TKS: Chelomei’s “Soyuz”

TKS spacecraft

A cutaway view of the TKS, with its associated Almaz station in the background. The VA is the white section at left, while the FGB is the green portion with the solar panels. Image originally published in Russian space magazine Novosti Kosmonavtiki.

What it was: A Soviet transport and resupply spacecraft for use with the Almaz space station.

Details: On February 7, 1991, Salyut 7 orbited the Earth for the final time, re-entering over southern Argentina and scattering its pieces over a wide area. Sixteen hours before this the Federation of American Scientists used Doppler radar to image it as it flew overhead, producing this remarkable picture. The murky image clearly showed the thing that made Salyut 7 most notable: on the top of the station proper was what was then known as Kosmos 1686. The Soviet station had been the first truly modular space station, and the Kosmos 1686 module had been docked to Salyut 7’s core module for more than five years. It was the harbinger of a new thing in orbit, space-based construction, that would be followed up in both Mir and the ISS. But as well as being the start of something it represented the end of one too: a crewed spacecraft that shares with the shuttle Buran the peculiar distinction of having flown, but never with anyone aboard.

The Kosmos label was used as a smoke screen for a variety of Soviet programs, and Kosmos 1686, along with numbers 929, 1267, and 1443 were used to hide perennial bridesmaid Vladimir Chelomei‘s answer to the Soyuz: the Transport Supply Spacecraft, or TKS, to use its Russian acronym (“Transportnyi Korabl’ Snabzheniia”).

The story of the TKS begins with the fallout of the battle between Chelomei’s OKB-52 and Sergei Korolev‘s OKB-1 over the Soviet Moon program in 1964-65. Korolev won the war but died before he could make his victory complete. Chelomei’s contribution was greatly reduced but still consisted of the rocket for the the circumlunar Zond mission, the capsule for which was to be based on OKB-1’s tech. Chelomei reloaded for space stations and took the capsule he was developing for the LK-1 (his alternative circumlunar craft) and the LK-700 into the new project. The station was soon dubbed Almaz, and the LK-derived TKS was worked up to serve as a crew and supply ferry, much as the Soyuz and Progress do for the ISS.

The first thing to note is that the TKS would run both missions simultaneously, as opposed to the aforementioned ISS ships, which do one or the other. Despite countless upgrades over the years the Soyuz spacecraft is still rather cramped and there’s only enough room for astronauts or supplies, not both. As a result the Russians have been trying to replace the Soyuz for almost as long as they’ve been flying it, which accounts for the Zarya, the Kliper, the Energia/Buran shuttle, and the one they’re working on now, Federation, just to name a non-exhaustive few. The TKS was bigger—a lot bigger—and was Chelomei’s flying rebuke to OKB-1’s compact ship.

The TKS consisted of two modules. The first was the orphaned VA crew capsule (Vozvraschaemyi Apparat, “Return Vehicle”), which was attached to the new FGB support module (Funktsionalno-Gruzovoy Blok, “Functional Cargo Block”) which also served as a crew habitation module.

The VA was made of two components itself (three, if one includes the abort tower that was jettisoned after launch). The main portion was a truncated-cone capsule with a habitable volume of 4.56 cubic meters and a base of 2.79 meters. While originally designed for one person to make a loop around the Moon, as a LEO craft it was to hold three. Many commentators have mentioned the similarity in appearance of the VA’s capsule and the Apollo capsule, but the TKS’ was considerably smaller than the one used by NASA, which came in at 6.17 cubic meters and 3.91 meters. Where the VA diverged from Apollo even more sharply was in its nose module, the NO (Nosovoj Otsek, “Nose Compartment”), which took some of the support functionality out of the FGB support module and perched it at the front of the craft. Most notably this included the de-orbiting engines, but the communications equipment and the parachutes were loaded in it as well. Altogether this part of the ship weighed 3800 kilograms and was 7.3 meters long.

The rather beaky-looking VA was attached at its base to the FGB, which was a cylindrical module another 5.9 meters in length and 4.15 meters in diameter. While the VA was capable of being used as a complete craft it had endurance for only 31 hours and could carry only 50 kilograms of cargo. This was where the FGB picked up the slack. Sporting two solar panels with a span of 17 meters and a habitable volume of 41.08 cubic meters, it extended the TKS’ mission duration to a week, or 200 days if docked to an Almaz. Discounting the abort tower, together they made a 17,510 kilogram spacecraft which meant that it cleared the payload limit of a Proton-K (AKA the UR-500 designed by Chelomei’s bureau) by a couple of tonnes. With the joint capabilities of its modules, the TKS was specifically designed to be a “space truck”, ferrying passengers and cargo to a space station: the FGB’s maneuvering engines (which burned N2O4 and UDMH, like the Proton) would let it rendezvous with one in a higher orbit, and the docking adapter at its aft end would let it connect up. As the adapter took up the usual position of a rocket motor, the engines—four of them—were moved to the sides of the FGB, as were the engines’ fuel tanks.

The most revolutionary aspect of the TKS was what happened when it was time to go home. If so desired the entire TKS could disconnect and return its cosmonauts to Earth (in particular to a landing in the Kazakh SSR, softened by last-moment solid fuel rockets), with the FGB burning up. However, the other possibility was to use the VA’s autonomous capability to do the same while the FGB, which could be customized to one of many roles, stayed behind to be the latest module of the station.

What happened to make it fail: Chelomei’s efforts were an entirely parallel space program to the one being run by Glushko’s Energia, a military one comparable to the X-20/Manned Orbiting Laboratory on the American side. It ran into the same difficulty as the American one too: there turns out to not be a lot of military use for crewed spacecraft and stations. As Buran was also being built on the insistence of the Soviet military and it was tremendously expensive, the TKS and the Almaz stations were constantly in danger of being cut entirely or folded into the Buran/Mir ecosystem.

The TKS had a champion, Minister of Defense Andrei Grechko, who died in 1976. From then on Chelomei was unable to resist the pressure coming from Valentin Glushko and his champion Dmitri Ustinov, candidate member of the Politburo and then full member and Grechko’s successor as Minister following Grechko’s death.Ustinov is known to have had a personal grudge against Chelomei dating back to Chelomei’s temporary time in the sun under Nikita Khrushchev: he perceived Chelemei as an interloper from the Aviation Ministry whereas he represented the Artillery, under which ballistic missiles had been assigned for decades. Well before he reached the height of his power, in 1970, Ustinov as the Deputy Minister responsible for space travel had already ordered that Almaz be melded with the Salyut station project underway at TsKBEM (as NPO Energia was called at the time). From 1976 onwards he continued picking away at it, eventually leading to the TKS program being subsumed by Mir.

Before then, though, Chelomei’s bureau managed to get off six uncrewed flights and recoveries of the VA capsule beginning in 1976 and four uncrewed flights of an integrated TKS (VA with NO, and FGB) beginning in 1977. The spacecraft was tested and ready to go. But Ustinov had his way and there was never a full-up flight of a TKS with a crew aboard—three of the four TKS flights were in support of NPO Energia’s Salyut 6 and 7, while Kosmos 1686 in particular was modified so that it could not undock from Salyut-7, and its VA was gutted and filled with instruments. While two cosmonauts used the final TKS for some experiments during the Soyuz T-15 mission in 1986 it was merely a part of the space station at the time.

What was necessary for it to succeed: A lot of the projects we’ve discussed on False Steps are well down at the far end of the plausibility spectrum; “on paper only” is one of the most commonly used meta-tags around here. TKS is the antithesis of that. It was done, had been flown remotely, and needed only a final push to turn it into an operational system. As a result there’s several possible ways one can imagine that gets flying cosmonauts.

