Gemini is what got me into space, science, all of it. Amy Shira Teitel can bring you up to speed.
Gemini worked out almost everything that had to be worked out to go to the moon. Not the part with the big fire cracker under the tin can to take off from the moon, but most of the rest of it.
Science Communication Gone Rong!
And, just for fun, right after I tweeted this post, I got this: