Rendezvous in Space: The Launch of Gemini 7

Today, spacecraft rendezvousing in orbit to support crews spending months at a time in space is fairly routine. But a half a century ago, the technology and skills required for these important tasks were just being developed. One of the key early missions to demonstrate these skills which are so vital to today’s space programs was the flight of NASA’s Gemini 7. This crewed mission would not only spend a record-long two weeks in space but it would also serve as a target for the first ever orbital rendezvous.

Gemini Program Objectives

The purpose of NASA’s Gemini program was to develop the technologies and techniques needed to fulfill President Kennedy’s goal of landing a man on the Moon by 1970. The major objectives of the program were:

– Demonstrate that humans and their equipment can survive up to two weeks in space
– Demonstrate rendezvous and docking techniques in orbit
– Demonstrate the technology and techniques needed to perform EVAs (Extra-Vehicular Activities)

Meeting all of these objectives was necessary if the Apollo lunar program were to be successful.

Diagram showing the major systems of the Gemini spacecraft. Click on image to enlarge. (McDonnell)

Gemini was a two-man spacecraft that was roughly conical in shape with a base diameter of 3.3 meters which stood 5.8 meters tall.  Built by the McDonnell Aircraft Corporation (which merged with Douglas in 1967 to become McDonnell Douglas which subsequently merged with Boeing 30 years later), it consisted of two major sections. The first section was the reentry module which housed the crew, their equipment, food supplies and so on in orbit as well as the recovery systems needed to safely return them to Earth. Unlike today’s crewed spacecraft, the Gemini crew cabin was pressurized with pure oxygen at about one-third standard atmospheric pressure to save weight. The next section, the adapter section, connected the reentry module to the launch vehicle during ascent and housed equipment needed to support the crew while in orbit. It consisted of a retrograde section which held a set of four solid retrorockets used to start the descent to Earth from orbit and an equipment section which housed the in-orbit propulsion systems, life support, power systems and all other equipment not needed for the return to Earth.

With a typical launch mass of up to about 3,700 kilograms or more, Gemini needed the largest operational rocket available at the time to get into orbit: a modified Titan II ICBM built by Martin Marietta (which is now part of Lockheed Martin). A number of modifications were made to simplify the operation of this rocket, smooth out its ride and improve its reliability to support crewed missions. With the Gemini spacecraft mounted on top, the Titan II GLV (Gemini Launch Vehicle) was 33 meters tall and had a fully fueled launch mass of about 154 metric tons.

Diagram showing the major components of the Gemini-Titan II. Click on image to enlarge (NASA)

After the first successful crewed test flight of the spacecraft during the brief three-orbit Gemini 3 mission launched on March 23, 1965, NASA was ready to work its way steadily up the learning curve to meet the Gemini program’s objectives (see “The Mission of Gemini 3”). The primary objective of the second crewed flight, Gemini 4 launched on June 3, was to start the step-wise process of increasing the duration of crewed missions by spending four days in orbit (see “The Forgotten Mission of Gemini 4”). A secondary objective of the Gemini 4 mission was to perform America’s first EVA which had been moved up in response to the EVA performed during the Soviet Voskhod 2 mission two months earlier (see “The Mission of Voskhod 2”). With the flight of Gemini 5, the mission duration had been extended to eight days – the minimum time necessary for Apollo to land on the Moon and return to Earth (see “Eight Days or Bust: The Mission of Gemini 5”). While the primary objective of the two-day Gemini 6 mission was to perform the first orbital rendezvous and docking, officials left reaching the ultimate Gemini program goal of spending two weeks in orbit to the Gemini 7 mission.

The Gemini 7 Mission

The primary objective of the Gemini 7 mission was to evaluate the effects on the crew and spacecraft of 330 hours in orbit. Secondary objectives included conducting 20 medical, science and engineering experiments ranging from assessing various aspects of crew health during a long duration mission to photography of the Earth and interesting weather phenomena from orbit. Immediately after reaching orbit, Gemini 7 would perform station keeping maneuvers with the spent second stage of their Titan II launch vehicle with the secondary objective of gaining more experience in these important operations. Other secondary objectives included conducting various spacecraft systems tests as well as an attempt at a precision reentry and landing.

