Sidebar: Sonnengewehr, the “Sun Gun”

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.

Kliper: Russia and Europe Try a Spaceplane

A schematic of the “permanent-wing” variation of the Kliper. The adapted Soyuz service module (hemisphere with docking pin at right) can be seen. Creative Commons Attribution-ShareAlike 3.0 Unported image by Julio Perez Suarez, via Wikimedia Commons.

What it was: A 2004-2006 joint project between Russia and Europe to build a small lifting-body/winged vehicle to replace the Soyuz and provide both groups with their own access to the ISS, as well as future stations. It also would have been able to fly short missions on its own without docking to an orbital facility.

Details: The Soviet Union and then Russia have tried multiple times to replace the venerable Soyuz craft—the Zarya capsule, the OK-M spaceplane, and the Buran/Energia shuttles that nearly pulled it off, among others—but never have done so. As of this writing they’re working on the PPTS spaceship, which seems to be making slow, unsteady progress and might fly before 2020. All have foundered on either Soviet politics or post-Soviet money problems and it’s not that the Russians haven’t been innovative in trying to fix the latter. Immediately prior to PPTS, RKK Energiya made a big push to get the European Space Agency on board with Kliper.

Kliper was based on work that Energia had already done in the 1990s, particularly an elaboration of it in 2002 that was the first to be called “Kliper”. But by 2004 Russian relations with the ESA were at a high point: work had just begun on the Ensemble de Lancement Soyouz, a Soyuz rocket launch pad at the ESA’s spaceport in Kourou, French Guiana, and so the Russians proposed expanding their co-operation to include a new spacecraft that would be launched on top of a substantially beefed-up version of the Soyuz, which they called “Onega” and eventually Soyuz-3.

The ESA’s Ariane 5 rocket was also powerful enough to lift a Kliper, but the Europeans were cool to the idea of launching anything but an unmanned ship on top of one. Even a Zenit rocket (derived from the side-boosters of the USSR’s last big rocket) was considered, but they’ve been under the control of the Ukraine since the collapse of the Soviet Union and the Russians have been leery of using them since then. In all likelihood, Kliper would have launched on top of a new Angara rocket—but the Angaras are still years away as of this writing, and the model likeliest to lift a Kliper (the Angara 3A) hasn’t even been begun yet. That was inconvenient to talk about, though, so the Onega it was, despite the fact that the most powerful variant of the Soyuz fired up until the end of 2004 was only about half as powerful as the one that would be needed. This new rocket was given specifications, with the idea being that it would use the N-33 engines that were to have been used in attempt to stop the N1 from exploding before that ill-fated program was cancelled. That said, it was very much a substantial project on its own.

The Kliper itself was, in 2004, a purely biconic lifting body—which is to say it had no wings at all and relied on its fuselage shape for its lift. By 2005, though, it had gained two small wings with large canards—the Sukhoi Design Bureau was brought into the circle to help with this aspect of the project. With the wings extending a mere 205 centimeters to either side of the 390 centimeter fuselage, the Kliper was a small package either way.

Three-quarters of the craft’s length—everything from its nose to the wings—were the re-entry module which would house its crew and passengers on the trip to orbit and during their return. Behind it was a tripartite service module consisting of a repurposed and upgraded Soyuz service module, a collar of support electronics as well as propulsion tanks and rockets for orbital maneuvering, and an Emergency Recovery System (ERS), which would push the Kliper the rest of the way into orbit if the rocket it was on failed near the end of the ascent to space—and give the craft the final necessary kick to high orbit and the ISS when the rocket worked well. While in orbit the Kliper’s service module would deploy two rectangular solar arrays to supply the spacecraft with electricity.

A mission would begin with the rocket stack being assembled horizontally and the Kliper placed on it. The resulting assemblage, some 47 meters in length of which the Kliper took up 12, would be transported to the pad and hoisted into a vertical position next to the gantry. As with a typical Soyuz launch, the Onega (weighing some 700 tonnes fully fuelled, of which the Kliper and its contents would be 15 tonnes for the lifting body version and 16-17 tonnes for the various winged iterations) would fire its four outer boosters alongside the central rocket engine to get the craft underway, then after they had burned through their propellants they would separate. The central rocket would then throttle up to full and get the Kliper most of the way to 100 kilometers up.

