The Early Lunar Shelter: Stay Just a Little Bit Longer

Garrett AiResearch Lunar Shelter

The Garrett Early Lunar Shelter, showing its roots in the LM Truck and, in turn, the LM that actually landed on the Moon. The tanks draped around it are hydrogen and oxygen for the fuel cells, shelter pressurization, and recharging the astronauts’ suits after EVA. Public Domain image via NASA from Early Lunar Shelter Design and Comparison Study, Volume IV. Click for a larger view.

What it was: A two-astronaut shelter/living quarters for use with the Apollo program once it had progressed to needing 30-day stays on the surface, studied in 1966-67 by Garrett AiResearch at NASA’s request. Variants for three astronauts and for a mobile version that could be hitched to a lunar rover were also examined.

Details: Certain big names show up repeatedly in conjunction with the American space program: North American Rockwell, Grumman, Boeing, Lockheed, and so on. Around the fringes, though are less familiar names such as Bendix and TRW. Another one of the latter was Garrett AiResearch, a mid-sized aerospace pioneer best known (at least as far as the space program goes) for designing and building the atmosphere controls for Mercury, Gemini, and Apollo.

In 1966, NASA commissioned Garrett to move beyond what they’d done to that point, and work on a  full-fledged, if tiny, Moon base. Dubbed the “Early Lunar Shelter” (ELS), the intention was to build it following the J-Class missions—what turned out to be Apollo 15 through 17. Having progressed from short surface stays like Apollo 11 to longer ones that had a lunar rover to work with, like Apollo 17, the next step was to be month-long stays and that required more than a single LM.

From the beginning, the Moon landings had been quite restricted in mass, as much of an LM was taken up with astronauts, the consumables they needed, and the fuel and engines needed to get them back to the CSM for the flight home to Earth. If you could forgo all of that with an automated lander, you could haul a lot more equipment to the Moon—to wit, 4.67 tonnes of it.

The fruit of this thinking was the LM/T, or Lunar Module Truck, which was for all intents and purposes a rocket-powered mule that would head to the Moon some time before its associated astronauts would start their journey in their own LM (called the LM Taxi in this context). Landing close to the LM/T, the astronauts could walk over, unload everything, and enjoy a huge quantity of equipment as compared to Aldrin and Armstrong.

There were any number of configurations for the LM/T, constrained only by the volume an LM occupied on top of a Saturn V and the limit to the mass it could safely land, but the Early Lunar Shelter was the answer to one particular question: “Suppose we devote the Truck’s volume entirely to living quarters for two astronauts and the scientific equipment they’d use. What would that be like?”

What Garrett came up with was a stubby cylinder, 8.1 feet in diameter and 16 feet long (2.5 meters by 4.9 meters) which rested on its side above the LM/T’s descent stage, looking not unlike contemporary bathyscaphes. It would be launched atop a Saturn V along with a crewed CSM, which would dock to a hatch on its upper side, then ferry it to the Moon after the usual Saturn IV-B trans-lunar injection. After reaching their destination, the CSM would disengage and return its crew to Earth, while the ELS would land automatically.

The shelter could sit on the Moon for as much as six months before its astronaut-dwellers arrived (thanks to another Saturn V/CSM combination), with a minimum seven days prior to their launch for checkout of the shelter. A SNAP-27 radiothermal generator would power the ELS until activation. Once aboard, the minimum time the astronauts would use it was assumed to be 14 days, with 50 days being the upper end of possibility. The first day days of the mission would be devoted to the astronauts activating the shelter for their use, unloading it, switching the shelter to running off fuel cells (which would also supply water) and transferring the RTG to their LM Taxi so their ride home could be deactivated but kept “alive” until it was needed at the end of the mission.

Interior layout of the Early Lunar Shelter

The interior layout of the ELS, same source as previous. One presumes the outer hatch was closed when the toilet was in use. Click for a larger view.

The interior of the shelter was to be divided into two main areas. One was a lunar EVA airlock taking up one end, the CSM hatch on top being used solely for docking with a CSM. It would have been big enough for two astronauts at the same time as well as storage of two hard space suits. The bulk of the shelter was 628 cubic feet (17.8 m3) of living space. Though about half of this would be taken up with supplies, bunks, and spacesuit storage, its shirt-sleeve environment compared well with a regular LM’s 4.5 cubic meters of habitable volume. Alternatively, as the Moon does supply gravity, the ELS can be sized another way: it would have had 68 square feet of floor space (6.3 square meters).

The arrangement of bunks/radiation refuge quarters in the ELS.

The spartan arrangement of bunks/radiation refuge quarters in the ELS. No Apollo astronaut was taller than 71 inches. Same source as previous. Click for a larger view.

The shelter was double-walled aluminum and fiberglass (the latter in the inside), with 58 mils (0.058 inches, or 0.15 cm) between them for meteoroid protection—the usual tactic, as invented by Fred Whipple. The other major danger entertained was radiation, and the aluminum walls couldn’t be made thick enough to sustain 500 rads (a hypothetical solar flare) without weight close to a half ton more than was otherwise necessary. Accordingly the study suggested putting the necessarily numerous  PLSS recharging canisters (for the life-support backpack worn while on the surface) stored in water filled sleeves around the bunk area located at the opposite end from the airlock. Altogether, they, the walls, and the bunk material made an acceptable, if awfully cramped, radiation refuge for everyone on-board.

One final, intriguing safety touch was the dual-purpose boom attached near the airlock. While primarily intended for unloading instruments or a rover, it would also have been used to get an incapacitated astronaut up next to the entrance to the shelter.

Arranged around and behind the shelter were four tanks: one compressed gaseous oxygen, one liquid oxygen, and two liquid hydrogen. These weren’t intended for use with the Truck’s landing engine—it had its own tankage—but rather for use by the astronauts and the fuel cells (and so, accordingly, their water). Garrett pinpointed the storage of LOX and LH2 for up to six months before the astronauts arrived as the main technical challenge facing the ELS.

Another issue was what atmosphere they would breathe: pure oxygen at 5.0 psia, or nitrogen/oxygen mix comparable to Earth. The former was desirable for mass reasons, and to keep the ELS as close in technology to the rest of the Apollo program as possible, but Garrett were concerned that there were no medical studies of a pure oxygen atmosphere for a long period of time; the 30-day maximum they note was apparently just an educated guess. They ended up punting the problem down the road as essentially an issue of how much they could keep the ELS from leaking; if that could be minimized, the problem was moot. Safety concerns weren’t mentioned at all, and in fact the final filing of Garrett’s study was on February 8th, 1967, not even two weeks after the Apollo 1 fire. After that the CSM would switch to a oxy-nitrogen atmosphere for launch, though the LM would stay with the low-pressure pure oxygen.

Mobile ELS variant, hitched to a notional rover.

The Mobile ELS variant, hitched to a notional rover. Same source as previous. Click for a larger view.

