Project Gemini: The Bridge to Apollo

PROJECT GEMINI

The Bridge to Apollo

BY CRAIG COLLINS Photos courtesy of NASA

By the time Gordon Cooper’s final Mercury mission splashed down on March 15, 1963, the U.S. space program was well aware of the gaps in its knowledge about space travel. Mercury had achieved its goals well, but those goals, while extraordinarily ambitious, had been limited. In 1963, the National Aeronautics and Space Administration (NASA) knew that humans could function normally in the weightless environment of space for a little more than a day; they knew that they could launch a spacecraft into high Earth orbit; and they knew that both astronaut and spacecraft could be safely recovered after spaceflight.

But the object of both the American and Soviet space programs was the Moon, and to NASA, it was not yet clear that the trip could be achieved. A lunar voyage would necessarily demand more than one astronaut, and it would require a command module and a lunar lander to separate, carry out separate tasks, and later rendezvous and dock together. To travel to the Moon and back – a distance, in total, of nearly a half-million miles – would require astronauts to remain in space for at least two weeks. The spacecraft itself would need to be powered for a much longer period than was possible with the kinds of batteries used in a Mercury capsule, and it would have to be controlled by the astronaut to a much greater degree. If there were a problem with the docking mechanism, astronauts would have to exit one spacecraft and make their way to another while in orbit – an extravehicular activity (EVA) or “spacewalk.”

Gemini VII photographed from Gemini VI during the first rendezvous between two manned spacecraft in Earth orbit. The spacecraft practiced rendezvous and station-keeping maneuvers for one day in orbit. Gemini VI, with Walter M. Schirra, Jr. and Thomas P. Stafford aboard, launched December 15, 1965. Gemini VII, with Frank Borman and James A. Lovell aboard, launched December 4, 1965.

It wasn’t as if NASA had been caught flat-footed by these issues. Even as the hardware for Apollo was being designed, NASA had been developing a separate “Mercury Mark II” program that would test the hardware, systems, and techniques needed to reach the Moon. The program was announced in December 1961, and became officially known as “Gemini,” named for the stars Castor and Pollux in the constellation Gemini (Latin for “twins”), which symbolized both the program’s two-man crew and its rendezvous mission.

GEMINI III March 23, 1965

Command Pilot: Virgil I. “Gus” Grissom Pilot: John W. Young 4 hours, 52 minutes, 31 seconds

GEMINI IV June 3-7, 1965

Command Pilot: James A. McDivitt Pilot: Edward H. White II 4 days, 1 hour, 56 minutes, 12 seconds. This marked the first extravehicular activity (EVA) by an American, a 22-minute spacewalk by White.

GEMINI V Aug. 21-29, 1965

Command Pilot: Gordon Cooper Pilot: Charles “Pete” Conrad, Jr. 7 days, 22 hours, 55 minutes, 14 seconds. Gemini V made the first weeklong flight and the first use of fuel cells for electrical power. It also completed 120 orbits.

GEMINI VII Dec. 4-18, 1965

Command Pilot: Frank Borman, Jr. Pilot: James A. Lovell, Jr. 13 days, 18 hours, 35 minutes, 1 second. Primary objective was to see whether humans could live in space for 14 days. Gemini VII was also used as a rendezvous target for Gemini VI-A.

GEMINI VI-A Dec. 15-16, 1965

Command Pilot: Walter M. “Wally” Schirra Pilot: Thomas P. Stafford 1 day, 1 hour, 51 minutes, 24 seconds. Achieved the first space rendezvous with Gemini VII, maintaining an assigned orbit (station-keeping) for more than 5 hours at distances from 1 to 300 feet apart.

GEMINI VIII March 16-17, 1966

Command Pilot: Neil A. Armstrong Pilot: David Scott 10 hours, 41 minutes, 26 seconds. Accomplished first hard docking in space. Armstrong overcame a thruster malfunction that caused a near-fatal tumbling. He also made the first emergency landing of a manned U.S. space mission.