  • When OKB-1 was shaken up and Vasily Mishin relieved of his leadership, have Chelomei be the new leader instead of Glushko. This is not very likely because of Ustinov, but is the most direct route.
  • Have Marshal Grechko live and stay on as the Minister of Defense for a few years more than he did.
  • Have Minister Ustinov hold less of a grudge against Chelomei despite events in the Khrushchev era.
  • Have Energia/Buran be just slightly less of a money sink than it actually was.
  • Or give Energia some teething pains rather than two successful launches out of two tries, so that the Soviet leadership outside of Ustinov started looking more closely at the alternatives.

Any one of these would have been enough, and once flying it’s easy to see the TKS becoming the Soyuz replacement that Russia has been looking for since before the fall of the Berlin Wall.

As it was, the intriguing ability of the FGB to dual-purpose between being a spacecraft component or a space station component led to it alone becoming one of the cornerstones of space station construction from 1986 to the present day. No less than five of Mir‘s modules were based on the FGB, and on the ISS one current (Zarya) and one future (Nauka) module have the same base. The jerry-built Polyus payload for Energia’s first launch was also based on an FGB.

Sources

Khrushchev, Sergei N. Nikita Khrushchev and the Creation of a Superpower. Penn State University Press. University Park, PA, 2010.

Portree, David S.F. Mir Hardware Heritage. Houston, Texas. Johnson Space Center, 1995.

The TKS ferry for the Almaz Space Station“, Sven Grahn.

TKS“, Anatoly Zak.

OLS: The Orbiting Lunar Station (Integrated Program Plan, Part III)

OLS Schematic

The (surprisingly crude) schematic of the OLS from North American Rockwell’s Orbiting Lunar Station (OLS) Phase A Feasability and Definition Study, Vol. V. Public Domain image via NASA.

What it was: An April 1971 study by North American Rockwell, commissioned by NASA, on putting an eight-astronaut space station in polar orbit around the Moon.

Details: There was a short period of time prior to NASA settling on the Integrated Program Plan when some within that organization advocated a more conservative “space stations everywhere” program instead. A combination of NASA administrator Thomas Paine’s insistence on being bold and Spiro Agnew’s enthusiasm for Mars got the focus shifted to the Red Planet, but the space agency did its due diligence and took a look at the suggested stations in the context of the IPP.

From the standpoint of the 21st century, the most unusual of of these was a space station around the Moon, plainly dubbed the Orbiting Lunar Station, or OLS for short. North American Rockwell got the contract to flesh out the idea and dropped the result on NASA desks in April of 1971, just as Apollo 13 was gripping the world.

NASA’s basic intention was that the orbiting station would have several purposes. Scientific study of the Moon from orbit was one, and so was a supporting role for a surface base—communications with the Far Side, for example, or serving as an emergency shelter, or as a command station for remote rovers (thus alleviating the roughly 2.5 second round-trip delay between the Earth and the Moon). There was also a requirement to use the station for astronomy, including an intriguing suggestion to perform high-resolution X-ray astronomy using the edge of the Moon as an occulting edge, and the idea that the station would serve as an excellent test bed for the systems that would be used in the orbiting command centers that would probably feature during interplanetary missions.

What North American Rockwell presented was a station that would have been launched on a Saturn INT-21 (essentially a Saturn V without its upper stage, similar to what was used to launch Skylab) or in the cargo bay of the then-conceptual Shuttle that NASA was working on. After being checked out in LEO by a crew which would return to Earth, the unmanned OLS would be sent into lunar orbit using a Nuclear Shuttle, and then the first eight-astronaut expedition to the station would be sent using another. The vagaries of the Moon’s orbit around the Earth suggested a mission every 109 days to the station, with North American Rockwell arbitrarily deciding to swap half the crew out each time. After ten years, the OLS would be decommissioned.

As to where the astronauts were going, exactly, North American Rockwell came up with two possibilities. One was a purpose-built station, to which they specifically assigned the name OLS, while the alternative was a refit of a modular station originally built for Earth-orbital activities, which they dubbed the MSS. The end result was functionally the same, however, so for the purpose of simplicity we’ll focus on the OLS.

DeckPlans

The four habitable decks of the OLS. Composite image from the same source as previous. Click for a larger view. Public Domain image via NASA.

The station would have been built around a cylindrical core module 60.83 feet long and 27 feet in diameter (18.5 × 8.2 meters). It would have four receptive docking ports around its side, and one “neuter” port on each end, all intended for docking visiting ships or expansion with further modules later. Within were six decks, four of which were pressurized for human habitation. Access between these decks was provided by a series of circular openings on the station’s long axis; the exception was between decks 2 and 3, which were connected by a hatch that could be sealed off in the case of emergency.

One of the end ports would be used to attach a 33.42′- (10.2 meter-) long power module, which would unfurl four solar arrays totaling 10,000 square feet (929 square meters) hooked to regenerative fuel cells for storage, while one of the four receptive ports would house experiments that needed “a clear field of view” (the astronomy experiments, one presumes) and a bay for storing and repairing satellites the station would drop into other lunar orbits. Altogether it would have a dry mass of 107,745 pounds (48.75 tons); compared to other stations it would have been intermediate in size to the larger Skylab and the smaller Salyut-7.

The core module would also have a radiation shelter on the second deck, containing a secondary control room, backup galley, and toilet, protected by the stations 16,000 pounds of water (roughly 7250 liters) stored in a jacket around the shelter. The water was also used by the thermal radiators to deal with what NAR termed “the significantly more severe” environment in lunar orbit.

The OLS’s ten-year lifespan was specifically targeted to the 1980s, giving some idea of how long North American Rockwell though it would take to get it up and running.

What happened to make it fail: Like the rest of the IPP with which it was associated (with the partial exception of the Space Shuttle) the OLS ran into the avalanche that was the early 1970s. As well as major budget cuts and indifference on the part of the government and the American public toward space ventures, it had the additional problem of no high-level advocate. NASA administrator Tom Paine in particular was critical of the “stations everywhere” approach and preferred Wernher von Braun‘s more audacious Mars mission. There it would be only a minor part, if it existed at all.

What was necessary for it to succeed: You’ve got to start somewhere, begin with an administrator or a “rock star” like von Braun backing it to the full. Then all you have to do is prevent the economic troubles of the 1970s, end the Vietnam War, and somehow get one of the President or the general public on side. Piece of cake.

If you relax the requirement for success to include a lunar station not directly descending from NAR’s study, the situation gets a little easier. The American and Russian space agencies have discussed the possibility of a lunar station as a follow-up to the ISS, and it’s to North American Rockwell’s credit that both have described a setup not too dissimilar from the OLS. Though NASA still seems more interested in an asteroid redirect mission or a Mars mission at the moment, there’s a halfway decent chance that, about sixty years after the fact, the OLS’s descendant will take flight.

Sources

Orbiting Lunar Station (OLS) Phase A Feasibility and Definition Study, Vol. V; Space Division North American Rockwell; Downey, California; April 1971.

The Space Shuttle Decision; T.A. Heppenheimer; NASA History Office; Washington, DC; 1999.

 

 

 

The Reusable Nuclear Shuttle: To the Moon, Again and Again (Integrated Program Plan, Part II)

Sample Nuclear Shuttle configurations

A 1971 slide prepared by Marshall Space Flight Center showing an unloaded Nuclear Shuttle (top) and two configurations with a various components docked to its forward end (middle and bottom). Public domain image by NASA via Wikimedia Commons. Click for a larger view.

What it was: The solution NASA envisioned to the difficulty of getting large payloads to anywhere much beyond Earth with mere chemical rockets. Something like a dozen of them would serve as the brute force “trucks” of the American space program beyond Low Earth Orbit.

Details: We’ve already discussed some aspects of the Integrated Program Plan, NASA’s ambitious 1969 proposal to follow up the Apollo Moon landings with a new goal and new technology. The new goal was a manned Mars Mission, but the new technology had two particular pieces that would do the grunt work of building a space station and a Moon base as intermediate steps to the red planet: a reusable orbiting space plane (not yet dubbed the “Space Shuttle”) and the Reusable Nuclear Shuttle (RNS), many of which would have been built. It would have been the space plane’s role to get astronauts and cargo into low Earth orbit, while the RNS would have been used for the “high frontier”, so to speak. If something was going to go higher a few hundred kilometers, it would be offloaded from the spaceplane to an RNS, and then sent on its way—potentially to the Moon, or even beyond.

The RNS was suited for this task and similarly restricted from landing on Earth for one reason: their engines were given oomph by a nuclear reactor, but approaching one too closely at the wrong angle would expose a person to a fatal dose of radiation.

Start with the Nuclear Shuttle’s advantages. A variety of factors affect the power of a rocket, but the dominant number is the specific impulse (ISP) of the propellants it uses (to be precise, it’s a proportional measure of how much propellant the rocket has to use to add or subtract a given amount of velocity, though confusingly its unit is the second). With variations due to several other factors, rocket engines that use UDMH and N2O4 produce a specific impulse in the neighbourhood of 280 seconds, while LOX/LH2 is much more efficient at around 450 seconds (the low density of liquid hydrogen hamstrings it, though, so it’s often only used in upper stages where the rocket is already well underway and moving fast).

Unfortunately, all chemical fuels with a better ISP than that are either fantastically explosive, corrosive, toxic, or some hellacious combination of all three of those characteristics. Even at that, the best known ISP ever obtained (with a tripropellant of lithium, hydrogen, and fluorine) is 542 seconds.

Ultimately this because chemical propellants depend on chemical bonds, and there’s only so much energy you can contain in those. Quite early on rocket engineers realized that a good way to higher ISP was to use a different source of energy. In the absence of real exotics like nuclear fusion and matter/antimatter reactions, nuclear fission was the way to go. Hydrogen heated by a nuclear reactor can have an arbitrarily high ISP; it’s just a matter of how much heat one can get away with before the physical components of the engine are melted away.

When John F. Kennedy made his famous 1961 speech that started the race to the Moon he made a largely-forgotten reference to the Rover nuclear rocket, a contemporary project that was working on a preliminary nuclear-fission powered rocket. This in turn led to successively more advanced nuclear engines with the colourful names KIWI, Phoebus, and Peewee-1. By the end of 1969, NASA had a design for a functional nuclear rocket engine, the NERVA-2.

NERVA-2 would have had a specific impulse of 825 seconds in vacuum, and be able to burn for 20 minutes and produce 399.5 kilonewtons of thrust. Compare this to the J-2, NASA’s comparable workhorse engine (used on the second stage of the Saturn V, among others): it produced 486.2 kN of thrust, but was far less efficient at just 421 seconds of ISP. Accordingly, even though the NERVA-2 was far larger and heavier than the J-2 (having an entire nuclear reactor on board does that), the savings on propellant mass and the mass of the tanks needed to store it would make any spacecraft using one smaller than the same spacecraft based around a J-2.

Getting to the Moon is considerably more difficult than getting to orbit—you need to add another 3 to 4 kilometers per second to your orbital speed—and so the radically reduced fuel consumption of a NERVA-2 engine was very useful. Enter the Reusable Nuclear Shuttle. This was a conceptually simple ship: a single large fuel tank containing LH2 would have a NERVA-2 attached to one end, while the other had a docking adapter that could connect up to a variety of payload containers. Attach your payload, light the engine, and the RNS would push the payload into high orbit, to the Moon, or even beyond. Ideally you’d also put it on a trajectory which would let it return to Earth orbit, as the NERVA-2 was designed for ten round trips before it would be unsafe to light up again.

The disadvantage of the RNS lay in the radiation environment it produced. The rocket’s exhaust was only marginally radioactive and so arguably acceptable to allow on a launchpad, but in the event of a containment breach on the ground or, worse, in the air the engine would have sprayed uranium all over the environment. Even in the heady days of the late 1960s this was considered too risky, so the plan was to launch an RNS on top of a Saturn rocket using conventional fuels—if the Saturn blew up, the reactors were sufficiently ruggedized that they could survive the accident intact and fall into the ocean safely (by 1960s standards anyway).

What was more problematic was the NERVA-2 in orbit. Once the reactor was up and running it needed a great deal of shielding to protect approaching astronauts. As shielding was heavy, the RNS wasn’t going to have much of it. Instead the approach chosen was the have a “shadow shield”, where the propellant tank and any propellant aboard would provide most of the shielding. This meant that humans getting close to an RNS had to approach it from the front at a fairly shallow angle, using the bulk of the RNS to cover them from the reactor. If they approached from the sides or, God forbid, the aft where the engine was located they were assured of radiation sickness or death. Even on top of the RNS, a crew member would get about the recommended annual maximum radiation dose each time the engine fired.

Nevertheless, the advantages of the RNS outweighed the disadvantages in NASA’s collective mind, and the Integrated Program Plan called for it to be the workhorse of the space program beyond Earth orbit. Each would be used up to ten times (with refueling gingerly taking place after each use), after which it would be discarded in a high orbit due to its extreme residual radioactivity. With it, crews and payloads could be sent to the Moon and returned, and ultimately the American manned Mars mission craft envisioned for the early eighties would be perched on top of three of them.

What happened to make it fail: As with much of the IPP, the nuclear shuttle never got built because of a combination of disinterest from the Nixon administration and the falling budgets that that caused. Of all its parts, only the re-usable Space Shuttle and its rocket stack made it off the ground.

The RNS has its own particular story embedded in this larger tale, though. For many years the nuclear rocket engine program had been championed by New Mexico Senator Clinton P. Anderson, as much of the work on NERVA had been done at Los Alamos. Just as NERVA-2 was ready to become operational he became seriously ill and unable to press his case as much as he had in the past. The White House convinced Congress to pull the plug on the nuclear rocket on the grounds that it would be the basis of a manned mission to Mars, a goal about which Congress was quite negative at the time. The plan was that the freed-up funds could be used for the more-practical Boeing 2707, a Mach 2.7 supersonic commercial passenger plane similar to the Concorde or the Soviet Tu-144. Ironically, Anderson had enough clout remaining in the Senate to apparently engineer a 51-46 vote against moving ahead with that project; the House of Representatives soon followed. While the exact maneuvering involved has never been documented, the vote was widely considered retaliation for the cancellation of NERVA.

Regardless, with its funding quickly dwindling despite Congressional efforts to keep it going, NERVA was cancelled on January 5, 1973, and the Reusable Nuclear Shuttle was dead.

What was necessary for it to succeed: Like much of the Integrated Program Plan, the RNS was doomed by the political currents in Washington, within NASA, and in the general public. When it came down to picking something to move forward on NASA picked the Space Shuttle and the hope that one day they would be able to move on to a space station from there. The RNS ranked third (with the Moon base and Mars landing fourth and fifth) on their priority list, and they even tried very hard to claim that without the Space Shuttle they would not be able to get any nuclear shuttles into space. This was not actually true as the initial plan to use NERVA involved an upgraded Saturn rocket, but it was a measure of NASA’s determination to do anything to get the Space Shuttle built.