As well as being a shelter, the ELS would have been a miniature scientific outpost. It would be equipped with a drill capable of getting 100 feet down into the Moon’s crust, carry explosive charges for seismic readings, and had three remote instrument stations that would be deployed far from the landing site thanks to the extended EVA capability the shelter would provide. All told, the shelter would come with 3470 pounds (1.57 tonnes) of science gear, while the shelter itself was a remarkably light 985 pounds (447 kg). Add in the expendables and altogether it could be successfully landed on the Moon by the LM/T with a mere pound and a half to spare. Let it not be said that they didn’t squeeze all the juice out of this one.

If the project had gone ahead, Garrett anticipated that the ELS would be operational in 1972. The study is silent on cost, apparently because the construction work was to be handed off to Grumman, and so it was their problem.

What happened to make it fail: It got caught up in the rapid ramping down of the Apollo program that started in 1968, not least the fact that Saturn V production was shut down and the rockets they had were all they were going to get.

By scrimping and saving (and cutting a couple of Moon landings) NASA managed to save Skylab, and eventually the detente-driven Apollo-Soyuz Test Project, but that was it. As any mission involving the Early Lunar Shelter was going to require two Saturn V launches it was an obvious target for a cut, taking up as it would two slots that could be used by two different, separate Moon missions. It was one of the first things to go, and did not make it out of 1968.

What was necessary for it to succeed: It’s interesting to compare the Early Lunar Shelter to the other Moon bases we’ve examined so far, Barmingrad and Project Horizon. Both were hugely ambitious and nowhere near happening in reality, while for this project the key word was early. A lot of people tend to conflate Moon bases with lunar colonies, or at least the next rank down of permanently inhabiting the Moon even if the personnel are swapped out periodically. What NASA put its finger on was that we’re not likely to make that big a leap all in one go. The first lunar bases are probably going to be temporary, just like the first space stations were before we worked our way up to Mir and the ISS.

On that basis it’s easy to get the ELS to fly, as it was a big part of the logical next step in lunar exploration (ignoring the elephant in the room that was automated exploration, mind you). With probably no more than some minor redesigning there could have been one on the Moon just a few years after when Garrett AiResearch pictured it: 1972.

As ugly as the post-1969 picture was for NASA’s funding, it’s not too much of stretch to see the three or four more necessary missions past Apollo 17 making it through the budget grinder and “Apollo ELS” flying sometime around late 1974 or early 1975. It’s a lot likelier than much of what NASA proposed post-Apollo 11, at least, if only because one mission like that would be as much or more of a punctuation mark at the end of the program as any other mission bar Apollo 11 itself.


Early Lunar Shelter Design and Comparison Study, Volume I and Volume IV, W.L. Burriss, N.E. Wood, and M.L. Hamilton. Garrett AiResearch. Los Angeles, California. 1967.

Chief Designers 6: Max Faget

"Cutaway Diagram of Project Mercury"

A cutaway drawing of Max Faget’s biggest achievement, the Mercury capsule.This 1959 diagram was drawn in an unsettled period between the “C” and “D” designs of the craft, the latter of which flew. Public domain image from NASA.

Maxime Allen Faget was the premiere American spacecraft designer from the days of the Mercury capsule to the initial stages of the Space Shuttle. It was due to his understanding of Harvey Allen’s “Blunt Body Theory” that American spacecraft had their iconic bell shape, and his strong opinion about his ideas for Mercury, Gemini, and Apollo led contractors to coin the aphorism “What Max Faget wants, Max Faget gets”. Experience proved that going against his intuitions was the quickest route to a losing bid in NASA design competitions.

Faget was born in Stann Creek, British Honduras (now Dangriga, Belize) on August 26, 1921. His father was a noted tropical disease researcher, employed by the British, and his family was of French descent via Hispaniola and New Orleans (his last name was pronounced in the French manner, fa-Zhay). His father was also American and so so was young Max; accordingly the family eventually returned to the United States. The younger Faget reportedly had a passion for science fiction—he had a subscription to Astounding Science Fiction—and model airplanes, interests which presumably led him to his ultimate career.

Max Faget and Frank Borman

Max Faget, foreground, and astronaut Frank Borman. This photograph was taken in April 1967 during the investigation into the Apollo 1 fire. Public domain image via NASA.

In 1943 he graduated from Louisiana State University (where his roommate was rocket designer Guy Thibodeaux) with a degree in mechanical engineering, then served on the submarine USS Guavina during World War II. After the war ended he joined NACA in 1946, which meant he was in on the ground floor when that agency became NASA in 1958.

Even before that happened he had been working on the design of a space capsule radically different from what had been considered before. Experiments in the mid-1950s with ballistic missiles had proven that the best simple way to get something safely out of orbit was with a blunt-ended capsule rather than the sharply pointed craft that had been imagined necessary until then, or the lenticular shape that was also considered at the time. Taking this idea, Faget came up with a rough sketch that would eventually evolve into the Mercury capsule.

This work was mostly done after Faget joined the Space Task Group, a group of 45 people—37 of them engineers—based out of Langley Research Center in Virginia until 1961. With the addition of Canadian Avro engineers, Faget gained his right-hand man for Mercury, Jim Chamberlin. Then in 1961, following Kennedy’s declaration that the United States was going to send a man to the Moon, the Space Task Group was greatly enlarged and moved to become the Manned Space Center (now the Johnson Space Center) in Houston, Texas. Their task was to follow through on Kennedy’s promise, and Faget was its Chief Engineer from February 1962.

As a result, Mercury went ahead with him in the lead; among other things, he created the escape tower for Mercury and later adapted for use with Apollo. He would then go on to shepherd the Gemini and Apollo spacecraft designs to completion.

Faget had an informal veto on NASA’s spacecraft designs from about 1958 to 1970, and he was not afraid to use it. Most notably the design competition for the Apollo spacecraft was jury-rigged to select the second-best scoring proposal over that of Martin-Marietta because it more closely resembled what he had designed himself in counterpoint to the external proposals.

Space Shuttle concepts

Space shuttle concepts around 1970. Faget’s “DC-3” is second from the top on the right. The bizarre SERV is top left. Public domain image from NASA.

His touch left him only once during his career at NASA, during the Space Shuttle design. At first he favoured something like Big G, but he soon came over to the side of a reusable spaceplane. While each NASA spaceflight centre had its own ideas, Faget considered all of them too complex and came up with a simpler, stubby-winged design called the “DC-3” in honour of the great cargo plane of the early days of aviation. This set off a battle within NASA over the cross-range capability of the Shuttle-to-be, with one side eventually settling on a delta-winged configuration and one side taking up Max Faget’s design as adopted and submitted by North American Aviation. Only the delta-wing arrangement would give the Shuttle a high cross-range, and that was felt to be useful enough that many in NASA held out against Faget’s proposal until the scales were tilted in their favour. Faced with a budget crunch, new NASA director James Fletcher arranged to have the US Air Force brought on as a partner for the spaceplane, and their requirement for cross-range was even higher than that envisioned by the delta-wing partisans at NASA. The DC-3 was abandoned and the Space Shuttle as we now know it began to take shape. His failure to get his design selected was apparently a source of minor annoyance to Faget for the rest of his life, but he dove into the construction of the new spaceplane and helped bring it to completion.

