Sidebar: The Multi-Role Capsule

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.

The Armstrong Whitworth Pyramid: For an Empire on the Up

pyramid-diagram

A diagram of the Pyramid re-entry vehicle as presented to the British Commonwealth Space Flight Symposium in August 1959. The basic design with is on the left, while the variant with caret wings is on the right. The crew would have resided in the small cylinder outlined with dashes in the centre of the craft. Click for a larger view.

What it was: A proposal put forward in 1959 by Armstrong Whitworth, a British aircraft manufacturer, to build a pyramidal spaceplane to put on top of a two-stage rocket composed of a Black Knight rocket poised on a Blue Streak missile (this latter arrangement actually becoming official less than a year later, as the Black Prince launch vehicle).

Details: The UK is the only country in the world to have developed a space launch capability and then give it up (one could make an argument for France as well, as the Ariane is technically European, but that rocket is clearly France’s baby). That said, at the end of 1945 the UK was one of the few countries on the cutting edge of rocketry—like the US and Soviet Union they benefited from the ransacking of the German rocket programs. For a period of roughly twenty-five years after that up to 1971 the UK did try to keep within striking distance of the pace set by their two rivals, and in the period immediately following Sputnik there were grand plans to get men into space too, plans only struck down by Britain’s poor economy as compared to the US and an inability to shoot dissenters as the USSR had in its favour. To paraphrase Dean Acheson, it was all part of Britain losing an empire and trying to find a role.

The ultimate expression of this was the Pyramid. The basic idea behind the craft actually dates to 1951, when as we’ve discussed previously the University of Belfast’s Terence Nonweiler invented the concept of waveriding: increasing lift by riding the shockwave generated by a hypersonic aircraft. By 1956 the British had begun slowly working on this; after Sputnik I was launched they greatly increased their pace.

In 1957-58 Armstrong Whitworth, part of the Hawker Siddeley aircraft consortium (which also included Avro Canada, of Avro Arrow fame) worked out a shape that would be able to waveride back to Earth from orbit and, more importantly, orbital speeds. At that time the equations used to model hypersonic aerodynamic flow were crude, and the answers they gave had to be calculated by hand, so the shape was as simple as possible: take a regular tetrahedron and push its top point down to produce a squat pyramid. Then take one of the base points and pull it out by about half until you have something resembling the platonic ideal of an airplane. For simplicity’s sake, the underside stays completely flat. The only wrinkle is the addition of two rudders on horizontal tail structures at the aft end of the craft, and in one variant two small caret wings (the designers also realized that the real Pyramid would have to have rounded edges and a blunted nose to keep sharp edges and points from burning off during re-entry).

As designed, the Pyramid would have weighed 1876 kilograms, somewhat larger than a Mercury capsule’s 1104 kilograms, but in the same range (a Gemini capsule weighed 3396kg). It would have been 7.7 meters long and 5.2 meters wide, with a height at its point of 2.8 meters—though as it was a flat pyramid much of its length was considerably lower than that. Under the point and the rear facet of the pyramid was the crew capsule itself, which would be cylindrical and contain two men. As was typical for very early spacecraft designs, its engineers were overly optimistic about how many astronauts could be crammed into a small space.

The craft would have been launched on a proposed launcher involving a Blue Streak missile (an IRBM being developed by the UK for their nuclear weapons) as the first stage and a Black Knight rocket as the second. This was actually proposed more formally a few months later by the British government and given the name Black Prince, and so while it’s slightly anachronistic to call it that in the context of Pyramid, we’ll use that name here.

pyramid-on-black-prince

A view of the Pyramid on its rocket (though this one looks more like a US Titan than the Black Prince). The “mirror Pyramid” added to the Pyramid-proper for aerodynamic stability can be seen here. Originally published in Flight magazine, August 1959, and so believed to be in the public domain. Click for a larger view.

