Salyut-4: Finally a breakthrough (original) (raw)

Salyut-4: Finally a breakthrough

On Dec. 26, 1974, the USSR launched its sixth attempt to establish habitable base in orbit, taking into the account four years of very difficult experience in launching and operating such complex vehicles. This time, the space station, publicly announced as Salyut-4, worked well, setting the stage for a very busy year in space.

Previous chapter: Soyuz-16

DOS-4 space station at a glance:

After the loss of the DOS-3 space station in May 1973, the TsKBEM design bureau, at the time still led by Vasily Mishin, immediately switched its attention to DOS-4. Thanks to several upgrades (INSIDER CONTENT), the second pair of DOS stations could support three rather then two expeditions.

As of the Fall 1972, the crews were expected to be delivered to DOS-4 on Soyuz 7K-T transport vehicles with production numbers 39, 40 and 41. (774) However, later in 1973, after the loss of DOS-3 and the use of Vehicle No. 37 for the Soyuz-12 mission, crew ships with production numbers 38, 39 and 40 were assigned to DOS-4.

Crew training for the DOS-4 project officially started on Dec. 10, 1973, with four pairs of cosmonauts remaining in the Salyut program after the transfer of Aleksei Leonov and Valery Kubasov to the Apollo-Soyuz project and the switch of Vasily Lazarev and Oleg Makarov to the Soyuz-12 test flight in September 1973. At the time, the active crews included:

• Aleksei Gubarev and Georgy Grechko;
• Vasily Lazarev and Oleg Makarov;
• Petr Klimuk and Vitaly Sevastyanov;
• Vladimir Kovalenok and Yuri Ponomarev.

In the Spring of 1974, medical specialists found some issues with Gubarev's health and he was sent to hospital for evalution while the Salyut crews were re-arranged by "moving" the commanders forward by one crew for the exception of Lazarev who already made a flight with Oleg Makarov aboard Soyuz-12. In the meantime, Anatoly Berezovoi was added to the fourth pair after his transfer from the Almaz project:

• Petr Klimuk and Georgy Grechko;
• Vasily Lazarev and Oleg Makarov;
• Valery Kovalenok and Vitaly Sevastyanov;
• Anatoly Berezovoi and Yuri Ponomarev.

However, by the Summer of 1974, Gubarev completed around two months of medical evaluation and returned to training for the rest of 1974, so all four crews were restored to their original composition. (231)

Like DOS-3, the fourth station was equipped with a series of experiments and payloads for civilian scientific research, primarily in the fields of astrophysics, space medicine and biology (50):

According to Russian sources, Salyut-4 also carried the ITS-K instrument for infra-red observations of the stars, the Moon and the Earth's surface and the Ryabina payload for capturing neutron and gamma particle flows. The Spektr payload was used for the characterization of the neutral gas and plasma flowing around the station, while the set of KSS-2 solar spectrometers was intended for recording the distribution of minute gas components in the upper atmosphere of the Earth. Also, the spectrometer Silya-4 was used for determining isotope and chemical composition of the light cores of in cosmic rays and for searching of deitons. (2)

Building DOS-4

The first order of business for the TsKBEM design bureau after the loss of DOS-3 was to learn the lessons from the latest failure, which stemmed heavily from flight control errors. On July 12, 1973, just two months after the DOS-3 fiasco, Mishin came to a meeting with his boss Dmitry Ustinov, who supervised the industry for the Kremlin, with a list of upgrades aimed at improving the reliability of the DOS-4 station in the wake of the accident. At the time, DOS-4 was in production at the Moscow Khrunichev plant, ZIKh, in accordance with the DOS-3 blueprints, but with some previously introduced changes in onboard payloads.

At the same meeting with Ustinov, who initially wanted to launch DOS-4 even before the end of 1973, Mikhail Ryzhikh, the Director at ZIKh, noted that the planned completion of DOS-4 by Oct. 30, 1973, would have to be postponed due to the latest changes in the design. (774)

By the end of Summer 1973, Yuri Semenov, then head of the Salyut project at TsKBEM, complained to Mishin that work on DOS-4 at ZIKh was still on the back burner, prompting Mishin to appeal to Minister of General Machine-building Sergei Afanasiev to approve some bonuses to better motivate the personnel at the plant.

After all the problems, the DOS-3 replacement was ultimately completed at the ZIKh plant in the first half of January 1974 and it was set for transfer to TsKBEM's Checkout and Testing Facility, KIS, in Podlipki near Moscow, on Jan. 25, 1974, for a series of final integrated tests before its shipment to the launch site.