Faget left NASA in late 1981, not long after the flight of STS-2. He founded Space Industries Incorporated in 1983, which focused on projects intended to explore the unique conditions of space as they could be applied to industry and chemistry. Their Industrial Space Facility—a small, unmanned space station—never flew, but the Wake Shield Facility (which used its motion through space to make a “shadow” of ultra-high vacuum behind it it) ran experiments on three Space Shuttle missions from 1994-96.
Faget died of bladder cancer on October 10, 2004 at the age of 83.

Sidebar: The Lunar Escape Device


The frontispiece for General Dynamics’ 1964 proposal “Study for a Lunar Escape Device”. Click for a larger view.

The LESS was far from the only suggestion for how Apollo astronauts could rescue themselves from the surface of the Moon—it was merely the best worked out. For example, in 1964 General Dynamics sent a report into NASA entitled “Study of a Lunar Escape Device”.

This was sufficiently far back in the past that the LEM (as it was still called at the time) hadn’t been fully designed yet; in the picture above it’s clearly still the first Grumman design rather than the one finally built. Even so the basic arrangement still held, and General Dynamics hit on the idea that when on the Moon even a wrecked LEM represented the best resource pool for astronauts trying to recover from a survivable crash. This approach also dove-tailed nicely with the major difference between the Apollo missions that would use the LED and the later missions for which the LESS was designed: there was no second lander to carry the escape craft and so it had to fit in the tiny weight allowance of the lander which was to carry the astronauts.


The world’s scariest IKEA instructions. How to dismantle a stricken LEM and turn it into an escape craft.

Accordingly, what General Dynamics designed was a kit of necessary extra components which would complement a number of much heavier parts cannibalized from the stricken LEM. Two of the lander’s legs would be removed and turned into a launch cradle. The LEM’s fuel and oxidizer tanks, its pressure tanks, the life support and comms equipment, and even a seat would be reclaimed too. Only support brackets for the tanks and seat, the main engine and small attitude controls, a star tracker, and a control panel would be unique to the rescue craft. Altogether the kit would come in at 49.5 kilograms and take up less than 60 liters of volume (2 cubic feet). General Dynamics’ pride at coming in at less than 0.4% of the entire LEM weight shines through the dry technical language of their proposal. Even once the cannibalized components are included the LED would have rung in at 460 kilograms (including propellant but not counting anyone on-board), which to best of the author’s knowledge makes it the smallest fully functional spaceship ever seriously proposed.


Literally flying by the seat of your pants. The crew arrangement for one and two astronauts aboard the LED.

The one-man version perched the astronaut at the end of what can only be described as some kind of high-tech witch’s broom, while the two-man version looks even more precarious. Under those circumstances, the seat was moved forward just enough for the second astronaut to stand behind the seat with his feet in stirrups attached to the bottom of its frame.

While quite clever, the concept suffers from two flaws. For one, it assumes that all the components of the LEM would be available for re-purposing, which seems optimistic when you consider that the LED would only be used if the LEM had crashed; it’s also unclear how the astronauts were supposed to remove two legs from the lander without causing further damage to it.

More subtly, the LED’s designers missed something that North American Rockwell picked up on when designing the LESS. The hard part of escaping from the lunar surface would not have been building a rocket that could do the trick—the Moon’s weak gravity and lack of air lets surprisingly dinky-looking craft make the journey to orbital heights. Rather the problem would be getting the escape craft into close proximity to the Command Module with a vector similar enough to allow the astronauts to transfer over. The later proposal spends many pages discussing how this could be accomplished, while the General Dynamics presentation merely states what the astronauts would need to do and then moves on in silence without discussing how they could possibly do it.

Apollo LM&SS: Mapping the Moon and the Earth (Apollo Applications Program, Part III)


The later design of the LS&MM. Unlike the earlier, larger module based on the KH-7 satellite, this one’s mapping module (right) was designed by Martin Marietta. As well as the crew compartment shown, an open truss containing the mapping cameras and sensors would be attached where the “End Airlock S016″ can be seen—retrieving the film from the cameras would require depressurizing the compartment and a suited astronaut reaching into space to get it. The section on the left is the usual Apollo CM. Public domain image from NASA document Technical Data AAP Mission 1A 60-Day Study. Click for a larger view.

What it was:  A tiny space station consisting of a photo reconnaissance module docked with an Apollo CSM in place of a regular LM. In return for being unable to land on the Moon, the LM&SS would become the first lunar-orbit space station, its mission to take high-quality photographs as the CSM was orbiting, and do it in a variety ways such as in regular light or infrared. It was originally targeted at the Moon, at first to survey Apollo landing sites and later for a more comprehensive scientific mapping mission. After cancellation and rebirth it turned into an Earth observation mission, partly for scientific study of the globe and partly to test the equipment for what had become a more hypothetical mid-to-distant-future Apollo lunar mapping mission.

Details: One of NASA’s earliest goals was to survey the Moon; there’s not much point in sending out a manned Moon lander if you don’t even know where they can put down safely. This goal was met by five very successful unmanned probes, Lunar Orbiter 1 through Lunar Orbiter 5, launched between August 1966 and August 1967. The first three of these specifically surveyed potential Apollo landing sites, while Lunar Orbiter 4 mapped almost the entire near side and Lunar Orbiter 5 almost the entire far side. Altogether they covered 99% of the Moon’s surface, and the last of the probes even photographed some of the surface down to a 2-meter resolution.

Before they were launched, though, NASA was worried that they might not accomplish what they were built to do—and rightfully so: the Lunar Orbiter’s predecessor, the Ranger program, had become a laughing stock after the first six attempts to get a probe to the Moon had failed. Even though the Rangers had the comparatively simpler goal of crash-landing (and photographing the impact region on the way down), from August 1961 to January 1964 they had done nothing but produce a sorry list of launch failures, camera failures, and outright misses of a target 3475 kilometers in diameter. Ranger 7 finally pulled off the trick on July 28, 1964, smacking into the Moon 69 kilometers from the eventual Apollo 11 landing site on the Sea of Tranquility, but NASA was still nervous about getting the quantity and quality of images they would need to keep an LM from accidentally landing on a boulder or on a steep slope.

So while they pinned their hopes on the Lunar Orbiter program, they also developed a backup plan they could use if they needed it: the Apollo Lunar Mapping and Survey System (LM&SS). At the time the new National Reconnaissance Office, after several years of teething problems themselves, had been building and flying the KH-7 spy satellite successfully since 1963. In the same year the Department of Defense, NASA, and the NRO agreed to share their technology and Kodak, Lockheed, and General Electric were contracted to build a variant of the KH-7 which had its station-keeping engines and film re-entry vehicle deleted but a small docking port added. So modified, one could be lofted into orbit in the part of a Saturn V that would normally house an LM.