GEMINI IX-A June 3-6, 1966

Command Pilot: Thomas P. Stafford Pilot: Eugene A. Cernan 3 days, 21 minutes, 50 seconds. Three different types of rendezvous, 2 hours of EVA, and 44 completed orbits. Docking attempt aborted when the shroud on the target vehicle did not completely separate.

GEMINI X July 18-21, 1966

Command Pilot: John W. Young Pilot: Michael Collins 2 days, 22 hours, 46 minutes, 39 seconds. First use of the Agena target vehicle’s propulsion systems. Collins had 49 minutes of stand-up EVA and 39 minutes of EVA to retrieve an experiment from the Agena stage.

The Gemini X spacecraft docked with the Agena Target Vehicle. The Agena display panel is clearly visible, as is the glow from Agena’s primary propulsion system as it pushed the docked spacecraft into a higher orbit of 475 miles above the Earth, which set a new altitude record for manned spaceflight.

GEMINI XI Sept. 15-16, 1966

Command Pilot: Charles “Pete” Conrad, Jr. Pilot: Richard F. Gordon 2 days, 23 hours, 17 minutes, 8 seconds. Gemini record altitude reached using the Agena’s propulsion after rendezvous and docking.

GEMINI XII Nov. 11-15, 1966

Command Pilot: James A. Lovell, Jr. Pilot: Edwin E. “Buzz” Aldrin Docked manually with the target Agena. Aldrin set an EVA record of 5 hours, 30 minutes, with one spacewalk and two standup exercises, demonstrating improvements on previous EVA problems.

The major goals of Project Gemini were, like Project Mercury’s, stated simply enough to understate their technical complexity:

• to subject astronauts and equipment to spaceflight lasting up to two weeks;

• to rendezvous and dock with orbiting vehicles, and to maneuver the docked combination by using the target vehicle’s propulsion system;

• to perfect controlled methods of re-entering Earth’s atmosphere and landing at a preselected site;

• to perform extravehicular activities while in orbit, and to develop the capabilities and techniques for working in space.

Preparations

To help the seven U.S. astronauts successfully conduct 10 two-man missions into space, NASA selected a second group, informally known as the “New Nine,” to complement the Mercury Seven. On Sept. 17, 1962, Neil A. Armstrong, Frank Borman, Jr., Charles “Pete” Conrad, Jr., James A. Lovell, Jr., James A. McDivitt, Elliot M. See, Jr., Thomas P. Stafford, Edward H. White II, and John W. Young were introduced to the public. Gemini missions would also include five astronauts from Group 3, the “Next Nine,” who were introduced a year later: Edwin E. “Buzz” Aldrin, Eugene A. Cernan, Michael Collins, Richard F. Gordon, and David R. Scott. As in Project Mercury, each member of the New Nine was immediately immersed in a specialty area in the development of Gemini, such as simulators, cockpit layout, or boosters.

Given its mission requirements, the Gemini spacecraft would differ significantly from the Mercury capsule. It would need to be bigger, in order to accommodate two astronauts. It needed more powerful on-board computers, to handle the complicated changes in its orbital path. It would, for its longer-duration missions, be powered by fuel cells in addition to batteries, and it would be equipped with two hatches that could be opened from the inside by both astronauts, to allow them to exit the craft and work in space.

Technicians from the McDonnell Aircraft Corporation, which built the Gemini spacecraft, make final inspections to Gemini III. Unlike manned rockets both before and after, Gemini didn’t have a rocket-powered launch escape system connected to the spacecraft. Instead, the astronauts sat in ejection seats. The photo was taken from the white room atop the Titan launch vehicle at Pad 19 at the Kennedy Space Center. Gus Grissom and John Young would ride the spacecraft into orbit for the first Gemini mission, a five-hour trip into space on March 23, 1965.

Astronaut Walter M. “Wally” Schirra, who flew in Mercury, Gemini, and Apollo missions, often said afterward that the Gemini craft was the most fun to fly. “[With] Mercury, the flight path was predestined,” he said. “You were aboard a ballistic flight around the world. So if you just went fast enough, you kept going around the world, until you slowed down and you came down,” he said in a 1998 NASA interview with NBC News science correspondent Roy Neal. The pilot of a Gemini capsule could move it forward, backward, and sideways in space, a truly piloted craft.