On March 14, 1974, the meeting of the Chief Designers Council reviewed the status of the DOS-4 integrated tests, apparently clearing the lab for delivery to the Tyuratam launch site before the end of the month. On April 2, 1974, Ustinov toured the spacecraft processing building, MIK KO, in Tyuratam, where DOS-4 was undergoing preparations, along with the Soyuz 7K-T crew ships No. 62 and 38, as well as the payload section for the L3 lunar expeditionary vehicle No. 8L. (INSIDER CONTENT)

As of November 1973, Mishin penciled the DOS-4 launch for as early as April 1974, to be followed by the liftoff of the station's top-secret military cousin — Almaz OPS-2 in June 1974, but the schedule conflict between the two programs first experienced in 1973 repeated itself.

Despite appeals by Mishin to Afanasiev, to the Head of the State Commission Kerim Kerimov and to other officials between February and April 1974, the Almaz program was given a priority.

Perhaps not coincidently, on Jan. 5, 1974, Mishin recorded in his agenda a nearly five-hour meeting with Ustinov who was seeking ideas for the militarization of the Salyut and Soyuz projects in order to incentivize the Ministry of Defense to support the ongoing piloted space flight effort at TsKBEM. Mishin apparently offered to quickly develop and install any military instruments aboard DOS-4 as well as to coordinate its mission with research in the field of anti-missile and anti-aircraft defense! (774)

On April 27, 1974, Mishin made a one-day trip to Tyuratam for a meeting of the State Commission on the DOS-4 project, where the station was declared to be in the 20-day readiness for launch, however it had to wait for Almaz, which was ultimately launched on June 27, 1974, under the cover name Salyut-3. (774, 231) Accordingly, the DOS-4 launch campaign then drifted all the way to the end of 1974, likely delayed by Mishin's ouster in May and the subsequent reorganization of the TsKBEM design bureau into NPO Energia under the new leadership of Valentin Glushko.

Salyut-4 lifts off

Between September and December 1974, several public updates on the status of the still-orbiting Salyut-3 disclosed that the station would no longer be inhabited. One such release was issued on Dec. 25, 1974, re-confirming that Salyut-3 would end its mission after an "extended period of research." (50) Not coincidently, just 24 hours later, came the announcement about the launch of Salyut-4.

The three-stage UR-500K rocket carrying the DOS-4 space station lifted off from the "Right" pad at Site 81 in Tyuratam on Dec. 26, 1974, at 07:15 Moscow Time. (400) After the station had successfully reached a 219 by 270-kilometer orbit with an inclination 51.6 degrees toward the Equator and its systems been successfully activated, the launch was publicly disclosed around four hours after the fact.

As usual, a very generic public report described the mission as testing the station design and its onboard systems as well as scientific and technical research.

The next public update on the status of Salyut-4 would not come until Jan. 6, 1975. This time, the official report disclosed that after a series of orbital maneuvers, the new station had reached a 343 by 355-kilometer orbit. According to Western observations, a total of three orbit corrections had been performed on Dec. 27, 29 and 30, 1974. (50) They were done so quickly to compensate for the lower parking orbit selected (INSIDER CONTENT) for the second pair of the DOS space stations.

On Jan. 14, 1975, commenting on the newly launched expedition to Salyut-4 aboard Soyuz-17 spacecraft, a former cosmonaut Konstantin Feoktistov, who worked as a leading engineer in the Soviet piloted program, disclosed that the 350-kilometer orbit promised to halve the propellant consumption required for maintaining the altitude when compared to the previous Salyuts operating in lower orbits. (50)

Given the bad luck that had beleaguered the DOS program in the recent past, the seemingly near-flawless operation of DOS-4 no doubt provided a huge relief to the engineering and management team at NPO Energia after long months of anxiety.

The subsequent crew operations aboard Salyut-4 showed that after five years of mixed success and a total of three lost orbital labs, the Soviet space station effort was finally approaching maturity. Salyut-4 hosted two expeditions lasting 29 and 63 days, with the second one becoming the longest Soviet space mission to date and likely approaching maximum duration which could be achieved with a station of that class without an in-flight re-supply.

Although one of three planned expeditions to Salyut-4 had not materialized due to a launch vehicle failure, the station itself functioned for two years and one month, boosting the confidence of the industry in the possibility of extending missions for the 20-ton spacecraft, which coincided with the realization that heavier one-module stations would not be feasible in the near future after the cancellation of the N1 rocket in May 1974.

Soviet launches within the Salyut-4 project:

Next chapter: Soyuz-17 mission

The article by Anatoly Zak; Last update:July 28, 2025

Page editor: Alain Chabot; Last edit: December 26, 2024

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A full-scale simulator of the second generation DOS-7K space station at the Gagarin cosmonaut training center. Click to enlarge.

Cutaway view of the working compartment aboard the second generation Salyut space station. Copyright © 2001 Anatoly Zak

To negate the influence of weightlessness after long-duration flights, the Salyut crew members were wearing Chibis suits at the end of their missions. The Chibis suits created low-pressure in the lower parts of the body, driving more blood toward legs as caused by gravity on Earth. Copyright © 2001 Anatoly Zak