The cloth of doom: The weird, doomed ride of Ariane Flight 36by Francis Castanos
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| A boilermaker was working on a steel coolant tube that would find its way on to Viking engine D, part of that booster. He was a reliable man doing a fine job. But against Murphy’s Law, he stood no chance. |
This put Ariane Flight 35 and Flight 36 into a kind of conflict. Enter SPOT-2, the second remote sensing satellite in a series continuing to this day. Thanks to Ariane’s extreme modularity, the company made a pretty clever booster and payload swap and ultimately managed to make lemons into lemonade.
Alas, the said lemonade would soon leave a very bad taste in their mouths.
That same fall of 1989 on the other side of the Atlantic, at the Socieété Européenne de Propulsion (SEP) plant in Les Mureaux—southwest of Paris in the direction of Normandy—the last touches were being made on a very ordinary Ariane 4 L220 first stage, number L407. A boilermaker was working on a steel coolant tube that would find its way on to Viking engine D, part of that booster. He was a reliable man doing a fine job. But against Murphy’s Law, he stood no chance. By some insane bad luck (explained later), his red cloth not only ended in the tube, it also managed to escape all the following checks. There were many of them, because Arianespace was hardly complacent: having lost a flight in front of President Mitterrand in 1985 had taught them humility.
I managed to track down a document quoting the inquiry report, which pinpointed how the cloth ended there in the first place. It is such a stupid story, you can only laugh or cry—or simply shook your head in disbelief:
During assembly of a Viking motor, a boilermaker cannot connect two pipes as shown on the plan. Thus he gives a little bit of polishing. But to follow the procedure, he must warn his superior that he has done something that was not planned. Now it is Friday evening, there is nobody in sight. Then, as the tradition of boilermakers in this case, he disconnects the pipes and puts his handkerchief in the pipe. He reasons that on Monday, the red, flashy color of the cloth will catch his eyes and he will be reminded. Of the cloth, of his polishing, and to warn his superior he had done something unplanned. Alas ! During the weekend, he fell ill. The colleague who replaces him Monday takes the two pipes; they adjust easily, and voilà.
As for the swap, it worked this way. The L220 first stage that flew on Flight 35 in January was L408. Initially, it was to launch as a 44L, so the flight would have no-cloth engines and a 44L having eight of them. That left zero luck to the unfortunate, doomed L407 riding on an Ariane 40; to launch (and kill) Spot 2.
Because of the earthquake having damaged Superbird-B, the following moves happened. The Viking engine pods attached to L408 were stripped down and attached instead to the (doomed) L407. And this was the exact move that spared the launch complex from a major disaster. In a nutshell: the doomed L407 now at least had four more engines around it to get its flawed hulk out of the pad and die away from it.
Now, the fine-tuned L408 would launch SPOT-2 on Flight 35 as part of an Ariane 40. And the cloth-of-doom L407 become part of Flight 36 Ariane 44L, with the two jinxed satellites. They were Superbird-B and a Japanese satellite with the name BS-2X. Now wait, Superbird-B had already survived an earthquake, but how was BS-2X jinxed in the first place? Well, more on this later.
On January 22, 1990 L408 launched SPOT-2 on a quasi-perfect Flight 35. And the crippled L407 was ready to meet its fate. The cloth was in the coolant tube, the tube was on the Viking attached to stage 1 of the 44L carrying the jinxed satellites. And the whole thing was stacked in Kourou.
| Arianespace officials were baffled: the mishap had taken them aback to such a point, they had discussed sabotage as the only possible cause of the mishap. |
From the moment of ignition, it went down the drain. The cloth blocked the coolant, the Viking overheated, lost power, screwed the trajectory. The Ariane electronic brains fought back, steering the sane Vikings to try and keep the trajectory under control, but to no avail. Once the engine bells steered to the maximum, nothing could be done and the booster self-destructed, with $500 million of comsats blown into smithereens raining down on French Guiana.
The French Foreign Legion started combing the swamps and jungle and mangrove near Kourou, looking for bits of Ariane scattered all over the place. And soon they found engine D. Inside the wrecked engine was the cloth: and it was pretty intact, the silly thing. The Arianespace officials were baffled: the mishap had taken them aback to such a point, they had discussed sabotage as the only possible cause of the mishap.
Well… no. A handkerchief had done the job, rather than the KGB. As for equally baffled Ford officials, they were left dryly noting their poor Superbird-B had survived an earthquake only to be lost to a cloth. A board of inquiry soon roamed many places across Arianespace supply chain, Les Mureaux included. One can imagine their faces when the truth came out.
During my Internet discussions on many forums over the years, I randomly stumbled on one of the Arianespace workers from this era, who confirmed the story and added dryly, “From this moment on, every single cloth had a number tattooed on it. We check the cloths and, if one is missing, everything grounds to a temporary halt until it is found again.” That’s pretty excellent wisdom born out of a hard-learned lesson.