The Black Prince wouldn’t have been capable of getting very much into orbit (it would have been hard-pressed with a payload of 100kg), so Armstrong Whitworth suggested killing two birds with one stone. The Pyramid would also be much too wide to fit into an aerodynamic fairing on top of its rocket, and as it generated lift at low altitudes it would try to push the rocket off course and make the climb into orbit all that more difficult. So the Pyramid would have been paired with an identically shaped fuel tank mated to its underbelly, balancing its aerodynamics and supplying more propellants to the first stage. Once the first stage had lifted the whole arrangement as high and as fast as it could take it, it and the mirror-Pyramid would be jettisoned and the second would carry the real Pyramid into a 130 by 650 kilometer orbit.

Once the mission was done, the Pyramid carried just enough fuel (only a few kilograms) to perform a retro-rocket burn at perigee, which would knock it down to 100 kilometers and allow it to re-enter. Here the waveriding aspect of the craft would kick in. At a high angle of attack a lifting shockwave would form on the flat underbelly and let the Pyramid guide its path; it could even perform a sinusoidal flight following successive great circle paths to minimize the amount of heat the underbelly had to absorb.

The designers were concerned that their original design was unstable at speeds below 130 km/h, and they didn’t know enough to make it so, so the plan was for the crew to eject out of a hatch in the rear of the Pyramid once they were low and slow enough to parachute to safety. The ship would then crash, obviously reducing its reusability. Armstrong Whitworth believed that after harvesting data from a few flights, though, they would have learned how to proceed so the future Pyramids could land safely. Then the hatch would serve for emergency exits only.

Long term planning-borderline-dreaming for the Pyramid was to upgrade the Black Prince with a cruciform set of ten engines and then stick a nuclear second stage on top of it. With that booster, the Pyramid could be given a landing engine and head for the Moon. As seems surprisingly common for early proposale, they even had a landing site picked out: Piazzi Smyth Carter near the eastern edge of the Mare Imbrium. After a few unmanned cargo launches, the manned mission would consist of several Pyramids landing their crew simultaneously nearby and getting to work on a Moon base.

pyramid-on-the-moon

An image of a Pyramid on the Moon, from “Surface Exploration of the Moon” in Spaceflight magazine, August 1961. Image believed to be in the public domain. Click for a larger view.

What happened to make it fail: The Pyramid can be broken down into two pieces, the re-entry vehicle and the rocket on which it was perched.

The crewed section failed for the usual reason: it was a paper proposal looking for government funding and it didn’t get it. The window for it to get that funding was particularly small too, as it was a primitive design and would have been completely obsolete based on what had been learned the previous few years if it had got underway by, say, 1963. That said, there were some wind tunnel tests on it, and Hawker Siddeley did study another, more sophisticated waverider in 1971; that system was radically different, being lofted by a winged booster and having an on-board ramjet.

The 1959 Pyramid’s rocket was more successful, bearing in mind that “successful” here is a relative term. As mentioned earlier, the Black Prince was actually given the go-ahead a few months later, but the reason for this was complex. The UK had been pouring money into the Blue Streak missile and, out of embarrassment at its cancellation with no return on that investment, allowed it to go ahead as a civilian rocket. Political embarrassment or not, the Treasury was uninterested in funding space, and repeatedly tried to cancel every ballistic missile and space launcher project until an attempt stuck—and in the case of the Black Prince and its follow-ons, no-one was actually interested in sticking up for it. Ultimately it came down to a struggle between expensive British independence and prestige, or cheaply relying on the US for technology.

What was necessary for it to succeed: The Pyramid re-entry vehicle had a lot going against it. First of all, waveriding has never been well-developed, not even in the 21st century: only one craft has ever used it, the American XB-70, and that plane never went much above Mach 3. Furthermore, the Pyramid’s design was too small for the two men it was supposed to carry, so it would inevitably have had to undergo a radical redesign. It also became obsolete very quickly as manned space travel took several great leaps forward in 1960-65. The Pyramid also wasn’t an official government project, being a proposal from private industry that Armstrong Whitworth then had to convince the UK government to fund. With the Treasury opposing everything to do with space, it wasn’t going to get that. Altogether it was never going to fly, either because of money problems or because the design was not going to work as planned.

