The flight of Soyuz-4 and Soyuz-5



Soyuz-4 and Soyuz-5 finally carried out the original mission foreseen for the first Soyuz mission in 1967, i.e. docking between two manned spacecraft and transfer of crew members between the craft. In early 1969 this mission was almost obsolete and had little connection with the major Soviet manned spaceflight project at the time, the N1-L3 manned lunar mission.

However, the Soyuz-4/5 mission was a technical milestone important for the future development of manned space stations. The date of this mission was not known ahead of time and there were no pre-launch rumors in Moscow during the days leading up to the launch. But after the flight of Soyuz 3 the "chief designer" (now known to be V.P Mishin) told reporters that the next mission would involve the docking of two Soyuz craft and that "we are already prepared for a new launch" (2).

The launch of the first craft was initially planned for January 13, but a problem in the launch vehicle delayed the lift-off by one day (6).

Launch of Soyuz-4 on 14 January 1969

Soyuz-4 (spacecraft #12) was launched from launch complex 31 at Baikonur on Tuesday, 14 January 1969 at 0730 UT (11) with cosmonaut Vladimir Shatalov on board. The call-sign for Soyuz-4 was "Amur". On the fifth revolution at 1335 UT the spacecraft, as per standard practice, raised its orbit from 173-225 km to 207-237 km, both orbits at 51.7 degrees inclination. About an hour and a half later, at 1516 UT, the spacecraft left the zone of radio visibility from the Soviet Union and at 1700 UT Shatalov retired to rest in the orbital compartment. During the last pass over the Soviet Union first signals acquired by Kettering station on 20.008 MHz at 1511:48-1519 UT. TASS had announced the transmission frequency 20.008 MHz (3).

Launch of Soyuz-5 on 15 January 1969

When the mission started everyone expected that it would be a rendezvous and docking between two manned Soyuz craft. Therefore, the launch of Soyuz-5 (spacecraft #13) the following day was fully expected. The launch took place as expected at 0704.57 UT (11) on 15 January 1969 from launch complex 1 (the "Gagarin Pad") with Boris Volynov, Alexei Yeliseyev and Yevgeny Khrunov onboard. The orbit achieved was 200-230 Km. The call-sign for Soyuz-5 was "Baikal". The launch was announced by Western media at about 0830 UT. TASS had announced the transmission frequency 15.008 MHz (4).

At injection into orbit the two craft were about 1200 km away from each other and according to Soviet sources two-way contact was established between the two craft (1). The orbit of Soyuz-5 was adjusted at 1430 UT to reach 211-253 km. Soyuz-5 was the passive ship and Soyuz-4 was the active chaser craft.

Rendezvous and docking on 16 January 1969

A first-orbit rendezvous and docking as rehearsed during the Kosmos-212/213 flight had originally been planned but replaced by a leisurely one-day rendezvous phase (6). The approach of Soyuz-4 to Soyuz-5 is shown below using the element sets on rev 7 for Soyuz-5 and those on rev 14 for Soyuz-4 (see separate listing). At 0506 UT, about three hours before docking, the orbit of Soyuz-4 was adjusted in preparation for the final approach. The Igla approach control system was switched on at 0737 UT over the South Pacific.

The figure below shows the range-rate between the two craft (negative range-rate means that the two craft are approaching). Near closest approach the range-rate fell to values well within the capability of Igla to handle.

The craft approached to within 40 meters as they crossed the African coast at 0805 UT. The docking occurred at 0820 UT while passing over Soviet territory within view of Yevpatoria in the Crimea (see map below). When the two docked craft passed over South America on the next orbit at about 0925 UT Yevgeny Khrunov peformed an EVA to transfer from Soyuz-5 to Soyuz-4. Alexei Yeliseyev repeated this maneuver when the docked vehicles passed over the Soviet Union about half an hour later. During this period signals on 20.008 MHz were received at Kettering (see figure below).

Undocking occurred again over the radio horizon of Yevpatoria at 1255 UT.