Five minutes after launch the central rocket would also be out of fuel and would detach, at which point the Kliper would coast for 10 seconds, jettison the aerodynamic faring around its ERS, and burn those engines for three and a half minutes to climb into the a 130×370-kilometer high orbit. The ERS would then be ejected too. This would get the Kliper’s perigee to within a few tens of kilometers of the orbit occupied by the International Space Station, and one more burn by the service module’s thrusters a half-orbit and 45 minutes later would circularize the path taken by the craft and allow a final approach to the ISS over the course of a day or two.

The final design of the Kliper approached launch slightly differently, so that it could be fully reusable—rather than have an expendable ERS, the craft would be serviced by an orbital tug named PAROM. Kliper would get to a low orbit on top of its Soyuz-3 and the PAROM (which would be docked to the ISS most of the time) would sally forth from the station’s higher orbit, attach itself to the aft end of the Kliper, and then carry up to higher orbit and a station docking.

Upon arrival at the station the Kliper would back into its berth, using the usual Soyuz-style docking pin and station docking rings to bring the two together and establish a solid connection. By itself it could last five days in orbit, but it could linger for a year if attached to the ISS’ systems.

The wingless Kliper variant comes in for re-entry and landing. Image source unknown, believed to be RKK Energiya.

For re-entry the craft would reverse the maneuver that lifted the lowest point of its orbit so that now a half-orbit sees it dip into the atmosphere. A final burn at this point would keep the Kliper at that height and the approach to home would begin. From orbital speeds down to Mach 1 the Kliper would act as a pure lifting body, starting at a high angle of attack slowly tilting forward as its speed dropped. The goal at this point was to keep re-entry forces to less than 5g and ideally below 3, and temperatures to no more than 1500 Celsius. The version of Kliper with foldable wings would deploy them when the craft dropped below the speed of sound, and either these or the permanent wings of the other main winged design would make the Kliper considerably more controllable as well as increasing lift and flattening out the ship’s descent as it came into a runway landing—the permanently winged version had a cross-range capability of 1200 kilometers, quite similar to that of the US’ Space Shuttle. The pure lifting body version of the Kliper had it deploy a parawing as it made its final approach, and one way or another it would be down to 65 kilometers per hour or so before its wheeled landing gear touched the tarmac. The pilots and passengers would then exit (or be retrieved, if sufficiently enervated by weightlessness) through the hatch on the tail end of the craft.

When first proposed in 2004, the idea was to have the Kliper flying no later than 2012. The very final versions of Kliper, studied by the Russians as a solo project in 2008, aimed for 2018. Each Kliper would have been good for sixty missions over the course of a fifteen year lifetime.

What happened to make it fail: Reports are that the European Space Agency’s various national factions couldn’t come to an agreement with Russia and RKK Energiya. In particular they couldn’t convince a majority of Europe’s “Big Three” in space (Germany, France, and Italy) because all think that a large part of the ESA’s value is that it lets them develop local high-tech skills and industries. Kliper would have been built on Europe’s dime but be designed and built almost entirely in Russia; while the ESA would end up with a manned spacecraft and the necessary infrastructure to launch it at the end of the process (as well as the prestige value of a manned space program), that it and of itself was not worth the cost. By December 2005 any chance of Kliper being built as a co-operative project had disappeared and Russia simply didn’t have the finances to do it themselves.

The possibility of continuing to work with Russia was maintained in June 2006 when Roscosmos and the ESA reportedly agreed to study the so-called ACTS (Advanced Crew Transport System), but this was a ballistic capsule. By Spring 2008, though, the two had completely gone their separate ways, with the Russians carrying on developing an early design of the ACTS that would eventually become the current PPTS spacecraft project.

What was necessary for it to succeed: As mentioned earlier Russia has moved on to the PPTS, while Europe is in the process of converting their unmanned ATV—currently used to take supplies to ISS, and itself derived from the work on ACTS—into a service module for the upcoming American Orion Crew Module. Whether or not this turns into a permanent arrangement remains to be seen (currently it is only for one Orion mission, Exploration Mission-1, which is scheduled to make an unmanned loop and return around the Moon in 2017), but at the very least the ESA will have developed one half of a manned spacecraft. The contrast with the way they were going to get much less experience and skill development with Kliper should be noted. The ESA had begun talking about adapting the ATV into a manned craft of their own in May 2008, in the wake of the Kliper and ACTS proposals failing.

This is, then, the one way to get Kliper flying: square the circle of Russian ambitions to build a spacecraft that someone else paid for while also getting two of Germany, France, and Italy a sufficiently large chunk of the interesting development work that they would sign on. The wildcard here is Japan, which expressed interest in joining the program if the ESA signed on for certain, but was in the middle of a long, deep recession and so uninterested in giving major financial support unless the ESA did. But other under circumstances they may have supplied a trickle of money large enough to get Kliper going, then stayed with it despite the inevitable money-related delays if the ESA pulled out later.

German illustrator Armin Schieb has made available a free book of computer-generated images (his master’s thesis) of a simple Kliper mission from launch to hypothetical future space station to landing available through Google Books. It gives a good idea of how Kliper might have been.

http://arminschieb.com/tag/kliper/

“Big G”: Getting to Orbit Post-Apollo

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.

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.

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

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.

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.

FLO: The First Lunar Outpost

One of two landers for the First Lunar Outpost, this an unmanned one with an adapted Space Station module on top for use as a place to live during the mission. The astronauts would arrive at roughly the same time aboard a manned lander. This picture is somewhat incorrect in that the real lander would have had two large solar panels stretching to the right and left. Public domain image from NASA.

What is was: A 1992 benchmark mission for NASA to return to the Moon, using expendable launchers and a direct descent lander, and build a small periodically-inhabited lunar base on the Mare Smythii.

Details: Early during the presidency of George H. W. Bush, the White House directed NASA via Vice-President Dan Quayle to come up with a plan to go to Mars—a goal announced to the public as the Space Exploration Initiative (SEI). To say that NASA botched this opportunity is to put it mildly.

Their (admittedly non-mandatory) orders were that NASA should come up with a plan that could get to Mars relatively cheaply, probably using technology that had developed since the end of Apollo. Instead they put forward an obvious relative of von Braun’s 1969 Mars Expedition, ditching the nuclear rockets but otherwise following the path of building a big space station, a permanent Moon base, and then finally moving on to Mars. The total cost of the program was estimated to be about US$540 billion over about thirty years—or, to put it another way, a rough doubling of NASA’s annual budget through the next several presidential administrations. This was political suicide and the whole thing collapsed in acrimony almost the moment it was put forward. Richard Truly’s career as NASA administrator came to an end in large part because of the fiasco and he was replaced by Dan Goldin in 1992.

Goldin’s mantra for NASA was famously “faster, better, cheaper” and he arranged for another study that would attempt to recover the manned lunar exploration part of the SEI. It was explicitly to be based on new ideas from the so-called Stafford Report (properly known as America at the Threshold: Report of the Synthesis Group on America’s Space Exploration Initiative) from the previous year. Out of this study grew the First Lunar Outpost (FLO) proposal.

An artist’s rendition of the proposed HLV for the mission, referred to informally as Comet. Public Domain image from NASA.

The first step to the outpost was literally getting there. The initial SEI plan had foundered in part because of its allegiance to the Space Shuttle which, as it could lift only 25 tonnes to LEO, meant that NASA needed to build their Moon craft in Earth orbit; that in turn required a space station. FLO was based on a return to an expendable launch vehicle, and it would have been a monster: the core of the launcher would either be an all-new rocket or a stretched version of the Saturn V (to the extent that that program could be revived 20 years after its end); either would have been flanked with two boosters. Its resulting payload to LEO was to have been in the vicinity of 200 tonnes. Contrast that with the Saturn V at 118 tonnes, or 88 tonnes for the Energia.

This massive increase in capability was to be used in two ways: the Moon craft would not have to reconfigure itself in Earth orbit like the Apollo arrangement did, and it would land directly at its destination on the Moon rather than sending down a landing craft followed by a lunar orbit rendezvous before returning to Earth. As well as making the missions safer by allowing more ways to abort and opening up more of the lunar surface for exploration, this simplicity was believed to be the route to a cheaper mission despite the upfront cost of the rocket that launched it.

The FLO spacecraft on top of its TLI stage in Earth orbit. Public domain image from NASA.

Nuclear thermal engines were studied for the trans-lunar injection stage of the FLO spaceship, but it was assumed that it would probably use a J-2S LOX/LH2 engine—essentially the same as was used by the Apollo S-IVB injection stage, though slightly upgraded to use a de Laval nozzle. The lander itself would have used four RL-10s, repurposed from the tried-and-true Centaur.  Again, these choices were made with an eye to saving money by using what the American aerospace industry already had to offer.

The direct-descent/direct-return profile of the actual landing forced the lander to be quite different, though. Admittedly a scaled-up version of the Apollo CM was perched on top of it, where it would carry four astronauts in the relative comfort of 11.3 cubic meters—somewhat larger than the old CM and LM taken together. Below that, though, was a much bigger spacecraft.

It would have packed no less than ten propellant tanks, four smaller ones in an upper tier for the ascent stage, and six larger ones underneath for the lander itself. Sitting on a relatively robust landing truss and four very long legs the whole arrangement would have been 56.7 tonnes with propellant, which is more than four times the mass of the Apollo LM. It would have towered 14.1 meters above the lunar surface, and been 18.8 meters from landing-leg foot to landing-leg foot.

Another big change from the Apollo program was actually a return to what had been planned for the original Moon landings post-Apollo 20. A second, unmanned lander would have been sent prior to the manned one and landed within an easy Moon rover drive, no more than two kilometers. Its entire ascent stage would be swapped out and replaced with a 35-tonne habitation module made in the manner of a Space Station Freedom module with as few changes as possible—again as a nod towards cost.

A sketch of the interior of the FLO habitation module on top of the unmanned lander Note the solar panels. Public domain image from NASA.

This module would have been the actual base. The crew of the manned mission launched in tandem with it would live there for 45 days, exploring the region within 10 kilometers using the aforementioned rover driven by astronauts, and up to 100 kilometers driving it by remote control from the habitat. The explorers would then return home to Earth but the base would not be closed up permanently. Powered by two solar arrays that brought the width of the base craft to just over 41 meters, the intention was that further groups of astronauts could be landed nearby as often as every six months and would find themselves with usable living quarters right away.

Leaving the Moon in the Ascent/TEI stage, leaving behind the landing stage. Public domain image from NASA.

Once the lunar surface mission was over, the astronauts would return to their original landing craft. Its central stack would ignite a hypergolic N202/MMH engine (hydrogen being too tricky to hold on to for 45 days on the lunar surface) and head directly for home. The final twist on the Apollo mission design would have seen the FLO capsule land on dry land, rather than splash down into the ocean.

By sticking as much as possible to technology they already had, or at the very least were already developing, the cost of the project to the end of the first landing mission was estimated at US$25 billion, with the unmanned base touching down around 2000 and the manned follow-up soon after. Just over half of this money would be for the development of the launcher and building three rockets. Even making allowances for the inevitable cost and schedule overruns, it was a remarkably different result from the original SEI.

What happened to make it fail: George H. W. Bush lost the 1992 presidential election and the Clinton administration was noticeably less interested in manned space exploration for its own sake. NASA reoriented itself toward keeping people in LEO, primarily building what had now become the International Space Station, and unmanned space probes beyond Earth orbit.

Extended manned lunar missions did creep back onto the agenda over the next few years, particularly as part of George W. Bush’s “Vision of Space Exploration” which pictured them as a test-bed for an ultimate Mars mission. But the discovery of water ice at the Moon’s south pole by the Clementine satellite in 1994 changed the nature of all future Moon base proposals by slewing them heavily towards using that water. Despite its generally innovative approach to a lunar landing, the First Lunar Outpost turned out to be the last gasp of an older paradigm for exploring the Moon.

What was necessary for it to succeed: This one is more speculative than most, but it’s interesting to consider the First Lunar Outpost in terms of what happened to Space Station Alpha in the same time period. The station came perilously close to cancellation and was only saved by a foreign policy decision: to turn it into the International Space Station, specifically in partnership with Russia in an attempt to absorb the time and skills of the Russian space engineers freed up by the collapse of the Soviet Union.