Ultimately that’s the main route to getting the RNS into the sky. NASA engaged in a great deal of internal debate from 1968 to 1970 over whether to continue with ballistic capsules or move on to a reusable, winged orbiter. Related to this was the debate over whether or not to focus on Earth orbit as a testing ground or push hard into the rest of the solar system. If both debates had gone the other way, a nuclear engine would have been very attractive to planetary mission planners and the money would have been there to continue with NERVA and the RNS–despite Congress’ objections to Mars missions, the presidential Office of Management and Budget had considerable discretion to ignore how it was told to allocate the money it received until a post-Nixon backlash in 1975.

Instead the arguments settled around a winged orbiter and sticking close into Earth unless the mission was unmanned, and we got the space program that we did from 1975 to the first decade of the 21st century. Nuclear rockets were revived for a short while during the days of the Strategic Defense Initiative’s Project Timberwind, but again it never came to anything.

Even if the RNS got built, there’s the possibility that it would have been much restricted in use or even cancelled outright no matter what successes it scored. The Three Mile Island accident in 1979 soured the American public on nuclear power in general, and after the Challenger explosion in 1986 NASA became very leery about dangerous payloads–for example, deciding against the planned Centaur-B booster that was to be orbited aboard STS-61-G later in the same year for the purposes of getting the Galileo probe to Jupiter. While both were specific incidents, they were each the culmination of long-term cultural trends that likely would have choked off the use of the RNS no later than the mid-1980s, and possibly earlier if one of them was involved in an accident.

Sidebar: Sonnengewehr, the “Sun Gun”

sonnengewehr

Illustration of the Sonnengewehr “Sun Gun” as published by Life magazine on July 23, 1945. Image copyright status unknown, possibly owned by Time, Inc.. Click for a larger view.

At the end of World War II the United States famously snapped up as many German scientists as it could with Operation Paperclip. While they were from a wide variety of disciplines, the ones most remembered today were the rocket designers and, as London and Amsterdam were still sporting spectacular V-2 craters, public interest in them was high at the time.

By the end of 1945 most of them would relocate to the United States, but in the period immediately following the end of fighting in Europe they were still in Western Europe and being interrogated by US intelligence personnel keen to learn about a line of weapons development in which the Nazis had jumped far ahead of the rest of the world.

It was in this setting that a few articles were published in major US newspapers and magazines (Time, Life, the New York Times and others) during July 1945 outlining one bit of information the US was getting from the captured scientists. All the articles were based on a single news conference held in Paris at the end of the previous month. While the conference apparently covered a wide variety of weapons that had been under development when the war ended, the articles picked up on one spectacular one and focused on it: the Sonnengewehr, quickly dubbed the “Sun Gun”.

The Sun Gun idea had been brought to the attention of the US by a group of scientists and engineers at Hillersleben, Germany (now part of the town of Westheide in Saxony-Anhalt, which was once part of East Germany). Though mostly unassociated with Wernher von Braun’s more-famous group they too had experience with rocketry, having worked on rocket-assisted artillery weapons and tank shells during the war.

As reported, in an unfortunately garbled way that makes it clear the reporters didn’t understand the underlying physics, the Sun Gun would have been a disc-shaped space station in a 3100-mile (5000-kilometer) orbit; some sources say 5100 miles, but this seems unlikely as German engineers would have expressed themselves in kilometers and that would be an unwieldy 8208 of them. Either way, neither would have been geosynchronous, an oddity pointed out even by some of the reporters in 1945.

Regardless, the station would have been coated with metallic sodium—chemically reactive and so easy to tarnish in the atmosphere, but which would stay clean in vacuum—polished into a mirror. The mirror would be pointed at a receiver off the coast of Europe and used to boil ocean water for power, but when the need arose it could be used on military targets—it had a projected ability to heat anything on the surface to 200 Celsius. Other numbers are scant and not clearly from the scientists themselves, but one that raises an eyebrow is that the mirror would have had an area of 5000 square miles (a round number in non-metric units, which is suspicious, and matches a diameter of 128.4 kilometers). Other sources suggest a much more realistic 9 square kilometers.

Life magazine was the most expansive on the topic, and published several drawings on the construction and operation of the station. Unfortunately their accompanying text and some of the details in the illustrations themselves suggest that the article’s authors were engaging in speculation on both topics. For example, they have the station being built of pre-made sections—cubes, oddly enough, which makes it a bit hard to produce a disk—when there’s reason to believe that it would have been made on a skeleton of long cables reeled out from a central station. Also contrary to this, Life has the inhabitable area around the edge of the disk, though this would have turned the Sonnengewehr into a “filled-in” version of the torus-shaped stations so favoured by von Braun during his lifetime

Immediate post-war reports to the contrary, it’s very unlikely that there was any sort of official work done on the Sonnengewehr beyond some tentative memos and discussions. If nothing else, consider the sheer mass of material that would have to be lifted into high orbit to build it. One source suggests one million tonnes of sodium metal, a figure considerably larger than the mass of everything ever lifted into orbit by all the world’s nations between 1957 and the present day.

Instead it seems to have been at best something batted around as a possible ultimate destination—even the scientists involved were thinking along the lines of the year 2000—in the culture of grandiosity that Nazism embraced and that also produced things like the Landkreuzer P. 1500 and Hitler’s architectural enabler Albert Speer. Even the mainstream rocketry program at Peenemünde was looking to run before it learned to walk, and this was just an extreme example of this attitude in the embryonic German space program. It may not have even been as tentative as that: at worst, it was merely discussions of an idea floated by the father of German rocketry, Hermann Oberth, in 1929.

Any gloss of reality the Sonnengewehr got likely came once the war was over and the Hillersleben group were under the control of the American military. In that precarious situation they would have been searching for anything to impress their captors of their usefulness and the Sun Gun inflated from cafeteria-table discussions to the preliminaries of a project. It did get them a little attention at the time, to be sure, but its sheer fantasticalness made it quickly drop back out of the limelight.

“Big G”: Getting to Orbit Post-Apollo

big-g-schematic

A schematic of one Big G configuration. The original Gemini capsule can be seen on the left, while everything from the passenger compartment on to the right was new. The adapter on the far right was designed to allow yet another cargo module, space lab, or habitation/life3 support module depending on the mission. Public domain image from a short briefing document given to NASA in December 1967. Click for a larger view.

What it was: A 1967 proposal by McDonnell Douglas to build a new Gemini spacecraft with an extra module attached to its aft end. This would be the craft for flying astronauts to and supplying the proposed space stations—both civilian and military—that were to follow the Apollo landings. It would have been able to deliver twelve people (ten on top of the pilot and co-pilot of the original Gemini) and 2500 kilograms of cargo to low Earth orbit; with an optional extension module it could have taken 27,300 kilograms.

Details: NASA was well into post-Apollo planning by 1967 and at that early stage it was far from settled that they were going to go for a spaceplane as their next major spacecraft. Even if they did go for one, some (including Wernher von Braun) felt that an interim system was needed until what was slowly turning into the Space Shuttle was ready. Basic research on lifting bodies was still underway and while landing on land was already considered desirable, at the time NASA’s chief spacecraft designer Max Faget favoured doing so with a ballistic capsule using a device that the agency had been working on for years: a Rogallo parawing to brake its descent.

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A clear view of the third, cylindrical module which would have been used for some Big G missions. Public domain image dating to 1969 via the NASA publication SP-4011 Skylab: A Chronology.