Ariane 4 soon returned to its pretty reliable routine, until 1994 when the HM-7 failed once again—twice, at both year ends. It had also failed in 1986, and in front of President Miterrand in 1985, and in 1982, too. Liquid hydrogen is a harsh mistress.
At the end of the day, from 1979 to 2003 the lower stages of Ariane 1, 2, 3, and 4 only failed twice in 144 flights: pogo during flight test 2 in May 1980 and, well... the cloth-of-doom. All five other failures were traced back to the HM-7: 1982, 1985, 1986, and twice in 1994. Ariane 5 was not so lucky and had extremely rocky beginnings from 1996 to 2003. By its 15th flight it had a truly appalling reliability rate that improved after a serious shakedown across Arianespace and CNES in 2003–2005. And yet, at some point Ariane 5, not 4, was to be human-rated for Hermes. Go figure.
The ironies are strong with this one. First, of course, is that Superbird-B survived an earthquake only to die by the hand of a cloth. Enough said.
Second, remember that other unfortunate satellite sharing its Ariane 44L ride, BS-2X? The Japanese, being cautious and smart people, built a backup. But perhaps they were a little angry at Arianespace—for obvious reasons—or maybe it was just a matter of launch insurance. Whatever, they elected to fly the backup on good old Atlas-Centaur, flight AC-70.
And guess what happened? The Atlas failed. Unbelievable. Once again, one can imagine the faces of these poor guys when the Atlas blew up. For the sake of curiosity I looked into that peculiar failure, and found Wayne Eleazer has discussed it (see “Launch failures: an Atlas Groundhog Day”, The Space Review, March 9, 2009)
When I read the following excerpt, I erupted into uncontrollable laughter:
So what had stopped the [Centaur] start-up? The answer was astonishing. The cleaning procedure for the propellant ducts involved scrubbing them with plastic scouring pads, pads exactly like those used to clean pots and pans in the home kitchen. The investigation concluded that small particles from the pads had gotten down into the expansion bellows for the ducts and lain there, unknown, until propellant began to flow. The particles had then gotten stuck in the turbopump, and while not offering much resistance, it was enough to stop the critical start-up procedure.
While BS-2X’s ride into orbit was doomed by a cloth, its twin, BS-3H, was lost to plastic scouring pads. This is no longer rocket science, but rather home economic. By this point in the story, one is left wondering whether the Japanese should have handled their satellites launches to housekeepers rather than engineers.
| Arianespace officials were baffled: the mishap had taken them aback to such a point, they had discussed sabotage as the only possible cause of the mishap. |
And yet the final, third irony is even weirder than all the above, which says something. And pretty scary, too. When the L407/408 swap happened, as we saw earlier, this made the flawed engine one among eight on an Ariane 44L, rather than one out of four in an Ariane 40. Well, when the startled engineers went looking at ELA-2 after the doomed flight 36 ascended and died, they found black marks on the launch tower and even on the mobile assembly shelter nearby. They realized to their horror (and probable relief immediately thereafter!) that Flight 36 had essentially launched and flown on seven engines, not eight, right off the pad. The unbalanced thrust had the Ariane 44L going sidewards to such an extent that it missed the launch tower by a mere three meters instead of the standard seven meters, scorching it and spraying black soot on it.
Well, remember that was an Ariane 44L: one engine out meant one eighth, or 12.5%, of the thrust missing. Now, had the original Ariane 40 been flown with the cloth-of-doom engine, it would have lost one of four engines: 25% of the thrust going away. The engineers made pretty clear it would have slammed into the launch tower and triggered a cataclysmic failure.
Make no mistake: the pad could and would have been rebuilt, and just like all other launch complexes on the planet, there was a backup one at a safe distance. The real issue, however, was that Ariane 4 burned storable propellants, and those things are poisonous and nasty pollutants. Two previous, similar low-altitude failures immediately come to mind: Titan 34D-9 at Vandenberg in 1986, and Proton in Baikonur in 1969. In both cases, cleaning up the storable nasty stuff was a major headache. And there is also the case that a toxic cloud of storable propellants wouldn’t do any good to Kourou or the nearby jungle, with Brazil not too far away on the other side of the border. It wouldn't be the end of Kourou or Ariane by any means, but still, a major setback and disaster for the French and Europeans.
At the end of the day because of that very weird chain of events three satellites worth billions died, and everybody ended screwed: Arianespace, Ford, and of course the Japanese, who lost two satellites to kitchen accessories. The only company that got lucky was SPOT Image, who barely saved their second remote sensing satellite out of sheer luck. Superbird-B and the Japanese, by contrast, were extremely unlucky: and that’s probably an understatement. Yet it could have been even worse. Had the cloth-of-doom stuck with the original Ariane 40, Kourou would have had a very bad day.
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