Twins In Orbit: NASA's Bridge To The Moon

The Gemini Program rarely gets the accolades it deserves. It wasn’t America’s first spaceflight program and it didn’t go to the Moon, but it did something more important: it taught NASA how to work and fly in space. The objectives of the Gemini program – long duration flight, orbital rendezvous, and precision reentry and landing – were vital to Apollo’s success. Had NASA not met these goals with Gemini, America might not have successfully landed men on the Moon in the 1960s.

Museum Exhibit: Gemini Earth Orbit Plot

Tracking a spacecraft and keeping tabs on missions became much harder when astronauts started going into orbit. This is because a spacecraft orbits faster than the Earth rotates – 90 minutes compared to 24 hours. So an orbiting spacecraft will pass over a different point on the planet with every orbit. This chart shows the orbital pattern of the first manned Gemini mission, Gemini 3, from the perspective of a stationary Earth. Charts like this with moving model spacecraft or digital ones with the image of a spacecraft moving in realtime, were a staple in mission control from the start of the Mercury program (though the first two showed just the arc of a suborbital flight). These maps allowed NASA to anticipate a spacecraft’s progress and ensure constant communication with the orbiting astronauts.

Fun Fact 1: The Gusmobile

After his Mercury mission, astronaut Gus Grissom moved to the Gemini program and helped design the new spacecraft around a pilot’s needs. The other astronauts called the spacecraft the Gusmobile, and the first one was built so closely around his 5 foot 5 inch frame that some men couldn’t fit inside.


Museum Exhibit: Gemini Heat Shield Plug

The Gemini spacecraft, like all spacecraft, needed a heat shield to survive the fiery reentry back into the Earth’s atmosphere. Derived from ballistic missile technology, the rounded heat shield created a shockwave underneath the falling spacecraft that kept most of the reentry heat at bay. The remaining heat dissipated through ablation: the heat shield, made of a silicone elastomer material poured into a rounded honeycomb form, charred and evaporated. Each heat shield could only be used once, but it was a vital part of the astronauts’ safe return to Earth. The section of heat shield here displayed came from the last Gemini mission to fly, Gemini XII. Launched on November 11, 1966, this was the mission that brought together everything NASA had learned over the course of the program. Commander Jim Lovell, who signed the piece here, and pilot Buzz Aldrin rendezvoused and docked with a target vehicle in orbit and Aldrin stepped outside for a spacewalk. The spacecraft splashed down on November 15, marking the end of NASA’s second manned spaceflight program.

heat shield

Fun Fact 2: Gemini to the Moon?

In the mid 1960s, NASA briefly considered sending a Gemini spacecraft to the Moon; the Apollo spacecraft was plagued with problems and the agency worried it failed to accomplish the lunar landing goal. The idea didn’t last. None of the agency’s leaders were willing to fund two simultaneous lunar landing programs.

Gemini spacecraft to the Moon

The Gemini program holds the record for fastest progression; NASA launched all 10 manned missions in just 20 months between 1965 and 1966. The agency also accomplished all its goals. Using the Air Force’s Agena as a target, four Gemini crews successfully rendezvoused and docked with another vehicle in orbit. Astronauts also learned how to work in the vacuum of space by stepping outside the spacecraft in spacesuits they would later use to walk on the Moon. The Gemini program is typically overlooked, but it was a vital step on the way to the Moon.