The Gemini program was the bridge from Mercury to Apollo. All tasks astronauts would have to perform on the lunar journey were tested during Gemini. However, the twelve-flight program was not always planned to begin and end the way it did. Instead, multiple capsule modifications would allow it to perform versatile missions— everything from docking with a space station to landing on the moon, though in this post we will not be discussing lunar Gemini proposals.
Gemini 7 spacecraft photographed by Gemini 6A (NASA)
Big Gemini, also known as Big G, was proposed to provide resupply to space stations. In 1967, it was pitched to NASA and the US Air Force (USAF), who were both developing their own separate space stations; the Apollo Applications Program Orbital Workshop, which would become Skylab, and the Manned Orbiting Laboratory (MOL), respectively. Space stations planned for the late 1970s would have been manned by crews of anywhere from six to twenty-four people and would require multiple resupply missions that existing spacecraft could not handle. Big G would have been able to fit nine to twelve astronauts at one time— far more than even the Space Shuttle could carry— as well as twelve metric tons of cargo. Due to its large size, it would have launched on a heavy-lift rocket, such as a Titan IIIM or Saturn INT-20 (neither of which made it past the drawing board). Big G would have the same hatch and heat shield configuration as the Gemini B and the cargo module could be accessed through a pressurized tunnel— no extra-vehicular activity necessary. Additionally, it would have docked aft end first to move cargo in and out of the space station. The crew module had a volume of 660 cubic feet (19 m³), a length of 38 feet (11.58 m), and a diameter of 14 feet (4.27 m) The USAF configuration had a cylindrical maneuvering and cargo module so it could fit on Titan boosters. The NASA configuration had a conical module so it could fit on top of a Saturn rocket. Due to its size, it would have been unable to make a water landing and instead would have returned to a designated site on land using skids and a parasail. If everything was to progress as scheduled, and if Big G received the funding it needed, operational flights would have started by 1971. However, Orbital Workshop 1 (Skylab), which was planned for 1970, would not be operational until 1973. NASA spent the rest of the 1960s and early 1970s landing men on the moon and the MOL program was terminated in June of 1969. By this time, the Gemini spacecraft and all the concepts derived from it were obsolete.
Illustrations of the Big Gemini spacecraft for their different launch vehicles
(image credit: Giuseppe Chiara)
A mockup of Big G at the McDonnell Douglas plant (McDonnell Douglas)
Blue Gemini was both a spacecraft and a program conceived as a joint USAF/NASA project. The program’s purpose was to prepare Air Force astronauts to fly MOL missions by having them fly with NASA Gemini astronauts. After two joint flights, two Air Force astronauts would fly the missions together but still perform tasks for NASA. The spacecraft would have been the same regular old spacecraft the Gemini program actually wound up using in 1965, but Blue Gemini's paper lifespan only lasted six months. Read my post "Hidden Histories: Blue Gemini" for more.
Gemini B configuration for Blue Gemini at the McDonnell Douglas plant 1968 (McDonnell Douglas)
Gemini B was the most tangible of Advanced Gemini proposals because it actually existed. It was developed for MOL and used a standard Gemini with a round hatch cut through the heat shield to allow astronauts access to the laboratory attached beneath them. If the heat shield was not properly intact during reentry, the crew would burn up and perish. In order to test this, a prototype was made using the already flown Gemini 2 capsule and a boilerplate, OPS 0855. The two parts were attached to a mock-laboratory made from a Titan II propellant tank and launched into space on a Titan IIIC rocket from Launch Complex 40 on Cape Canaveral in 1966. The flight was a success and the new Gemini B became the first capsule to fly in space twice. Like with Big Gemini, the Gemini B concept was abandoned after MOL was terminated, and the unique test article is now on display at the Cape Canaveral Space Force Museum at Launch Complex 26 on Cape Canaveral .
The Gemini B on display at the Cape Canaveral Space Force Museum (image credit: Aeryn A.)
Paraglider Gemini was supposed to use a Rogallo wing and a set of wheels or skids to land on the ground after reentry. A Rogallo wing is a self-inflating flexible wing as shown in the picture below. Three test articles called Test Tow Vehicles were towed and dropped by helicopters to test the functionality of the paraglider in 1964 and 1965. This method of landing was unfavored due to delays in development and failures in testing, as the final test occurred after the success of Gemini 3 and was no longer of interest to NASA. This is also how Big Gemini would have landed.
Flight-tested Gemini Paraglider now on display in the National Air & Space Museum
(National Air & Space Museum)
Soon after the cancellation of their X-20 Dynamic Soarer program, the Air Force proposed the use of a winged Gemini capsule for manned spaceflight. The unique wings were developed and tested during the ASSET program, which stands for the Aerothermodynamic Elastic Structural System Environmental Test, and was used to study the overall reliability of winged vehicles in space with emphasis on reentry. However, the Winged Gemini was not designed to maneuver in orbit. To do so, it would have needed to launch on a Titan IIIA or Titan IIIC rocket and use the transtage for maneuvering. If maneuvering was not a concern, it would have launched on the standard Titan II Gemini Launch Vehicle NASA used. McDonnell Aircraft also proposed a version of the capsule that would have been capable of a piloted runway landing. The spacecraft Icarus from the 1969 film Planet of the Apes draws inspiration from both the Winged Gemini and X-20.
A diagram of the Winged Gemini (McDonnell Douglas)
While Advanced Gemini proposed a number of modifications to the Gemini spacecraft, none are as iconic as the baseplate spacecraft itself. Its use in the program gave some of the most famous astronauts their first flights in space and both flown capsules and test articles are on display all across the country.
Author's note: Thanks for reading and be sure to like and share this post!
 The museum's original name (the name I grew up with) was the Air Force Space & Missile Museum.
Day, Dwayne. “The Big G.” The Space Review: The Big G, 7 Dec. 2015, www.thespacereview.com/article/2879/1.
Downey, Ron. “McDonnell Winged Gemini Report.” Aviation Archives, 4 Oct. 2019, aviationarchives.blogspot.com/2019/10/mcdonnell-winged-gemini-report.html.
Teitel, Amy Shira. “The Paraglider: How NASA Tried And Failed To Land Without Parachutes.” Popular Science, 29 Feb. 2016, www.popsci.com/paraglider-how-nasa-tried-and-failed-to-land-without-parachutes/.
Wade, Mark. Gemini, www.astronautix.com/g/gemini.html.