Gemini 6A (officially Gemini VI-A) was a 1965 manned spaceflight in NASA's Gemini program. It was the 5th manned Gemini flight, the 13th manned American flight and the 21st spaceflight of all time (includes X-15 flights over 100 km -- 62 miles.). It was the last U.S. spacecraft to be flown using batteries as the primary power source (except for the Apollo Lunar Module, which used batteries, but was augmented by the fuel cells on the Apollo Command Module while docked). All remaining Gemini flights used fuel cells.
Launch date: December 15, 1965, 13:37:26 UTC
Landing: December 16, 1965, 15:28:50 UTC
Measured 3 inches (7.62 cm) across.