Can I restart AirPort Base Station from terminal?

Something curious occasionally happens on my LAN. Time Machine on my MacBook Air is configured to back up to Time Capsule.

However, from time to time, Time Machine says it hasn't backed up for 10+ days. When this happens the Time Capsule is still working to some extent. The WiFi still works. The Apple TV connected by ethernet still works. The light is still green. I can ping it.

But when I open AirPort Utility it asks "Enter Password" and there's nothing I can do except pull out the power and restart the Time Capsule. After I've done that, AirPort Utility lets me view the configuration of the Time Capsule no problems, and Time Machine starts working again.

Why does it partially crash like this? Can I restart it without yanking the power cord out (with Terminal)?