The camera of a KH-7 satellite, and so a close analog of the original LM&SS. The re-entry vehicle for the film (left) would have been removed and replaced with a docking adapter. Public domain image from the NRO. Click for a larger view.

As with the regular Apollo missions, this one would have been sent on its way to the Moon by the upper stage of the Saturn V and then a short way into that journey the CSM would have undocked, moved away a short distance, rotated 180°, and then returned to dock nose-first—the difference being that it would be docking with the LM&SS, not a more-usual LM.

Upon arrival at the Moon, the LM&SS (which was also the name used for the entire craft) would enter a polar orbit, slicing the Moon up photographically as it rotated beneath. The entire mission would take 35 days, 28 of them in lunar orbit so that the Moon could make one complete turn on its axis and the LM&SS cover the entire surface; this would have required a change to the CSM’s life support systems so it could handle a journey that long.

The film in the camera would be retrieved periodically and then once all the photographs were taken the LM&SS would have been ejected to crash into the Moon (as it would do sooner rather than later because of the way lunar mascons wreak havoc on stable lunar orbits) and the CSM would return to Earth following the usual Apollo mission profile.

This variant KH-7 would have been about five meters long and enclosed entirely in a near-featureless cylinder about a meter and a half in diameter. When docked to the CSM it would have looked, appropriately enough, as if the CSM was sporting an enormous telephoto lens on its nose.

By 1967 an internal battle at NASA between those who felt that the Lunar Orbiter survey was sufficient and those who wanted the higher-resolution LM&SS pictures ended with the former in the ascendant. Four LM&SS modules were at various stages of completion by then, but this particular version of the lunar mapping mission was cancelled.

Among the factors contributing to this was the fact that the mission would have needed a precious Saturn V launch just at the time when NASA were discovering that Congress wouldn’t pay for as many of those rockets as they would have liked. That explains in part the second variant of the LM&SS program, the Apollo Applications Program launch that was designated AAP-1A.

As the name suggests, this would have been an early Apollo Applications Program mission—the third, confusingly enough, after AAP-1 and AAP-2 which would have launched the proto-Skylab Orbital Workshop space station and its first crew. AAP-1A would have originally brought the LM&SS equipment to the OWS, but after the OWS’ mission planners became concerned that the first crew already had too much to do they decided not to go ahead with installing the LM&SS on the station. AAP-1A became a standalone mission more like the LM&SS’ original conception: a CSM and the LM&SS docked to one another to make a miniature space station of its own.

Whether attached to the OWS or the LM&SS, AAP-1A’s goal was Earth observation, but also to put the LM&SS through its paces for a nebulously planned Lunar observation mission that would get back on the schedule as a pure science mission sometime in the future. The basic problem this mission looked to address was interpreting the photographs of that hypothetical lunar mission. Observation missions during wartime had shown that it was actually quite hard to figure out what an aerial photo was trying to tell you if the enemy wasn’t about to let you look at what you were photographing with a later visit on the ground. With the Moon there was no enemy other than distance and cost, but establishing the “ground truth” was equally difficult. It was entirely possible that the LM&SS photos would be misinterpreted in critical ways because there was no way to cross-check those interpretations.

So somebody came up with the idea of launching the LM&SS on top of a Saturn IB. It couldn’t go to the Moon that way, but it could stay in Earth orbit and image parts of the United States that could be reached easily. Follow-up field trips on the ground would then go and look at what was imaged and learn how what was on film compared with the view on terra firma.

Somewhere along the way (and for reasons we’ll examine shortly) NASA decided not to use the full KH-7 module. Instead they commissioned Martin Marietta to develop a stripped-down version consisting of a small manned module with a small airlock to the film compartment; the astronaut using it would have to suit up, depressurize the LM&SS manned compartment, and then reach out through the lock into space to retrieve the reels. In return for the smaller size of the main camera arrangement, it was now possible to add a large suite of other sensors and cameras to the LM&SS as well as a few unrelated experiments. Martin Marietta designed an open tetrahedral truss made of aluminum, and wrapped it around the module to support the instruments. The module in turn was then docked to the CSM. While the truss-supported instruments were open to space and so generally intended to be self-sustaining, the LM&SS did have a second man-sized airlock so that an astronaut could go on a spacewalk to fix or retrieve one.

AAP-1A was planned out quite thoroughly and aimed to launch in either late 1968 or early 1969, just prior to Apollo 11 and as the Earth-orbiting mainstream CSM/LM tests Apollo 7 and 9 were underway.

What happened to make it fail: The Lunar Orbiter program was a roaring success: five out of five launches did what they were supposed to do, in contrast with the poor, benighted Rangers. The complementary Surveyor probes worked well too: seven landers and seven landings, though two did crash rather than coming down softly as designed. Apollo 12 even visited Surveyor 3 thirty-one months after it had proved its target to be a suitable landing site. Even so, as mentioned previously some NASA personnel thought that the Lunar Orbiter photos weren’t enough, and that something higher resolution would be needed. Nevertheless, the consensus emerged that what they’d got from the Orbiters was good enough, and that the LM&SS didn’t need to fly.

What may have tipped the balance that way was another pressure on the LM&SS mission. For many years it was believed that the LM&SS module was a modified LM, not a KH-7; only a little information about the program leaked out from industry insiders. Why? The KH-7 may have been obsolete (it was being replaced with the KH-8 just as NASA starting working on theirs), but it was still classified and it stayed classified until September 2011. While the NRO as a whole was willing to supply NASA with the equipment they needed, they  were nervous about even officially disclosing the existence of American spy satellites. If Apollo had absolutely needed it, they were would go along with putting one of their birds in the halogen-lamp glare of the Space Race in the hopes that no-one would look at it too closely and believe the cover story that it was a piece of NASA equipment.

So the first iteration LM&SS was cancelled because of the clandestine nature of the equipment they would have had to use. The radically less-open culture of the NRO that was supplying that equipment made it certain that it wouldn’t move forward once the primary goal of protecting the astronauts (or, more to the point, preventing American propaganda disaster) could reasonably have been said to be reached.

This is what morphed the LM&SS module into its new shape. Even though it was using the same camera, the module was heavily redesigned so as to make it less obvious where the camera came from. Even then the NRO was also apparently unhappy even to reveal that the US had the capability to image the Earth at high resolution, as would become obvious once AAP-1A’s photos were made available to the public; a document declassified in December 2011 named presidential science advisor Donald Hornig as the higher-up who pushed the issue. With their budget shrinking quickly NASA probably would have cancelled AAP-1A anyway, but certainly the concerns of the NRO were another straw on that particular camel’s back

What was necessary for it to succeed: Each of the variants of the LM&SS program failed for different reasons, so let’s take them in order.