Radio tracking of the mission by the Kettering Group

As soon as the mission got under way, the Kettering Group swung into action. The announced frequency for Soyuz-4 was 20.008 MHz confirming that the traditional Soyuz frequencies would be used. Therefore the main emphasis in listening was put on 20.008 MHz and 15.008 MHz which was the announced frequency for Soyuz-5. It seems that this is indeed how the radio frequencies were used, but when Soyuz-4 had landed Soyuz-5 was heard on both frequencies. In addition, the CW-PDM frame length seemed to have been different for the two craft. Soyuz-4 had a frame length of about 17.3 seconds, while that of Soyuz-5 was 18.3 seconds.

World-wide coverage

In the graph below I have summarized all observations by the Kettering Group. I have not made distinction between the two craft, but in general signals on 20.008 Mhz before the landing of Soyuz-4 cane from that craft and signals on 15.008 MHz probably came from Soyuz-5. Of course, after the landing of Soyuz-4, all signals came from Soyuz-5. The graph reflects a combination of transmission patterns from the two spacecraft, the day/night conditions at the the tracking sites, the daily schedules of the trackers and short-wave propagation conditions. In any case, the early morning hours UT seem to be rather "empty" of signaling. On the other hand, during January 15 and 16 the Kettering Group heard the two craft for 9-10 hours each day.

As for myself, I had just started to work full time for the Institute of Meteorology at the University of Stockholm after having finished my M.Eng degree. Therefore, I had to rely on my time switch to record signals while at work. This also limited me to covering just one frequency, because I had to leave the radio (an Eddystone EC-10) switched on and tuned to a precise frequency when I left home. On 14 january I learned of the launch when I picked up the afternoon papers at 1630 UT and saw a little flash item about the launch of Soyuz-4. The next day, when Soyuz-5 was launched I returned home for an hour around lunch to listen to the recorded tape (which was empty) and pick up signals on 20.008 MHz in real time. This became my routine for the two following days - using the time switch and going home for lunch to pick up signals in real time.

Biomedical subcommutation

On January 15, 1969, the first day of the flight of Soyuz-5 carrying a three-man crew, word 8 in the 15.008 MHz signal from Soyuz-5 was observed in Kettering to vary in length, producing at time three short pulses in the middle of the frame. Upon later investigation it was found that it had one of three values, short, medium or long. The graph below shows this effect in a recording from Soyuz-4 made on the 16 January 1969 that I have recently located in my old reel-to-reel tape spools.

Not until the flight of Soyuz-6,-7-,8 was the significance of this was understood. Soyuz-8, with a two-man crew exhibited only two word lengths, medium and long. Then it was fully understood that the number of levels that word 8 could assume represented the number of crew members on board. At the time of the recording below where word 8 assumes three different lengths, there were indeed three crew members on board Soyuz-4. It seems that word 8 indicates which cosmonaut is being sampled by other telemetry channels. Indeed, word 4 was found to show variations consistent with such a scheme (8). Indeed, in the figure below it is easy to see variations of word 4 between frames.

Here is Geoff Perry's account of how he discovered the "biomedical subcommutation" in the signal from Soyuz-8 (9):



"... 15 October 1969: ... Periodic variation of eighth word found to be 2.0 min; the same as on previous day, so decided that this was not due to tumbling after all. John Marshall [another teacher at Kettering Grammar School] had suggested whilst we still thought it to be tumbling that the length would provide an attitude read-out. Devoted the two-period lesson in afternoon with 4P to evolving theory that this was evidence of sub-commutation - the alternate sampling of two cosmonauts at one minute intervals. This suggested that at a certain time the sequence of three medium length and four long pulses should change to four medium followed by three long. This prediction was confirmed during the transit from 1402 to 1420 Z and again on the following transit. Felt great excitement at this discovery. ... ..16 October 1969.... I mentally determined to go back to the Soyuz 4 and 5 tape recordings to see if I could locate evidence for a three-cosmonaut crew. .... .. 27 October 1969 .. Spent morning (and part of yesterday afternoon) making pen records from Soyuz 4 and 5 tapes. It is possible to see three cosmonauts in Soyuz 5 as the eighth word shows the following sequence of short, medium an long pulses: SSS MMM LLL SSS MMMM LLL SSSS etc. Moreover you can see this pattern appear in Soyuz 4 after they have performed the EVA crew transfer ..."





The entire telemetry sequence is available here (warning! the file size is 0.6 MB) for listening. The reader can try identifying the subcommutation by simply listening to the recording.

