The first to present was Vasiliy Mishin, who described how the Soyuz 11 spacecraft differed from its predecessors. He pointed out that a total of 19 spacecraft had been launched since November 1966, with Soyuz 10 and Soyuz 11 being the 7K-T crew ferry. The main difference between the two recent ships was the modification to the docking system following its failure on the Soyuz 10 mission. According to Mishin, Soyuz 11 suffered no major problems until the separation of its modules. It is not clear whether he told the Commission of the difficulty in closing the hatch prior to undocking. Based on data recorded by the onboard memory device, Mir, the module separation occurred at an altitude of about 150 km (some sources say 168 km) and lasted just 0.06 seconds. The pressure in the descent module began to fall rapidly at that moment. At a.m., two seconds prior to jettisoning the orbital module, the pressure in the descent module was 915 mm of mercury, which was normal. But some 115 seconds later the pressure had dropped to 50 mm, and was still falling. In effect, there was no longer any air in the cabin! In fact, the book relating the history of RKK Energiya (as the TsKBEM later became) states that the pressure fell even more rapidly than this, reaching near-zero in only 30-45 seconds.

Decompression could result from two causes: (1) the premature opening of one of two valves located at the top of the descent module, or (2) leakage from the hatch. Mishin presented diagrams featuring curves corresponding to these two modes of decompression. The curve calculated for a loss of pressure due to the valve opening exactly matched the actual loss of pressure recorded by the 'black box'. In addition, the force resulting from the air venting from this valve upset the stabilisation of the module, which prompted the automated control system to fire six 10-kg thrusters to compensate. The thruster firings calculated on the assumption that the air was being vented matched those recorded by the 'black box'. The maximum deceleration load of 3.3 g was recorded when the descent module reached an altitude of about 40 km, where the atmosphere began to thicken. At this point, air began to enter through the inadvertently opened valve. The second valve was automatically opened as planned, at an altitude of about 5 km. Although the cabin rapidly filled with fresh air, it was too late for the cosmonauts.

The conclusion was inescapable: one of the two valves had opened prematurely as the orbital module was jettisoned. The possibility of an incorrect command could be discarded because both valves were on the same electric circuit. Based on the 2-cm size of the valve's tube, the internal volume of the descent module, and the fact that the air would have passed through the valve at the speed of sound, the time for the pressure to diminish to near-zero was calculated at 50-60 seconds. If Dobrovolskiy, Volkov and Patsayev had been wearing pressure suits they would not have been in danger, but the Soyuz was a 'shirt-sleeve environment' and so they became the first men to die in space.

For the State Commission, two facts relating to the tragedy of Soyuz 11 crew were of crucial importance: spacesuits and valves. The decision to send cosmonauts into space without pressure suits had been taken years earlier. To create a 'spectacular' for Khrushchov, in early 1964 Korolev had ordered Feoktistov to adapt the Vostok spacecraft to accommodate three men, and in order to create the impression that this was an entirely new vehicle it was to be named Voskhod. As there was insufficient room for three men dressed in the pressure suits worn by the Vostok cosmonauts, it was decided that the crew should wear casual clothing. During a meeting on this issue Korolev said that working in the spacecraft in a pressure suit was as uncomfortable as working inside a submarine wearing a wet suit. Furthermore, to fit three couches into the capsule, it was necessary to discard the ejector seats, so the Voskhod crews were the first to be launched with no means of escape if their rocket were to have a malfunction during the first 27 second of its flight. Feoktistov was initially doubtful, but led the modification when Korolev promised that one of the designers could be a member of the first Voskhod crew. Because the descent module of the three-seat Soyuz was not much larger than the old spherical capsule, it was likewise designed for use without pressure suits.1 In March 1964 Korolev advised Khrushchov of the possibility of sending a three-man crew into space. The American Apollo that was to be capable of carrying three astronauts was not expected to start flying until late 1966, so Khrushchov eagerly accepted Korolev's proposal; he was unperturbed that the cosmonauts would fly without pressure suits - for him the most important thing was once again to beat the Americans.