While there had been discussions about using the parawing with an Apollo capsule, the Gemini had the advantage in that it was the one where that program had begun; it had progressed as far as manned drop tests—Jack Swigert of “Houston, we’ve had a problem here” fame started his career as an astronaut flying a Gemini mockup under a parawing. McDonnell Douglas then sweetened the pot by reconfiguring their Gemini B so that it had the same base diameter as an Apollo capsule (making it simple to attach to a Saturn rocket) while giving twice the cargo capacity of its competitor. A modification of the Apollo CSM had studied in the years prior to Big G, and the so-called MODAP could match this increase, and even go beyond it with external cargo capsules—but then this is where the Big G’s cylindrical extension module came in and blew the Apollo derivative out of the water.

The Gemini B had begun as a logistics craft for the USAF’s Manned Orbiting Laboratory that, for the purposes of this discussion, had one important difference from the regular Gemini. It needed to be able to dock to the MOL and the most reasonable way to do so was at its aft end. This necessitated cutting a hatch into the capsule’s heat shield. While this looked like a dangerous strategy on the surface, it was proven to work and it became possible to attach other things to the Gemini B’s underside. For the basic Big G this was a truncated cone that increased the base diameter of the new craft to match that of the Apollo spacecraft, making it easier to mate it with Apollo hardware—and not just rockets. While they preferred their own cylindrical module for the third module that made a regular Big G into the nearly thirty-ton large cargo craft, McDonnell Douglas also came up with a side proposal to use Apollo Service Modules in that slot if NASA so desired.

The Big G was designed to be launched by one of three rockets. In its smallest configuration, it would be lofted by a Titan IIIM, a man-rated version of the Titan III which the USAF had started working on as a rocket for the Dyna-Soar program and then moved over to the MOL when Dyna-Soar was cancelled. This was the least powerful of the three alternatives, and would have been able to launch only the basic Big G. For one with the full complement of extra modules the choices were one of two Saturn variants that NASA was interested in building, either the Saturn INT-11 (the first stage of a Saturn V with four of the strap-on boosters used for the Titan IIIM) or the Saturn INT-20 (which would have consisted of a Saturn V’s third stage directly mated to the same rocket’s first stage).

As Big G was proposed not long after the Apollo 1 fire, it was designed to use an oxygen and helium mixture for its atmosphere, a difference from the pure oxygen of the original Geminis. The interior of the craft was also heavily reworked, with all of its systems upgraded and improved from the original’s. After all, as successful as it had been the previously flown Gemini had been only the second model of spacecraft flown by the United States.

When launched the Big G could have flown directly to a space station of short resupply or astronaut delivery-or-return missions. Alternatively the third module could be adapted to be a mini space lab, or a life support and habitation module capable of stretching the flight to 45 days; when the Big G was first being discussed, the then-record longest spaceflight of 13 days, 8 hours, 35 minutes had been achieved in an original model Gemini.

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Coming in for a dry-land landing under its triangular parachute, the Rogallo wing. Public domain image from McDonnell Douglas briefing to NASA, December 1967.

As previously mentioned, the end of the mission would see the re-entry capsule of the Big G bring its  astronauts home to somewhere in the United States by landing with a Rogallo wing. The capsule itself would have three landing skids that would cushion the impact of swooping into the ground, and then bring the vehicle to a stop.

Using the Big G as its transportation backbone, NASA’s hope was to have a 12-man space station in orbit by the time the Space Shuttle was ready to fly in 1975 (to use what turned out to be the optimistic estimate of 1969).

What happened to make it fail: The late 60s were an era of falling budgets for NASA, and there was a great deal of concern that the cost of launches was going to sink the manned space program—the Saturn V was notoriously expensive on a per kilogram-to-LEO basis (one figure, adjusted for inflation to modern dollars is $US22,000 per kilogram). Prices were anticipated to come down, but in general even the cheapest expendable launch vehicles have only beaten this figure by about a factor of three.

A re-usable launch vehicle had the promising appeal of bringing these costs down a great deal (projections, unfortunately based on unrealistic launch schedules, ranged as low as $US1,400 per kilogram). For crew return this made a glider of some sort necessary—either a lifting body or a winged craft—and when a high cross-range capability in NASA’s next spacecraft was cemented as desirable about 1970, wings became an absolute necessity. All possibility of a capsule, Big G included, fell by the wayside.

What was necessary for it to succeed: In retrospect the Space Shuttle looks like a mistake—its most basic reason for existence was to be a cheaper way to orbit than missions launched on expendable launchers and it never did so—most calculations pin it as more expensive per kilogram to orbit than the already expensive Saturn rockets it replaced. It’s important not to apply too much hindsight to this decision, but even in 1969 there were signs that sticking with capsules for manned spaceflight was the way to go. NASA had a strong constituency for this approach including, at first, the chief designer for the manned spaceflight program Max Faget. If he had stayed on-board with capsules, there’s a good chance that things would have turned out that way.

If they’d decided to go with a capsule, the two main options were continuing using Apollo spacecraft or building the Big G. Apollo had the advantage of still being in production, and it could have been launched on very similar rockets to the ones suggested for Big G. Big G, as mentioned, had the advantage of considerably more cargo space. Which of the two would have been picked comes down to an impossible-to-settle question of which advantage would be seen as tipping the scale.

The other possibility is that the Shuttle could have gone ahead, but that NASA could have realized just how long it was going to take before it flew: instead of going to space in 1975 its first mission was pushed back to April 12, 1981. If in 1967-69 they had had a better handle on the challenge they faced, the idea of using Big G as an interim logistics craft until the Space Shuttle was ready to fly would have been more attractive. The only problem with this scenario is that the Shuttle’s development costs put a big dent in NASA’s budget through the 1970s, so the space station that the Big G would have supported would have been hard to build while also going ahead with the orbiters.

Mir-2: The Once-and-Future Station

mir-2-schematic-1993

A schematic of the final Mir-2 design circa 1993. DOS-8 is the large module just above the central junction. Image source unknown, believed to be NPO Energiya. Click for a larger view.

What it was: The next in in the long line of increasingly large and sophisticated Soviet space stations that stretched from Salyut 1 in 1971 to Mir in 1986.

Details: Mir is the least-heralded of the major space firsts. Sputnik-1 and Yuri Gagarin rightly retain their fame, and of course the United States can answer with Apollo 11. Yet of the “big five” goals of the early manned space programs (the fifth being the still-yet unclaimed manned Mars landing) Mir fulfilled one: the first “real” space station. There had been other stations before, as far back as Salyut 1 and Skylab in the early 1970s, but they were not what was envisioned when an orbital outpost had first been seriously discussed in the late 1950s. Unlike the earlier single-piece stations Mir was the first “building” in space, in the literal sense of the word, constructed out of multiple components sent up over time and joined to make a functional whole. Salyut 7 had had one experimental module (TKS-4) attached after launch, but Mir was the real thing.

The station was built around the so-called Base Module (DOS-7), the ultimate version of the DOS framework derived from Vasili Mishin’s civilian Salyuts and Vladimir Chelomei’s Almazes. While it was being built the Soviets also built a backup base module, DOS-8, in case something went wrong with the first one. From the beginning, though, they were also making plans for what to do with the backup if DOS-7 and its launch went as planned. When they did, DOS-8 definitely became the centrepiece of a second space station.

At first Mir-2 was to have been “just another Mir”, which is not too surprising considering that they shared the same design for the core module. The only major difference between the two was the addition of a truss extending from the end of the station, greatly increasing its length, for solar panels and other equipment. But in 1982 Leonid Brezhnev died and was replaced by Yuri Andropov; in the United States, Ronald Reagan had become president the year previous and four months after Andropov’s takeover the US leader initiated the Strategic Defense Initiative. Andropov chose to fight fire with fire, and the Soviet space program was re-oriented to deal with the newly perceived threat. Mir-2 began to change.