The rocket had a chance, though. The turning point there was probably the Nassau Agreement of 1962. After the cancellation of the Blue Streak, the UK had been planning to use the American Skybolt missile and when that was cancelled as well they were left in a dire situation as far as nuclear deterrent was concerned. Expensive or not, it looked for a while as if the UK was going to have to spend their way out of the problem and uncancel the Blue Streak. If so, the British would have had a much easier (and much better funded) path to the Black Prince that they could have taken.

Instead PM Harold Macmillan convinced John F. Kennedy to sell Polaris missiles to the UK. The Blue Streak stayed dead, and all of the UK’s independent space plans went with it over the course of the next few years. Change the course of history there and you might get the UK in space using Pyramid’s launcher

The Blue Streak cancellation notwithstanding, the launcher half of the Pyramid system did move ahead for a while. The embarrassment-driven Black Prince derivative proceeded until the end of 1960. The British couldn’t convince Australia or Canada to help finance it, though, so it too was cancelled, signalling the end of Britain’s large-scale ambitions in space.

It still stumbled along for several more years, morphing into two different projects, the British/French/German European Launcher Development Organization’s Europa (which was cancelled and replaced with Ariane in 1971-3) and the Black Arrow—both of which suffered from lack of support from the UK to the point of deliberately being set up for failure. Nevertheless the latter of these was launched four times, with the last being the first successful British launch of a satellite, Prospero, in October 1971. It was also the last: the Black Arrow program had already been cancelled in July, and the launch had only gone ahead because the final rocket had already been built and shipped to Woomera in Australia for its flight.

MTFF/Columbus: Europe’s Space Station

Columbus docked to Hermes

The initial module of Columbus, the MTFF, docked with the proposed mini-shuttle Hermes. At this point the space station would be unpressurized and unmanned except when astronauts were retrieving its experiments, but the APM (which eventually evolved into the ISS module Columbus) would be attached later to add a small living space. Image source unknown, believed to be the ESA; if you know the source of this picture, please contact the author. Click for a larger view.

What it was: A European effort to turn their contribution to the American space station Freedom into an independent space station of their own, hoisted into orbit by ESA rockets and serviced by an ESA shuttle.

Details: The European Space Agency signed on to Ronald Reagan’s suggested internationalization of the Freedom station right from the moment he made the offer in 1984. They had been developing the pressurized Spacelab module for use in the Space Shuttle’s cargo bay since the early 1970s, and now pushed for the new space station to build on components derived from their work. As part of this they started the Columbus project, which among other goals would have them make one such component—the Attached Pressurized Module (APM)—on their own for inclusion in the completed Freedom.

Another part of the project was to be semi-autonomous right from the initial planning, though. The Man-Tended Free Flying Platform (MTFF) was to have been a two-segment unmanned Spacelab module which would detach from Freedom and move to a nearby orbit. This would allow for sensitive, teleoperated microgravity experiments away from the noisy, manned Freedom and, a round of experiments completed, it would return for maintenance at the main station.

During the mid- to late-1980s, though, Freedom had a rough ride in the US Congress and the ESA started developing contingency plans for what to do with Columbus if the American station was cancelled. Couple this with massive increases in prices to use the Space Shuttle—then the Challenger disaster temporarily making its cargo bay unavailable at any price—and from 1989-92 these plans culminated in an entirely autonomous station that the Europeans would try if remaining part of the now downsized and re-named Alpha (AKA “Space Station Fred”) became too unpalatable.

The initial station would have been the unmanned MTFF, but now the experiments would have been retrieved by the ESA’s Hermes shuttle, which along with the Ariane-5 rocket had been approved as an unrelated project in 1987. In 1991 the three were melded into one big project.

altenative-expansions-of-columbus

Two suggested expansions of Columbus beyond its initial two modules. Image source unknown, believed to be the ESA. Click for a larger view.