During Korolev's lifetime, only Kamanin had sharply objected to this idea. In fact, he had attempted to force a return to the use of pressure suits. On 5 and 7 July 1971 he made the following entries in his diary expressing his disappointment:

Cosmonauts and the Air Force specialists insisted many times both verbally and in writing to the Central Committee of the Communist Party on the need to have on the ship pressure suits and equipment to pump air. But they were always refused - over a period of seven years! Responding to our requests, Mishin several times said that we were overcautious, that the decompression of the Soyuz spacecraft is completely excluded, meaning that "it is possible to fly [on it] in shorts''.

The crews of our ships have flown without pressure suits for seven years. Cosmonauts have written to Khrushchov, Brezhnyev, Ustinov and Smirnov about the danger of such flights. Kutakhov sent a letter to Mishin concerning the fact that cosmonauts "fly in shorts'', with a request to have pressure suits on board. But all our requests were refused - first by Korolev and in recent years by Mishin, who said that hundreds of unmanned satellites and piloted spacecraft have flown in space without a single case of decompression.

In the early phase of the Soyuz programme Mishin's responsibilities were related to rocketry; he had very little involvement in the design of manned space vehicles. When he succeeded Korolev as the Chief Designer in 1966 the development of the Soyuz was nearing completion. It would have been possible to modify it to accommodate a crew wearing pressure suits, but only by eliminating one of the couches.2 Korolev's fundamental error, with the active

1 In all other respects, of course, the Soyuz was more sophisticated than the Voskhod, particularly in having an escape system in case of a malfunction in the launch vehicle.

2 Three pressure suits would have weighed a total of about 80 kg, and there would have to have been additional apparatus to support them independently of the cabin environment. The Soyuz spacecraft simply was not designed for such a configuration.

support of Feoktistov, was to have designed the spacecraft for use without pressure suits. As Feoktistov said 24 years after the loss of the Soyuz 11 cosmonauts, "the feeling of guilt persists". The second major error was the decision not to install the tanks which would have supplied additional air to the crew in the event of a decompression. This was accepted by Mishin despite the protests of General Kamanin and the specialists at the TsPK. Interestingly, no one at the OKB-1/TsKBEM had the courage early in the design to seriously analyse the risk of flying without pressure suits and then challenge Korolev and Feoktistov.

Later, in one of his interviews, Mishin defended Korolev's decision by saying that during over 1,000 tests of the descent module there had been no problems relating to decompression. Noting that for decades hermetically sealed aircraft have flown at altitudes of 10 km or greater carrying crew and passengers wearing casual clothes rather than pressure suits, Mishin said: "I think Korolev's decision was correct, and that after this it was necessary to focus attention not on individual protection, but on the protection of the entire module - on group protection. Our idea was to develop such a robust hermetic unit that we would not need a backup for each element.''

While the descent module was at the landing site, it was established to be pressure tight. On its arrival in Moscow it was examined by experts from the TsKBEM. The hypothesis that a valve had been inadvertently opened when the orbital module was jettisoned looked good on paper, but despite being subjected to powerful shocks and vibrations the valves remained shut. The fortnight deadline allowed by the Kremlin for the investigation expired without such tests validating the hypothesis that on this occasion there had been an unexpectedly severe shock associated with the release of the orbital module. Later, Academician Keldysh pointed out that since the tests had been done in normal atmospheric conditions the forces would have been diffused by the air, and he suggested that the separation of the modules should be simulated in vacuum in an altitude chamber. Two tests were made in the TsPK, but in both cases the valves remained shut. Undeterred by this 'proof of the design of the valves, the specialists devised tests involving incorrectly configured valves in an effort to gain insight into the issue. Tests that applied a variety of individual loads and modes of malfunction to the valve failed to open it. However, when these were all applied simultaneously, the valve opened. With this proof that it was possible for the valve to be shocked open, the premature opening of the valve during the separation of the modules of Soyuz 11 was officially accepted as the cause of the decompression.

