It is often said that history is written by the winners. Space history is no exception.

Everyone knows that Apollo 11 that landed the first man on the Moon. Very few people know about the important role Gemini played in that accomplishment. In a very real sense, it was Gemini, not Apollo, that landed Neil Armstrong on the Moon.

The mission profile NASA originally planned for Apollo lunar landings was very different from the profile that finally got Apollo to the Moon. The Apollo command/service module was already in development when President John F. Kennedy made his historic speech calling for America to land a man on the Moon. Contrary to popular belief, Apollo was not originally designed for lunar landing missions. It was intended as a direct follow-on to Project Mercury for longer duration missions in Earth orbit and, perhaps, a reconnaissance mission to lunar orbit. That changed on September 12, 1962. When Kennedy called for a lunar landing, NASA began to study ways of landing the Apollo command/service module on the Moon.

Apollo Direct Ascent Command/Service Module landing on the Moon

NASA had two competing architectures for lunar landing. One, called Earth Orbit Rendezvous, called for launching the lunar vehicle in sections, which would be assembled in space. This architecture, which had long been favored by Dr. Wernher von Braun, used moderate-sized rockets. Unfortunately, it also required a space station, if NASA wanted to do it right, and building a space station did not fit into Kennedy’s timeline.

The other architecture, called Direct Ascent, launched the lunar vehicle in one piece. This architecture required a huge rocket, which led NASA to start development of the Saturn V. Unfortunately, as development of Apollo progressed, the weight grew and it soon became obvious that even the Saturn V would not be capable of landing the Apollo command/service module on the Moon. Apollo seemed to be on the verge of failure

What saved NASA was the emergence of a third architecture, called Lunar Orbit Rendezvous. LOR called for the development of a small lunar lander that would separate from the command/service module and descend to the Moon. LOR was promoted by John Houbolt, a young engineer at NASA Langley Research Center.

The Lunar Orbit Rendezvous idea initially met with considerable resistance, but Houbolt persisted and famously went over the heads of his superiors, writing directly to NASA Associate Administrator Dr. Robert Seamans. Finally, the powers that be came to agree with Houbolt. This led to the development of the Apollo lunar module, which made the lunar landing possible.

Size comparison for lunar lander -- Direct Ascent vs. Lunar Orbit Rendezvous

So far, this sounds like the story made famous in the Tom Hanks miniseries From the Earth to the Moon. There is more to the story than the Hollywood version, however.

The actual text of Houbolt’s letter contains some statements that are a bit mysterious in the context of this story. At one point in the letter, he writes, “Give us the go-ahead, and [Saturn] C-3, and we will put men on the moon in very short order – and we don’t need any Houston empire to do it.” That is obviously a reference to the Manned Space Flight Center – what does he mean by not needing the Houston empire?

Elsewhere in the letter, Houbolt refers to  “a manned rendezvous experiment… with the Mark II Mercury.” Mercury Mark II was the original name for Project Gemini. At the time Houbolt wrote his letter, there was considerable rivalry between Langley, an older Langley NASA center that had played a leading role in Project Mercury, and the new Manned Space Flight Center in Houston. There were also two competing capsules in development. MSFC was the lead center for Project Apollo, but Langley favored Gemini.

According to the official histories, Gemini was merely a “stepping stone”  to Apollo – an interim program to prove out rendezvous and docking techniques that would later be used for the Apollo lunar missions.

If that was true, how do we explain the Gemini 11 mission? On that flight, Pete Conrad and Richard Gordon docked with an Agena upper stage used it to propel the Gemini capsule to a record altitude of 739 miles above the Earth. To this day, that remains the highest altitude any human has ever reached, apart from the lunar missions. The record flight was not necessary for proving out rendezvous and docking techniques, however. So, why was it done?

In fact, Gemini was intended to be more than just a stepping stone to Apollo. It was intended to go to the Moon. Jim Chamberlin, the brilliant Canadian engineer who designed Gemini, had that goal in mind all along. After the initial flights in Earth orbit, there would be a Lunar Gemini or “Gemini L.”

