This is the last in a series of articles on the historic Gemini 6 and 7 missions. The story about the original rendezvous and docking mission of Gemini 6, which was cancelled when its target vehicle was lost during launch, was covered in “The Unflown Mission of Gemini 6”. The story of the launch and first few days of the Gemini 7 long-duration mission, which would now also serve as the rendezvous target for the alternate “Gemini 6A” mission, was told in “Rendezvous in Space: The Launch of Gemini 7”. The hurried preparation and first launch attempt of the Gemini 6A mission, which ended in the now famous on-pad launch abort, are discussed in “Rendezvous in Space: The Gemini 6 Launch Abort”.

The Long Grind

As Gemini 7 passed over Cape Kennedy at 9:54 AM EST on December 12, 1965, Frank Borman and Jim Lovell could see the plume from the brief ignition of the Titan II first stage engines that were suppose to send Gemini 6 on its way to an orbital rendezvous. But based on their own experience and having witnessed the launch of a Polaris A-3 SLBM from orbit just six days earlier, they could tell that the launch had been aborted – an observation confirmed by Mission Control. With the long awaited rendezvous postponed, the Gemini 7 crew continued their marathon mission in orbit.

At 1:25:18 PM EST, as engineers and technicians on the ground were still assessing the cause of the Gemini 6 launch abort, Borman and Lovell surpassed the 190 hour, 55 minute, 14 second space duration record set just 3½ months earlier by the crew of Gemini 5 (see “Eight Days or Bust: The Mission of Gemini 5”). Although December 12 was going smoothly for them in orbit, the strain of the long duration mission was taking a toll on the Gemini 7 crew especially after the launch abort. Neither astronaut was in the best of spirits with Borman observing “Jim and I are beginning to notice the days seem to be lengthening a bit.” With the uncomfortable cabin temperature, lack of adequate toilet or cleaning facilities and the tight confines of the Gemini crew cabin, Borman added “We’re getting a little crummy up here.”

The psychological impact of the long duration mission was especially noticeable on Borman who was the mission commander. While for the first few nights of the mission Borman was averaging about six hours of sleep like Lovell, by the end of the first week in orbit, he was typically only sleeping 4½ to 5 hours a night despite being allowed to remove his G5C spacesuit for the first time during the sixth day of the mission. Keenly aware of his responsibilities, Borman slept fitfully and woke frequently to scan the spacecraft’s instruments before drifting back to sleep.

The day after the launch abort, it became clear that Gemini 6 could not only attempt another launch but that the ground crews could shave a day off of the normal four-day turn around. Another launch attempt would be made on the morning of December 15. Meanwhile in orbit, Borman and Lovell had to contend with another fuel cell issue. A warning light indicated that excess water was building up in the waste tank. This was flushed out by forcing extra oxygen through the system from the crew compartment’s reserve supply. On December 14, the crew continued with their experiments in orbit. This included observing the reentry of an ICBM reentry vehicle over the Eniwetok Atoll in the Pacific Ocean after it had been launched from Vandenberg Air Force Base in California by a Minuteman ICBM – the first such observation from space.

At 4:00 AM EST on December 15, Wally Schirra and Tom Stafford were woken up for their third attempt to get Gemini 6 into orbit. After showering and getting dressed, they had breakfast with astronaut Al Shepard and got a briefing from their back up crew, Gus Grissom and John Young, who had spent the predawn hours with the ground crews preparing Gemini 6 for launch. After donning their G4C spacesuits, Schirra and Stafford slipped into their spacecraft just past 7:00 AM with a sign saying “Good luck from 2nd shift” hanging on the spacecraft. As the final seconds ticked off in the countdown, the announcement from the LC-19 blockhouse was made, “Gemini Six, you are GO!”. At 8:37:27 AM EST the first stage engines of the Titan II GLV-6 ignited with Wally Schirra heard to exclaim “Go! D’you hear the man, GO!”

