How the Gemini Spacecraft Worked

By: Jonathan Strickland

Overview of the Project Gemini

A distant view of the Gemini VI launch.
A distant view of the Gemini VI launch.
Image courtesy NASA

The Gemini Project included 12 flights, two of which were unmanned. NASA intended these flights to test the effects of prolonged space travel on humans. Spacewalks became an important part of several Gemini missions, so NASA devoted a lot of time and effort into improving the design of space suits. Earlier versions of the suits were meant as emergency backup systems only. As such, they weren't very flexible or comfortable.

All the astronauts in the Gemini program returned to Earth safely. The Gemini missions included:


  • Gemini I and II, the two unmanned missions, which tested the spacecraft's systems and compatibility with the Titan II launch vehicle
  • Gemini III with the two-man crew of Virgil "Gus" Grissom and John Young. Grissom gave the spacecraft the nickname "Molly Brown." It was the only spacecraft in the project to receive a nickname. Young also made a unique contribution. He smuggled contraband on board the spacecraft: a corned beef sandwich, which he returned to a pocket in his space suit once he realized crumbs could get into the instrument panels.
  • Gemini IV saw the first American extravehicular activity (EVA), also known as a spacewalk. Edward White took a 22-minute space stroll during the mission.
  • Gemini V was the first Gemini flight that used fuel cells as a power source. Earlier spacecraft relied on battery power.
  • Gemini VI had the odd distinction of launching out of order. That's because the unmanned vehicle with which the Gemini VI should have docked exploded during its launch. NASA decided to delay the Gemini VI launch. They launched Gemini VII on schedule and then launched Gemini VI days later to rendezvous with it. The two spacecraft met and flew in formation for several hours.
  • Gemini VIII ended early due to a malfunctioning thruster that caused the spacecraft to rotate once a second.
  • Gemini IX was supposed to dock with an unmanned vessel, but an obstruction in the target vessel's docking mechanism prevented the maneuver.
  • Gemini X had two successful docking attempts with two different unmanned vessels, proving that vehicles could dock together in space.
  • Gemini XI flew in a higher orbit than any previous manned spacecraft and also relied entirely on computer guidance during re-entry.
  • Gemini XII, the final mission in the program, included the longest spacewalks in the program. Edwin "Buzz" Aldrin accumulated more than five hours in space over three spacewalks.

What was the launch vehicle for the Gemini Project like? Find out on the next page.