For lunar missions, the Gemini capsule would be significantly modified.  The Earth-orbital version of the capsule was covered with gray shingles manufactured from a high-temperature alloy called René 41. The design of these high-temperture shingles gave the capsule a distinctive corrugated appearance, similar to that of the SR-71. René 41 was not adequate for the higher-speed reentry on lunar  return, however, so the shingles would be replaced by an ablative coating. To save weight, the size of the parachute recovery system would be reduced and the nose section, which housed the parachutes, slightly shorted. The Lunar Gemini would also have a large, steerable high-gain antenna, similar to the antenna on the Apollo service module.

Radiation might seem to be a problem for Lunar Gemini missions. The Gemini capsule did not have nearly as much radiation shielding as the Apollo capsule. This made the capsule considerably lighter but would also put the astronauts at considerable risk while on the way to the Moon, above the protection of the magnetosphere. The Gemini designers found an elegant solution to this problem, however. Instead of shielding the entire cabin, as Apollo did, they would simply shield the astronauts, using lead blankets similar to those used in dentists’ offices.

To get the Gemini from the Earth to the Moon, Langley considered a number of options. One option was to use a three-engine version of the Saturn rocket (the C-3 mentioned by Houbolt in his letter). Another option called for Gemini to rendezvous with a separate upper stage (probably a Centaur) in Earth orbit and use the upper-stage engine for translunar propulsion. That is the technique that was, in fact, being tested on Gemini 11.

Once in lunar orbit, the two Gemini astronauts would spacewalk from the cabin to the equipment module at the rear of the capsule, where to folding lunar landers were stowed. The astronauts would unfold the lander legs, then fly the two landers down to the lunar surface.

Project Gemini lunar lander

This is the concept Houbolt had in mind when he wrote, “we don’t need any Houston empire.” He was advocating Lunar Gemini, the program that conceived Lunar Orbit Rendezvous. Lunar Gemini was highly controversial, however, and Apollo engineers initially resisted LOR quite strongly. They finally relented, when it became obvious that LOR was the only way NASA was going to get to the Moon.

While NASA program managers finally accepted Lunar Orbit Rendezvous, they remained vehemently opposed to Lunar Gemini. That is hardly surprising given the amount of money being pored into Project Apollo and the political brokering that accompanied it. Lunar Gemini still had friends, however, not only at Langley but in Houston as well. Within the astronaut corps, Captain Pete Conrad was a strong advocate who would not back down, even in the face of opposition from NASA management. His persistence led to the approval of the Gemini 11 mission, which proved of feasibility of rendezvousing with an upper stage in Earth orbit and using the stage to move the Gemini to a higher orbit. Unfortunately, even a determined naval aviator like Conrad has his limits, and Gemini never went any farther than that. Friends who worked with Pete Conrad in later years tell us that he never really gave up and always believed NASA had made a mistake.

In some ways, Gemini would have made a better capsule for lunar missions than Apollo. Critics of Gemini will point out that the Gemini cabin was amazingly cramped, like the cockpit of a fighter plane. NASA’s astronauts were hardly strangers to fighter pilots, and to a man, they much preferred the Gemini to the larger, transport-like Apollo. (See Flying the Gusmobile.)

Because of its cramped cockpit, Lunar Gemini would have avoided some medical problems that came up on Apollo. Gemini astronauts never experienced space sickness, which was seen for the first time in the Apollo program. Space sickness became a problem when astronauts had enough room to leave their seats and move around the capsule. Unfortunately, when an astronaut becomes space sick, it takes about 2-4 days for the body to adapt to weightlessness and the sickness to go away. That was a real problem for Apollo, since it takes about three days to get to the Moon. Worse, two of the astronauts would then leave the Apollo command module and descend to the Moon. On the Moon, they would lose their adaptation to weightlessness, so they would have another opportunity to get space sick on the way back.

It is often stated that Apollo was a more advanced, third-generation capsule. The truth is just the opposite. Apollo was the original Mercury follow-on. It was already in development when NASA realized another capsule might be needed and approved development of Gemini. Gemini flew first because it was developed more quickly, but Gemini (not Apollo) was the real third-generation capsule. Because Apollo was already in development, the Gemini designers were able to incorporate lessons learned from both the Mercury and Apollo capsules.

