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Soyuz 7K-T No. 61

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Soyuz-14

First expedition on Salyut-4

On Jan. 11, 1975, just three weeks after the launch of the Salyut-4 space station, the USSR orbited its first crew slated to occupy the outpost for nearly a month. During their expedition, members of the Soyuz-17 crew overcame a series of technical challenges to conduct pioneering research in orbit.

Georgy Grechko (left) and Aleksei Gubarev inside the Salyut-4 simulator.

Soyuz-17 mission at a glance:

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Soyuz-17 heads to Salyut-4

The Soyuz 7K-T vehicle No. 38 with Commander Aleksei Gubarev and Flight Engineer Georgy Grechko lifted off from Site 1 in Tyuratam on Jan. 11, 1975, at 00:43 Moscow Time (January 10 GMT and US Eastern Time).

After the launch vehicle successfully released the spacecraft into a 193.9 by 265.6-kilometer initial orbit, the mission was announced as Soyuz-17.

The Soyuz-17 spent around one day in autonomous flight, intercepting Salyut-4 in a 340.6 by 357.7-kilometer orbit. (2) According to Soviet reports, the rendezvous with the station was conducted in a fully automated mode up to a distance of around 100 meters from the station, at which point, the crew switched to manual controls and successfully docked to the station at 04:25 Moscow Time, on Jan. 12, 1975.

The subsequent opening of the hatches between the transport ship and the lab marked the resumption of the civilian space station program in the USSR after 3.5 years of troubles, including the Soyuz-11 disaster in 1971, as well as the loss of the DOS-2 and DOS-3 space labs in 1972 and 1973.

In the following weeks, the official Soviet press provided almost daily reports on the status of the expedition in notable contrast with the coverage of the all-military crew who had been working aboard Salyut-3 six months earlier.

In one of the first house-keeping chores aboard Salyut-4, the crew adjusted the internal temperature in the habitable compartments from a chilly 17C degrees to a more comfortable 20C degrees. The cosmonauts also activated various secondary systems and removed transport attachment from equipment and payloads. (152)

Oazis-1M experiment

On the second day of the flight, Grechko activated one of the most "perishable" experiments aboard Salyut-4 called Oazis-1M, but informally known as "kosmichesky ogorod" (space vegetable garden) containing pea seeds in nutrition-rich soil planted on an area of around 0.2 square meter. (622) According to a post-Soviet publication, likely based on recollections of cosmonauts made years after the mission, the Oazis experiment ran into trouble due to excessive humidity. It turned out that the capillary channels embedded in the soil by the experiment developers had driven water through the system much more intensively under microgravity conditions. After a long process of trial and error, the cosmonauts were reportedly able to tune up the Oazis unit for a correct amount of water supply. (231)

A more specialized source on the subject indicated that the problem with excessive watering had been known since the original Oazis-1 experiment aboard Salyut-1 in 1971, and it was actually attributed to the lack of gravitational drainage in weightlessness. In fact, the larger Oazis-1M greenhouse aboard Salyut-4 was apparently equipped with a newly designed automated pressure controller in its roots module, addressing the issue by employing a combination of hydrophobic and hydrophilic membranes, which the Soyuz-17 crew tested in flight. (622)

By the end of the expedition, out of 36 seeds inside the Oazis-1M unit, only three produced viable plants. The experiment showed that only those seeds whose roots were oriented into the soil and the tops pointed directly toward the source of light would germinate and grow. (231)

Working with the OST telescope

Official reports also indicated that as early as Jan. 15, 1975, the cosmonauts used the Stroka teleprinter aboard Salyut-4 to receive long-term instructions from mission control, thus greatly reducing the need for interruptive voice radio communications. (50)

Also according to the Soviet sources (152), the activation and testing of the OST solar telescope took place on January 16. (50) The first such instrument was disabled aboard Salyut-1 by a stuck external cover, while two others never had a chance to operate due to the failures of their host space stations.

As it transpired later, the initial attempts to activate the fourth copy of the OST aboard Salyut-4 also ran into a nearly fatal obstacle due to a problem with its guidance system. The investigation showed that a strong glare within the guidance system was causing a "fake sun" effect which was confusing sun sensors and was preventing them from homing in on the "real" Sun.

