Gemini

Overview

Gemini was not pure pioneering like Mercury, nor did it have the excitement of Apollo. But its success was critical to Kennedy’s goal of reaching the Moon “by decade’s end."

The program was announced to the public on January 3, l962, after Apollo already was well underway. Gemini’s primary purpose was to demonstrate space rendezvous and docking-techniques that would be used during Apollo, when the lunar lander would separate from the command module in orbit around the Moon, then meet up with it again after the astronauts left the lunar surface. Gemini also sought to extend astronauts’ stays in space to two weeks, longer than even the Apollo missions would require.

It was during the Gemini program that space flight became routine. Ten piloted missions left the launch pads of Cape Canaveral, Florida, in less than 20 months, and the Manned Spacecraft Center (renamed the Johnson Space Center in 1973) outside Houston, Texas, took over the role of Mission Control. Ground operations became smooth and efficient, due in part to fleetingly short launch windows-the Gemini XI “window” opened for only 2 seconds-dictated by the need to rendezvous with targets already in orbit. Meanwhile, sixteen new astronauts chalked up experience in space.

The Gemini spacecraft was an improvement on Mercury (it was originally called Mercury Mark II) in both size and capability. Gemini weighed more than 3,628.72 kilograms-twice the weight of Mercury-but ironically seemed more cramped, having only 50 percent more cabin space for twice as many people. Ejection seats replaced Mercury’s escape rocket, and more storage space was added for the longer Gemini flights. The long duration missions also required fuel cells instead of batteries for generating electrical power.

Unlike Mercury, which had only been able to change its orientation in space, Gemini needed real maneuvering capability to rendezvous with another spacecraft. Gemini would have to move forward, backward and sideways in its orbital path, even change orbits. The complexity of rendezvous demanded two people on board, and more piloting than had been possible with Mercury. It also required the first onboard computers to calculate complicated rendezvous maneuvers.

Gemini rode into orbit on a Titan 2 launch vehicle. The target for rendezvous operations was an unmanned Agena upper stage, which was launched ahead of the Gemini. After meeting up in orbit, the nose of the Gemini capsule then fit into a docking collar on the Agena.

To avoid long delays between flights, Gemini spacecraft were made more serviceable, with subsystems that could be removed and replaced easily. An adapter module fitted to the rear of the capsule (and jettisoned before reentry) carried on-board oxygen, fuel and other consumable supplies.

Gemini gave U.S. astronauts their first real experience with living and working in space. They had to learn to sleep and keep house on long flights in crowded quarters, both of which were difficult. Gemini astronauts also made the first forays outside their spacecraft, which required a new spacesuit design. Space walks proved more difficult than expected-following Ed White’s successful solo on Gemini IV, it wasn’t until the final Gemini flight that another extravehicular activity went as smoothly as planned.

By Gemini’s end, an important new capability-orbital rendezvous and docking-had become routine, and space doctors had gained confidence that humans could live, work and stay healthy in space for days or even weeks at a time. Gemini also completed a long list of onboard science experiments, including studies of the space environment and Earth photography. Above all, the program added nearly 1,000 hours of valuable space-flight experience in the years between Mercury and Apollo, which by 1966 was nearing flight readiness. Five days before the launch of the last Gemini, Lunar Orbiter 2 had been sent to the Moon, already scouting out Apollo landing sites.

Gemini Statistics

Bibliography

NASA Sources

• Dethloff, Henry C. "Suddenly Tomorrow Came...": A History of the Johnson Space Center. NASA SP-4307, 1993. Available online at http://www.jsc.nasa.gov/history/suddenly_tomorrow/suddenly.htm.
• Grimwood, James M., and Hacker, Barton C., with Vorzimmer, Peter J. Project Gemini Technology and Operations: A Chronology. NASA SP-4002, 1969. Available online at http://history.nasa.gov/SP-4002/cover.htm.
• Hacker, Barton C., and Grimwood, James M. On Shoulders of Titans: A History of Project Gemini. NASA SP-4203, 1977. Available online at http://history.nasa.gov/SP4203/cover.htm.
• Pitts, John A. The Human Factor: Biomedicine in the Manned Space Program to 1980. NASA SP-4213, 1985. Available online at http://history.nasa.gov/SP-4213/sp4213.htm.