A fish-eye view of the Gemini 7 crew cabin. (NASA)

Because of the length of this mission, it was felt that the standard G4C space suits worn on the earlier Gemini missions would prove to be too uncomfortable. Another secondary objective of the Gemini 7 mission was to evaluate the new lightweight G5C spacesuit. Designed and manufactured by the David Clark Company, development of the G5C suit had started in April 1965. It dispensed with as many of the hard parts in the G4C suit as was possible and consisted of only two nylon-based layers to get the garment’s mass down to 7.2 kilograms. Like the Sokol spacesuit used today on Soyuz flights, the G5C suit had no hard helmet. Instead it had a nylon hood with a clear visor integrated with the suit that could be easily unzipped to open. To protect their heads during key parts of the flight, the astronauts would wear modified pilot’s helmets inside their suits with built in headphones and a microphone for communications.

The crew of the Gemini 7 mission wore the new lightweight G5C spacesuits during their mission like he one being modeled here. (NASA)

The new suits were designed so that it could be partially doff during flight for comfort and take only 35 seconds to close up in an emergency. It was also designed to be completely removed while in orbit and be donned in five to ten minutes. As a safety precaution, mission planners would allow only one astronaut at a time to remove his spacesuit and wear just lightweight undergarments. This would be the first time an American astronaut would go without a spacesuit while in orbit, although the three cosmonauts on the Voskhod 1 mission back in October 1964 flew their entire one-day mission without spacesuits (see “The Mission of Voskhod 1”). The two astronauts would alternate removing their suits during the 14-day mission and both would be required to wear the G5C during critical phases of the mission such as launch and reentry.

Portrait of the prime crew for the Gemini 7 mission: James A. Lovell, Jr. (left) as pilot and Frank Borman (right) as command pilot. (NASA)

In order to take advantage of their already extensive training, the backup crew of the Gemini 4 long-duration flight were assigned to fly the Gemini 7 mission. The command pilot, 37-year old USAF Major Frank Borman, was a West Point graduate with extensive experience as a pilot and instructor in thermodynamics, fluid mechanics as well as flight and spacecraft testing. The pilot for this mission, 37-year old USN Lt. Commander James A. Lovell, Jr., was an Annapolis graduate with an equally impressive military career as a pilot and instructor. Both men were part of the second group of NASA astronauts selected in September 1962 and neither had flown into space before. Borman and Lovell’s back up crew consisted of USAF Major Edward H. White II, who was the pilot on the four-day Gemini 4 mission, and rookie astronaut, USAF Major Michael Collins.

The Gemini 7 mission patch. (NASA)

A Change of Plans

In preparation for a December 1965 lift off, Gemini spacecraft number 7 was flown from McDonnell’s St. Louis facility and arrived at Cape Kennedy, Florida on October 5. The Titan II GLV-7 launch vehicle serial number 62-12562 was shipped from Martin’s Baltimore plant and arrived at the Cape on October 19. But before the hardware could be erected on the pad at Launch Complex 19, plans for Gemini 7 had changed. On October 25, Gemini 6 was suppose to lift off for a two-day mission to perform the first rendezvous and docking in space. Unfortunately, the Agena target vehicle for this mission never made it into orbit because of a failure of its primary propulsion system (see “The Unflown Mission of Gemini 6”). With no replacement target vehicle readily available, the original Gemini 6 mission plans were scrapped and a new plan devised to keep the fast paced Gemini program on schedule.

Artist’s concept of the Gemini 6 and 7 rendezvous mission. (NASA)

The new plan called for Gemini 7 to be launched first on its original long duration flight from LC-19 on December 4, 1965. Ground crews would then quickly refurbish the pad and prepare what was now officially designated “Gemini 6A” for launch with the original crew of Walter Schirra and Thomas Stafford nine days later. Gemini 6A would then use Gemini 7 as a rendezvous target and perform a station keeping exercise. No docking would be attempted because of insufficient time to develop the needed hardware and procedures as well as address all of the safety concerns. In addition to supplemental training for Borman and Lovell who had already been practicing station keeping maneuvers with the Titan II, the only modifications required for Gemini 7 to support the new mission was the addition of an L-band radar transponder for Gemini 6A to track as well as target acquisition and orientation lights on the Gemini adapter section to improve visibility. The new plan was approved and publicly unveiled on October 28.