For the initial one, using the KH7 to examine the Moon for Apollo sites, there’s the obvious possibility that Orbiters would have proven to be a second run of the Rangers. Alternatively, the faction of NASA that felt the images from the Orbiters still weren’t good enough and that the LM&SS module should fly might have come out on top. Having a rocket they could have used would have helped there. While the Saturn V wasn’t formally put aside until 1968, NASA had to have seen the writing on the wall, as they had been requesting funding for the sixteenth and seventeenth Saturns since 1966, and never could get it. If one or more of those had come through, the Lunar mapping program would have been right near the top of the list to be perched on one.


Apollo 15’s Endeavor with its scientific instrument bay open, photographing the Moon. Its camera was located at to the right of the white rectangle that can be seen near the centre of the bay. Public domain image from NASA.

The second proposal for lunar mapping, the scientifically oriented one that was to follow at an indeterminate point after the Earth Sciences test, fell by the wayside with the decision to do lunar mapping from CSMs of the regular Apollo missions. People often don’t realize that while two astronauts from each Apollo did their work down on the lunar surface, the third astronaut wasn’t idle while in orbit in the CSM above. Among the things he’d do while circling the Moon, at least during the J-class Apollo 15, 16, and 17, was photograph it using a 24-inch panoramic camera based on those used by the KH-7’s predecessors in the CORONA spy satellite program.

The difference that made flying one of those easier than an using an entire LM&SS was the nature of the camera. It wasn’t very hard to cover it up as a bespoke piece of equipment made for NASA, since in essence that was what it was, and its presence wasn’t as obvious because it was small enough that it could be stuck in the section of the Service Module (the SM being subdivided internally into six radial compartments) that was reserved for scientific equipment. Contrast that with the KH-7 module, which was obviously a piece of surveillance equipment, and one that massed 2000 kilograms and had to be docked to the front end of a CSM for the lack of anyplace else it would fit. There was no hiding that. The CORONA cameras may not have been as capable, but they were a lot more politically palatable. NASA’s willingness to take the CORONA cameras as “good enough” would have had to change before they would have pushed back against the NRO and tried for the full KH-7 LM&SS on this mission.

The Earth Sciences version of the LM&SS fell to several nibbling problems. By 1969 NASA’s budget was shrinking rapidly, so being able to shrink down to a cheaper Saturn IB was now not good enough—it was no longer even clear that the money to build the extra CSM and then support the mission would be there. On top of this the NRO continued to have concerns about what the capability of the LS&MM’s cameras would reveal to the world about their spy satellites, and weren’t keen to waste that secrecy on something as trivial as better maps of the world’s resources.

Next, by the time AAP-1A was planned to go in mid-1969, it had become clear that unmanned satellites were close to being able to map the Earth to the same level of fidelity (and in fact would start doing so with Landsat 1, which launched in 1972). And finally, even NASA had to accept that “testing Moon mapping systems” was putting the cart before the horse; it was far from obvious that they were going back to the Moon at all once the main line of Apollo missions had ended, as of course they haven’t in the years since. So what was the point of that? As there were so many things running against it, this is the version of LM&SS that was least likely to ever fly.

As a final aside it’s worth mentioned that NASA once again has their hands on some high-quality spy satellite cameras. In June 2012, the NRO donated two surplus telescopes to them, with media reports saying that their main mirrors were comparable in size to that of the Hubble Space Telescope. While it’s still unclear at the time of this writing what they’re going to do with them, NASA is believed to be considering plans to use them in a replacement for that aging orbital observatory sometime after 2020.

MOLAB/MOLEM/MOCOM/MOCAN: The Eagle Gets Around (Apollo Applications Program, Part II)


The MOLAB, heading away from the astronauts’ LEM on a 14-day mission. As well as this purpose-built version of the rover shown here, NASA considered three other versions that re-used other equipment being built for Apollo. Image from Lunar Mobility Systems Comparison and Evolution Study (MOBEV): Final Presentation Report. Click for a larger view.

What it was: Four proposals to deal with the same issue: once the lunar lander touched down, it was stuck there and its crew had to suit up and walk to anywhere they wanted to study. As the Apollo lunar base was getting up and running, one of these four ideas would be used to give astronauts a mobile laboratory with a “shirtsleeve” environment in which they could trundle around the surface of the Moon on jaunts to various interesting locations.

Details: We’ve previously discussed one suggestion for using Apollo hardware beyond its base purpose of getting people to the Moon and bringing them back. The Manned Venus Flyby was by far the most extreme option considered, but there were many other possibilities: NASA and its contractors put a lot of work into figuring out what else the various bits of Apollo hardware (with modification) could do.

The MOLAB was, as its name suggests, a mobile laboratory. The first Apollo missions relied entirely on legwork for getting around, and while Apollos 15 through 17 had the benefit of the lunar rover (LRV), it was far from perfect. If nothing else, mission duration was restricted by the fact that it had no life support—its passengers relied on their spacesuits for air and the like, and so missions could be no more than a few hours long.

Before budget pressures forced NASA to cut back to one Saturn V per mission, the plan was to support extended Apollo missions by sending a second lander (the LM Truck) carrying support equipment. Accordingly NASA was generous with weight—potentially up to 3860 kilograms was allowed—and came up with a plan for an entirely new piece of equipment, the MOLAB proper. After delivery to the Moon it would then be offloaded from the truck, set up, and then boarded by the astronauts and used while their LEM was put into hibernation. But aware of the eye of Congress on them even before the budget cuts started to hit, though, they also asked Bendix Corporation (builders of scientific packages for Apollo, and a company that had been studying lunar rovers and fliers for NASA since 1961) to look at three other possibilities for enclosed vehicles that the Truck could bring.


The LEM, repurposed as the crew cabin for a MOLAB. Image from Lunar Surface Mobility System Comparison and Evolution (MOBEV): Final Report. Click for a larger view.

The first was the MOLEM. The basic idea here was that the Lunar Excursion Module (LEM) was primarily designed to give astronauts someplace to live while on the surface of the Moon, so why not just keep going with that idea? Though some redesign would be necessary even beyond the deletion of its ascent rocket and the addition of wheels, it would be cheaper than starting from scratch with a full MOLAB.

Carrying a crew of two, the MOLEM would have been able to drive for 400 kilometers and go up a 35° incline. This meant it would be going around craters and other rough terrain rather than over it, so Bendix felt this translated to an 80 kilometer radius for missions. With a roaring top speed of 16.7 kilometers per hour these travels could be spread out across two weeks, with another week in emergency supplies if they were needed. The air inside was to have been 100% oxygen at 0.34 atmospheres, a choice that at first places the Bendix report prior to the Apollo 1 fire (and it is, having been completed in November 1966) until one realizes that the real-world lunar modules used pure oxygen as well. It’s hard not to think that, given the extra payload capability supplied by the LM Truck, this would nevertheless have changed if any of the MOLABs had gone ahead.

Altogether the MOLEM would have rung in at 3516 kilograms, which was a point in its favour. Not only could the LM Truck carry it, there was even leftover room for other equipment.


An Apollo CM as the MOLAB. Image from same source as previous. Click for a larger view.

