The Gemini program: 50 years on

March 23 marked the 50th anniversary of the launch of Gemini III – the first manned mission of the now-legendary Gemini program. Following hot on the heels of the Mercury missions, and only a short time after President Kennedy's famous speech in which he announced his intent to put a man on the Moon by the end of the decade, Gemini was tasked with testing the technologies and techniques that would lead America to victory in the space race.

Whilst the earlier Mercury program was hailed a success, the Russians (then the Soviet Union), had triumphed by putting the cosmonaut Yuri Gagarin in space ahead of the Americans. Temporarily defeated, but not beaten, NASA knew that there were other firsts to achieve – the race to the Moon was on, and national pride was at stake like never before.

To lay the groundwork for an eventual Moon landing, a number of key technologies had to be developed and honed. This was the purpose of Gemini. The program had four primary goals – to test the effects of prolonged exposure to space on a team of two astronauts, to successfully execute rendezvous and docking maneuvers with a second spacecraft in orbit, to perfect re-entry and landing, and finally, to assess the physical and psychological effects of weightlessness and confinement on the crews of the Gemini missions.

The program ran from 1962 to 1966, and saw the launch of two initial uncrewed test missions, seven target vehicles, and 10 crewed missions. The total cost for the Gemini program ran to nearly US$1.3 billion in 1967, which paid for the testing of cutting-edge technologies.

The spacecraft was essentially an enlargement of NASA's original manned Mercury spacecraft. Once separated from the launch system, Gemini could be split into two sections – the re-entry module and the adaptor module. The cone-shaped re-entry module was able to support two astronauts in relative comfort in the confines of its pressurized cabin. The capsule boasted life support, instrument panels and two large hatches located directly above the astronauts' seats that could be opened for extravehicular activities.

The adaptor section housed a retrorocket segment fitted with four re-entry rockets, and an equipment section at the base of the spacecraft contained communications systems, fuel for propulsion and other vital assets such as oxygen and water. Upon re-entry, the equipment section would be separated, exposing the retrorockets. The four solid fuel boosters would then fire, inserting the spacecraft into a safe re-entry trajectory, after which the section would detach, leaving the capsule to face the extreme heat of atmospheric re-entry alone.

To protect the crew while returning through Earth's atmosphere, Gemini spacecraft were fitted with a heat shield constructed from an ablative material, which was fitted to the base of the re-entry module and bolstered with heat-resistant shingles made from Rene 41 and beryllium. Once safely through the atmosphere, a series of parachutes would deploy from the nose of the capsule, allowing it to land relatively gently in water at a 35-degree angle.

The first manned Gemini mission launched on March 23, 1965 from Complex 19 of the Cape Canaveral Air Force Station atop a two-stage Titan II rocket. The Titan family of launch vehicles had begun life as an ICBM prior to being modified and certified to insert astronauts into orbit.

The Gemini III spacecraft was crewed by Virgil Grissom and John Young, who were tasked with evaluating the performance and capabilities of a number of experimental technologies, including the orbit attitude and maneuver system, and the worldwide tracking network – two systems without which, rendezvous would be rendered impossible. The flight lasted 4 hours and 52 minutes, concluding with a successful re-entry and splashdown in the Atlantic Ocean, where the crew and capsule were recovered by helicopter and transported to the U.S.S. Intrepid.

The missions that followed tested numerous other vital technologies and maneuvers. Gemini IV, crewed by James McDivett and Edward White, undertook the first-ever spacewalk by a US astronaut. On a later mission, Neil Armstrong and David Scott became the first astronauts to successfully rendezvous and dock with another spacecraft in Gemini VIII. This maneuver in particular was vital to the eventual success of Apollo 11, and was trialled over the course of a further three Gemini missions.

Astronauts Buzz Aldrin and Jim Lovell were the last to fly in the program, crewing the Gemini XII spacecraft. Aldrin and Armstrong went on to be the first men to walk on the Moon, while Lovell never made it to the lunar surface. As Apollo 8 command module pilot, he was among the first to orbit the Moon. In a later mission his spacecraft, Apollo 13, suffered a catastrophic malfunction, forcing Lovell to abandon the lunar landing, instead having to be nursed back to Earth in a rescue operation that reminded the world of the dangers inherent in space exploration.

President Kennedy summed up the spirit of the American space program when he stated, "We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win."

This ethos, combined with the labor of an army of scientists and engineers, made the Gemini program a resounding success, validating technologies and allowing it to accomplish all but one of its primary goals – safely touching down at a pre-determined landing point on solid ground. The breakthroughs achieved over the course of those missions paved the way for the Apollo program that followed shortly after and succeeded in landing men on the Moon, capturing the hearts and minds of a generation, and inspiring many to come.

Source: NASA