Gemini 6 finally lifted off the pad at LC-19 but out of view of Gemini 7 overhead due to clouds along their line of sight. The spacecraft accelerated until the first stage finally burned out 156 seconds after launch. Stafford checked the guidance computer at that moment and got a velocity reading of 7,830 meters per second indicating that they were well on their way after a false start three days earlier. A brief flash engulfed the ascending spacecraft as the second stage ignited. After five minutes and 41 seconds of powered flight, Gemini 6 was finally in a 161 by 259-kilometer orbit some 1,992 kilometers behind Gemini 7. A few minutes later, Borman and Lovell finally observed the contrail from Gemini 6 and even caught a brief glimpse of the spacecraft itself as they passed over Africa. The Gemini 7 crew donned their G5C lightweight spacesuits and waited for company to arrive.

The Rendezvous

With Gemini 6 finally in orbit, the US had started its first two-spacecraft crewed mission. The Soviet Union had already flown dual space missions before with their one-person Vostok spacecraft: Vostok 3 and 4 in August 1962 followed by Vostok 5 and 6 in June 1963. But the relatively primitive Vostok was incapable of performing an actual rendezvous and these spacecraft simply passed within about five kilometers of each other just because of good aiming at launch. Gemini 6 and 7 were real “spaceships” in the sense that they could maneuver from one orbit to another using computer processed radar information to bring them together in orbit.

A number of different rendezvous modes with an orbiting target had been identified during theoretical studies of the issue. The most aggressive and fastest of these, which would be preferred for the Apollo missions when the Lunar Module departed the Moon’s surface, was the “first apogee” method where the active spacecraft would be launched directly into an elliptical orbit that would allow a rendezvous with the passive target spacecraft during the active spacecraft’s first apogee. This method required a fast-paced sequence of precisely timed and executed maneuvers in order to be successful. For the Gemini 6 mission, the “coelliptical” method was chosen instead where the active spacecraft would first be placed into a circular orbit below and some distance behind the passive target spacecraft (Gemini 7, in this case) which is in its own circular orbit. The active spacecraft would then catch up to its target over the course of several revolutions then maneuver to match the target’s orbit in order to perform the actual docking. While this approach took longer, it was much more flexible and allowed more time to plan and execute maneuvers – a desirable characteristic for the first attempt of the untried orbital rendezvous procedure. For this mission. Gemini 6 would attempt what was called an “M=4” profile where the rendezvous would take place during the 4th revolution.

Being in a lower orbit with a shorter period, Gemini 6 was able to close in on Gemini 7 very quickly. About 94 minutes after launch with Gemini 6 trailing Gemini 7 now by 1,175 kilometers, Schirra used the OAMS (Orbital and Attitude Maneuvering System) thrusters on Gemini 6 to increase its velocity by 4 meters per second raising its apogee up to 272 kilometers. After two hours and 18 minutes of flight, Schirra added 19 meters per second to the chasing craft’s velocity to begin the phase adjustment to reduce the distance further and raise the perigee to 224 kilometers. A half an hour later over the Pacific, another OAMS burn maneuvered Gemini 6 into the same orbital plane as Gemini 7 which was now only 483 kilometers away.

After three hours and 15 minutes, Gemini 6 activated its L-band radar to attempt to detect the transponder carried by Gemini 7 and established a lock at a range of 434 kilometers. At mission elapsed time of three hours 47 minutes, the aft OAMS thrusters of Gemini 6 were fired for 54 seconds to increase the velocity by 13 meters per second. This placed Gemini 6 into a nearly circular 270 by 274-kilometer “final intermediate orbit” to slowly catch up to Gemini 7 now only 319 kilometers away. Four minutes later, Schirra and Stafford entered an automatic rendezvous mode under the control of their onboard computer.