Non-NASA Sources

• Collins, Michael. Carrying the Fire: An Astronaut Journeys. (Farrar, Straus & Giroux, 1974).
• Harland, David M. How NASA Learned To Fly in Space: An Exciting Account of the Gemini Missions. Apogee Books, 2004.
• Shayler, David. Gemini: Steps to the Moon. Springer-Praxis, 2001.

Gemini Missions

Gemini III

23 March 1965

Crew: Virgil I. “Gus” Grissom and John W.Young

In a playful reference to the Broadway hit The Unsinkable Molly Brown, Gus Grissom nicknamed the Gemini III spacecraft Molly Brown, hoping that it would not duplicate his experience with Liberty Bell 7. (All Gemini flights were designated by a Roman numeral. Gemini III was the only flight to use both a Roman numeral and a call-sign/nickname given by an astronaut.) The mission’s primary goal was to test the new, maneuverable Gemini spacecraft. In space, the crew fired thrusters to change the shape of their orbit, shift their orbital plane slightly, and drop to a lower altitude.The spacecraft was supposed to have enough lift for a precision landing, but reality did not match wind tunnel predictions: Gemini III splashed down some 111.1 kilometers (69 statute miles) short of its intended target. The capsule was designed to land on its side, suspended at two points from a parachute. But during the descent, when the astronauts threw a switch to shift Molly Brown to its landing position, they were thrown forward with such force that Grissom’s faceplate cracked. Still, the first test of the two-seat spacecraft, and of Gemini ground operations, had been a success.

Gemini IV

3–7 June 1965

Crew: James A. McDivitt and Edward H. White II

Theplanforthisfour-day,62-orbitmissionwasforGemini IV to fly in formation with the spent second stage of its Titan II booster in orbit. On this first attempt, however, spaceflight engineers learned something about the complication of orbital rendezvous.Thrusting toward their target, the astronauts only moved farther away.They finally gave up after using nearly half their fuel. (On later rendezvous missions, a spacecraft chasing another in orbit would first drop to a lower, faster orbit before rising again.) The mission's highlight was Edward White’s 22-minute spacewalk, the first ever for an American.Tied to a tether and using a handheld “zip gun” to maneuver himself, White swam through space while James McDivitt took photographs. Gemini IV set a record for flight duration and eased fears about the medical consequences of longer missions. The new Mission Control Center outside Houston was put into use for the first time. It had to conduct the first three- shift operations because of the long flight duration.

Gemini VII

4–18 December 1965

Crew: Frank Borman and James A. Lovell, Jr.

This 14-day mission required NASA to solve problems of long-duration spaceflight, not the least of which was stowage (the crew had practiced stuffing waste paper behind their seats before the flight). Timing their workday to match that of ground crews, both men worked and slept at the same time. Gemini VII flew the most experiments (20) of any Gemini mission, including studies of nutrition in space.The astronauts also evaluated a new, lightweight spacesuit, which proved uncomfortable if worn for a long time in Gemini’s hot, cramped quarters. The high point of the mission was the rendezvous with Gemini VI. But the three days that followed were something of an endurance test, and both astronauts, heeding Pete Conrad’s Gemini V advice, brought books along. Gemini VII was the longest spaceflight in U.S. history, until the Skylab missions of the 1970s.

Gemini VI-A

15–16 December 1965

Crew: Walter M. Schirra, Jr., and Thomas P. Stafford, Jr.