If you were looking to start an American make-work project in 1993 that capitalized on Russian expertise, a space station made the most sense. After all, Mir was beyond anything the United States had ever accomplished. But it’s not too hard to picture the busy-work being fulfilled by a different major space program. Since a manned Mars mission was out of the question due to expense, the relatively cheap First Lunar Outpost might have been the choice if the Clinton White House had been more interested in the inspirational side of space exploration than its nuts and bolts. They wouldn’t have been the first administration to feel that way.

LK-700: The Soviet Union’s Other Road to the Moon

Three views of the mockup of the LK-700 built before the program’s cancellation. On the left the craft as it would be at TLI, with its three lateral rockets. In the centre, a close-up view of the VA capsule, and on the right as the craft would appear on the trip back from the Moon (the lattice supporting it is not part of the craft). Image source unknown.

What it was: Vladimir Chelomei’s plan for a direct-descent lunar lander. While never the forerunner for a Soviet Moon landing, it was always a strong alternative that Chelomei and his supporters kept pushing forward whenever they could get a step up on Sergei Korolev or Vasili Mishin.

Details: For a very short period of time Vladimir Chelomei was on the verge of becoming the top man in the Soviet space program, and used his influence to cut Sergei Korolev’s OKB-1 out of the USSR’s manned lunar flyby mission and replace it with his OKB-52. He never did manage to gain control of the manned lunar landing, which was always officially going to be the N1-L3 or a derivative, yet it’s clear that if Nikita Khrushchev had not been ousted from power October 1964 he would have pushed to take it over too—and very possibly would have got it. While strictly speaking the LK-700 didn’t come until after Khrushchev’s fall, it’s what we would have seen as the Soviet effort at a lunar lander if Chelomei had remained on top.

The LK-700 began as the LK-3, and was first formally proposed after Chelomei and Valentin Glushko had thoroughly studied their alternative to the N1, the UR-700. Unlike OKB-1’s rocket, which was repurposed from designs for a Mars mission, OKB-52’s proposed launcher had been built with the Moon mission in mind and though the LK-3 was not formally approved until October 1965—after Khrushchev’s fall— the two had apparently been worked on in lockstep since about 1962.

This meant that it had one intrinsic advantage when the N1-L3 program ran into weight issues. It had become clear in late 1964 that the first few N1 rockets were not going to be powerful enough to perform a single-launch Moon mission, and that OKB-1 was going to have to evolve their launcher into something that could do the job. As the UR-700 and what was now the LK-700 were designed for each other, they would have been able to go on an earlier flight and so—all else being equal—get to the Moon first. The October 1965 decision to stick with the N1 but also move ahead with Chelomei’s plan, albeit at a much lower level of funding, was specifically intended as a backup if the N1 turned out to be a failure. From then on the advancement or retardation of the LK-700 tracked the N1’s highs and lows.

The LK-700 also had the advantage of being quite conservative. It was a direct-descent lander, which meant no dockings in space, whether in Earth orbit or around the Moon; as that profile needs more mass the rocket itself had to lift a larger payload, about 150 tonnes, but would be based on the tried-and-true storable propellants nitrogen tetroxide and UDMH. So would the LK-700—the highly toxic nature of the fuel was glossed over.

A Moon mission on the LK-700 would see two cosmonauts (or three in later missions) be launched into a 200-kilometer parking orbit by Glushko’s proposed booster. There they would spend five orbits checking out the craft’s systems before committing to a trip to the Moon. The fully-fuelled craft would weigh some 154 tonnes, as mentioned, and be about 13 meters long (not counting its abort tower, which brought the length up to 21.2 meters during launch). This is immense compared to the L3 proposed by OKB-1, and would have even been larger in mass than the Apollo CSM and its S-IVB injection stage at trans-lunar injection if fuel is included.

The Apollo craft was considerably longer than the LK-700 would have been, though. Rather than use Apollo’s linear arrangement with one engine and tank on the injection stage and the actual spaceship perched on top, the LK-700 would have used a laterally clustered arrangement. Three of a proposed new engine, the 11D23, would be attached to tanks of propellant arranged in a trefoil around another 11D23 and tank attached to the aft end of the LK-700’s crew capsule (the VA) and lunar landing stage/ascent stage (the Block 1V). The three engines would fire to add another 3.1km/s to the LK-700’s speed and send it on its way to the Moon, at which point they would be jettisoned.

