Soyuz-8: New docking challenge
Sen—On Oct. 13, 1969, one day after the launch of Soyuz-7 and two days after Soyuz-6's blast off, a third spacecraft, Soyuz-8, entered a 205 by 223-kilometer orbit, after a successful liftoff from Pad 31 in Tyuratam at 13:19 Moscow Time. Onboard Soyuz-8 were two veterans of the Soyuz-4 and Soyuz-5 joint mission, Vladimir Shatalov and Aleksei Yeliseyev. Unknown to the world, Shatalov and Yeliseyev originally constituted a backup crew and were appointed for the mission less than a month before launch to replace the primary crew of Andriyan Nikolaev and Vitaly Sevastyanov, who showed poor results during training.
For the first time, an armada of three manned vehicles were orbiting Earth with a total of seven cosmonauts onboard. The Soviet press declared Shatalov the overall commander of the triple flight, perhaps hinting the crucial role the Soyuz-8 was to play in the mission. In fact, Soyuz-8 carried the active part of the Igla (needle) rendezvous system, thus being responsible for all key maneuvers leading to docking with Soyuz-7, which was scheduled for the following day. However, in its nominal automated mode, the Igla system onboard Soyuz-8 failed to capture its target as the two ships passed within several kilometers from each other, making autonomous rendezvous impossible. Ground control then attempted to navigate Soyuz-8 for another flyby of Soyuz-7 using its own trajectory calculations, which it hoped would be accurate enough for the crew to initiate a manual final approach.
On October 15, Soyuz-8 passed less than two kilometers from Soyuz-7, but it turned out to be still too far for the crew to conduct the manual approach. According to Soviet sources at the time, all three ships came within few hundred meters from each other, however the official press never mentioned that the docking had been planned. After a short period in formation flying, the ships started drifting apart. No photos of any of the three spacecraft in orbit have ever surfaced. It is possible, their crew were too busy with rendezvous operations to document the process, or they were too far apart to discern each other.
The Soviet engineers realized that the automated docking system, which was successfully used in the Soyuz-4 and Soyuz-5 mission, as well as in unmanned test flights, was still far from operational readiness, which could be used reliably in the lunar program. The failure also meant that cosmonauts had no a backup manual mode, which could save the day during lunar missions. Clearly, more test missions in Earth's orbit were required.
Fortunately, all other critical systems onboard Soyuz-8 continued working normally and the crew switched to secondary tasks of the mission. In particular, cosmonauts employed the newly launched Molniya communications satellite to establish contact with ground control and with the Kosmonavt Vladimir Komarov tracking ship. The crew also conducted experiments into the polarization of the sunlight in the upper atmosphere. Finally, Soyuz-8 apparently conducted two orbit-correction maneuvers, but their exact purpose is still unclear. Possibly they were meant to align the orbit with the most favorable landing path.
After a five-day flight, the descent module of the Soyuz-8 spacecraft with Shatalov and Yeliseyev aboard successfully landed on Oct. 18, 1969, at 12:09 Moscow Time, 145 kilometers north of the Kazakh city of Karaganda. Last to be launched in the triple mission, Soyuz-8 also became the last to land. The exact duration of the mission was four days 22 hours 50 minutes.