Orbital Focus - International Spaceflight Facts and Figures
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The DOS Space Stations

Tyneside, UK
2024 Jun 15
Saturday, Day 167

Curated by:

Salyut 1

Salyut 4

Salyut 6

Salyut 7

The next Salyut gets a new name
First Expedition to Salyut 6 - Sep 1977 to Mar 1978

The first occupation of Salyut 6 spans two sets of missions. The launch of Soyuz 25 within a couple of weeks of Salyut 6 going into space was probably intended to be an occupation of the station lasting about two months. Cosmonauts Kovalyonok and Ryumin may have received a visit from a second crew and would have hosted the first Progress re-supply craft. As it was, their docking failed and led to a significant rescheduling of events.

Salyut6The real Expedition 1 did not start until the Soyuz 26 crew got aboard but the chronology below includes events from the Soyuz 25 mission.

Mission planners took a risk by orbiting Soyuz 26 during December - the next launch opportunity when orbital safety constraints permitted a mission to take place. The crew then stayed in space over the winter, something normally avoided because of the extreme weather around Baikonur and in the landing zone. Until this mission, the Soviet Union's piloted space programme had generally been limited to an 'open' season between about April and October each year.

By having the Soyuz 27 crew return to Earth in Soyuz 26 (which had been docked at Salyut's aft port because of the Soyuz 25 failure), Salyut 6 was finally configured as required for the first visit by a Progress spacecraft. Mission planners had also demonstrated the ability to exchange Soyuz spacecraft part-way through a mission. This was going to be a necessity over the next few years as mission durations were to increase and eventually become longer than the safe lifetime for a Soyuz vehicle in space.

Business then took off in earnest and Salyut 6 was ready to receive a steady stream of visitors over the next few years.

One "first", in 1978, was the orbiting aboard Soyuz 28 of Vladimir Remek of Czechoslovakia - the first non-Soviet and non-American citizen to go into space.

Another 'first' was the refuelling of Salyut 6 by Progress 1, the first in a long line of space freighters. They started by supporting the Soviet Union's later Salyut stations and Mir. They are now a major element of supporting the ISS. They saw the project over a particularly difficult period while the US Shuttle was out of action following the destruction of 'Columbia'.

The In-Flight Refuelling of Salyut 6 by Progress 1

The following was written by Novosti Correspondent G Lomanov.

Successful in-flight refuelling of Salyut-6 by the automatic freight carrier Progress-1 is regarded by Soviet space engineers as a significant step towards the long-term maintenance of orbiting space laboratories.

Salyut-6 carries its fuel and oxidiser separately in six tanks fitted with metal bellows which force the fuel to the engines under pressure of nitrogen stored in pressure bottles at about 200 atmospheres.

At the time refuelling was due to take place, the pressure in the tanks themselves was about 20 atmospheres. The simple solution of providing the refuelling tanks of Progress-1 with even higher pressures to overcome the back pressure of Salyut's tanks would have involved an unacceptable weight penalty in the freight carrier.

Equally it was not possible to generate assisting gravity forces by accelerating the Salyut-Soyuz-Progress complex in an appropriate direction without upsetting the flight plan. The most rational solution available was to reduce the pressure in Salyut's tanks by pumping back nitrogen into supply bottles before refuelling started.

In the event, a powerful compressor on Salyut-6, run from the batteries which are recharged from the solar cell array, reduced the nitrogen pressure in the tanks to three atmospheres.

This pressure was low enough for the Progress-1 pressure vessels to overcome, so refuelling then took place.

It was a slow process owing to the heavy drain on the batteries but it ensured that no gas bubbles could be created in the fuel supply.

All the fuel involved had been cleared of dissolved gases by flushing with helium before loading.

Date Time (UTC) Event
1977 Oct 9 02:40 Soyuz 25 launched from the Baikonur Cosmodrome by Soyuz rocket into 194 x 241 kilometre orbit with Vladimir Kovalyonok and Valery Ryumin aboard
1977 Oct 10 04:09 Soyuz 25 starts its final approach to the forward port of Salyut 6 - docking should have occurred about ten minutes later but the attempt is unsuccessful - although the two craft come into contact, it proves not possible to latch them together - orbit of Salyut 6 is 341 x 348 kilometres
1977 Oct 10 After the docking attempt, Soyuz 25 moves away from Salyut 6 - orbit is 329 x 352 kilometres
1977 Oct 11 03:25 Soyuz 25 lands 195 kilometres north-west of Tselinograd
1977 Dec 10 01:18 Soyuz 26 launched from the Baikonur Cosmodrome by Soyuz rocket into 195 x 235 kilometre orbit with Yuri Romanenko and Georgi Grechko aboard
1977 Dec 11 03:02 Soyuz 26 docks at the aft port of Salyut 6 - orbit is 337 x 354 kilometres
1977 Dec 19 21:36 Romanenko and Grechko start space walk to inspect the forward docking unit - Grechko uses specially-built tools to check the alignment of various parts of the structure but finds no problems - there is no visible evidence of the contact with Soyuz 25 - he also attaches material samples to the outside of Salyut 7 for collection by later crews
1977 Dec 19 23:04 Romanenko and Grechko complete space walk after 88 minutes
1978 Jan 10 12:26 Soyuz 27 launched from the Baikonur Cosmodrome by Soyuz rocket into 190 x 237 kilometre orbit with Vladimir Dzhanibekov and Oleg Makarov aboard
1978 Jan 11 14:05 Soyuz 27 docks at the forward port of Salyut 6 - orbit is 330 x 351 kilometres - for the first time ever, three spacecraft are docked together in orbit
1978 Jan 16 08:05 Soyuz 26 undocks with Dzhanibekov and Makarov aboard - the aft port is now free for use by Progress 1 re-supply mission
1978 Jan 16 11:24 Soyuz 26 lands - 310 kilometres west of Tselinograd
1978 Jan 20 08:24 Progress 1 launched from the Baikonur Cosmodrome by Soyuz rocket into 179 x 249 kilometre orbit
1978 Jan 22 10:12 Progress 1 docks at the aft port of Salyut 6 - orbit is 328 x 349 kilometres
1978 Feb 3 09:00 Approximate time of completion of the first ever propellant transfer from one spacecraft to another - part of Progress 1 cargo was pumped into Salyut 6 fuel tanks
1978 Feb 6 05:53 Progress 1 undocks, is allowed to drift away from Salyut 6 to a distance of 10-15 kilometres, and then approaches the station again in a test of its back-up rendezvous control system
1978 Feb 8 02:39 Progress 1 fires its manoeuvring engine to initiate re-entry
1978 Feb 8 03:25 Approx time - Progress 1 enters the Earth atmosphere above the southern Pacific Ocean and is destroyed by frictional heating
1978 Mar 2 15:28 Soyuz 28 launched from the Baikonur Cosmodrome by Soyuz rocket into 192 x 246 kilometre orbit with Alexei Gubarev and Vladimir Remek (Czechoslovakia) aboard - the first international space crew to go into orbit
1978 Mar 3 17:09 Soyuz 28 docks at the aft port of Salyut 6 - orbit is 335 x 353 kilometres
1978 Mar 10 10:23 Soyuz 28 undocks with Gubarev and Remek aboard
1978 Mar 10 13:44 Soyuz 28 lands - 328 kilometres west of Tselinograd
1978 Mar 16 07:58 Soyuz 27 undocks with Romanenko and Grechko aboard
1978 Mar 16 11:18 Soyuz 27 lands - 265 kilometres west of Tselinograd
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