After five hours and four minutes of flight, Schirra spotted Gemini 7 just 100 kilometers away as a bright star. Twelve minutes later, Schirra began the final series of maneuvers to bring the two spacecraft close to each other. During the terminal stage of the rendezvous, Schirra and Stafford both saw Gemini 7 aligned with the stars Castor and Pollux in the constellation of Gemini as they completed their last nighttime pass before finishing the rendezvous. Gemini 7 blazed into view as it passed into sunlight 200 meters ahead of Gemini 6 at orbital dawn. After a series of small braking maneuvers, Gemini 6 finally stopped 40 meters from Gemini 7 completing the first rendezvous in the history of spaceflight at 2:33 PM – just under six hours into the mission of Gemini 6. Cheers erupted at Mission Control as flight controllers waved American flags and celebratory cigars were lit.

High above the Pacific Ocean, the four astronauts happily exchanged greetings and jokes. “You guys sure have beards” quipped Schirra as he saw the smiling faces of Borman and Lovell through the windows of their Gemini 7 spacecraft. At one point, Stafford (who was a graduate of the US Naval Academy like Schirra and Lovell) placed a “Beat Army” sign in his window as a friendly dig at West Point alumnus, Borman, in reference to the traditional Army-Navy football game (which had ended in a 7-7 tie 2½ weeks earlier).

For the next three orbits, all four astronauts took turns controlling their respective spacecraft during station keeping exercises as they drifted as far apart as 90 meters and maneuvered in as close as just 0.3 meters. The crews performed a series of tests and determined that they had no problems maneuvering their spacecraft accurately with respect to each other or visually tracking each other even during the night time passes. According to the final tally, the rendezvous of Gemini 6 had used only 51 kilograms of propellant with 62% still unused in the spacecraft’s tanks. With the successful conclusion of this exercise, NASA was now ready to attempt a docking during the upcoming Gemini 8 mission. With the end of a long day in orbit approaching, Schirra performed a separation burn to pull the two spacecraft a safe distance of 16 kilometers apart. Both crews ate a good meal and went to sleep to get some well deserved rest as a pleasing observation “we have company tonight” came in from Gemini 7.

Coming Home

The morning of December 16, Schirra woke up with a stuffy head and a runny nose. Fortunately, the Gemini 6A mission had met all of its primary objectives and was ready to return to Earth after only a day in orbit freeing up tracking and recovery resources for the last three days of the Gemini 7 mission. But before Gemini 6 left orbit, Tom Stafford radioed in “This is Gemini Six. We have an object, looks like a satellite, going from north to south, up in a polar orbit. He’s in a very low trajectory… looks like he may be going to re-enter pretty soon. Stand by… it looks like he’s trying to signal us.” A few seconds later this was followed by a rendition of “Jingle Bells” from a small, four-hole Hohner harmonica Schirra had carried with him and the tinkling of little bells by Stafford – Christmas was only nine days away and the crews were going to start heading home.

With a final call to Gemini 7 from Schirra, “Really good job, Frank and Jim. We’ll see you on the beach.” Schirra then flipped Gemini 6 blunt-end forward and fired the retrorockets on schedule for the return to Earth in the primary recovery zone in the west Atlantic Ocean. The final objective of the mission was to perform a precision reentry and landing. Schirra initially placed the descending reentry module in a heads-down attitude then banked to 55° left at an altitude of 100 kilometers. The onboard computer took control of the descent at 85 kilometers banking the module one way then the other to keep on course.

At an altitude of 24 kilometers, the Gemini 6 reentry module was coming straight down with the parachute deployment starting at 14 kilometers and the main chute out at 3,200 meters. Gemini 6 splashed down just 12.9 kilometers from the planned aim point at 10:28:50 AM EST after a mission of 25 hours, 51 minutes and 24 seconds. While Navy frogmen were in the water and attached a flotation collar on the reentry module, Schirra and Stafford opened the hatches and opted to be picked up by the recovery carrier, the USS Wasp, 62 minutes after landing. In another first, the whole operation was broadcast live back to television viewers in the US from the USS Wasp via satellite. After so many false starts, the Gemini 6 mission was successfully concluded.

