Time Capsule does not appear in Disk Utility

I recently got a new MacBook Pro, and soon after dusted off my old faithful Time Capsule to use as one of my backup drives. It seemed to work for a few weeks, but a few days ago it hit a snag. I get a Time Machine error pop-up that says Time Capsule doesn't have enough space to perform a backup. Otherwise, the drive seems to be working. At least the little light is glowing a healthy green.

I figure I should be able to erase the drive and start over. (That would be okay, as I have another much newer drive that's pulling Time Machine duty, and I have an online backup.) I launched Disk Utility to erase the Time Capsule, but DU does not see my Time Capsule drive. What do I do now?