The Gemini 3 flown $2 bills (along with a set of flown $1 bills) are some of the most famous, and well documented flown paper currency. Russ Still documented their flight - and story - in his wonderful Relics of the Space Race book. As the story goes, three members of the McDonnell Douglas launch crew assembled 50 $2 bills and 41 $1 bills and stowed them inside the capsule with Gus Grissom's permission. The bills were stuffed behind the instrument panel on the right side. This gave Gus Grissom the opportunity to execute one of the great space race Gotcha's of all time. He had his secretary find all the play money she could. He secretly took it with him on the flight, and during orbit, switched out the real money with the play money. Upon return, when the launch crew went into the capsule to recover the flown currency, they found the play money instead. The guys never said a word. Grissom later called the guys to explain how "funny things can happen in space" and then hung up. Later, the guys received a package from Grissom -- inside were all the flown bills, signed and flight certified by both crew members. Later, Don Wagner designed the above certificates to record the flight status of each bill, and they, too, were signed by the crew.