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The Launchbox, PoD 15: The Near Misses of Gemini (Part 3)

By Andy Cooke

In my last article, I’d covered Gemini up to Gemini 9 – Gene Cernan’s hellish spacewalk, which uncovered that EVA was a damn sight more difficult than they’d previously expected from Ed White’s gentle float on Gemini 4.

This article looks at the rest of the Gemini series.

Gemini 10

Gemini X launch. Image credit: NASA

This was not to be just a rerun of Gemini 9. As well as docking with its own Agena target vehicle, John Young and Mike Collins would fire the Agena’s rocket motor to boost themselves into a higher orbit. Then, they would track down Gemini 8’s unused Agena target vehicle, proving they could dock with a passive target (as the latter’s batteries had long since run out). A spacewalk by Collins would then see him retrieve a micrometeorite collection package from the Agena.

The first docking did not go smoothly – while trying to track down the target and change orbits to catch it, Collins had mistaken the airglow off the atmosphere for the horizon, and then the sextant didn’t work for him. After updates from the ground, they fired the engine for the rendezvous while the spacecraft was slightly turned off target. They caught the Agena, but used up a lot of fuel in doing so – three times as much as any previous mission. Repeating the docking for practice was scrubbed off the mission, but they went ahead with the burn of the Agena rocket engine.

Agena engine firing and accelerating Gemini X to higher orbit. Image credit: NASA

Firing the rocket in front of them shoved the astronauts forwards in their seats for 80 seconds as the Agena lifted their orbit’s apogee (highest point) to 763 kilometres. They then carried out a rather worrying medical experiment – measuring the radiation at that altitude to check it wasn’t unsurvivable for humans (a full commitment sort of experiment for Young and Collins…). As a relief to the two astronauts, the radiation dosage was “within tolerable limits”. A second burst of the Agena rocket (facing the other way) somewhat later lowered the orbit back down to come up towards the abandoned Gemini 8 Agena. The rendezvous and docking were successful, and Collins went outside to carry out his task.

He found it every bit as difficult as Cernan had reported and lamented the lack of handholds, losing his camera partway through. After some drifting (and use of a hand-held “zip gun” for propulsion and direction) he was successful. On returning to the Gemini, the umbilical linking him to the spacecraft got wrapped around him and needed to be unrolled. And, unfortunately, when the reopened the hatch to throw out the now useless umbilical, the micrometeoroid experiment floated off as well. Other than eye irritation during one of the EVAs (solved by swapping fans), no issues were raised prior to a successful re-entry and splashdown.

What If – Not much here. Even if they’d used less fuel in their first rendezvous, not much would have changed. A Titan explosion during launch, or something else unexpectedly going wrong during the mission could have occurred, but these are “standard” potential PoDs. Problems with rendezvous, docking, or orbit change using the Agena could have required the Gemini programme to be extended, but that’s about all.

Gemini 11

The view from the highest point in the orbit of Gemini 11 - the highest orbit of any Gemini mission. Image credit: NASA

Pete Conrad “rotated” around from his Gemini 5 mission straight onto Gemini 11, along with Dick Gordon, on his own first flight. Upping the difficulty of rendezvous, Gemini 11 hunted down and docked with its Agena target vehicle on its very first orbit (all previous rendezvous attempts had taken multiple hours, but NASA needed to be able to do it a lot faster if they were going to be able to dock with the Lunar Module over the Moon, on its return from the surface).

Conrad had been entranced with a plan to send Gemini around the Moon – a concept that had been periodically revived since Gemini began. NASA top brass repeatedly rejected the plan as a distraction – and a potential competitor to Apollo itself (NASA Administrator Webb saying that if Congress wanted to make the funds available for such a trip, it would be better to plough them straight into accelerating Apollo). Conrad, instead, pushed for the highest possible orbit in a Gemini, using as an excuse that they could test out experiments.

The tether experiment on Gemini 11 - which managed to create a (very small) amount of artificial gravity. Image: NASA

As well as blasting for their high orbit flight (which worked well, and they reached an altitude of 1,372 kilometres before lowering their orbit back down), they attached a tether to their Agena, extended it, and spun both spacecraft around the tether, generating a (very low) level of artificial gravity. Gordon also got to try out some additions (deployable handrails) to try to overcome the previous issues on spacewalks, with some limited success.

The success of all objectives allowed them to add an extra rendezvous with their Agena later on (after leaving it and deliberately wandering off). They followed up with the first fully automatic re-entry (watching the computer closely), which was also successful.

What If – more thin gruel here for the What Ifs. What if things hadn’t gone so well? An addition of an extra mission? What if NASA had managed to get the extra handholds and stirrups for EVA sorted perfectly on this try? Deletion of the final Gemini mission? The biggest What If (a Gemini Moon mission) is reserved for later.

Gemini 12

Lovell and Aldrin head to their Gemini 12 spacecraft. Image credit: NASA

The Gemini programme had triumphantly achieved almost all of its objectives – multi-astronaut flight, prolonged flight, orbital changes, rendezvous, docking, fast rendezvous and docking, EVA … but not that an astronaut could work easily and effectively outside of the vehicle. The issues experienced by Cernan, Collins, and Gordon caused some consternation. The final Gemini mission had to test out and prove ways of working outside of the capsule.

