All of the Gemini ( Latin meaning Twins ) Space Flights
( two-manned space craft ) were launched between 1964 and 1967,
followed by the Apollo series of three-man spacecraft.
The Gemini program was chiefly designed to test the ability of astronauts to
maneuver their spacecraft by means of manual control and helped to develop
the techniques for orbital rendezvous and docking with a target vehicle
( procedures that were vital to the subsequent Apollo Moonlanding program ).
All of these were directed by the National Aeronautics and Space
Administration ( NASA ). Gemini 12 ( November 11, 1966 )
was the last in the series, and made the first automatically
controlled reentry into the Earth's atmosphere.

Presented here are the actual ‘flight recovery envelopes’ posted aboard the USNaval Ships responsible for picking up the manned capsules after they
parachuted into the ocean. Two cachets adorn each envelope;
the first shows a mission logo ( eg an anchor, space capsule, ships etc. )
naming the mission / the second lists the names of the astronauts aboard each
capsule, the number of orbits made, the dates, name of recovery ship
and other information. The postmark gives, the name of the US Naval
vessel that made the recoveryalong with the actual date of
postmarking along on patriotic style stamps.