Cooper, also a Mercury and Gemini astronaut, explained to Neal another significant difference between the Mercury and Gemini capsules. “The noise level in Mercury was really quite high,” he said, “because of the inverters and the motors and all the things running right in the same shell you were in. So in Gemini, we moved all of these systems out into an adapter section. We needed more room, too, for putting in fuel cells and batteries and a propulsion system, to be able to do a little bit of orbital maneuvering for rendezvous.”

Because it was bigger, the Gemini capsule was also heavier, weighing around 8,400 pounds – too heavy to be lifted into orbit by the Atlas rocket that launched Mercury’s orbital flights. For its Gemini launch vehicle, NASA turned to the more powerful Titan II ballistic missile, which the Department of Defense had placed into service in 1963.

The Missions

By the end of the Mercury program, the United States had pulled even with the Soviets in the space race, and in the first half of the 1960s, the Russian space program, to demonstrate to the world that it still owned the lead, pulled off a series of flashy stunts. In June 1963, they sent the first woman into space: Valentina Tereshkova, an amateur parachutist plucked from her job as a cotton mill loom operator to join the cosmonaut program. In October 1964, the spacecraft Voskhod I was launched into space, an occasion which, the Soviets pointed out, marked several firsts. It was the first spaceflight to carry more than one person (it carried three people, crammed into a capsule designed for one, which required each to go without a pressure suit), and it was the highest spaceflight then recorded.

Meanwhile, Project Gemini forged ahead, slightly behind schedule but still on target. The first two Gemini missions were unmanned. Gemini I was launched April 8, 1964, and demonstrated the structural integrity of the launch vehicle and its ability to place the spacecraft in orbit. After a pair of launch pad failures involving the guidance system and the fuel cells, Gemini II, an unmanned suborbital flight, was launched on Jan. 19, 1965, and successfully demonstrated the module’s heat shield protection, the spacecraft’s structural integrity, and the performance of the spacecraft’s on-board systems.

On March 18, 1965, the Soviet cosmonaut Alexei Leonov stepped out of the airlock of his spacecraft, the Voskhod 2, and floated free in space for 12 minutes and 9 seconds. The world’s first EVA was an amazing achievement that thrilled the world, and it proved that the United States still had some catching up to do, but NASA’s leaders remained unflappable. To them, the Moon was the finish line, and they remained relatively unconcerned – however impressive the Soviet’s achievements might be – with the lead changes that took place in the interim.

The First American Spacewalk

Edward H. White II, pilot of the Gemini IV spacecraft, floats in the zero gravity of space with an Earth limb backdrop. The extravehicular activity (EVA) represented the first time an American had stepped outside the confines of his spacecraft. White was attached to the spacecraft by a 25-foot umbilical line and a 23-foot tether line, both wrapped in gold tape to form one cord. In his right hand, White carries a Hand-Held Self-Maneuvering Unit (HHSMU). The visor of his helmet is gold plated to protect him from the unfiltered rays of the sun.

Before NASA would attempt to match Leonov’s achievement, it launched a brief test flight of the manned Gemini systems, Gemini III, commanded by Mercury veteran Virgil I. “Gus” Grissom and co-piloted by John W. Young, on March 23, 1965. The following month, Ed White opened his hatch and stepped out of the Gemini IV capsule, tumbling out into the open vacuum of space – America’s first EVA. To compensate for being second overall, NASA made sure its images of White’s 22-minute free fall were far superior to the blurry black-and-whites returned from Voskhod 2. The images snapped by Gemini IV’s commander, James McDivitt, were breathtaking: They captured White, tethered to the spacecraft by a golden umbilical, floating high above snowy-looking clouds and brilliant blue oceans. Among all the images NASA has collected since, these remain some of the most beautiful and awe-inspiring. Almost immediately after they were developed, one was made into a U.S. postage stamp. The experience was certainly moving for White, who, when ordered back into the capsule, expressed reluctance, and when once again seated next to McDivitt, said, “It’s the saddest moment of my life.”