There were actually several major redesigns of the station before 1993. One was still fairly close to the original Mir, in that most of its modules were designed to be lifted by Proton rockets and so had to stay in the 20-tonne range. But the station’s solar panels and a larger core module were designed with Energia in mind, and could range up to ninety tonnes. In fact the Energia’s first test payload the space weapon testbed Polyus, which was hurriedly cobbled together from several pieces of equipment, was in part based on a test article of the proposed Mir-2 core. The truss was also turned into a long docking tunnel meaning that one more manned ship or supply craft could visit this version of Mir-2 as compared to the original.

While that design went a fair distance, by the end of the 80s Mir-2 had grown again into what was formally called the Orbital Assembly and Operations Center but generally referred to as “Mir 2.0”. The first two designs had belonged to the Fili Branch of TsKBM, which is to say largely the Almaz design bureau that had been taken from Vladimir Chelomei after the death of his Politburo supporter Andrei Grechko. This version of the station was entirely NPO Energia’s baby and so under the close watch of Valentin Glushko.

mir2-energia-npo

The largest version of Mir-2, with its dual keels. Public domain image via NASA.

The new design was similar in appearance to the largest of all the American designs for their space station Freedom, the dual-keel arrangement proposed by McDonnell-Douglas in 1986; Mir 2.0 was to have been constructed around a rectangle made of four trusses. After the launch of DOS-8, Energia rockets would do the rest of the work: a 90-ton core module, then the truss and solar panels, then three more launches carrying three more 90-ton modules. The modules and the solar panels would be attached to a cross-beam on the truss, while various pieces of equipment would be balanced around the rectangle to balance tidal forces as the station orbited Earth.

By the time Mir 2.0 was getting really underway though, the ground had shifted again. Andropov and his successor Konstantin Chernenko were gone, replaced by Mikhail Gorbachev. The US and the Soviet Union had begun reducing their nuclear arsenals with the INF Treaty, Eastern Europe had cut ties with the Soviet Union, and the USSR itself was in an economic collapse. Now Mir-2’s design started heading in the other direction.

“Mir 1.5” was once again based on the DOS-8 block. Dedicated Energia launches were no longer in the picture, so smaller modules in the seven tonne range were assumed now. The real twist was that now DOS-8 was to be launched sometime around 1994 along with the second flight of the Soviet shuttle Buran—its first manned mission. Using the orbiter’s robotic arm, DOS-8 would be maneuvered to join up with the original Mir station; a power module and a biotechnology module would be launched and automatically docked later. When those were all in place, some two years later, DOS-7 would be detached and allowed to deorbit. The newly hatched station would then be built up with additional modules (including a second biotech lab) and a long cross-truss on which to attach solar panels and some equipment, the latter brought by another flight of Buran. This version of Mir-2 would see the second Soviet shuttle (supposedly to be named Burya) arrive every six months to swap out the biotechnology modules, returning their manufactured goods to Earth.

Then the USSR came apart completely. Toward the end of 1993 Mir 1.5 was no longer going to begin its life attached to the original Mir. It was down to just four modules at this point, and would hold a crew of two. By this point, except for the cross-truss, it was largely the same model as Mir, made better primarily by the experience of building the first station.

What happened to make it fail: By then the Soviet Union itself had come apart, and the Russian economy was approaching its nadir, contracting something like 40% in the first half of the 90s. Meanwhile, the American space station Alpha was in very severe trouble. In March of 1993 the new President Bill Clinton had told NASA to look at bringing Russia into the space station effort (which, while primarily American, was also being supported by the ESA, Japan, and Canada). On November 1 of the same year NASA and the Russian Space Agency agreed to merge Mir-2 and Alpha into the International Space Station.

What was necessary for it to succeed: In a sense it did. The third piece of the ISS was the Russian module Zvezda, which is in fact the well-travelled DOS-8 block. Altogether there are five Russian pieces to the ISS as of this writing and, while most of them are newly designed for this station, one more beyond DOS-8 has its roots in the older project: the Rassvet module is built on the repurposed hull of the SPP module which was to have powered the final redesign of Mir 1.5 prior to its folding into the international effort.

For that matter, the ISS is due to be decommissioned sometime after 2020. In 2008, Roscosmos informed the US that they intend to detach some of their modules—both already in space and planned to be attached to the ISS between now and then—starting in the late 2010s and use them as the core of a new station, OPSEK (“Orbital Piloted Assembly and Experiment Complex”, in Russian). One of the modules to be detached is DOS-8, and the designs of OPSEK seen to date bear a family resemblance to Mir’s once-proposed descendant.

Sidebar: The Mercury Space Station

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One of two configurations of a proposed Mercury-based space station. The other had the capsule stay in place with an inflatable tunnel running between the two hatches. Click for a larger view.

(Another little experiment along the lines of the Chief Designer posts. I’m finding a few space projects here and there that couldn’t support an entire discussion in False Steps’ usual format, but that still are worth examining. I’m thinking that perhaps they can be used as short sidebars here and there in the final product. I’ve tried two of them out on Reddit so far and they seem popular enough, so here they are for you too.)

In August 1960 McDonnell Aircraft suggested to NASA that a Mercury capsule should be extended into a small space station. This was despite the fact that a human being could just barely fit into a Mercury capsule, and couldn’t live in one for long—the final Mercury, Mercury-Atlas 9, could only last a full day because it was stripped down to hold more consumables, and even at that Gordon Cooper was only able to get it back to Earth through heroic efforts on his part.

That didn’t deter McDonnell. They suggested building a secondary, cylindrical capsule with the main Mercury capsule mounted to one end, and then sticking the whole thing on top of an Atlas LV-3B to fire it into space. Since it would be too heavy for that rocket to lift, the new capsule would have an Agena motor attached to its other end, which would finish pushing the spaceship into orbit.

They stated that the one man aboard the capsule could, with the aid of the extra living and storage space, live on board for an entire two weeks, performing experiments and whatnot until it was time to return home. As a result, they pitched it as a “space station”, but it really was no such thing. Altogether the whole thing only massed a few hundred kilograms more than the Vostok capsule that carried Yuri Gagarin into space; its internal living space was actually smaller than a modern-day Soyuz capsule. Nobody calls either of those craft space stations.

The Mercury Station never got built and likely the kicker was that the Mercury was pretty much an experimental craft. It was never intended to be upgraded and so McDonnell had to resort to a remarkable kludge just to let the astronaut onboard climb between the two pressurized volumes. Ideally there would have been a tunnel directly between the two when they were docked normally, but the Mercury’s retrorockets were in the way. So as designed, this craft would have had to take one of two approaches. Either the Mercury would stay in place and an inflatable half-toroid would join the hatch on the side of the capsule with the hatch on the secondary module, or else the Mercury would bend backwards on a hinge until its side hatch actually touched the side of the new capsule. Only then would the astronaut be able to clamber from one to the other.

NASA said no thanks and nothing ever came of it, but the basic idea seems to have evolved into the Manned Orbiting Laboratory for the US Air Force. Gemini was called “Mercury Mark II” after all, and was configured so that a tunnel could run between its base and any add-on modules behind it. It was quite natural, then to take the concept and adapt it to the newer, more capable spacecraft.

Orbiting Primate Spacecraft: The Cape Flying Monkeys (Apollo Applications Program, Part IV)

orbiting-primate-spacecraft

An unfortunately cluttered schematic diagram of the Orbiting Primate Spacecraft, which was studied in 1967 as a way of learning about the long-term effect of microgravity on living things prior to sending astronauts on long missions to space stations or other planets. Public domain image from Orbiting Experiment for Study of Extended Weightlessness, Volume I. Click for larger view.