The fourth engine and its propellant (Block 11), still attached to the outbound craft, would be used for course corrections during the 80-hour journey to the Moon. Upon arrival the Block 11 would fire again to slow the craft down to about 30 meters per second somewhere between three and five kilometers above their destination—notionally the Mare Fecunditatis, though Chelomei’s bureau never got anywhere near actually picking a landing site.

A view of the Block 111 landing gear. The rest of the craft sat on top, with the landing/TEI engine protruding out the bottom. It would remain behind on the Moon. Image source unknown.

At that height the Block 11 would run out of fuel and be ejected, exposing the Block 1V engine. The LK-700’s landing platform and gear (AKA Block 111) enclosed the Block 1V cylindrically, but let the rocket fire downwards to bring the craft to a soft landing on the Moon. The ship would have been designed to stay on the Moon for 12 to 24 hours, during which time the two cosmonauts it carried would make two surface excursions between two and two-and-a-half hours long.

When it was time to leave the Block 1V would fire again and launch the LK-700 back toward Earth while leaving the Block 111 behind. This would be a direct injection towards home, meaning that unlike the Apollo landings or the N1-L3 there would be no orbiting of the Moon either on landing or takeoff. This had the advantage of opening up a much larger fraction of the Moon’s surface for exploration, as there was no need to stay within the belt around the Moon’s equator where an orbiting mother ship would fly over the landing site with regularity.

The return journey would be somewhat slower than the outbound, taking four days, and after re-orienting the craft for re-entry at 150 kilometers above the Earth, the VA crew capsule would separate from the rest of the ship at 100 kilometers. The LK-700’s capsule was quite similar in shape to the Apollo CM, though considerably smaller: 3130kg as compared to 5809kg, and an interior volume of 4.0 cubic meters as compared to 6.17. Having the same outline and comparable small thrusters gave the VA the same rough steerability as an Apollo CM, and the crew aboard the last remaining component of the LK-700 could aim for a particular spot in the Soviet Union with about 11,000 kilometers of downrange and 300 kilometers of cross-range performance. Like other Soviet manned spacecraft, it was designed for a soft landing on land.

What happened to make it fail: Even though Chelomei was never able to get enough of the Soviet leadership to support his program over the N1-L3, the LK-700 trundled along at a low level for quite some time. The Central Committee of the Communist Party (at that time in the ascendance because of its support for Leonid Brezhnev’s takeover) re-authorized continuing work on it in September 1967. In the wake of the second N1 explosion in 1969, Chelomei even felt confident enough to push for the cancellation of the N1-L3 and its replacement with an LK-700/UR-700 based mission, making the good argument that re-designing and re-certifying the N1 so that it would stop blowing up on the pad would cost just as much as building the UR-700 anyway. Perhaps unfortunately for the USSR’s lunar landing ambitions that effort also failed to get enough backing and the N1 continued.

In the real world the LK-700 reached the mockup and early testing phase when it was killed definitively in 1975, along with all other Soviet Moon landing and flyby plans, by that shift in viewpoint towards space stations, Energia, and a Soviet space shuttle.

What was necessary for it to succeed: The LK-700/UR-700 was a very creditable attempt to make a Moon mission and certainly could have succeeded if technical skills were all that were necessary. Vladimir Chelomei had notable successes in his future, while the UR-700′s Valentin Glushko is arguably the greatest rocket engine designer of all.

Instead it never came to pass purely because of the poisonous politics of the Soviet space program from 1964-1975 (though of course if they hadn’t been like that it’s unlikely Chelomei would have been able to work on it at all once the decision was made to go with the N1-L3 in 1965). So at first the obvious answer to this question is “Vladimir Chelomei has to be able to maintain his remarkable drive to the top of the Soviet space program, rather than fall even more quickly than he rose”. To that end the continuing rule of Nikita Khrushchev would work very well, though it isn’t strictly necessary.

The main difficulty with this answer is Chelomei’s speed in developing his ideas. He had a strong tendency to go his own way and come up with unusual, if plausible, ways of solving problems. As a result his programs often required considerable fundamental work and testing as compared to more conservative approaches to the same problem. To his credit he took that time whenever it was politically possible to do so, but it meant long waits before missions were ready to go. While he would have been able to move considerably faster if OKB-52 had had the funds that OKB-1/TsKBEM had for the N1-L3 program, his deliberate pace on his other more successful projects strongly suggests that he would not have been able to beat the United States to the Moon by July 1969.