Voice on shortwaves

During the flights of the Vostoks and Voskhods short waves was very much used for voice communications, so the Kettering group was much disappointed at the lack of voice on shortwaves during the flight of Soyuz-4 and Soyuz-5. We now know that the main voice link was on 121.75 MHz and short waves was a back-up voice link.

However, a short voice transmission was picked up from Soyuz-5 in 17 January 1969 at 1231 UT on 20.008 MHz when Boris Volynov could be heard calling "Zarya ya Baikal". Additional voice was picked up at Kettering briefly at 1505.50 UT and also at 1532-1537 UT. I had my receiver and tape recorder running under time switch control at the time, but the BFO (beat-frequency oscillator) was on preventing clear reception of the voice. Interestingly, the voice receptions coincided with passes over the horizon at Kettering.

Little did we know that short waves was used to broadcast messages to the crew giving times for VHF communications sessions. This subject is covered in a separate article.



Telemetry during the final orbit of Soyuz-5

Myself and Christopher Wood at Fiji heard signals on 20.008 MHz from Soyuz-5 the morning it landed. We both heard the command-off of the 20.008 MHz signal at 0732.41 UT. I have not been able to locate the tape recording of this event, but I have kept a servo-pen recording of the last two and a half telemetry frames before the command-off. These are reproduced below. "r" denotes the synchronization signal. Word 7 was long here even though this was thought to be an indication of the docked state as observed during the docked flight of Soyuz-4 and -5.

The mission ends - dramatically for Soyuz-5

The retro-fire for Soyuz-4 occured at 0611 UT on Friday 17 January 1969. Soyuz-4 landed at 0650.47 UT at a spot about 40 km NW of Karaganda, where the temperature was -35oC (1). Sports commissar Ivan Borisenko received the cosmonauts and peasants from the "Bersznyaki" collective farm rushed to the scene (5).

The end of the Soyuz-5 flight was not so routine. The original plan was to land at about 0630 UT and for Volynov to orient the ship manually for retro-fire. He even rehearsed this on the pre-landing orbit and reported that he had completed the task in the 9 minutes available. Despite this Volynov was directed to try the manual orientation. The spacecraft left eclipse at 0539 UT and the planned retro-fire was at 0548.49 UT. At about 0556 UT Volynov reported (to the ship off Africa?) that he had not had enough time to complete the maneuver. However, stored commands to carry out an automatic orientation on the next orbit had already been uplinked. The automatic sequence for orientation and retro-fire worked as planned. (12).

After the end of retro-fire the instrument module did not separate despite the fact the explosive bolts fired. Boris Volynov could see the antennas on the solar panels and realized that the instrument module was till attached. he reported this through some coded radio channel to mission control (7). This could have been on short waves soon after the end of retro-fire because the spacecraft was still out of VHF range from the Soviet Union at that time. The report could have been sent later, through VHF, when approaching Soviet ground stations, but while still not in the reentry blackout phase. It is interesting to note that signals on short waves ceased abruptly at 0732.41 UT. Myself and Christopher Wood at Fiji heard the command-off. This is normally assumed to be the time of separation of the instrument module, and in all probability it was the time when the separation pyros fired. Probably the electrical connections but not the mechanical connection between the re-entry vehicle and the instrument module were severed.

This was a life-threatening situation. Eventually, propellant tanks in the instrument module exploded due to the re-entry heat and the two modules separated. The re-entry vehicle which had taken the reentry aerodynamic and heat loads in the area of its top hatch swung around to the normal re-entry attitude and made a purely ballistic reentry. Upon landing the parachute had problems to deploy properly, but the craft landed, and the landing shock was such that Volynov was thrown across the cabin and broke some of his front teeth. A detailed account of this near-disaster can be found at James Oberg's web site. According Encyclopedia Astronautica a failure of the soft-landing rockets caused the landing to be much harder than usual (10).

The map below shows the final orbits of Soyuz-5, receptions by myself in Stockholm and Chris Wood at Fiji in addition to the planned and actual landing spot. Interestingly, TASS announced the intended landing spot and not the actual one, which was 600 km short of the planned one (7). The drama of the landing was not known at the time, it was revealed much later, in the 1990's.

References and notes