What it was: A tentative plan to explore the long-term biological effects of free fall on primates before sending human beings into space for extended periods. It was in essence a tiny, automated space station inhabited solely by monkeys.

Details: By December 1967 the longest manned flights in space had still fallen far short of what would be necessary for long-term habitation of space stations, let alone trips to Mars or Venus. The record holder, Gemini 7, had lasted for 13 days and 18 hours and only three other missions had stayed in orbit even as long as four days.

Accordingly while there were hints that there were biological consequences to being in microgravity for extended periods of time their exact nature was a mystery. As part of one approach to solving the problem NASA’s Langley Research Center gave a contract to Northrop Corporation (and to Lockheed, which developed a similar alternative) to study ways of conducting automated and teleoperated animal experiments over a year-long period in orbit.

The result was an Apollo Applications Program proposal, the Orbiting Primate Spacecraft (OPS). The plan was to build a small pressurized compartment big enough for two rhesus monkeys and their perishable supplies, and attach it to an unpressurized section based on the LM&SS truss; this would carry life support equipment such as a water tank and a lithium hydroxide CO2 scrubber.

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An Apollo CSM injecting the OPS into its higher orbit. The solar panels would actually only have been deployed once the station had been undocked from the main spacecraft. Image from Orbiting Experiment for Study Extended Weightlessness. Click for a larger view.

If the mission had gone ahead the OPS would have been put in the upper stage of a Saturn IB, in the spot normally reserved for the LEM. An Apollo CSM carrying either two or three astronauts would have been placed above it as per usual and then the rocket launched from Cape Canaveral. The upper stage, the OPS, and the CSM would end up in a 185 kilometer, 28.5° orbit, at which point the CSM would undock, turn around, and then re-dock nose-first with the exposed OPS—again, much like an LM would be treated. The CSM would then fire its engine and boost itself and its scientific payload to a more long-lasting 460 kilometer orbit where the OPS would be released and the astronauts could get on with the rest of their mission.

Inside it, the two monkeys would be in individual pods sealed off from the rest of the craft and each other, to prevent fighting, with a small opening for some social contact. This design prevented stray waste or food from gumming up the instruments during a year-long mission with no humans on board. Northrop decided to further solve the latter problem by by conditioning each monkey to respond to a food light flicking on by going to its feeder and placing its lips over its outlet—a pellet of their usual monkey chow would then be put into its mouth so that food wouldn’t fly off in zero-g. The proposal does discuss feeding them with pastes or other more tractable foods, but that approach was rejected over worries that the subjects would be sufficiently unhappy with the change from their usual Earth diet that it would affect the results of the experiments.

“Monkey waste” was noted as the much more difficult issue. Without gravity or a human to keep the life pods clean, Northrop had to spend considerable thought on their design and still felt their solution needed more work. One wall of the pod was made into an open wire grid (which not incidentally gave the monkeys a “floor” to hang on to if they wanted one) over a storage receptacle; a forced airflow would have been passed through the pod and pushing waste toward it whenever needed—the monkeys were to be under observation by television camera anyway. If something stuck, another wall was movable and Ground Control could command it to scrape the compartment.

The movable wall was primarily for another purpose, though: forcing the monkey into a recovery capsule attached to the bottom of the OPS once the mission was over. As the capsules could be sealed off from the rest of the spacecraft one could also have also been used to store and isolate a monkey that had died for whatever reason prior to the end of the mission.

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The entire OPS wouldn’t have returned to Earth. Instead a second mission would have astronauts in a CSM retrieve two small lifepods containing the experimental monkeys. Image from Orbiting Experiment for Study of Extended Weightlessness.

Approximately one year after the Orbiting Primate Spacecraft was set floating on its own, a second Apollo CSM would be sent up to retrieve the its simian inhabitants. Once again the ship would dock nose-first with the station, and the monkeys (or the mortal remains of one or both of them) would be retrieved by a spacewalking astronaut. After a short capsule-enclosed spacewalk of their own the two subjects would be stowed aboard the CSM and returned to Earth, while the OPS would be deactivated and left in orbit. The monkeys would then provide a wealth of data to supplement what they had already given—the plan was to test them onboard using a lights panel they had been conditioned to obey prior to the mission, as well as possibly surgically attaching various wireless telemetry probes to them (though that technology was quite advanced for the time). One part of getting this data actually turned out to be the other major problem past monkey waste that Northrop couldn’t crack: how to weigh—or technically, mass—the monkeys in zero-gravity without a human on board to do it.

Though the Orbital Primate Spacecraft never made it past a fairly speculative stage, it was positioned quite clearly in NASA’s schedule as it existed in December 1967. Northrop examined the various Apollo missions that weren’t headed to the Moon (primarily Apollo astronaut training and the building and supplying of Skylab at its subsidiary stations as it was then conceived) and settled on Saturn/Apollo Applications flight 218, then scheduled for late 1970. Retrieval was more nebulously scheduled beyond the basic parameter of keeping the experiment running for six to twelve months, and was relegated to any one of the resupply missions SAA 221 to 228.

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Northrop’s other suggested uses for an OPS module. Description of all of these take up less than a page, so it’s not clear how seriously these should be taken. Image from Orbiting Experiment for Study of Extended Weightlessness. Click for larger view.

While the Orbiting Primate Spacecraft weightlessness experiment was the primary mission described, Northrop also briefly described a few other possible uses for a variant OPS, such as mounting it on an LM landing stage and studying the biology of the rhesus monkeys under lunar conditions, or putting one at the far end of a tether attached to a (presumably unmanned) CSM acting as a counterweight for spinning up the arrangement and running artificial gravity experiments. They also somewhat bizarrely tout it as a possible habitation module extension for a spacecraft built around the Gemini B being developed for the Air Force’s Manned Orbiting Laboratory, and even joining two of them in sequence as an emergency shelter in orbit.

What happened to make it fail: The Apollo schedule was very much in flux by the time Northrop submitted their study to NASA in December 1967. The Apollo 1 fire in February of that year had suddenly made it that much harder to reach the goal of landing a man on the Moon by the end of 1969 and NASA refocused their efforts much to the detriment of anything that didn’t directly lead up to Apollo 11. The Apollo Applications Program suffered accordingly.

By the time the AAP got back on track, budget was a problem. Several AAP proposals were cancelled because there were no more Saturn Vs available no matter what money could be thrown at them, but this wasn’t one of them. Had the money been there, there wouldn’t have been much difficulty coming up with a Saturn IB, a CSM, and the OPS. But this project was going to have to wait until after Skylab no matter what, and considering that that didn’t get going until May 1973—five years after the flight date assumed for the proto-Skylab in the proposal—this mission would have flown during the absolute nadir of NASA funding. By then the Space Shuttle program was absorbing everything they had.

The author also has a suspicion that the mission never went very far because it lacked dignity—while intellectually the OPS is a reasonable experiment, it’s hard to not react to it emotionally as “monkeys in a can”. Shepherding a mission from conception to flight is a political process, and what ex-military man or sober scientist is going to champion it and expose himself to ridicule (unfair or not) when there are so many other impressive or even heroic space missions to choose from?

As it was, it never advanced beyond the Phase A stage, which is to say simply determining how the mission would work in general and not serious design work, and NASA settled on getting their biological data by gradually extending the length of human missions. Skylab 2 lasted 28 days; Skylab 3 lasted 59. The longest American stay in space to date is still only 215 days (Michael López-Alegría, on ISS in 2006-2007), while only two human beings (Valeri Polyakov and Sergei Avdeyev) have exceeded the year that this experiment would have lasted.

