On September 14, 1966, NASA's Gemini 11 mission established a significant spaceflight altitude record, reaching 850 miles above the Earth, a standard that remained unbroken for nearly six decades until 2024. The mission was commanded by Pete Conrad and piloted by Dick Gordon, who orbited the Earth for three days in their Gemini spacecraft.
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After launch, the astronauts executed the first direct-ascent rendezvous with an Agena target vehicle. Once docked, they employed the Agena rocket to ascend to their record altitude. Also notable during the mission was the creation of a brief period of artificial gravity, achieved as the duo rotated the combined spacecraft using the thrusters.
Despite its designation, Gemini 11 was actually NASA's ninth crewed Gemini mission. The relatively brief mission included two spacewalks and marked the first orbital docking with an Agena vehicle, following the first in-space docking achieved in a previous mission, Gemini 8. The highest altitude of 853.8 miles (1,374.1 kilometers) set by Gemini 11 remained unchallenged for 58 years.
The mission involved eight scientific experiments, one of the most remarkable being a demonstration of artificial gravity. During a spacewalk, Gordon tethered a 30-meter line from the Agena booster to the Gemini capsule. After reaching peak altitude, Conrad undocked and initiated a gentle spin, creating a slight gravitational acceleration that lasted for three hours before the tether was released.
Additionally, Gemini 11 marked a milestone in automated technology as it executed NASA's first automated reentry.
The altitude record stood until September 10, 2024, when SpaceX's Polaris Dawn mission reached 870 miles (1,400.7 kilometers) in orbit. This mission also included the first private spacewalk performed by Jared Isaacman and Anna Menon.