A rendezvous and docking with an unpiloted Agena target was this mission’s original objective, but when Mission Control lost contact with the Agena during an October launch attempt, an alternate mission was substituted: a meeting in space of two Gemini spacecraft. Eight days after the launch of Borman and Lovell’s Gemini VII, Walter Schirra and Thomas Stafford tried to join them, but their Titan II launcher shut down on the pad (the cool-headed Schirra did not eject, even though the countdown clock had started ticking—he felt no motion and trusted his senses). Three days later, GeminiVI made it into orbit. Using guidance from the computer as well as his own piloting, Schirra rendezvoused with the companion spacecraft in orbit on the afternoon of 15 December. Once in formation, the two Gemini capsules flew around each other, coming within 0.3048 meters (1 foot) of each other but never touching. The two spacecraft stayed in close proximity for 5 hours. One of Gemini’s primary goals—orbital rendezvous—had been achieved.

Gemini VIII

16 March 1966

Crew: Neil A. Armstrong and David R. Scott

A second major objective of the Gemini program was completed less than 6 hours after launch, when Neil Armstrong brought GeminiVIII within 0.9144 meters (3 feet) of the prelaunched Agena target and slowly docked, completing the first orbital docking ever. What followed, however, were some of the most hair-raising minutes in space program history. The Gemini VIII capsule, still docked to the Agena, began rolling continuously. The crew undocked from the Agena, but the problem was a stuck thruster on the spacecraft that now tumbled even faster, at the dizzying rate of one revolution per second. The only way to stop the motion was to use the capsule’s reentry control thrusters, which meant that Armstrong and David Scott had to cut short their mission and make an emergency return to Earth 10 hours after launch. They were still nauseated after splashdown, as well as disappointed: Scott had missed out on a planned spacewalk.

Gemini IX

3–6 June 1966

Crew: Thomas P. Stafford, Jr., and Eugene A. Cernan

Thomas Stafford and Eugene Cernan became the first multiperson backup crew to fly in space after the intended first crew of Elliott See and Charles Bassett died in a plane crash four months before the flight. The highlight of the mission was to have been a docking with a shortened Agena called the Augmented Target Docking Adapter (ATDA).The docking was canceled, though, after Stafford and Cernan rendezvoused with the target and found its protective shroud still attached, which made it look, in Stafford’s words, like an “angry alligator.” Cernan also was to have tested an Astronaut Maneuvering Unit (AMU), a jet-powered backpack stowed outside in Gemini’s adapter module to which the spacewalking astronaut was to have strapped himself. But Cernan’s spacewalk was troubled from the start. His visor fogged, he sweated and struggled with his tasks, and he had problems moving in microgravity. Everything took longer than expected, and Cernan had to go inside before getting a chance to fly the AMU. The device was not finally tested in space until Skylab, seven years later.

Gemini XI

12–15 September 1966

Crew: Charles “Pete” Conrad, Jr., and Richard F. Gordon, Jr.

With Apollo looming on the horizon, Gemini project managers wanted to accomplish a rendezvous immediately after reaching orbit, just as it would have to be done around the Moon. Only 85 minutes after launch, Pete Conrad and Richard Gordon matched orbits with their Agena target stage and docked several times. Conrad had originally hoped for a Gemini flight around the Moon but had to settle for the highest Earth orbit—1,367.94 kilometers (850 statute miles)—ever reached by an American manned spacecraft. Gordon’s first spacewalk once again proved more difficult than ground simulations and had to be cut short when he became overtired. A second, 2 hour “stand-up” spacewalk went more smoothly. Gordon even fell asleep while floating halfway out the hatch. An experiment to link the Agena and Gemini vehicles with a 15.24-meter (50-foot) tether (which Gordon had attached during his spacewalk) and rotate the joined pair was troublesome. Conrad had problems keeping the tether taut but was able to generate a modicum of “artificial gravity.” The mission ended with the first totally automatic, computer-controlled reentry, which brought Gemini XI down only 4.5 kilometers (2.8 statute miles) from its recovery ship.