The next option was the MOCOM. This was a less-obvious possibility, being an Apollo Command Module (CM) with wheels attached. Unlike the LEM this piece of equipment was never designed to go anywhere other than orbit, but the thinking was it was also designed to support its own weight while on Earth, so in all it should be able to handle the lunar environment. The lack of air on the surface was the same as conditions in orbit, and the Moon’s 0.16 gravities would be a snap compared to Earth’s hefty pull.

This CM’s heat shield would be scrapped as useless, as would the various bits of instrumentation and attitude control rockets needed for flight. As the regular CM hatch proved to be badly placed for a lunar vehicle, an airlock would be added along with the wheels, drive train, and transmission. As it would use essentially the same powertrain as the MOLEM, it would have the same duration and trip length, while also carrying the same amount of cargo (320 kilograms). The major difference between the two would be in the amount of space the astronauts would have to move around in during their excursion: the MOLEM was smaller at 4.2 cubic meters in volume (compared to the MOCOM’s 6.2 cubic meters), and had less floor space (2.4 square meters as opposed to 4.1)—which meant that the MOLEM wouldn’t let the astronauts sit down while driving. Finally, while the MOCOM was slightly heavier at 3743 kilograms, it too would fit on the LM Truck.


A Boeing CAN — intended for a variety of uses on the lunar surface, but primarily a cargo container for the LM Truck — converted for use as a MOLAB. Image from same source as previous. Click for a larger view.

The final possibility was to use a CAN, a proposed piece of hardware—the Multipurpose Mission Module—from Boeing. Unlike the LEM and CM this wasn’t already developed when the Bendix report dropped, but it was considered a strong contender for a variety of uses in the future Apollo lunar base. As the base was still a going concern at the end of 1966, NASA clearly felt that it would be worth seeing what good a CAN could serve as a MOLAB if they were already going to be building them anyway. The CAN was specifically designed to be as large as something could be while still fitting on top of the LM Truck, which meant that it was considerably more roomy—38.2 cubic meters and 7.9 square meters of floor—than the LEM and the CM: a major plus if you’re planning on sticking two people in it for two weeks, and a size that even allowed a crew of up to four. Unfortunately, as it was already as big as what the LM Truck was supposed to handle, and didn’t really have anything that could be stripped out, it rang in at 4326 kilograms if given the same capabilities as the other two vehicles. To get it down to fighting weight it had to be reduced to 200 kilometers of travel and eight days of life support (not counting the emergency extension supplies).

All this can be compared to the real MOLAB. It, again, had the same basic trip characteristics as the MOLEM and MOCOM, but being specifically designed for its purpose was able to do so with the lowest weight of all, 3221 kilograms, and so had the associated advantage of letting the LM Truck carrying other things besides just it. It also had more interior space than anything except a CAN, at 7.7 cubic meters.

The final decision of the Bendix report was that the need to make the driver stand while using the MOLEM took it out of the running, while the MOCAN’s restricted duration and range did the same for it. The MOCOM was “just right” but at the cost of being slightly less comfortable for the astronauts while also using up over 500 kilograms more of the LM Truck’s payload capacity. At that point they then threw the problem back at NASA, essentially telling them to pick based on what was more important to them: saving money by re-using a CM, or maybe not having a useful piece of equipment on the Moon because of those 500 wasted kilograms.

What happened to make it fail: Like much of Apollo, even the last few planned missions up to Apollo 20, budget cuts prevented any version of the MOLAB from reaching the Moon.


The seating issue that took the LEM variant of the MOLAB out of the running. Image source same as previous. Click for a larger view.

The Apollo Lunar Base was cancelled outright in 1968, but MOLAB’s death came about more particularly because of the cancellation of the Saturn V past the original production run of 15 rockets. MOLAB depended entirely on the LM Truck, and the LM Truck depended on there being two Saturn V’s available for each mission—one to launch the astronauts as per the usual Apollo mission, and one to launch the Truck with the cargo the astronauts would be using. Once that became impossible, any rover weighing 3800 kilograms was a no go. The actual lunar rovers that were sent to the Moon could be loaded up with the astronauts’ LEM, as they massed a mere 210 kilograms.

What was necessary for it to succeed: The best bet might have been for someone other than Thomas Paine to follow James Webb as NASA administrator in 1969 (or for the Democrat Webb to carry on somehow even as the White House changed from Johnson to Nixon). Paine was very much committed to a technically feasible but politically impossible agenda for NASA based on advancing the state of space technology and moving on to Mars. Someone more realistic might have committed to the Apollo Application Program’s goal of sticking with Apollo-era hardware and improving it incrementally as technology got better over time—an approach quite similar to what the USSR and Russia have done with Soyuz and the R-7 rocket family down to the present day, though to be fair they’ve never had to maintain a lunar launch capability. It may have taken a lot longer than they thought it would in 1966, but something similar to the MOLAB might have hit the lunar dust eventually.

The sticking point here was the Saturn V. It was already shut down in August 1968, with NASA just living on the ones already built until 1973, and the ability to get the production lines running again disappeared over the next few years. Knowledge of the Saturn V’s powerful F-1 engine lasted longer and might have been used for something similar to a Saturn V (without necessarily being a Saturn V) for a few more years after that, but ultimately the clock was ticking just as NASA’s budget was reaching its nadir in the mid-1970s.

The Martin 410: Apollo of Santa Ana


A cutaway view of the Martin 410 as it would have been configured en route to the Moon (excepting the escape tower, at left, which would be ejected after launch). Note the lifting body shape of the crew compartment, and the stubby cylinder of the habitation module enclosed in the larger toroidal equipment and propulsion module. Image from Glenn L. Martin Company’s “Apollo Final Report: Configuration” delivered to NASA in 1961. Click for a larger view.

What it was: One of several formal proposals made to NASA in 1961 as part of the design competition for the Apollo spacecraft. It had certain similarities to the one that was actually built (as did all of the proposals, as they had to meet criteria set by NASA) but was primarily different in two ways. As Apollo was still pictured as a direct descent mission at the time, it didn’t use the Lunar Orbit Rendezvous technique that was used for the real missions, and the re-entry vehicle was a lifting body instead of a ballistic capsule.

Details: On October 9, 1960, fourteen different companies answered NASA RFP-302, which asked them for feasibility studies on advanced manned spacecraft for the upcoming Project Apollo. Among them were Lockheed, Boeing, General Electric, and Grumman, as well as the subject of this post: the Glenn L. Martin Company of Santa Ana, California.

Within two weeks the contest was down to three: GE, Convair, and Martin with what they called their Model 410. Up against the contractors was an internal design by NASA’s Langley Research Center, specifically their Space Task Group, which had designed the Mercury capsule. Time passed and with the agency buoyed by the first successful American manned spaceflight on May 5, 1961—Alan Shepard’s Freedom 7—May 17 saw the final proposals for all four on NASA desks and the process of evaluating and deciding between them underway.

