Hermes: The European Spaceplane


A cutaway diagram of one of the later designs of the Hermes spaceplane. Like all later versions it has an expendable payload and airlock bell at the aft end. Only the plane itself would re-enter for re-use. Image source unknown. If you know where it comes from, please contact the author. Click for a larger view.

What it was: A project by the French national space agency CNES (Centre national d’études spatiales) beginning as early as 1975—eventually expanding to an ESA-wide effort in November 1987—to produce a small spaceplane. Launched on the then-yet-to-be-developed Ariane 5, it would have given Europe an independent manned space capability sometime around the turn of the 21st century.

Details: The Ariane 5 has been the ESA’s workhorse launcher since 2003, and has been that space agency’s heaviest launcher since 1998, yet it will never fulfill what was its original mission: to be a part of Europe’s manned space program. Hermes began as internal discussions at the CNES in 1975 for a winged re-entry vehicle to be launched on the Ariane 4, but by 1978 it was decided to upgrade the capabilities of the mooted craft. This would push its mass above anything the Ariane 4 could lift, so a brand-new, more powerful rocket was assumed. The French began their work on the Ariane 5 specifically because of the spaceplane they wanted to build.

The craft they wanted to design in 1978 was given a few basic specifications. It would weigh approximately 10 tonnes and be less than 12 meters long. It would carry five astronauts, two of them pilots, or with just the two pilots have a cargo capacity of 1500 kilograms to low Earth orbit with maximum mission duration of two weeks. Launched vertically, it would land horizontally on a runway.

This, like every other Hermes configuration, didn’t last for very long. For the rest of its existence as an active program, Hermes would suffer from repeated cycles of feature creep and then a battle to get its weight and cost back down to something its budget and the Ariane 5 could handle. In March 1986,  having come to the conclusion that they could not afford the spaceplane by themselves, the French government informed the ESA that they were going to formally push for the “Europeanization” of the project. In the meantime Dassault and Aerospatiale in France were given the go-ahead to start designing and building.

Unfortunately opening up spaceplane to the rest of Europe brought in too many stakeholders. The first (and longest lasting) problem stemming from this approach came with Ronald Reagan’s State of the Union Address on January 24, 1984. In it he proposed that the United States build a permanent space station, and the ESA fell into factions: one wanting to build an independent European presence in space and one looking to continue their partnership with the United States on the Space Shuttle and do the same on the space station project. There was even the possibility of trying to find a hybrid path between the two. Hermes was pulled in different directions depending on which of the possibilities it was supposed to supplement.

In the complicated setup of the ESA, there was a constituent for every possible way to move forward. Of the ESA’s “Big Four”, the French were the most devoted to Hermes as an independent system, while Germany was willing to go along but inclined to work on space station Freedom; their major concern came with an understanding that the station might not be built out of Spacelab-derived components, that program being Germany’s main space science effort. Italy was inclined to the space station as well, while the UK was cool to Hermes as they were considering a spaceplane of their own, HOTOL.

The Challenger Disaster in 1986 brought many doubters on-side, as Europe’s access to space was affected as much by it as the United States’, then NASA’s political faux pas of introducing a US$14.5 billion first design for Freedom brought even more to the table when Congress decided that it was far too expensive for their blood. While a cheaper station re-design was soon underway, the uncertainty over relying on the US finally convinced the ESA to come to Hermes completely as part of a three-pronged compromise plan in November 1987. The Ariane 5 would continue; Hermes would be put on top of it and be capable of missions to Freedom and on its own; Europe would also develop a space station module, Columbus, but hedged its bets as to whether or not it would be specifically associated with Freedom or be a small, independent, European space station in association with another project (the Man-Tended Free Flyer) maintained by Hermes launches.

This was Hermes’ high water mark: fully funded with political backing from all of the ESA’s players, and the cornerstone of a fairly impressive little manned space program that made Europe a strong #3 in space behind the US and USSR. Politics and engineering began to complicate the picture, though.

What happened to make it fail: The politics were two-fold. The US’ gyrations over Freedom kept the Hermes coalition together, but complicated the compromises that had been made. NASA managed to get a plan approved and formally arranged for Europe to be part of the station with the MTFF free-floating nearby with Columbus being attached to the rest of the station modules. This made it harder to design, as now it had to cover three possible outcomes instead of the already difficult two.