Gemini 6 and Gemini 7 rendezvous in Earth orbit

On Mercury and Apollo, numerous  systems were located inside the capsule’s pressure shell. That made ground servicing very difficult, since there was little room for technicians to work inside the capsule. To service one system, it was often necessary to remove several others just to gain access. The Gemini capsule was designed more like a military fighter plane. Instead of pressurizing the entire capsule, as with Mercury and the Apollo command module, the Gemini designers only pressurized the cockpit. Most of the systems were located outside the pressurized compartment and could be serviced from outside the capsule by simply removing an access plate.

If Lunar Gemini had been approved, even as a backup, it’s possible that NASA might have avoided the tragic Apollo fire which claimed the lives of Gus Grissom, Ed White, and Roger Chafee. Engineers knew that the Apollo capsule was buggy and troublesome but rushed to get it into service anyway because of fears that the Soviets were about to launch a circumlunar flight ahead of the US. The Gemini capsule was more mature, having flown sooner, so there would have been less of a rush to get it ready. (It’s possible that a Lunar Gemini astronaut might have died in some other fashion, of course. There is no perfect safety this side of the grave.)

Ironically, while NASA has decided to return to space capsules, Project Gemini remains almost forgotten. When President George W. Bush announced his Vision of Space Exploration, he cited Apollo as the model for the new Crew Exploration Vehicle. NASA Administrator Mike Griffin spoke of “Apollo on Steroids.” Contractors such as Lockheed took note, and the Orion program is building a big Apollo. History is written by the winners, and no one seems to remember that the United States once built a more advanced capsule.

We can only speculate on how NASA’s space programs might have evolved after Lunar Gemini. Lunar Gemini was a faster, better, cheaper approach to getting to the Moon. Would it have been cheap enough to avoid being cancelled, as Apollo was? We will never know. Gemini contractor McDonnell Douglas also proposed a number of Gemini derivatives, including a five-man Rescue Gemini and a Big Gemini capable of carrying 9 to 12 astronauts. If Lunar Gemini had been approved, instead of Apollo, some of those variants might have been approved as well. NASA astronauts might be using an evolved Gemini variant to get to the International Space Station today, instead of being dependent on Russian Soyuz capsules.

Written by Astro1 on April 6th, 2012 , Space History Tags:

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COMMENTS
    Duggi commented

    SpaceX Dragon is a biger Gemini

    Reply
    April 7, 2012 at 2:07 pm

    Wow, this was a fantastic article. I never considered that Gemini was more advanced than Apollo. I wonder what would have happened if it was Gemini, not Apollo that made it to the moon. It sounds like the capsule was not only faster to build but more stable and cheaper. Although in all fairness I believe it was Gemini VIII that had issues with its thrusters and caused it to tumble for just under a minute. I don’t think Mercury or Apollo had that issue.

    Reply
    April 9, 2012 at 1:38 pm
      Prof. Erwin Corey commented

      I think Neil Armstrong was on that flight. He had many close calls.

      Reply
      January 11, 2015 at 5:12 pm
    Dwayne Day commented

    “LOR was invented by John Houbolt…”

    No it wasn’t. The idea predated him, Houbolt advocated for it.

    There are a lot of problems with the assumptions in this article, included the overall assumption that a spacecraft and lunar landing method that was never built would have been superior to one that was. For example, this:

    “Once in lunar orbit, the two Gemini astronauts would spacewalk from the cabin to the equipment module at the rear of the capsule, where to folding lunar landers were stowed. The astronauts would unfold the lander legs, then fly the two landers down to the lunar surface.”

    Attempts to perform an EVA to the rear of the Gemini proved to be very difficult. There is no reason to believe it would have been easier with two people. Also, that’s two landers to fail, not one. That’s two landers that need to dock with the Gemini, not one. That also requires the Gemini to operate in lunar orbit by itself while the astronauts are on the surface. In short, this would have been an incredibly risky mission and more difficult than Apollo. And to then speculate how things would have been different 40 years later is very dubious.