With spare parts starting to prove a problem (as resources were now devoted to Apollo itself), a thirteenth Gemini mission would be unlikely. Although if Gemini 12 did not succeed, something would have to be considered. Jim Lovell and Buzz Aldrin (only flying due to the tragic deaths of Elliot See and Charlie Basset) carried out all mission objectives. More than that – the radar failed, so the computer could not carry out docking. However, Buzz Aldrin (nicknamed “Dr Rendezvous”, who had a doctorate in exactly this situation) pulled out his charts and a manual sextant, and they rendezvoused successfully after two orbits (using very little fuel).

Practice docking and undocking (with both pilots taking turns) was carried out (despite the Agena docking cone jamming on the first attempt; Lovell successfully “rocking free” by using manoeuvring thrusters). A planned jaunt to higher orbit was abandoned when the Agena reported low pressure in its main engine – Mission Control deciding that it wasn’t really that important.

Aldrin installs a handrail. Image credit: NASA

Aldrin carried out the important part of the mission – the EVA – slowly and deliberately, insisting on working for short periods and resting, ensuring he was acclimatised. The handrails, stirrups,, and other deployable assistances were used – and worked perfectly. The insistence on taking time, adding in rest periods, and using the new deployable assistance elements worked perfectly. New tools were used (including a torque wrench that stabilised itself so as not to try to turn the astronaut around it) also worked well. Gemini finished triumphantly.

What If: Well, essentially, what if Aldrin hadn’t been on board? Would the rendezvous have been carried out as successfully (after all, Aldrin was available to assist from the ground, and his techniques had been freely shared, so the answer is: probably). What if the EVAs hadn’t gone as well (perhaps if NASA hadn’t been so successful in their design of astronaut assistance devices)? Answer: maybe another mission, or maybe they’d have punted it into Apollo. Again, not much to chew on.

Gemini To The Moon…

Gemini spacecraft docked with a (proposed) Centaur target vehicle, as part of an Advanced Gemini mission. Image W D Graham

I have to give you at least one decent What If.

There had been various proposals for Lunar Gemini. Options including sending Gemini into lunar orbit and even landing on the Moon (or having a Gemini “lunar rescue” ship to help in case of Apollo problems on the Moon. These could create an entire article for themselves at a future date, but here, I’ll just consider the most straightforward one, and the one that could have been achieved with minimal extra equipment.

If Gemini docked with a Centaur upper stage (instead of an Agena), it could provide sufficient extra fuel to boost the apogee (the highest point in an elliptical orbit) out to lunar distances – achieving a slingshot around the Moon and its return. It might be challenging on the numbers, and if this was to prove impossible, a Titan-3C launched Transtage could do it, as long as the Gemini had 521kg of mass deleted (and could achieve half of that simply by removing the sold fuel retrograde rockets used for re-entry, instead re-engineering the liquid fuel OMS for increased reliability.

From Mark Wade’s “Astronautix” site:

“The Titan 2-launched Gemini would rendezvous and dock with a Titan 3C-launched 'Double Transtage'. The Double Transtage consisted of an unmodified first Transtage that would place itself and a second Transtage into low earth orbit. The first Transtage retained the navigation and maneuvering systems necessary to move the assembly to the rendezvous orbit with Gemini. The second Transtage would be stripped of unnecessary equipment (the orbital maneuvering system) but was equipped with an Agena-type docking collar.

After docking with the Double Transtage, the first Transtage would be cast off and the second Transtage would propel the Gemini into a circumlunar trajectory. The flights themselves, assuming go-ahead was given in September 1965, would follow immediately after the last Gemini flight. In December 1966 a Titan 3C would drive a 2450 kg circumlunar Gemini capsule to 11 m/s re-entry velocity to verify the heat shield design. This would be followed by a February 1967 manned qualification flight in earth orbit. A manned Gemini would dock with a Double Transtage and be propelled into a high orbit and re-entry speed. In April the sequence would be repeated, this time the Gemini being sent by Transtage into a loop around the moon.”

This plan was unveiled in a memo from a meeting between the contractors and NASA management, pushed for by Pete Conrad (as described above).

Translunar injection (TLI) would occur about six hours after Gemini launch.

Impression of Gemini over the Moon. Image by Andy Cooke from a NASA image of Gemini 7 (credit NASA) and Earthrise by NASA (credit William Anders, NASA)

The acceleration from the transtage (pushing them "backwards", giving what astronauts call "eyeballs out" g-forces) would climb from an initial 0.6g to a staggering 5g at burnout, 6 minutes and 40 seconds later, as the fuel is depleted and the entire structure becomes lighter. After burnout, the Gemini reverses away from the transtage and turns around to face the direction of flight.

After another 82 hours, the spacecraft passes behind the moon, which is in last-quarter phase (viewed from Earth), ensuring half the lunar far-side is illuminated by the Sun and visible to the astronauts. As it whirls back around and plummets back towards the Earth, the Gemini adapter and retro sections are cast off to reveal the new, improved heatshield. Flight time at splashdown: 143 hours.

What If… it had gone ahead? There was so much that could go wrong – and so much that could go right.

The pressure for Apollo 8 to try a lunar orbital mission would have been removed – a lunar flyby would have been achieved as early as 1966! The Russian Space Race would have had to focus solely on a lunar landing, for a start. And would public support have dried up after “we got to the Moon” (all right, we didn’t land, but still – that’s just the last few miles, right?). Or would frustration have built as the “final few miles” proved so intractable – especially after the Apollo fire?

Might the Gemini lander programme have been revived? Or the entire lunar landing programme scrapped? The possibilities are huge.


Andy Cooke has written the sci-fi Endeavour trilogy (The End and Afterwards, Diamond in the Dark, Beyond the Sunset) and the political alternate history Lectern books (The Fourth Lectern, The Fifth Lectern), published by SLP.

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