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Soyuz-8 landing completes triple mission
The flawless landing of the Soyuz-8 spacecraft wrapped up the simultaneous flight of the three piloted spacecraft and gave the Soviet government plenty of cause for celebration. In the meantime, behind the scene, engineers and cosmonauts pondered many important lessons from the failed docking between Soyuz-7 and Soyuz-8.
On this official photo, likely taken at Star City near Moscow, are left to right, front row: Valery Kubasov and Georgy Shonin from the Soyuz-6 crew; Vladimir Shatalov and Aleksei Yeliseev representing the Soyuz-8 crew. In the back row are the crew members from the Soyuz-7 (left to right): Viktor Gorbatko, Anatoly Filipchenko and Vladislav Volkov.
October 18: Soyuz-8 lands
With Soyuz-6 and Soyuz-7 safely on the ground, it was now the turn of Soyuz-8 to land on October 18, 1969, completing the triple Soyuz mission.
During a communication session with mission control in the morning of October 18, Shatalov and Yeliseev told Kamanin that they had already closed the main hatch of the Descent Module and depressurized the Habitation Module. Despite minor damage found in the locking mechanism on launch day, the hatch showed no pressure leaks inside the cabin. (820)
As in previous missions, the descent sequence program aboard Soyuz-8 was triggered by a radio command from the NIP-3 ground station in Sary Shagan at 10:19:29 Moscow Time and re-confirmed at NIP-15 in Ussuriisk in the Soviet Far East, exactly 10 minutes later. (774)
According to the program, the braking engine firing was to be initiated at 11:29:29 Moscow Time and was scheduled to last for 145 seconds. However, according to the information relayed to mission control from tracking ships deployed in the Atlantic, although the engine was activated exactly as planned, it quit firing almost a minute prematurely. The reported burn duration seemed to be enough for leaving orbit, but it also meant that the touchdown could take place far short of target. Fortunately, the data about the premature cutoff was quickly proven to be erroneous. (820)
When mission control finally established direct communications with Shatalov, he reported that the braking maneuver had been just four seconds shorter than planned.
The separation of the Descent Module with the cosmonauts from the instrument module took place at 11:41:35 Moscow Time, but clear reports from Shatalov continued coming through to mission control during much of the descent. In addition, General Pushkin, in charge of search operations, also provided many details live.
The capsule was reported to be at a parachute-opening altitude of seven kilometers at 11:56:24 Moscow Time, leading to a touchdown southeast of Tselinograd in Kazakhstan. (774)
Shortly after the expected landing of the capsule, the news came to mission control that a helicopter had touched down next to the Descent Module and that the cosmonauts had come out of the spacecraft. (820)
By the end of the day, the crew of Soyuz-8 flew from the Kazakh city of Karaganda, which was used as a staging area for search operations, to the launch site in Tyuratam. Shortly thereafter, all seven cosmonauts of the joint mission reunited in a hotel at Site 17. (820)
Communications sessions between Soyuz-8 and ground control on October 17 and October 18, 1969*:
Barely 24 hours after the completion of the triple flight, all seven cosmonauts met members of the State Commission to deliver their first impressions. (820)
Like several of his predecessors, Georgy Shonin, from the Soyuz-6 crew, complained about too much dust in the spacecraft, and Vladislav Volkov even recommended to have a vacuum cleaner onboard. The focus of the conversation was obviously on the failed docking between Soyuz-7 and Soyuz-8.
According to Shonin, who was aboard Soyuz-6, he was able to discern Soyuz-7 in the black sky as a star of the 1st magnitude. However, most problems came up at shorter distances. Volkov commented that the periscope aboard Soyuz had a field of view of only 15 degrees, which greatly complicated the effort to locate a small spacecraft in the vastness of space. Moreover, the division of responsibilities between the two crew members, where one is navigating the rendezvous with the help of a periscope and the other controls the motion of the vehicle was a mistake, according to Volkov. He also said that the spacecraft was easy to control, but (for the success of long-range manual rendezvous), that future cosmonauts would just need a range-finder, enough propellant and daylight. Yeliseev estimated that with the range-finder, the manual docking could be conducted from a distance of three or even four kilometers.
Like some of his colleagues, Volkov complained about medical sensors and suggested that it was time to abandon them.
In parallel with cosmonauts and officials, Soyuz engineers also looked for culprits which could have led to the docking system failure. Even before leaving mission control in Crimea on October 19 after the successful landing, Mishin's top deputy Boris Chertok and his colleagues had already identified the problem. In order for the transmitter and responder on the vehicles engaged in the rendezvous to contact each other, their radio systems had to operate in a well-synchronized frequency. To achieve that, signals emitted by rendezvous transmitters were stabilized by a special quartz resonator, whose crystals had to be maintained at strictly constant temperature, which was achieved by placing them inside a special thermostat. It was quickly established that a thermostat failure had disabled the Igla rendezvous equipment.
In the larger picture, Soyuz developers also had to take another critical look at their design philosophy of relying entirely on automated systems for rendezvous. The circumstances of the failed docking clearly demonstrated to Chertok and his colleagues specialized in flight control at the TsKBEM design bureau that a set of relatively simple navigational tools, such as range-finders, aboard the spacecraft, could greatly help the pilots complete rendezvous.
Mishin also echoed Chertok, noting in his diary, that the experience with long-range rendezvous based on guidance from the ground had opened an opportunity for achieving this task by simpler means.
Still, despite being unable to fulfill the primary goal of the mission, the cosmonauts and space officials involved in the Soyuz project were met in Moscow by the fanfares of the Soviet media, which declared the triple flight a complete success, obviously, with no hint of the planned docking during the mission. (820) All crew members got the usual hero welcome in the capital, followed by a reception in the Kremlin on October 22, where they got the nation's highest awards. At the press-conference a week later, officials and the cosmonauts also boasted about the pioneering welding operation during the mission, again without any mention of a dangerous incident in the experiment. (466) Interestingly, behind the scene, Mishin considered integrating the next version of the Vulkan hardware on the exterior of the Zenit spy satellite and arranging a TV broadcast, video or photo documentation of the welding processing via external cameras.
Crews of Soyuz-6, -7 and -8 spacecraft walk on the red carpet upon their return to Moscow after the triple mission.