What type of missile guidance system is designed to maintain a trajectory based on external commands?

The command guidance system is specifically designed to maintain the trajectory of a missile based on external commands provided during flight. This system relies on signals sent from a ground-based or aerial controller that instructs the missile on how to adjust its course. It allows for real-time updates and precise target tracking, making it particularly effective in scenarios where dynamic target movement must be accounted for.

In contrast, the other guidance systems operate differently. Homing guidance systems rely on the missile's ability to detect and follow a signal emitted by the target, making them more autonomous. Inertial guidance systems utilize pre-programmed data and internal sensors to navigate the missile along a predetermined path without external input. Visual guidance systems employ imagery from a sensor to track and home in on a target but still do not rely on external commands during flight. Thus, the defining characteristic of command guidance is its dependence on external inputs to direct the missile's flight path.