Eight days later John F. Kennedy challenged Congress to achieve “the goal, before this decade is out, of landing a man on the moon and returning him safely to the earth”, and things changed—the White House had had its interest piqued back in October when the study contracts were awarded and had been working behind the scenes with NASA. The Langley group rapidly metamorphosed into the much-larger Manned Spacecraft Center—now the Johnson Space Center—and by September started the move to land in Texas donated by Rice University (which is why Kennedy’s second famous space speech, the “We choose to go to the moon” one, was made there).


The suggested layout of the Apollo spacecraft for the second phase of the competition. Note the considerable similarity to what actually got built. From Chariots for Apollo: A History of Manned Lunar Spacecraft. Click for a larger view.

Even before then, the Langley group had swung into action. Their chief engineer was Maxime Faget, an American of Belizean birth, had designed the Mercury capsule, and his head of engineering (Canadian Jim Chamberlin, formerly of Avro) was in the middle of designing the Gemini. Their job was to synthesize what the contractors had developed with their own design and use it to develop a new set of specifications—in actuality, a nearly complete design of its own—that could meet Kennedy’s challenge. While the three previous contractor proposals had been paid for by NASA to the tune of US$250,000 apiece (though all of them took a loss, spending in excess of $1 million apiece), the other contractors had been encouraged to carry on with their work on their own. This attitude now paid off: a new competition was begun for a final design, open to all groups who’d tried back in October not just the three previous winners. On July 28 twelve contractors (two had dropped out back during the first phase, Cornell and Republic Aviation) were asked to submit again based on the new prerequisites. Several of the contractors teamed up with each other, reducing the number of replies to five, but Martin once again went with the M-410 on their own.

Not counting the rocket adapter ring (which all the proposals had so they could mate to the upper stage of a Saturn), the M-410 was made up of three parts: a command module for use any time an engine was burning and for re-entry, a mission module in which the crew would live at other times, and a composite equipment and propulsion module.

The command module was the most interestingly divergent component compared to the Apollo spacecraft that actually got built. All three contractors evaluated ballistic, winged, and lifting body re-entry vehicles. The latter was a particular one NASA called an M-1, and Martin went above and beyond by evaluating a number of other shapes in all three categories before settling on a variation of the M-1. Their solution made the M-410’s re-entry moderately controllable, especially as it would have had four control flaps; Martin considered this a big improvement on Mercury or the Soviet Vostok. It would have been built out of aluminum alloy, and had a composite heat shield made out of ablative material and a superalloy (undecided at the time, but something like René 41 or an Inconel). The version of the M-410 submitted post-Kennedy’s speech was also unusual because of the four rectangular flaps that would deploy from its underside, which would expose solar panels to power the craft. During launch the command module had an emergency escape tower perched on top of it, though this would be jettisoned on reaching 90 kilometers in height.

The three crew would live for the majority of their mission in the mission module. This supplied a little over eleven cubic meters on top of roughly the same for the command module (contrast this with the 12.9 cubic meters of the combined Apollo Command Module and LM).

These two were then mated to the equipment and propulsion module. As well as the usual electronics for a Moon-bound manned spacecraft, it packed a single LR-115 engine (a design which later evolved into the R-10 and derivatives used for the Saturn I and the Centaur) and 4740 kilograms of liquid oxygen and liquid hydrogen.

Having launched in an unspecified way (NASA was still trying to decide if they were going to use multiple smaller rockets to establish a fuel depot in orbit, or go as they actually did with a larger rocket like the Saturn V), Martin suggested that the M-410 be sent on its way to the Moon using a lower stage attached to the rocket adapter ring. This stage would have contained roughly 13 tonnes of LH2 and LOX and been pushed by three LR-115s.

This was powerful enough to get it down to the Moon, because the entire thing was designed to land there. Exactly how this was to be accomplished remained to be seen, as NASA was then in the middle stages of its most historic argument: land directly via an Earth Orbit Rendezvous profile, or send a separable landing module and rendezvous above the Moon. Going in to the proposal period it was assumed that the former was likeliest, though the contractors were asked to consider what they would have to do if the latter won (as, of course, it did).


One of the ideas studied, but explicitly rejected, for giving the M-410 artificial gravity: spin it up using the booster stage as a counterweight. From “Apollo Final Report: Configuration“. Click for a larger view.

Assuming it did land directly, though, the lower stage would be left behind as the propulsion module had sufficient thrust to lift itself back off the Moon and home to Earth. One thing the lower stage would not be used for was the generation of artificial gravity—Martin took the time to figure out if it were possible to generate a bit of it during the mission, including putting the lower stage out on a tether and using it as a counterweight to spin up the rest of the craft. They decided that for a trip as short as one to the Moon it wasn’t worth the extra weight needed for systems that could pull the trick off.

At the end of the mission, the command module would separate from the rest of the craft and re-enter. The M-410’s CM lifting body was designed to touchdown on water or land, with a combination of parachutes and retrorockets slowing it to just one meter per second as it touched the ground.

What happened to make it fail: On October 9, 1961 the new proposals were received, and two days later the five competing contractors gave presentations on their work. The evaluations began immediately thereafter, and were completed on October 28th. At the end of the competition, the M-410 was first with an average score of 6.9 points in each of the categories that NASA had outlined. Next came General Dynamics and North American Aviation, tied for second with 6.6 points; the GE-led and McDonnell-led contractor coalitions were the also-rans.

Despite the win Martin lost the contract to North American on November 28, 1961; NAA would go on to build the actual Apollo CSM. NASA administrator James Webb and his deputy Robert Seamans justified their decision on the basis of an external factor: NAA’s experience building the X-15.

The real reason is widely believed to be that North American had made the conscious decision to stick as closely as possible to Max Faget’s post-synthesis Langley design, and that NASA wanted that regardless of the merits of any other approach. Faget reportedly had been annoyed by the fact that none of the three initial designs had gone for a blunt-body re-entry vehicle, which was why he had come up with the Langley design in the first place and then convinced the agency to re-open the competition. He then had enough influence to disqualify any bid that didn’t follow his lead, including the Martin 410.

From this point onwards (and most noticeably in the proposals for the Space Shuttle a decade later, excepting the oddball SERV) NASA contractors understood that the implicit rule in any spacecraft design competition was “What Max Faget wants, Max Faget gets”. Despite the obvious possibilities for disaster with this approach giving him a veto turned out to be a pretty good idea: history has proven Maxime Faget was a talented spacecraft designer, arguably the best ever.

What was necessary for it to succeed: Not an awful lot more than what actually happened—the M-410 is one of the likeliest “what-ifs?” of the Apollo program.  It won the Apollo design competition, and if a small number of people (Faget, Webb, and Seamans) hadn’t been able to shift the results arbitrarily, it would have gone ahead. There would have been changes made, as happened in the real world to NAA’s design between 1961 and the first completed Block II Apollo craft flown in October 1968, but otherwise this design could have gone to the Moon.