What was necessary for it to succeed: The Apollo 1 fire was obviously a major problem, but simply eliminating it probably doesn’t help—it was a symptom of a wider problem at NASA and something else would have come along to disrupt the AAP schedule (and delay the OPS) instead.

The best bet would have been some greater commitment to space stations in the 1970s than NASA actually had. After Skylab the American record for consecutive time in space languished for a very long time until the ISS was up and running. Under those circumstances there was no need to push forward long-term microgravity knowledge. By the time it became necessary, the US even had some access to Russian data, as the USSR had had several long manned missions to the Salyut stations and Mir and the two countries were co-operating to an extent after the end of the Cold War.

Having the US follow the same path as the Soviets wouldn’t have been too hard. The Integrated Program Plan of 1969-70 had several components and the Space Shuttle and a space station were the two likeliest to go forward once it became clear that the entire IPP was a political impossibility. NASA chose the Shuttle, but that was a somewhat surprising decision at the time. Get them to pick a station as their primary goal instead and suddenly the Orbiting Primate Spacecraft starts to look a lot more attractive.

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

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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.

kh-7-camera

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.

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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.

Project Horizon (Part II): The Minimal Orbital Station and the Orbital Return Vehicle

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A “conceptual view” of the Minimal Orbital Station. Based on the mockup of the initial two-module station (linked below), the actual MOS would have looked somewhat different, but one module would be for human habitation and the rest would be gas tanks for fuelling the Moon ship and its injection stage, top. Another tanker is approaching, as it would take four fuellings in total to top up for a journey to the Moon. Image from Project Horizon: Volume I. Click for a larger view.

What it was: Project Horizon was the US Army’s full-blown proposal to put a man on the moon (and, in fact, start up a whole lunar base) by the end of 1966. While much of its focus was on the base itself, it also included extensive discussion of both the Earth-bound and orbital infrastructure they felt was necessary to reach their goal. The Minimal Orbital Station (MOS) was essentially a gas station in LEO for ships headed to the Moon, while the Orbital Return Vehicle was to be used to bring the gas station’s attendants back down to Earth when their tour of duty was done.

Details: In Project Horizon, Part I we discussed the US Army’s proposed launch facility on Christmas Island in the Pacific. Had it gone ahead, American soldiers and civilian experts would have been loaded on Saturn I rockets (or possibly a “Saturn II”, an early design of what would lead to the Saturn V) and launched into orbit.

Where would they go? To the space station, of course. The Project Horizon proposal blandly asserts “It is very likely that a previously constructed completely equipped space platform will be available in 1965 for use as housing facilities and for other support for the refueling operation.” It does then admit that it’s at least possible that 1965’s near-inevitable space station might not be suitable as a base for the Moon mission (by, for example, being in the wrong orbit). On the off chance that this happened, they proposed the Minimum Orbital Station.

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A view of the MOS mockup shown in 1960. The bottom module is a Saturn stage converted for habitation. The cone at top is the ORV. Public domain image from NASA. Click for a larger view.

Building the station would start with a launch of a Saturn I with a payload of men in the nosecone. Once in a 640 kilometer equatorial orbit (a height selected so that the station would circle the Earth in an even fraction of a 24-hour period, making it easier to return to the launch point after the mission was over) the nosecone and the upper stage of the rocket would both reach orbit, at which point the two would disengage. The upper stage’s remaining propellant would be blown out, and the aft end of the nose cone would be mated to the top of the stage—or possibly the side if this variety of Saturn I was redesigned to have an airlock there. The astronauts could then enter the empty stage and fit it out as a living and working space; this “wet workshop” concept would appear again in the designs of the Manned Orbiting Laboratory and the original Skylab.

This basic MOS was enough to house the astronauts, but not to support a Moon mission. Project Horizon assumed that the lunar landing would be a direct descent, which implies a considerably heavier load of fuel than was needed for the Lunar Orbit Rendezvous approach that NASA came to favour in the years following the Army proposal. The Saturn I was completely incapable of lifting both a direct-descent landing craft and the necessary fuel at the same time, so the two had to go up separately. Once the MOS had one empty stage housing its crew, another Saturn I would be sent up, only this time it was carrying a full load of fuel instead of men. The fuel-laden tank would attach itself to the side of MOS, and then the process would repeat: the baseline lunar landing mission in the proposal suggested four tanker launches would be needed before enough fuel was in orbit. More missions might be sent up carrying men, depending on how many orbital personnel were deemed necessary for the next step: getting the lunar craft fuelled and underway.

One final Saturn I launch would loft an unfuelled direct descent ship (that’s six launches now, if you’re keeping count), which would rendezvous with the MOS. The station’s crew would get into their spacesuits, spacewalk out into LEO, and transfer the fuel from one to the other. Three crew would then get aboard the lander and head off to the Moon. The remainder would either re-board the station for the next mission (the pace of Project Horizon’s launches, as discussed in Part I, was downright frantic), or head back to Earth.

Those headed back to Earth would use the Orbital Return Vehicle. This is where the word “minimal” really comes into play, as it was essentially just a conical capsule roughly 7 meters long and 4 meters at its base. After detaching from the MOS, a small retrorocket would knock it out of orbit and its crew would ride down to the ground. Astonishingly, the Project Horizon report suggests that it would have carried anywhere from 10 to 16 men at a time—bear in mind that the actual Gemini capsule gave its two astronauts 5.7 x 3.05 meters to play with, and no-one ever described the Gemini as “roomy”. This feat was accomplished by dividing the interior into no less than three decks (four, if you count the equipment compartment in the nose). There would be no room for sitting or standing here, so the astronauts would lie prone for the entire trip. Here’s hoping they didn’t miss their initial de-orbit burn time and have to wait 90 minutes for the next.

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An unfortunately blurry diagram of the ORV from Project Horizon: Volume II. Notice the number of astronauts depicted. Click for a larger view.

Ultimately, the plan was to turn the MOS into a destination in its own right, chaining together more and more Saturn stages converted for habitation and then eventually curving the chain back on itself to form a ring station that could be spun for artificial gravity.

What happened to make it fail: As mentioned in Part I, Project Horizon fell afoul of Eisenhower’s dislike of military activity in space. He’d already tried to pry manned space programs away from the Army, Air Force, and Navy by forming ARPA in February 1958. When that failed (ARPA then famously moving on to other projects like the development of the primitive Internet), he tried again and got them transferred to NASA.

In the particular case of the Horizon space station part of the larger Project Horizon. The Army’s main interest was militarizing the Moon, and the station was just a step toward that was made necessary by an EOR mission profile. When Eisenhower specifically took space exploration missions away from the services and gave them to NASA, the Army Moon program was dead and an Army space station to support it became superfluous.

What was necessary for it to succeed: The station was only going to go ahead if the Army had been given the green light on all of Project Horizon. Something like it might have been built if NASA had decided to use an EOR strategy for the Apollo program, but even that isn’t certain. The USSR considered a similar approach and felt that they didn’t need a station: their Moon ship would have fuelled up directly from the tanker rockets.

When NASA decided to go with a Lunar Orbit Rendezvous lunar landing in July 1962, the chances of seeing something like the MOS dropped from “maybe” to “none”. Space stations would be built in future, from Salyut to Skylab to Mir and the ISS, but none of them would serve the peculiar function of the MOS. Any similarity between them and the Horizon station was a function of position only, and not purpose.

As it was, the MOS and ORV made it to the mockup phase and no further; a diagram of one of these mockups can be found further up this page. Oddly enough it was put on display at the Daily Mail‘s 1960 Ideal Home Show in London, of all places. Somewhere between 150,000 and 200,000 visitors passed through it, and by all accounts it was one of the hits of the show.