The MTFF, Hermes, and the French launcher were to be joined by a fourth piece of the puzzle: the APM, now divorced from Alpha. Once the unmanned MTFF-based station was proven, the APM would be completed and launched on an Ariane-5 (or possibly in an US Shuttle’s cargo bay, if renting it turned out to be cheaper and more convenient). It would then dock with the MTFF to produce an entirely European manned facility, Columbus. The long-term, if somewhat nebulous, plan was then to add more and more modules as time went by.

Statistics on the Columbus are surprisingly hard to come by. Based on the actual ISS module that was derived from it, though, we can presume that its two working modules would totaled about 14 meters in length, with the power module and station-keeping ion engine at the MTFF end adding about another 5 meters.  Its total mass would have been in the range of 25 to 30 tonnes, which would have made it a bit bigger than the Soviet Salyut stations, but less than 25% the size of Mir and about 6% the size the ISS. Accordingly it probably would have had the same sort of missions as the Salyuts, involving two or three astronauts for a few days up to several months.

The budget for the station was calculated at US$5.3 billion, including operations for five years.

What happened to make it fail: Two trends pulled the APM back to where it started: attached to the ISS.

First, the United States got its act together. The Space Station passed through another session budget shrinkage and soul-searching under Bill Clinton in 1993, but finally stabilized into what is recognizably the ISS that got built. As uncertainty over the American contribution faded away, and the Russians signed on to ISS rather than build Mir-2, it became clear that it would be safe to co-operate rather than go it alone—though the ESA did keep contingency plans for Columbus in place as late as 2001.

The ESA itself was also running into budget difficulties. The collapse of the Soviet Union did open up another possibility, as there was talk for a while of perhaps attaching the APM to Mir-2, but a related event back down on Earth proved to be more important. The costs of German reunification made Germany scale back its contributions to the ESA by nearly a fifth, which brought a budget crunch to the agency as a whole. With Hermes already over-budget, it was cancelled entirely, as was the MTFF, and the APM’s costs were scaled down by committing to the American station project after all—the name Columbus was co-opted for it alone rather than the entire project, and it became the Columbus science laboratory module that was attached to the ISS in February 2008. Only the Ariane-5 launcher managed to emerge from the crisis unscathed. As it turned out, the late 80s and early 90s were something of a Golden Age for European manned space exploration. Not only has the over all ESA budget been declining slowly since then, the percentage of it devoted to manned space travel has dropped precipitously. The ESA’s focus has shifted to more commercial uses of space such as telecommunications satellites and the Galileo satnav system.

What was necessary for it to succeed: The main necessity is the stillbirth of the ISS, which isn’t too hard to engineer. The Challenger disaster had called it into question, repeated budget cuts hit it in 1989 and 1990, and in June 1993 a bill to cancel its immediate ancestor Alpha had failed by only one vote in the House of Representatives.

Given that event, the budgets floated for MTFF even after the Germans had run into reunification money problems had it flying by 1999 so long as the ESA doesn’t make the real world turn into budgeting more for commercial applications that it did. This gives us the first component of the station.

If MTFF did get off the ground, the next component of the program was still very likely to have changed. Hermes was not going to fly on a reasonable budget in a reasonable timeframe, which kicks out one leg of the station’s autonomy. However if the MTFF had gone ahead it’s likely that the ESA could service it with an (relatively) quick upgrade to the simpler Automated Transfer Vehicle they had begun developing in the mid-1990s. It flies in the real world on unmanned missions to the ISS, and its manufacturer EADS Astrium has been floating a proposal to turn it into a manned capsule since 2008. British Aerospace had actually suggested manning and supplying the station using a capsule of their own design in the mid-80s, only to have it squelched in favour of the French mini-shuttle.

The combination of an MTFF serviced by a manned ATV would likely have worked, leading to the attachment of the APM and a completed, manned ESA station Columbus sometime in the middle to late 2000s.