Since the Titan II GLV-6 already installed on the pad did not quite have the performance needed to launch the long-duration spacecraft number 7, which was almost 120 kilograms heavier than the one for the Gemini 6 rendezvous mission, spacecraft number 6 was destacked on October 28 and its Titan II removed from the pad at LC-19. The following day, GLV-7 was erected at LC-19. The modified spacecraft number 7 was finally mated to its launch vehicle on November 22. After a final simulated flight test on November 27, everything was ready for the launch of Gemini 7.

Lovell (left front) and Borman (right front) having their prelaunch breakfast with fellow astronauts. (NASA)

In order to keep Borman and Lovell in peak condition for their mission, it was decided not to disturb the crew’s preflight work and rest cycles so launch was scheduled for 2:30 PM EST. This allowed Borman and Lovell to sleep in until 7:00 AM on the December 4, 1965 launch day. During the course of the comparatively leisurely morning schedule which included the usual preflight medical examines, the crew had a traditional steak and eggs breakfast at 10:00 AM with some fellow astronauts. Included was a briefing from the backup crew, White and Collins, who had spent the morning working with the ground crews preparing Gemini 7 for launch.

Lovell and Borman exiting the suiting trailer wearing their G5C spacesuits on their way to LC-19. (NASA)

After breakfast, they were off to the trailer at LC-16 to don their new G5C spacesuits. Afterwards, the Borman and Lovell were transported to LC-19 and got into their seats in the waiting Gemini. Following a nearly perfect countdown, Gemini 7 lifted off at 2:30:04 PM EST under clear skies and towards orbit for the longest crewed mission ever attempted. Almost immediately, ground crews began work to prepare LC-19 for the launch of Gemini 6.

The launch of Gemini 7 from LC-19 at 2:30:04 PM EST on December 4, 1965. (NASA)

First Days in Orbit

After the Titan II second stage had shutdown, the 3,663-kilogram Gemini 7 was in a 161 by 327-kilometer orbit with an inclination of 28.9°. Frank Borman fired Gemini’s aft OAMS thrusters for just two seconds to pull away from the spent second stage then turned the spacecraft around to start the station keeping exercise. In less than a minute, they had the spent rocket stage in view. Over the course of the next fifteen minutes, the astronauts took turns at the controls and were able to easily maneuver as they wished around the stage at distances of 18 to 46 meters thanks to the hours of practice in the simulator. The only complication was fuel venting from a broken line causing the Titan II second stage to tumble at about 2 RPM.

A view of the spent Titan II second stage during the Gemini 7 station keeping exercise immediately after reaching orbit. (NASA)

After Gemini 7 had performed a brief separation burn and had drifted away from its target, a 75-second OAMS thruster firing raised the low point of the spacecraft’s orbit to 222 kilometers ensuring that the orbit would not decay before the end of the nominal two-week mission. After a meal and some housekeeping chores, the astronauts settled down for their first night of sleep in orbit. Meanwhile back on Earth, work proceeded overnight at LC-19 where the post-launch assessment had revealed surprisingly little damage.

Lovell and Borman wearing their G5C spacesuits inside the Gemini 7 crew cabin. (NASA)

On the morning of December 5, ground crews began erecting Titan II GLV-6 back onto the pad at LC-19. As Borman and Lovell began their scheduled activities for their first full day in orbit, there were some minor glitches in orbit. The crew was having problems with the reticule of the photometer for the D-5 Star-Occultation Navigation experiment. Eventually the experiment was cancelled because of continuing issues with the hardware over the next few days. Frank Borman also accidentally pulled off an EEG electrode he was wearing for the M-8 Inflight Sleep Analysis experiment. The crew attempted to replace the electrode but were unsuccessful.

Frank Borman seen with an EEG electrode in place before his flight. This electrode was accidentally pulled off during the second day in orbit. (NASA)

On the third day, Jim Lovell was finally allowed by ground controllers to remove his G5C spacesuit. Lovell felt much more comfortable and was eventually given approval to sleep without his suit. Among the activities on this third day, the crew observed the launch of a Polaris A-3 SLBM (Submarine Launched Ballistic Missile) just off the coast from the Cape. The SLBM was fired by the “Gold Crew” of the nuclear-powered ballistic missile submarine, USS Benjamin Franklin (SSBN-640), as part of its shakedown cruise. That night, Lovell slept comfortably as Borman sweltered in his fully donned suit.

