article image

Soyuz-12: recovering from a catastrophe

Anatoly Zak, Spaceflight Correspondent
Sep 27, 2016, 11:03 UTC

Sen—The tragic loss of the Soyuz-11 crew in 1971 triggered a long period of soul-searching inside the Soviet space program. In hindsight, it was clear to everybody involved that safety features of the Soyuz spacecraft had been utterly inadequate.

Immediately, engineers at Sergei Korolev’s design bureau, (renamed TsKBEM after his death in 1966) began a major overhaul of hardware and procedures in the human spaceflight program.

No cosmonaut would ever be allowed to launch, land or conduct docking operations aboard Soyuz without wearing a protective spacesuit in case of depressurization. It was harder said than done, because all existing Soviet spacesuits were far too bulky to fit into the small Kazbek seat of the Soyuz spacecraft, which required cosmonauts to keep “an embryo” pose during launch and landing. To resolve the problem, engineers at the Zvezda enterprise urgently fashioned a special rubber-made Sokol-K (falcon) rescue suit based on previous designs for military aircraft pilots. Although they managed to keep the mass of the Sokol-K at just 10 kilograms, the addition of an emergency air supply kit into an already cramped descent module forced a reduction of the crew size onboard future Soyuz ships from three to two.

During an uneventful flight, the Sokol-K suit would be ventilated with cabin air, however in the case of a sudden loss of cabin pressure, it would instantly switch to a supply of mixture of oxygen and nitrogen. Cosmonauts were certified to wear the Sokol for up to 30 hours under normal circumstances and up to two hours in the unpressurized cabin. This time was considered enough to make an emergency return to Earth. The Sokol-K could even help cosmonauts survive in cold water, even though Soyuz crews would also have specialized Forel (trout) flotation suits in their safety kits.

In a drastic weight-saving measure, the Soyuz was stripped of its solar panels. Proponents of the idea argued that for short trips to the space station, onboard batteries would suffice. The new version of the spacecraft was designated 7K-T, where “T” stood for “transport.”

The flight testing of the 7K-T spacecraft started with an unmanned launch on June 26, 1972. In accordance with the Soviet practice, the real identity of the spacecraft was kept secret behind the public designation Kosmos-496.

Following the successful landing of Kosmos-496 on July 1, the transport Soyuz was declared fit for its role of a taxi to the space station.

Finally, a year after the catastrophe, the USSR made its second attempt to orbit a space station. A near-replica of the original Salyut orbital lab was to pave the way to rehabilitation of the Soviet manned space flight after a fatal accident. Designated 17K DOS-2, the station blasted off from Tyuratam on a Proton rocket on July 29, 1972. However three minutes into the flight, the booster’s second stage was prematurely shut down after its failing stabilization system had sent it tumbling out of control. The brand-new orbital lab crashed just 536 kilometers from the launch site.

Following that failure, engineers decided to take a fresh look at their space station designs. Back in 1970, even before the launch of the original Salyut, they drafted a more advanced project of a space laboratory. Most importantly, the new design featured rotating solar panels, which could track the Sun all by themselves, and thus save a lot of precious propellant for the station. To save mass, some propellant tanks were removed, while the outpost’s orbit was increased to a more stable altitude of 350 kilometers. Many other innovative technologies were also introduced, including the Kaskad attitude-control system, the Delta navigation system and the first version of the water-recycling facility SRV-K. The standard “manufacturer’s warranty” for the station was extended from 90 to 180 days, even though engineers hoped for a much longer lifespan.

After a three-day delay caused by problems with the launch vehicle, the new-generation space station, DOS-3, was launched on May 11, 1973. This time, the Proton rocket worked flawlessly, however a human error at the mission control led to a complete drainage of propellant onboard DOS-3 shortly after it had reached orbit.

Counting an in-orbit failure of the military cousin of Salyut in April of the same year, three Soviet space stations were lost in less than a year! The Soviet security services now got involved checking for alleged sabotage and at least one top manager at TsKBEM lost his job as a result.

With no destination to go to, another unmanned Soyuz was launched in June 1973 for a series of tests under a cover name Kosmos-573.

Finally, more than two years after the Soyuz-11 tragedy, on Sept. 27, 1973, at 15:18 Moscow Time, Soyuz-12 resumed Soviet manned spaceflight. Cosmonauts Vasily Lazarev and Oleg Makarov, who spent two years preparing for work on both ill-fated space stations, DOS-2 and DOS-3, had to content with a two-day test flight.

Still, in addition to trying out their new spacesuits and related safety gear, cosmonauts were able to practice the scientific work that would later become a routine activity on future Soviet space stations. They photographed the Earth in six different bands of spectrum covering infrared and ultraviolet range.

In addition, Soyuz-12 performed maneuvers, which were tracked not only by the Soviet mission controllers, but also by their American counterparts, in preparation for the joint Apollo-Soyuz mission two years later.

Most importantly, the successful landing of Soyuz-12 on Sept. 29, 1973, at 14:33 Moscow Time, some 400 kilometers southwest of Karaganda, finally put the Soviet human spaceflight program back into business.