The next two missions encountered several glitches. Gemini V, an eight-day, 120-orbit flight by Gordon Cooper and Pete Conrad, revealed balky performances by the craft’s new fuel cells, and Gemini VI, the first mission calling for rendezvous with a target vehicle – an unmanned Agena rocket stage – was scrubbed when the Agena rocket exploded shortly after launch.

Gemini VI and VII: A Hard-won Rendezvous

Rather than abandon the mission altogether, however, NASA flight controllers devised a bold alternative: Gemini VII, a 14-day flight commanded by Frank Borman and co-piloted by Jim Lovell, would be taking off in December 1965. Why couldn’t the Gemini VI capsule hunt down and rendezvous with them? The vehicles weren’t yet prepared for docking, but they could still demonstrate rendezvous maneuvers – and place four Americans in space at one time.

Gemini VII launched into orbit on Dec. 4; on Dec. 12, the renamed Gemini VI-A encountered more trouble – this time, a much more frightening situation. During launch, the engines of the Titan launch vehicle inexplicably shut down. The on-board computer indicated that the rocket had briefly left the launch pad, which meant the crew – Commander Wally Schirra and co-pilot Tom Stafford – would have to forcibly eject themselves from the capsule.

Astronauts Edward H. White II (left) and James A. McDivitt inside the Gemini IV spacecraft wait for liftoff. The objective of the Gemini IV mission was to evaluate and test the effects of four days in space on the crew, equipment and control systems. White successfully accomplished the first U.S. spacewalk during the mission.

Schirra was faced with an agonizing split-second decision. If the rocket had, in fact, lifted off the ground, even as much as a foot, it would likely settle back down and collapse in a fiery explosion. If Schirra and Stafford activated their explosive ejection seats, they would ruin the capsule for another mission; more important, ejection at such a low altitude could kill them. Schirra, his hand on the ejection ring, waited for the imminent explosion, but heard nothing. Launch controllers quickly figured out the automated system had detected a problem and shut down the engines before liftoff. Schirra’s experience had paid off, and he and Stafford were back in the capsule a few days later. They caught up with Lovell and Borman on Gemini VII’s last day in space, and proved the precise maneuverability of the Gemini spacecraft; at one point, the two capsules were a mere foot apart as they hurtled over the Earth at about 25 times the speed of sound. Borman and Lovell’s 14-day flight was essentially flawless, and the two astronauts splashed down in good health after two weeks in space.

Armstrong Averts Disaster

Now that Gemini VI and VII had demonstrated the fine maneuvering of the capsule, it was time to attempt a “hard dock” with a target vehicle. Gemini VIII, commanded by Neil Armstrong and co-piloted by David Scott, performed the first successful hard dock in space on March 16, 1966, but shortly thereafter, things went horribly wrong. What followed were some of the most terrifying moments in the history of the U.S. space program. A thruster on the Gemini VIII capsule was held open by a short circuit in the electrical system, and sent the capsule and target vehicle spinning end-over-end.

Gemini VIII astronauts Neil Armstrong and David Scott with Navy divers after their splashdown in the Pacific Ocean on March 17, 1966.

Fortunately, Gemini VIII had a quick-thinking commander. Armstrong had been a test pilot for the X-15 rocket plane, which had also been controlled by maneuvering thrusters – and which had flown at speeds that literally raked the paint from its fuselage. Armstrong, struggling to stabilize the capsule, jettisoned the target vehicle, but Gemini VIII’s tumbling worsened, spinning now at about one rotation per second, a rate that could, in time, cause both Armstrong and Stafford to lose consciousness.

Armstrong made the emergency decision to use re-entry fuel to counter the thrust. His skillful counterfires stabilized the capsule enough that the rate of spin was slowed until the stuck thruster ran out of fuel. Because they had consumed re-entry fuel, however, their mission was cut short, canceling Scott’s planned spacewalk, and Gemini VIII was brought down for an emergency splashdown in the Pacific after a mission that, once again, validated the wisdom of placing a skilled pilot in the cabin of a NASA spacecraft.

