A rendezvous in space is a dream for most of us. Getting aboard a spacecraft is no easy task at the moment, and is likely to remain so in the foreseeable future. When two spacecraft arrive at the same orbit and approach a very close distance, it is called a space rendezvous. This requires high precision as both the position vectors and orbital velocities of the two spacecraft have to match. Rendezvous might sometimes be followed by docking, a procedure by which the two spacecraft come together and create a link between them.
While the first docking was achieved in 1966 when Gemini 8, under the command of American astronaut Neil Armstrong, docked with Agena Target Vehicle, the latter spacecraft was uncrewed. The first instance of a docking in which both spacecraft were crewed took place on January 16, 1969.
On January 14, Soviet spacecraft Soyuz 4 was launched successfully. It was followed by Soyuz 5 24 hours later. Based on the problems faced by the crewed Soyuz 3 during its unsuccessful attempt to dock with an uncrewed Soyuz 2 in October 1968, a first-revolution docking was not planned.
Instead, the automatic rendezvous began during the 34th revolution of Soyuz 4 and the 18th revolution of Soyuz 5 on January 16. When the two spacecraft were just 100 m apart, Soyuz 4’s only crew member Vladimir Shatalov took over manual control, guiding it to an accurate docking on the very first attempt.
Soyuz 5, meanwhile, had a three-member crew of Boris Volynov, Aleksei Yeliseyev, and Yevgeny Khrunuv. Immediately after docking had been achieved, Yeliseyev and Khrunuv started preparing for their extravehicular activity (EVA).
Khrunuv exited into free space during Soyuz 4’s 35th revolution and started moving towards that spacecraft. One of his lines, however, became tangled and even though he quickly undid it, the incident distracted Yeliseyev. As a result, Yeliseyev forgot to mount a camera on the orbital module of Soyuz 5 before exiting the spacecraft, depriving us of a planned video of the spacewalk. A video transmission of poor quality was the only record of the hour-long EVA.
On entering Soyuz 4 without incident, the two cosmonauts were greeted by Shatalov once the orbital module had been pressurised. In all, Soyuz 4 and Soyuz 5 had been docked together for four hours and 35 minutes before separation.
While the now three-member crew of Soyuz 4 returned without incident on January 17, Volynov, on his own in Soyuz 5, had an unbelievable re-entry and was lucky to survive and tell the tale. This was because the service module failed to separate after retrofire. Even though this had happened before in previous flights, it was a more serious problem for Volynov as the module was much larger.
Miracle saves Volynov
The combined spacecraft positioned itself nose forward with the heavy descent module at the front and the service module at the back – the most aerodynamically stable position. Volynov relayed the situation to the ground station, but there was very little that he could do himself.
While he lost consciousness during the descent, a miracle kept him alive. The descent and service modules broke off or burned through because of the high thermal and aerodynamic stresses. The descent module then turned around to an aerodynamically stable position at hypersonic speed, with the heat shield taking the brunt of the heating as per original design. While the damage to the capsule during all this meant that the landing was much harder, Volynov survived and only broke some teeth.
Despite the drama surrounding Soyuz 5’s re-entry, the docking of Soyuz 4 and Soyuz 5 in space remains an important landmark. Rendezvous and docking are much more common these days and remain one of the key aspects of many space missions.