Meanwhile in orbit, the departure of Gemini 6 was a real let down for Borman and Lovell who still had two days left before their return to Earth. They continued to deal with fuel cell issues as well as other minor system malfunctions and were growing less tolerant of each other. At 9:30 AM on December 16 as Gemini 6 was preparing to leave orbit, a problem was noted in two of the thrusters on Gemini 7 used for yaw control. With the station keeping exercise completed and with only three days left, it was decided that backup systems and operating in a free drift mode would suffice for the remainder of the mission. But there was also some good news for the weary astronauts: After consultation with doctors and engineers, it was decided that the Gemini 7 crew would be much more comfortable out of their G5C spacesuits and that the benefits far outweighed the risks. For the first time in the mission, both astronauts were allowed to remove their spacesuits at the same time and leave them off until their return from orbit.

On December 17, Borman and Lovell were given the final go to complete their 14-day mission despite ongoing fuel cell issues. Analysis by NASA and McDonnell engineers indicated that they would perform adequately for the remainder of the mission. With the relief of this good news, Borman slept better than he had before during the mission. Learning from the experiences of the Gemini 5 long-duration crew, the Gemini 7 crew brought along a couple of books to help pass the time and relax during periods of drifting flight over the last couple of days in orbit. Borman read some of Mark Twain’s Roughing It recalling the author’s adventures in the American West during the 1860s. Lovell brought part of Drums Along the Mohawk Trail by Walter D. Edmonds. Both books were chosen, in part, because they had nothing to do with spaceflight.

After stowing all of their gear and two-week’s worth of trash not to mention getting back into their rather soiled G5C spacesuits for one last time, Frank Borman and Jim Lovell were ecstatic about finally coming home on December 18. With only 24 hours of oxygen, 10 hours of power and almost no water left, the retrorockets on Gemini 7 fired automatically to begin the return to the west Atlantic recovery zone where the USS Wasp was waiting. Like Gemini 6, the last objective of Gemini 7 was to perform a precision landing. Borman banked the reentry module at 35° due to a ground controller error instead of the planned 53°. By the time the error was noticed, the computer was already online and commanding the reentry maneuvers. Borman had a wager with Schirra about who would come down closest to their aim point during their precision landing and this was not a good start. Guided by the computer, the Gemini 7 crew experienced braking loads of 3.9 Gs which “felt like a ton” after a fortnight in weightlessness.

Gemini 7 came through its reentry and made its splashdown at 9:05:05 EST after a flight lasting 330 hours, 35 minutes and 1 second – just 5½ hours short of two weeks and a space endurance record that would stand until the 18-day Soyuz 9 mission in 1970. And despite the initial navigation error, Gemini 7 came down only 11.8 kilometers off target and 1.1 kilometers closer than Schirra in Gemini 6. Although Borman felt a little dizzy at first, Lovell felt fine. And while the astronauts had initially planned on taking off their spacesuits immediately after landing, they decided it was not worth the effort and opted to leave them on until they were recovered.

As before, Navy frogmen were in the water to secure the Gemini reentry module shortly after splashdown. Borman and Lovell, who opted for a helicopter recovery, were on the deck of the USS Wasp only 32 minutes after landing followed a half hour later by their spacecraft. Aside from a general sense of fatigue, the Gemini 7 crew survived their long-duration mission and were soon back to their preflight condition. With the successful conclusion of this two-week flight (which was longer than any planned for the Apollo lunar missions) and the first rendezvous in space, NASA was one step closer to the Moon. While the Gemini program had accomplished much during 1965, there were still five more flights scheduled for 1966 to gain experience in docking and EVA.

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Related Video

Here is an excellent NASA documentary on the Gemini 6 and 7 mission from 1966 entitled “Proud Conquest: Gemini VII and VI”.

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Related Reading

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

“Rendezvous in Space: The Launch of Gemini 7”, Drew Ex Machina, December 4, 2015 [Post]

“The Unflown Mission of Gemini 6”, Drew Ex Machina, October 25, 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