe actions on its own. Defenses therefore focus on signed commands, strict authorization, tamper-resistant logs, and policy-bounded autonomy that limits what the system can do. Good design also includes fail-safe modes so the spacecraft can preserve control and recover safely when the ground link is lost.