On Sept. 14, 1966, NASA's Gemini 11 mission set an spaceflight altitude record that lasted for nearly six decades when two astronauts reached an orbit of 850 miles above the Earth. It remained the highest altitude ever achieved by a crewed, non-lunar mission until 2024.
Gemini 11 command pilot Pete Conrad and pilot Dick Gordon spent three days orbiting the Earth in their cramped Gemini spacecraft. After launch, they performed the first-ever direct-ascent rendezvous with an Agena target vehicle.
Once the two spacecraft were adjoined, they used the rocket on the Agena target vehicle to ascend to their record-breaking altitude. They also created a little bit of artificial gravity while in orbit by using their thrusters to rotate the combined spacecraft.
Why it mattered
Despite its name, Gemini 11 (or Gemini XI) was actually NASA's ninth crewed mission of the two-person Gemini spaceflights. The mission was relatively short, just three days, and included two spacewalks, and what NASA calls the first orbital rendezvous and docking with an Agena target vehicle (the first in-space docking occurred three missions earlier on Gemini 8).
But for 58 years, the Gemini 11 mission marked the highest astronauts flew above Earth without going to the moon. The astronauts used the rocket engine on the Agena booster to raise the orbit of their docked spacecraft to reach a peak altitude of 853.8 miles (1,374.1 kilometers).
Conrad and Gordon performed eight different science experiments, but perhaps one of their most striking feats was the artificial gravity demonstration. During one of his spacewalks, Gordon attached a 30-meter tether from the Agena booster to the Gemini capsule. After reaching their peak altitude, Conrad undocked the capsule from the Agena, backing away them starting a rotation that created a very slight "gravitational acceleration," NASA said. They spun together for 3 hours, before the tether was cut loose and Gemini 11 left the Agena behind.
Conrad and Gordon also performed the first automated reentry during their landing, with their Gemini 11 capsule flying itself in a first-ever for NASA.
The Earth orbit altitude record set by NASA's Gemini 11 mission stood until Sept. 10, 2024, when the private SpaceX mission Polaris Dawn, bankrolled by American billionaire Jared Isaacman (currently serving as NASA administrator), launched into an orbit that reached 870 miles (1,400.7 kilometers).
That Polaris Dawn mission also included a spacewalk by Isaacman and SpaceX's Anna Menon, marking the first-ever private spacewalk.