Meanwhile the US Congress kept interfering with the budget for building Freedom, slowing and even temporarily stopping the allocation of funds. By 1990 it had become clear that the redesign itself was overambitious and the project was halted until a second, smaller redesign (the sarcastically named “Space Station Fred”) could be made. Finally in 1992 “Fred” itself came within a whisker of dying before being turned into a hybrid of Fred and Mir-2, the latter not getting built either because of the collapse of the Soviet Union. While all the turmoil gave the independent-Europe-in-space coalition more steam—the ESA committed to pairing up the MTFF and Columbus as a completely independent station—it piled more and more redesigns on top of all three components of the plan in order to save the compromise deal. This made the work even more long and complicated—and expensive.

The second political difficulty was a combination of the USSR’s end and the increasing expense. With the collapse of the Soviet Union Germany was free to re-unify, but at the cost of dragging the former East Germany up to West German economic levels. Combined with a coincidental recession in 1990-91, none of the ESA’s Big Four were willing to pay for the Hermes’ ever-increasing expenses, and even had difficulties coming up with the money they had promised in the first place. Germany itself stayed with Hermes only because the MTFF was their baby just as the spaceplane was France’s, and building it would have been pointless without some way of getting astronauts to it.


A version of the Hermes’ detachable cabin. Later the whole nose would come off, then that was replaced with ejection seats.

Finances aside, the ultimate killer was the engineering side of things. Partly to accommodate the necessary compromises and partly because they didn’t know any better, Hermes’ weight kept increasing past the limit of an Ariane 5’s lifting capacity, launching yet another redesign to bring it back down again. Payload capacity suffered more often than not, and as Hermes’ payload was never large to begin with it was constantly flirting with an inability to carry anything to orbit at all. This led to one major redesign: the deletion of a detachable crew cab for emergency escape and its replacement with lighter ejection seats derived from those used on the Soviet space shuttle, but other safety concerns in the wake of Challenger had brought the vehicle’s safe re-entry weight well below the launch weight they were already having trouble meeting.

In an attempt to fix both problems, 1989 saw a major redesign of the spaceplane. Most of Hermes’ payload and the airlock to exit the craft were moved into the adapter that attached the spaceplane to its Ariane 5. Upon reaching orbit the adapter, now renamed the MRH (Module de ressources Hermes) would remain attached to the aft end of the Hermes, then be jettisoned at the end of each mission before re-entry. While clever, this once again increased costs as the system was no longer completely re-usable.

The Hermes program was designed from the beginning to have a second “go forward/stop” decision made at the end of 1990, and as the deadline approached it was clear that the spaceplane was in a lot of trouble. France negotiated with rest of the ESA for a one year extension to the initial phase of the program, and then when that didn’t prove to be enough a one-year “period of reflection” before the final decision was made. In the interim the building schedule for the first launch was extended from 1999 to 2000 (having been pushed back from its initial 1995 several times already), and the number of Hermes to be built was cut from two to one. It wasn’t enough.  At the end of 1992 the ESA formally decided that it was not technically possible to build Hermes with the necessary capabilities without a radical increase in budget. Hermes was cancelled and the ESA moved on (for a while) to partnering with the Russian space agency Roscosmos to develop new ways of getting astronauts into orbit such as Kliper.

What was necessary for it to succeed: This program was the most serious effort by any group or nation to put a man into space outside of the US or USSR before the Chinese succeeded in doing so in 2003. Even so, it’s a cautionary tale for any space program as even if the politics worked out (and they were such a morass it’s a bit hard to see how they possibly could have), the engineering was never going to work.

Even if Hermes’ design had been locked down at an early stage (and an inability to come up with something and stick to it was a proximate cause of the failure), the problem was more fundamental. Europe was trying to do something that had never been done before even though this was their very first attempt at building a spacecraft. The US Space Shuttle and the Soviet Buran were considerably larger than Hermes would have been, which at first would seem to make it easier to build. While true to a certain extent it meant there was less room for error as the spaceship’s weight grew. The Shuttle, for example, was initially projected for about 30 tonnes to LEO and when built instead could carry 24.4 tonnes at best—an unfortunate loss, but not a show-stopper. On Hermes losing five tonnes like that, or two (or even one) pulled the craft into the red. And European inexperience in space technology made this kind of problem inevitable,

In the early 1980s there were proponents of a capsule for Europe’s first spaceship, to the point that the British pushed one from British Aerospace for a while. They didn’t go ahead because spaceplanes were “in the air”: STS-1 had flown from 12-14 April 1981, and it was well-known that the Russians were building one too. Even the Chinese were not far away from considering their own.

In going this way, though, Europe doomed themselves. The Ariane 5 was built, as was the Columbus module (sans MTFF); this makes the ESA’s effort by far the most successful failed attempt to build a manned space program ever. But the Hermes was the cornerstone of it, and so sowed the seeds of that overall failure from the start.