Solving the Spacewalk

One of the remaining unsolved questions for NASA, after Ed White’s fanciful tumble through space, was whether an astronaut could work purposefully in space. The first attempt to do so was made by Eugene Cernan in June 1966, on Gemini IX-A – a mission that had also been delayed by the failed launch of an Agena target vehicle. Though a second attempt was successful, the shroud that was supposed to peel back over the target vehicle’s docking mechanism became stuck, and Cernan and Commander Tom Stafford turned their attention to rendezvous maneuvers and Cernan’s spacewalk, during which he was scheduled to test a new backpack Astronaut Maneuvering Unit (AMU).

Cernan found the going rough in space. With nothing to hold onto or push against, he flailed about ineffectually, his considerable strength of no help at all in the weightless environment. His advisers on the ground became concerned when his heart rate rose to near his maximum, the exertion so great that his visor fogged, obscuring his vision. His EVA was cut short after an exhausting 2 hours – he was later found to have lost 10 pounds during that time – and Cernan never made it to the AMU. Even with careful direction from Stafford, he barely made it back inside the spacecraft.

The next two EVAs – by Michael Collins in Gemini X and Richard Gordon in Gemini XI – revealed similar difficulties. Collins, on July 19, 1966, performed a “stand-up” spacewalk, bracing himself in the frame of the hatch rather than venturing outside, but a second spacewalk was riddled with problems: After a struggle, he retrieved a micrometeorite collector from the side of the spacecraft, but the collector later floated out of the cabin and was lost. He traveled over the Agena to retrieve another collector, but could not find anything to hold on to, and had trouble making it back to the capsule. The gas gun Collins used for maneuvering in space stopped working, and it took the two men eight minutes to close the hatch as they struggled to tame the 15 feet of Collins’ umbilical cord. Gordon’s first EVA, during which he straddled the target vehicle and attached a tether that would make for an easier rendezvous, was cut short at 33 minutes after he became overtired. The next day, he performed a 2-hour, stand-up EVA.

The Augmented Target Docking Adapter (ATDA) as seen from the Gemini IX spacecraft during one of three rendezvous in space. The ATDA and Gemini IX spacecraft are 66.5 feet apart. Failure of the docking adapter protective cover to fully separate on the ATDA prevented the docking of the two spacecraft. The ATDA was described by the Gemini IX crew members as an “angry alligator.”

In advance of their last manned Gemini mission, NASA astronauts had arguably not demonstrated an efficient working EVA. Its crew for Gemini XII, its last shot, would prove well chosen: Edwin “Buzz” Aldrin, a Ph.D. who had written his thesis on orbital mechanics, studied the problems reported by White, Cernan, Collins, and Gordon, and developed underwater simulations to study the mechanics of moving in low gravity. Based on his experiments and the input of the other spacewalkers, NASA engineers tried to improve the odds of a successful EVA by adding handholds and railings to the capsule and target vehicle, as well as shoe restraints in the area where Aldrin would be working.

Gemini XII, commanded by Jim Lovell, launched on Nov. 11, 1966, and performed its rendezvous, docking, and orbital adjustments relatively smoothly – even demonstrating, after the failure of a radar guidance unit, that the docking procedure could be conducted manually. After a 2-hour stand-up EVA on Nov. 12, Aldrin ventured out of the hatch on Nov. 13 to photograph star fields, retrieve a micrometeorite collector, and tether Gemini XII and the Agena target vehicle together. Each of his movements was planned in advance, and Aldrin didn’t break a sweat during the two-and-a-half hours he spent in space. His approach to planning and simulating an EVA became a standard for NASA.

With Gemini XII, NASA had at last achieved what had, perhaps unexpectedly, become the trickiest of its mission objectives – the purposeful spacewalk. After Aldrin’s pioneering studies and successful demonstration, NASA had the EVA down.

Surveyor I, NASA’s first unmanned lunar lander, had, just a few months earlier, sent back close-up images of the surface of the Moon – a milestone, but still behind the Russians, whose Luna 9 probe had performed the first soft Moon landing in February 1966. By the end of the Gemini program, however, as the Apollo launch complex was being constructed at the Kennedy Space Center on Merritt Island, Florida, the achievements of American astronauts had surpassed those of Soviet cosmonauts. The Moon had never been closer.