Are there any Agena / Gemini target backups or mockups on display
anywhere? I remember seeing a mockup at KSC back in the Apollo days,
but I don't think there's one there anymore.

Also, what's the etymology of Agena as being used for the upper-stage
name? As far as I know, Agena is a 1st-magnitude star in Centaurus,
and its name means "the knee."