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  • Writer's pictureAeryn Avilla

Eight Days or Bust: Fifty-Five Years since Gemini 5

Updated: Mar 24, 2021

Fifty-five years ago today, astronauts Gordon Cooper and Pete Conrad took to the skies on the third manned Gemini flight, Gemini 5. It was the ninth crewed US spaceflight and the seventeenth crewed spaceflight overall. The primary purpose of the mission was to remain in orbit for the length of time it would take to fly to the moon, land, and return.

Gemini 5 was the first mission to have an insignia patch. After Gemini 3, NASA prohibited its astronauts from naming their spacecraft. The agency would not lift this ban until Apollo 9 in 1969: This was the first flight to include separate spacecraft, the command/service module and the lunar module, and different callsigns were needed. Gordon Cooper, the mission's commander, realized he had never served in a military organization without a patch (although this precedes the souvenir Mercury flight patches most people are familiar with, small insignias were painted on the side of the spacecraft). NASA agreed and Cooper chose the image of a covered wagon, an icon associated with pioneering and exploration. He wanted to include the slogan "8 Days or Bust" but the agency felt it placed too much emphasis on mission length and feared the public would see the mission as a failure if it did not last the full duration. The original designed actually did have the phrase written on the covered wagon but a piece of nylon cloth was sewn over it before launch. Most reproductions include it.

Cooper's original patch design and the exact kind worn on the crew's spacesuits (NASA)

The mission was commanded by Gordon Cooper, the sole pilot of the Mercury-Atlas 9 spaceflight that closed out the Mercury program in 1963. He became the first person to fly two Earth-orbital missions (Gus Grissom was the first person to fly in space twice on Gemini 3 but his first mission, Mercury-Redstone 4, was suborbital). The pilot was Pete Conrad, a rookie and the fourth of his class to fly a mission. Cooper would later serve as the backup commander for Apollo 10 but was replaced by Alan Shepard. Conrad would later command Gemini 11, Apollo 12, and Skylab 2, and become the third man to walk on the moon. The backup commander was Neil Armstrong, the future commander of Gemini 8 and Apollo 11. The backup pilot was Elliot See, the original commander of Gemini 9. He and Gemini 9 pilot Charles Bassett perished in a T-38 crash in 1966 a few months before their scheduled launch.

Future moonwalker Conrad with Mercury veteran Cooper (NASA)

Gemini 5 launched from Cape Kennedy's Launch Complex 19 on August 21, 1965 at 9:59 a.m. EST (13:59:59 UTC). The launch went perfectly except for a few seconds of Pogo oscillation, which is vibration of the rocket. It was caused by improper gas levels in an oxidizer standpipe and Gemini 5 was the only flight of the program that experienced these oscillations. The first major event of the 8-day flight occurred at 2 hours and 13 minutes into the mission with the ejection of the Rendezvous Evaluation Pod (REP). At this time, the crew found that pressure in a fuel cell had dropped and Cooper decided to shut the fuel cells down. This meant the spacecraft was unable to rendezvous with the REP and it could have also meant a premature end to the mission. Tests back on the ground found that it was possible for the fuel cell to work, as it was above the pounds per square inch minimum. It was decided to turn all the fuel cells back on and further tests conducted while in orbit found that the mission could continue. Gemini 5 was actually the first space mission to use fuel cells instead of chemical batteries and the development of these cells were pivotal for future Apollo flights.

Artist's rendition of Gemini 5 approaching the REP. The REV is superimposed over a photo of the capsule and Earth taken onboard Gemini 4 (NASA)

On the third day of the flight Gemini 5 performed a phantom rendezvous, in which the Gemini spacecraft maneuvered to a predetermined position in space. Flight controllers discovered another problem with the fuel cells on day four. They were producing waste water that was too acidic for drinking. Fortunately, this issue was not critical and the astronauts still received cool drinking water. They did, however, report a high quantity of gas bubbles in it.

On the fifth day, one of the thruster blocks of the spacecraft malfunctioned repeatedly. This meant cancellation of all experiments requiring the use of thrusters. The crew was not able to get them operating again. Seventeen experiments were planned and only one was cancelled since it involved photography of the REP. Some involved photographing both celestial objects and the ground for the Department of Defense. Others involved measuring the brightness of celestial backgrounds and of rocket plumes. Yet another focused on changes in the crew's eyesight during the mission.

Neither Cooper nor Conrad had much of an appetite during the mission and took in substantially fewer calories per day than what the flight surgeons recommended. Dandruff was a problem to the point where the flakes of skin would settle on the capsule's instrument panel and partially obscure some instrument readouts. This was believed to be due to very low humidity in the cabin, causing the astronauts' skin to become dry. Postflight medical examinations also show some loss of red blood cells and plasma and it took a few days for both men's circulatory systems to return to normal. Cooper and Conrad had difficulty staying warm and sleeping, as did the crew of Gemini 4. Instead of sticking with alternating rest periods like the flight surgeons had planned, they took them together but still received little sleep. Despite these reasons, it was determined that longer duration flights were feasible.

Gemini 5 re-entered on August 29 during the 121st orbit of the mission and splashed down in the Atlantic Ocean. It doubled the US spaceflight record of 4 days (set by Gemini 4) to 8 days and broke the Soviet Union's record of almost 5 days set by Vostok 5 in 1963. Gemini 5's record would be broken by 14-day Gemini 7 in December.

The Gemini 5 capsule is on display at Space Center Houston in Houston, Texas. The top half of the Titan II's first stage was recovered after launch and is now on display at the US Space and Rocket Center in Huntsville, Alabama.

Quick Facts

Command Pilot: L. Gordon Cooper

Pilot: Charles "Pete" Conrad

Backup Command Pilot: Neil A. Armstrong

Backup Pilot: Elliot M. See

Launch Vehicle: Gemini-Titan II

Launch Date: 21 August 1965

Launch Site: LC-19, CCAFS

Orbits: 120

Landing Date: 29 August 1965

Recovery Carrier: USS Lake Champlain


Insignia patch

Insignia patch worn on a spacesuit



  • Becker, Joachim. “Gemini 5.” Spaceflight Mission Report: Gemini 5,

  • “Gemini 5.” NASA Space Science Data Coordinated Archive,

  • Wade, Mark. Gemini 5,

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