LESS: The Lunar Escape System

LESS-CM docking

The final moments of the open-to-space LESS rescuing two astronauts stranded on the lunar surface by a faulty lunar module. Getting to this point would have been difficult, but the alternative was death by suffocation within a few hours. Image from the NASA document Lunar Escape Systems, Volume I: Summary Report. Click for a larger view.

What it was: A proposed emergency booster from North American Rockwell that could be used by Apollo astronauts in the case that they were stranded on the Moon. It was built around the assumption that the stricken crew would be safe on the ground but with an LM that couldn’t take them back to the Command/Service Module in lunar orbit. Using fuel siphoned from the ascent stage of the lunar lander they would sit in open space, using their space suits for life support, and manually guide themselves into orbit for a rendezvous with the CSM.

Details: Under the influence of the USAF, NASA studied various ways of escaping a stranded ship in orbit. The Apollo program took a different tack, partly because of the difficulty of coming up with an escape system that would work to return the astronauts from such a distance and partly because weight on the lander was at such a premium. Serious work didn’t begin until NASA started planning for the long-duration missions that would lead up to an Apollo-technology lunar base.

The Apollo landings were divided into two phases. Apollos 11 through 14 were of relatively short duration, while Apollo 15, 16, and 17 were “J-Class” missions using the Extended LM to allow longer stays. The Extended LM also had a higher cargo capacity (which is why the final three Moon missions had a Lunar Rover to drive around in). Once the J-Class missions were done, later missions were to use two LMs, one of which (the “LM Truck”) launched unmanned from Earth solely to carry more equipment. With that in mind NASA looked into equipment that could be carried to make landing on the Moon safer.

Neil Armstrong said later in life that he’d had nightmares for two years prior to launch that he’d get back into the LM to begin the trip home and the engines would fail to start; apparently he wasn’t the only one, because one of NASA’s suggestions for the extra equipment tried to deal with the issue. In June 1970 North American Rockwell sent a first-stage feasibility report to NASA for the Lunar Escape System (LESS), based on a flying rover they’d already been working on (the Lunar Flying Vehicle, or LFV). By September of the same year they’d fleshed it out further, including some initial lab and engineering work.

The LESS was very bare-bones, but bear in mind that until something like it was added to the lunar lander the astronauts were facing certain death by suffocation if the LM failed on them. In that dire situation, the stranded men would take two hours to unload the LESS from the side of the LM (where it had been stored in a configuration looking for all the world like an IKEA flat pack) and then siphon fuel from the lander’s ascent stage tanks; the theory here was that if the LM was dysfunctional due to a landing hard enough to crack those, the astronauts weren’t going to be in any shape to rescue themselves anyway.

LESS Schematic

A schematic diagram of the LESS from Lunar Escape Systems, Volume II: Final Technical Report. Click for a larger view.

Having fuelled the LESS, the astronauts would not get in it, but rather sit on it, exposed to open space. The pilot would give them an initial kick skywards to 3000 meters (a trip that would take about sixty seconds), then heel the LESS over to thirty degrees so that they’d continue rising while also starting to make headway horizontally. At about 6 minutes they’d be high enough and have enough vertical velocity that they’d then turn over the rest of the way and head for the CSM completely horizontally. The LESS was to be equipped with three gyros to help determine the attitude of the ship.

Once they were in what they hoped was a 110 kilometer orbit, the LESS crew would make observations of the sun angle and (if launching during the day) the angle to the lunar horizon and their apparent speed over passing landmarks below. Using these they could calculate their actual orbit–by hand, as the LESS had no on-board computing ability and the astronauts spacesuits didn’t have enough air for ground control back on Earth to give them the figures they needed. While too high was obviously a problem, as the orbit was very likely to be elliptical rather than the ideal circular, too low at perilune was the main issue. After testing with simulators, Northern Rockwell blandly states that LESS rescues would obtain “marginally acceptable orbital accuracies in terms of avoiding lunar impact.”

The CSM pilot would likewise be trying to figure out where the LESS was going to be. The launch of the rescue craft would be timed so that as it reached its height (and assuming it was on target) it would pass within 20 kilometers before they started to diverge. Using a sextant to observe a flashing beacon on the LESS and using a VHF rangefinder, the CSM pilot would use his onboard computer to calculate an intercept with the LESS. Unfortunately the LESS not very visible to the CSM pilot if the LESS was too far from where it should be: only to a maximum 90 kilometers by eye. The North American Rockwell report says “Visibility and acquisition of the target with the CSM optics was found to be a problem” and suggests no solutions. Ultimately it came down to hoping that the LESS astronauts hadn’t missed their correct orbit by too much.

The CSM’s orbit would take it around the Moon, during which he’d execute a burn that would put him at the same place at the same time as the LESS before the end of its first orbit. If absolutely necessary he could bring his craft as low as 80 kilometers above the surface. The stranded astronauts would have at best a couple of hours of air left, so a second chance on the next orbit was out of the question.

It was very likely that the two would miss each other by some distance, anywhere up to one kilometer and with somewhat differing speeds, so as they got close it was necessary for the CSM to start a new maneuver to lessen the gap. Meanwhile the LESS crew would be changing the orientation of their craft so it pointed towards the nose of the CSM. The Command/Service Module actually flown to the Moon had a VHF transponder and flashing light beacon of its own for use with LM docking, and these would be turned on for a LESS flight, giving the astronauts on it a target to aim for.

Assuming all went well the LESS would dock with the Command Module using a special docking attachment on the latter’s nose. Once there was a firm connection, the astronauts could climb onto the CM and enter its hatch, opened from within by the CSM pilot.

At that point the CM’s cabin would be repressurized and the presumably relieved crew could begin the process of returning to Earth used by a regular Apollo mission.

What happened to make it fail: The late dates at which the feasibility studies came back to NASA are a clue. While the space agency was still planning for expanding the United States’ presence on the Moon, Apollo was shrinking quickly. The same month as the second report came out, budget cuts forced NASA down to just three extended LM missions, and there was no sign of funding for the longer missions they wanted after that. In fact it never came, and there was no need for the LESS to rescue astronauts because no-one was going to the Moon anyway.

What was necessary for it to succeed: It was part and parcel of the Apollo program’s continuation according to its initial plan. If Apollo had kept going, or been revived fairly quickly after going into abeyance for a while in the early 1970s, something like it would have been desirable until stranded astronauts had a long-term Moon base to return to in case of emergency. As long as the CSM was the only place to go to, LESS would have been a plausible addition to the astronauts’ equipment.

The difficulty here is that the Apollo program relied on the Saturn V, and the Saturn V stopped production in August 1968. The ability to start it back up again disappeared very quickly, and it’s estimated that NASA would have needed an extra billion dollars to keep it going after 1970. Without Saturn the entire Apollo program falls apart as nothing else is powerful enough to launch the heavy Apollo Lunar CSM/LM combination. Ultimately the success of the LESS comes down to avoiding the US’ budget crunch in the late 1960s, like so much else did in the American space program of the time.