On 10 July 1971, while the tests were underway, the State Commission released a 200-word statement. After pointing out that the flight of Soyuz 11 was normal until the onset of re-entry, it went on: ''On the ship's descent trajectory, 30 minutes prior to landing, a rapid drop of pressure occurred in the descent module leading to the sudden deaths of the cosmonauts. This is verified by the medical and pathological-anatomical examinations. The drop in pressure was the result of a loss of the ship's hermetic seal. An inspection of the descent module showed there to be no failures in its structure. A technical analysis has determined several possible causes for the loss of the seal. The study of these continues.'' Incredibly, this is the only report ever to have been officially released describing the deaths of the Soyuz 11 crew!

The fact that the Commission's statement said that the cosmonauts died suddenly 30 minutes prior to landing owing to a pressure leak, whilst also saying there were no failures of the structure, led Western observers to conclude that the cosmonauts must have erred! In fact, two days after the tragedy some Western newspapers had reported an anonymous Soviet journalist who claimed the crew died because "they failed to seal the hatch of their spacecraft properly". At week's end, the Evening News in London reported that Russian scientists attending the funeral had blamed the cosmonauts. Victor Louis, the paper's Moscow correspondent, wrote: "human error and mechanical failure between them caused creeping depressurisation in the spacemen's 9-foot cabin and deprived the cosmonauts of life-supporting oxygen during the final phase of their journey''. During the turbulent re-entry, Louis said, the spacecraft's hatch had opened sufficiently to allow the air to escape into space. Although there was some basis for this story - the difficulty in sealing the hatch just prior to undocking - the State Commission had ruled out the hatch seal as the cause of the decompression.

The Commission completed its investigation in early August and recommended a number of improvements intended to preclude a repeat of the Soyuz 11 tragedy. At the final meeting, Academician Keldysh pointed out that the "opening of the valve was due to a shock wave propagating across the metal structure of the spacecraft'', and after noting that "to be simulated it is necessary to perform tens or hundreds of experiments in the altitude chamber'' he suggested that if the steps proposed by the Commission were adopted then to continue "expensive and complicated tests'' in an altitude chamber would "not make sense''.

Interestingly, three of the most important documents about the Soyuz 11 tragedy were not made public, and presumably remain in the archives of either the Kremlin or the TsKBEM. These are:

• The final report of the State Commission, including the individual reports of its subcommissions.

• The data recorded by the 'black box' in the descent module prior to, during, and after the separation of the modules.

• The full reports of the autopsies by the Burdenko Military Hospital - even the Ministry of Heath's Institute for Biomedical Problems, which is the leading space medicine institution in Russia, does not have copies of the autopsy results!

As in the case of Komarov's death, the Kremlin hid the truth about the Soyuz 11 tragedy from the Soviet people. The fact that Dobrovolskiy, Volkov and Patsayev died as a result of a valve inadvertently opening was revealed by the Washington Post on 29 October 1973 - more than two years after the fact! In planning the joint mission during which an Apollo was to dock with a Soyuz in the summer of 1975, the NASA officials said during a visit to Moscow that they had a need to know what had gone wrong with Soyuz 11. The Washington Post reported that a vent valve was accidentally forced open, and that the air in the descent module leaked to space in a matter of seconds. The valve had opened just after the orbital module was jettisoned. This procedure involved the firing of explosive bolts, and it was reported that the shock, which was greater than that expected, had been sufficient to cause the valve to open. Two of the cosmonauts had tried to unstrap from their couches in order to close the valve but had not been able to act fast enough. In ten seconds the cabin pressure was so low that it could no longer support human life. After a further 45 seconds there was no air left at all. Following a period of unconsciousness, the crew died from pulmonary embolisms. The tissue damage to their bodies was due to the boiling of their blood during the 11.5-minute interval that they were exposed to vacuum - a symptom that could at first have been misinterpreted as being indicative of an instantaneous and catastrophic decompression.

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