On Aug. 29, 1965, two NASA astronauts returned from their record-breaking Gemini 5 mission.
Astronauts Gordon Cooper and Pete Conrad spent eight days in Earth orbit, and for the first time, the United States set a world record for the duration of a crewed spaceflight.
The Gemini 5 mission launched on Aug. 21, 1965 atop a Titan II rocket from what was then the Cape Canaveral Air Force Station (now the Cape Canaveral Space Force Station) in Florida. While in orbit, the astronauts were supposed to test rendezvous capabilities and maneuvers using a pod that deployed from their spacecraft. But due to an electrical problem, they had to cancel those plans along with several science experiments.
Pete Conrad later called the mission "eight days in a garbage can," referring to the cramped quarters of the Gemini spacecraft.
Why it mattered
Human spaceflight was still pretty new in 1965 when NASA's Gemini program was in full swing. The first crewed launch was just four years earlier, when Soviet cosmonaut Yuri Gagarin orbited Earth for just 108 minutes on Vostok 1.
By 1965, NASA's longest mission had run just 4 days, but the space agency needed missions at least twice as long if it was to send astronauts to the moon and back under Project Apollo.
That brings us to the Gemini 5 mission, which NASA envisioned as an endurance test to prove that astronauts could survive for eight days on a long trip to the moon and back.
Cooper commanded the flight with Conrad as pilot. (Their backup crew included future Apollo 11 moonwalker Neil Armstrong and Elliott See, both rookies at the time.) It was Cooper who designed the Gemini 5 mission patch, which featured a Conestoga wagon and the words "8 Days Or Bust," to celebrate the flight's endurance run.
It was a cramped flight, but the astronauts proved the human body could live and work in space for an extended time, setting the stage for even longer flights to follow.
It was a fuel cell oxygen tank pressure issue that forced the crew to scrap their planned rendezvous demonstration, NASA has said. While the rendezvous target was deployed as planned and tracked by radar, Mission Control called the demo off when the pressure glitch occurred because the fuel cells were key to power Gemini 5 for its full 8-day mission.
Cooper and Conrad powered down non-essential systems to conserve power on the flight. They also weathered some thruster failures on the fifth day of the mission, but a "drift-and-correct" workaround allowed the mission to continue. They also performed Earth observatoin and medical experiments during the flight.
When the Gemini 5 crew splashed down in the Atlantic Ocean on Aug. 29, they broke the previous space endurance record set by Vostok 5 cosmonaut Valery Bykovsky, who spent nearly 5 days in space in 1963.
"Although both had lost weight, they were in good physical condition after their record-breaking eight days in space," NASA wrote of the crew's condition.
Today, an 8-day mission may seem quaint, given that astronauts and cosmonauts have spent over a year in space. The longest single spaceflight lasted 437 days and was set between 1994 and 1995 by Russian cosmonaut Valeri Polyakov on the Mir space station.
You can see the Gemini 5 space capsule today at the Space Center Houston near NASA's Johnson Space Center in Houston.
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