According to NASA, the Gemini 11 mission set a crewed Earth-orbit altitude record of 850 miles on September 14, 1966, when command pilot Pete Conrad and pilot Dick Gordon used an Agena target vehicle’s rocket to ascend. This milestone stood for nearly six decades until a private SpaceX Polaris Dawn mission reached 870 miles in September 2024.
The 1966 Gemini 11 Altitude Record and Mission Profile
NASA’s Gemini 11 mission carried astronauts Pete Conrad and Dick Gordon into Earth orbit for a three-day flight that pushed human spaceflight boundaries. According to NASA records, the mission launched on September 14, 1966, marking the ninth crewed flight of the two-person Gemini program. Shortly after launch, the crew performed the first-ever direct-ascent rendezvous with an Agena target vehicle.
Once docked, Conrad and Gordon ignited the rocket on the Agena target vehicle to push their spacecraft to a peak altitude of 853.8 miles, or 1,374.1 kilometers. That achievement established an altitude record for crewed, non-lunar spaceflight that remained unbroken for 58 years.
Did you know? During the Gemini 11 mission, Conrad and Gordon also executed NASA’s first automated reentry, allowing their capsule to fly itself back to Earth without manual pilot control during the landing phase.
Artificial Gravity and Spacewalk Experiments in Earth Orbit
Beyond the altitude milestone, the three-day flight featured eight distinct science experiments, most notably an artificial gravity demonstration. According to NASA accounts, astronaut Dick Gordon conducted a spacewalk during which he attached a 30-meter tether between the Agena booster and the Gemini capsule.
Following the tether connection and the attainment of their peak altitude, Conrad undocked the capsule from the Agena and backed away to pull the tether taut. The crew then used their thrusters to start a slow rotation between the two connected vehicles. This maneuver generated a slight gravitational acceleration that lasted for three hours before the crew cut the tether and left the Agena behind.
How SpaceX Polaris Dawn Broke the Six-Decade Altitude Record
The Earth orbit altitude record set during the Gemini program stood unchallenged until late 2024. According to mission data, the private SpaceX mission known as Polaris Dawn launched on September 10, 2024, eclipsing the 1966 benchmark.
Bankrolled by American billionaire Jared Isaacman, the Polaris Dawn flight reached a peak altitude of 870 miles, or 1,400.7 kilometers. The mission also featured a historic commercial spacewalk performed by Isaacman and SpaceX engineer Anna Menon.
Frequently Asked Questions
What was the peak altitude reached by Gemini 11?
According to NASA, Gemini 11 reached a peak altitude of 853.8 miles (1,374.1 kilometers) on September 14, 1966, using the propulsion system of a docked Agena target vehicle.
How long did the Gemini 11 altitude record last?
The record stood for 58 years until September 10, 2024, when the private SpaceX Polaris Dawn mission reached an altitude of 870 miles (1,400.7 kilometers).
Who were the astronauts on the Gemini 11 mission?
The two-person crew consisted of command pilot Pete Conrad and pilot Dick Gordon.
What was the purpose of the tether on Gemini 11?
Astronaut Dick Gordon attached a 30-meter tether between the Agena booster and the Gemini capsule to demonstrate artificial gravity by rotating the joined spacecraft using thrusters.
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