    Reply
    April 11, 2012 at 12:53 pm
      admin commented

      Oddly enough, leaving the capsule in orbit while the astronauts go down to the surface is exactly what NASA planned to do with Orion. The difference being that they planned to leave Orion in orbit, unattended, for a far longer period of time — weeks rather than hours.

      The assertion that “there is no reason to believe it would have been easier with two people” is an odd one which flies in the face of common experience. Anyone who has ever served in the military, gone scuba diving, or been a Boy Scout knows the value of the buddy system.

      If having two landers that can fail scares you, then you shouldn’t be going to the Moon at all. Ultimately, Apollo put six landers on the Moon. That’s six chances to fail. When humans go back to the Moon in significant numbers, there will be hundreds of landers and hundreds of chances to fail.

      Any new idea is “risky” and “dubious” to critics who fear the unknown. Managing risk is what spaceflight (and aviation) are all about. You can pretend that Apollo was risk free, but it wasn’t. Three astronauts died in the Apollo 1 fire because NASA didn’t listen to pilots like Scott Crossfield. That was a failure of risk management. Another three astronauts almost died on Apollo 13. It was not only the hard work of Mission Control that saved them, it was also a lot of luck. Spaceflight is an inherently risky venture. We can never eliminate risks, but we can understand and manage them. See Misunderstanding safety.

      Reply
      April 11, 2012 at 2:34 pm
        Dwayne Day commented

        “Oddly enough, leaving the capsule in orbit while the astronauts go down to the surface is exactly what NASA planned to do with Orion.”

        In 2018, as opposed to 1969. Fifty years difference. Gemini was not designed for autonomous operation.

        “The assertion that “there is no reason to believe it would have been easier with two people” is an odd one which flies in the face of common experience.”

        Two people, trying to climb to the back of the Gemini, and climb into two separate landers. Compare that to crawling through a docking ring in a pressurized cabin. More difficulty, not less.

        “If having two landers that can fail scares you, then you shouldn’t be going to the Moon at all.”

        I was not arguing that the goal is no risk. The goal should be minimizing risk. Your article is based upon the false premise that Gemini Lunar would have been a superior choice to what they actually did with Apollo. And yet you’ve provided no evidence of that, and the method you describe–leaving the spacecraft unattended in lunar orbit, performing a two-person EVA rather than crawling through a docking port, operating two lunar landers (meaning two launches, two rendezvous and docking events)–is inherently more complex and more risky.

        Reply
        April 11, 2012 at 5:27 pm
          admin commented

          “Two people, trying to climb to the back of the Gemini, and climb into two separate landers. Compare that to crawling through a docking ring in a pressurized cabin.”

          You weren’t comparing two-astronaut EVA to “crawling through a docking ring.” You were comparing it to single-astronaut EVA. Now you’re confusing the issue by switching arguments.

          “The goal should be minimizing risk.”

          No the goal should not be minimizing risk. It should be managing risk. There is only one way to minimize risk — that is to fly no missions.

          “Your article is based upon the false premise that Gemini Lunar would have been a superior choice to what they actually did with Apollo. And yet you’ve provided no evidence of that”

          No, we provided evidence. The Gemini capsule was more mature (it had already flown), and it incorporated lessons learned from the Mercury and Apollo designs. Anyone with a technical or operational background can tell you what that means.

          “operating two lunar landers (meaning two launches, two rendezvous and docking events)–is inherently more complex and more risky.”

          Two launch and landing cycles is not scary to anyone with an operational background. That’s a low-tempo operation, by military standards. To “minimize risk,” you want have the United States avoid doing anything even remotely ambitious in space. That doesn’t actually minimize risk, it merely leads to a small number of very expensive (cost-ineffective) missions which are also very dangerous because you never leave the steep part of the learning curve.

          Reply
          April 11, 2012 at 7:19 pm
    Robert Clark commented

    Thanks for that. Going small I believe is how we can return to the Moon. I discuss this on my blog.

    Bob Clark

    Reply
    September 17, 2013 at 1:44 am