At that point the question becomes one of the Russian leadership’s attitude to a Moon landing after losing the race. It’s likely that the UR-700/LK-700 combination would have been less accident-prone than the N1-L3 (it hardly could have been worse), and so it seems that the Kremlin might have been greater tolerance for it if it ran late. Ultimately the success of the program would have come down to a race between Chelomei’s dream and a cancellation brought about by a desire to save money or (as in real-life) a re-orientation of the USSR’s space program toward military objectives. If the dream won the contest, a cosmonaut would have set foot on the Moon sometime around 1975-1980, with a likely Soviet Moon base to follow; if not, then we’d have seen an outcome rather similar to what happened in the real world, with only the doomed technology being different.

Sidebar: The Multi-Role Capsule

The only contemporary image of British Aerospace’s Multi-Role Capsule—a competitor to the ESA’s Hermes spaceplane—of which the author is aware. The capsule itself is the larger aft section to the right, while the service module is in the foreground left. Originally published in Flight International magazine, October 24, 1987. Click for a larger view.

When the ESA settled on the Hermes spaceplane in November 1987 there was one dissenter from the ambitious space program of which it was part. The British government of Margaret Thatcher was in the process of killing the British spaceplane HOTOL due to its technical difficulties and weren’t keen on supporting another one. As a result one of HOTOL’s designers, British Aerospace, was about to be left out of the European initiative. Without much support from anyone they suggested just prior to the formal adoption of Hermes that Europe might want to talk a look at an expendable capsule for trips to and from the US’ as-yet-unnamed Freedom space station. They also put it forward to NASA as a possible lifeboat if astronauts ever had to leave Freedom in a hurry.

BAe knew that Hermes was the favorite, and so positioned what they called the Multi-Role Capsule (MRC) and being cheaper and quicker to build. It would also have been capable of being lifted by a modified Ariane 4, rather than the new specifically-designed-for-Hermes Ariane 5 on which the ESA was spending so much of its budget.

The spacecraft consisted of two modules, a crew cabin called the Descent Module (DM) and an ejectable Service Module (SM) for any systems that weren’t needed for re-entry and the DM’s splash-landing on Earth. This is the arrangement of many capsule-based designs, built or merely proposed, but the MRC was unusual in that the SM was considerably smaller than the capsule (796 kilograms, versus an unfuelled mass of 6204kg for the latter) and mounted on the nose of the DM instead of its tail. The SM’s low mass did mean that the MRC would not have had much maneuvering capability while in orbit.

After launch the capsule would have held four to six astronauts, or none at all if the mission didn’t need a human touch. One of the latter type would have been docking with the upcoming US Space Station Freedom for use as an escape capsule if the station had to be evacuated. BAe specifically positioned this as the MRC’s first role, hoping that a go-ahead from NASA would overcome Hermes’ momentum, or at least get the MRC developed in conjunction with the spaceplane. British Aerospace sweetened the pot further by making the DM reusable (the SM was to have been expendable) and proposing to build a full MRC for a relatively inexpensive US$183 million—after adjustments for inflation, comparable to an Apollo CSM.

Unfortunately for British Aerospace they couldn’t get the ESA to back their idea, and their fallback of building them for the US didn’t work either. NASA did study return capsules for Freedom and Alpha, but did so in house: as might have been suspected up front, they already had extensive experience building their own space capsules and didn’t see any good reason to have them designed and built out of the country. Even at that, NASA ended up deciding against capsules for rescue missions anyway because they felt that the high g-loads of a capsule re-entry would be a problem in the case of a medical emergency (though in the end not even the Americans ended up building the mini-spaceplane that would be necessary to get around that problem).

It’s also telling of British isolation from the ESA’s mainstream at the time that, after the Multi-Role Capsule had faded away, a coalition of the aerospace contractors Aérospatiale, Deutsche Aerospace, and Alenia Spazio (respectively representing France, Germany, and Italy) went ahead with an independent study of a capsule-based escape craft for the ISS, thus essentially duplicating what the British Multi-Role Capsule was to have done as its first job. The ACRV, as it was called, was also cancelled.