A photograph taken by the Gemini 7 crew during the launch of a Polaris A-3 SLBM off the coast of Cape Kennedy on December 6. The missile’s contrail is visible as a thin line in the upper right corner. (NASA)

On December 7, Borman fired the OAMS thrusters in the first of a series of maneuvers for the upcoming rendezvous with Gemini 6. This day’s trajectory adjustment placed Gemini 7 into a 188 by 302-kilometer orbit – the first step towards circularizing the orbit to approximate that of an Agena target vehicle. After much discussion, Lovell was allowed to sleep for another night with his suit off. As a concession to Borman, he was allowed to sleep with his gloves off and his hood fully opened to make his situation a bit more comfortable.

A view from Gemini 7 on December 8 across the Pacific Ocean showing the Moon above the horizon. (NASA)

As the Gemini 7 crew continued their marathon mission in orbit, Borman and Lovell had to contend with some minor spacecraft issues. On the sixth day there were indications of some issues in one of the fuel cell stacks. Since the power produced by the fuel cells was vital to the long duration mission, crew and ground controllers continued to monitor their performance. On the morning of the seventh day the crew woke up to find Gemini 7 tumbling at a rate of 10 degrees per second probably as the result of exhaust from a water boiler used for cooling the spacecraft systems. The affected radiator was manually bypassed and OAMS thrusters were employed to steady the craft.

Fuel cells like these were the only way to power long duration mission such as Gemini 7 and the Apollo lunar missions. (NASA)

By December 9 it was apparent that preparations for the launch of Gemini 6A were proceeding ahead of schedule and that launch could take place a day early on December 12. In preparation for this launch, Borman fired Gemini’s thrusters for 78 seconds to raise its perigee to 299 kilometers. A second burn a half orbit later lowered the apogee to 303 kilometers. Gemini 7 was now in its “circular” orbit to wait for the arrival of Gemini 6.

A view of the Mission Control Center in Houston, Texas during the Gemini 7 flight. (NASA)

By the next day, the temperature inside the Gemini 7 crew cabin had risen to an uncomfortable 29.4° C and once again the issue of spacesuits was raised. Because of various delays, Borman had remained in his spacesuit since launch while Lovell had spent the previous four days in the relative comfort of his undergarments. Finally after Borman’s multiple requests, the crew was instructed late in the afternoon to switch suit modes – Lovell had to put his suit back on while Borman was finally allowed to remove his. Borman would finally have a chance to cool off and get a comfortable night’s sleep. The next day, the long duration crew performed more experiments and made preparations for the launch and rendezvous of Gemini 6.

Frank Borman shown inside the Gemini 7 crew cabin performing a visual acuity test. (NASA)

The story continues in “Rendezvous in Space: The Gemini 6 Launch Abort“.

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Related Video

Here is 8 mm movie footage by Peter Faulkner (with a synched soundtrack) of the NBC coverage of the launch of Gemini 7.

Related Reading

“Rendezvous in Space: The Gemini 6 Launch Abort”, Drew Ex Machina, December 12. 2015 [Post]

“The Unflown Mission of Gemini 6”, Drew Ex Machina, October 25. 2015 [Post]

“Eight Days or Bust: The Mission of Gemini 5”, Drew Ex Machina, August 21. 2015 [Post]

“The Forgotten Mission of Gemini 4”, Drew Ex Machina, June 3, 2015 [Post]

“The Mission of Gemini 3”, Drew Ex Machina, March 23, 2015 [Post]

General References

David Baker, The History of Manned Space Flight, Crown Publishers, 1981

Barton C. Hacker and James M. Grimwood, On the Shoulders of Titans: A History of Project Gemini, SP-4203, NASA History Division, 1977

David J. Shayler, Gemini: Steps to the Moon, Springer-Praxis, 2001

“Gemini 7/6”, NASA Press Release 65-362, November 29, 1965