Ground simulations of possible glare sources conducted on the prototype of the telescope paved the way to a potential solution. The movable mirror of the telescope had to be placed into a middle position, matching the main axis of the instrument's optical system which would then be possible to point toward the center of the solar disk by using the station's attitude control system. However, in order for the cosmonauts to establish the mirror's middle position, they were offered to listen to the humming of its motor during its movement from one extreme position to another, then to measure the time it took for the entire motion and, finally, dividing it in half to find the required time to move it to the middle point!

The repeated attempts by the crew to hear the small motor behind the pressurized hull of the station were all fruitless, until Grechko came up with the idea to use a stethoscope from the medical kit aboard the station. He applied it to the wall of the instrument compartment, where he thought the telescope was located and, indeed, was able to hear and measure the time for the mirror to make a full swing. On Jan. 26, 1975, or 14 days into the Soyuz-17 expedition, the fourth OST telescope performed its first observations of the Sun. (231)

On January 17, or the 328th orbit of the Salyut-4 mission, the cosmonauts were reported activating the Filin X-ray telescope. In the early observation sessions, it imaged the constellations Hercules, Scorpion, Perseus and Taurus. (152) During the second week, the instrument was also used to observe the Crab Nebula formed by the remnants of a supernova which exploded in 1054. (50)

Another X-ray telescope aboard Salyut-4 — RT-4 — used its own high-precision guidance system to look at pre-programmed X-ray targets.

Medical and biological research

A considerable portion of the Soyuz-17 mission was also dedicated to space medicine. According to Soviet sources, the crew had multi-functional clinical equipment for cardiovascular measurements, as well as the Chibis vacuum suits for generating negative pressure on the lower part of the body. The crew also performed some experiments in the field of genetics, embryology, physiology and biology, which involved insects, micro-organisms, algae, frog eggs, tissue and plants.

At the end of the first week on the station, the Soyuz-17 cosmonauts were reported taking turns on an onboard stationary bicycle and on a treadmill, while wearing multiple sensors for recording their vital signs.

The second week in orbit started for the Soyuz-17 crew with a comprehensive electrocardiography test. They also took blood samples for subsequent analysis on the ground.

In the field of geophysics, the Soyuz-17 crew measured the temperature of the upper atmosphere and characterized the neutral gas and plasma with dedicated instruments aboard Slayut-4. (152)

On Jan. 19, 1975, Soviet sources also revealed that Salyut-4 had been operating ion sensors within its attitude control system, improving efficiency and response time during orientation of the lab in space. (50) The crew was also reported "practicing new means and methods for the autonomous navigation of the station using advanced optical instruments." (152)

On the 14th day of the mission, the cosmonauts took a break from experiments to catalog various data from the already completed research, to conduct inspection of the equipment and, finally, take some rest. However, the physical exercise routines had to be conducted as usual to keep the cosmonauts healthy in a long-duration flight.

Re-coating telescope mirror

On Feb. 2, 1975, the Soyuz-17 crew conducted the most advanced technological operation of their expedition. Using a special remote-control console in the pressurized compartment of the station, Grechko sprayed a fresh aluminum coating material on the receiving and focusing mirrors of the OST telescope, located in the unpressurized instrument compartment. The experiment demonstrated the possibility of re-coating dust contaminated and radiation-damaged mirrors in the vacuum of space. (50)

According to the crew, after the coating procedure, OST produced sharper images and even revealed details that had not been visible before. (231)

End of the expedition

The Soyuz-17 crew started active preparations for the return to Earth on Feb. 7, 1975, with powering down some of the systems aboard Salyut-4 and transferring the results of their experiments aboard the transport spacecraft.

Soyuz-17 undocked from Salyut-4 on Feb. 9, 1975, at 09:08 Moscow Time and, after slightly less than five hours in autonomous flight, the Descent Module with the crew successfully landed on the same day at 14:03:22 Moscow Time, 110 kilometers northeast of Tselinograd, in Kazakhstan.

The crew spent 29 days in space, which was the longest Soviet space mission at the time and the world's third longest, after the last two expeditions to NASA's Skylab in 1973 and 1974. (50)

Next page: Salyut-5 space station

The article by Anatoly Zak; Last update: January 12, 2025

Page editor: Alain Chabot; January 11, 2025

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Soyuz-17 crew inside the Salyut-4 simulator. Click to enlarge.

The Soyuz-17 crew boarding their spacecraft on Jan. 11, 1975.

A museum display of a Chibis vacuum suit, reportedly used aboard Salyut-4. Click to enlarge. Copyright © 2001 Anatoly Zak

The Soyuz-17 crew possibly photographed after landing in the steppes of Kazakhstan on Feb. 9, 1975.