Union MS-11: Accident, which was not?
The landing of Soyuz MS-11 on June 25 was complemented with intrigue — first, the media reported about the accident, then Roskosmos officially stated that the landing took place regularly, and some information agencies reached as far as the words “Roskosmos” concealed the incident with "" . Based on open sources, try to figure out what happened.
"Union" slows down for descending from orbit, a screenshot of the Orbiter simulator
The full process of landing the ship, fortunately, recorded and posted on YouTube.
On June 25, the Union MS-11 undocked from the ISS at 02:25 Moscow time ( 4:10:34 on video).
At 04:55 the next important stage began - the ship began braking ( 06:40:12 ). The maneuver was successfully completed after four minutes and 39 seconds, the speed of the ship, as planned, decreased by 127.98 meters per second. And after three minutes ( 6:48:06 ), the alarm was sounded:
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Separation of compartments passed regularly at 05:22, as planned. The ship made a successful landing in the estimated area at the expected time (05:48 MSK).
And after landing Roskosmos published an official message:
What is K1B? This is the first engine collector mooring and targeting large thrust. On the previous version of the ship, Soyuz TMA-M, for controlling the position of the ship in space and maneuvering when approaching / docking there were 16 large thrust DPO-B and 12 small thrusters (DPO-M). At the Soyuz-MS, which is now flying, they implemented a fully duplicated system of two sets of 14 large thrust engines with one manifold (switchgear) per set.
"Soyuz TMA-M", red closed DPO-B, visible DPO-M
Soyuz-MS, all engines are the same
Accordingly, in case of failure of the main collector, the ship switches to the backup and continues to fly.
Let's try to answer the most obvious questions.
Was there an accident at all?
Judging by the NASA-TV broadcast, there was a signal about the accident, because the cosmonauts reported about it. The Roscosmos informational message acknowledges that a reserve collector was prepared, but not sufficiently informative to unequivocally say what exactly happened. For example, a signal could turn out to be false or disappear after some time. Negotiations in the broadcast blocked NASA-TV speakers, and what happened next is unknown.
How dangerous was that?
The scenario “the brake engine of the spacecraft failed, and it cannot return to Earth” is deadly, so engineers laid down emergency systems in this case at the dawn of cosmonautics. The Soviet Vostoki launched into an orbit from which they would descend within a reasonable time even in the event of a complete failure of the brake propulsion system, the American Mercury carried three solid-fuel brake motors that were reliable due to simplicity, and their total impulse was chosen with a large reserve - the ship would return even in case of failure of two engines out of three. Specifically, in the case of Soyuz-MS, the ship nominally brakes the SKD main engine (pictured below at the center, closed with a lid), and in case of its failure, there are still two sets of DPO-B engines.
In addition, the Union Soyuz MS-11 has already managed to perform a brake maneuver on the SKD main engine. The mooring and orientation engines would in any case be dropped together with the aggregate compartment in twenty minutes, and after separation of the compartments, the descent vehicle was controlled by its own orientation engines. Another confirmation that the flight program did not break down - the ship sat in the regular area at the expected time. In case of problems, the automation of the descent vehicle goes into ballistic descent mode, and the ship lands with a large undershoot, in the reserve landing area. So the general conclusion - there was no danger for the astronauts.
Have there been similar incidents in the history of astronautics?
In 2015, the docking of the Soyuz TMA-19M spacecraft with the ISS was obtained only from the third attempt and in manual mode, because one of the DPO engines did not betray full traction. On the "Union of MS" a similar accident would have no effect on the docking, because the automation would be switched to the backup manifold engine.
On September 6, 1988, a rather unpleasant situation arose on the Soyuz TM-5. The uncertain operation of the orientation sensor was perceived by the on-board computer as a failure, and braking at the estimated time was blocked. Orientation was restored after 7 minutes, and I had to turn off the manually started computer engines in order not to sit down in China. After two turns, the on-board computer began to execute the erroneously loaded docking program, and it was necessary not only to turn off the engine manually, but also urgently to block the activated automatic separation, so as not to remain in orbit without engines and oxygen supply. The astronauts had to wait a day without a toilet (the household compartment was planned to be dropped in advance), but the landing the next day, September 7, passed without problems.
On April 10, 1979, problems arose with the main engine of the Soyuz-33. The astronauts successfully returned to the backup. This modification of the ship still had two main engines and a separate DPO circuit on another fuel. The unified fuel system for SKD and DPO appeared in 1986 on the Unions of TM.
In general, it should be noted that a huge number of space flights, which remained in history as “full-time”, in reality, faced with various problems, too small to get on the pages of encyclopedias. This is normal - space technology is complex and can never be 100% reliable.
And, finally, stories like the one that happened on June 25 are being told, however paradoxical it may seem, about the reliability of the Soyuz and the fact that they were well designed.
PS At the end of May, Hiktre turned the hubs of the former Giktays into non-core ones. Together with the changes in the rules that resolved the repost, in my opinion, it looks like a direct recommendation “try to write to specialized publications, and then you can repost here.” I am grateful to Habra for a good and pleasant platform, and accept the fact that time passes and everything changes. By a happy coincidence, along with this news representatives of several resources came out to me, so I didn’t even have to throw a cry in social networks, “Does anyone need a space columnist?” ordered to live long, and now the materials will be released without any timetable.
"Union" slows down for descending from orbit, a screenshot of the Orbiter simulator
Chronology
The full process of landing the ship, fortunately, recorded and posted on YouTube.
On June 25, the Union MS-11 undocked from the ISS at 02:25 Moscow time ( 4:10:34 on video).
At 04:55 the next important stage began - the ship began braking ( 06:40:12 ). The maneuver was successfully completed after four minutes and 39 seconds, the speed of the ship, as planned, decreased by 127.98 meters per second. And after three minutes ( 6:48:06 ), the alarm was sounded:
Passed the generalized accident K1B, 05:02:54.MCC specified "switched to the second collector?". And then, alas, the negotiations were blocked by a translator and commentator NASA-TV, and it is impossible to disassemble them.
')
Separation of compartments passed regularly at 05:22, as planned. The ship made a successful landing in the estimated area at the expected time (05:48 MSK).
And after landing Roskosmos published an official message:
According to the results of the analysis of telemetric information during the landing of the crew of the transport manned vehicle, all the onboard systems and units of the Soyuz MS-11 (including the combined propulsion system) worked in normal mode, in strict accordance with the flight program. No comments.
After full completion of the landing tasks, the reserve collector (in the pneumatic-hydraulic circuit of the KDU) was prepared for use (in case of possible occurrence of necessity).
Thus, the messages distributed by some media about the occurrence of certain “abnormal situations” during landing are unreliable.
Materiel
What is K1B? This is the first engine collector mooring and targeting large thrust. On the previous version of the ship, Soyuz TMA-M, for controlling the position of the ship in space and maneuvering when approaching / docking there were 16 large thrust DPO-B and 12 small thrusters (DPO-M). At the Soyuz-MS, which is now flying, they implemented a fully duplicated system of two sets of 14 large thrust engines with one manifold (switchgear) per set.
"Soyuz TMA-M", red closed DPO-B, visible DPO-M
Soyuz-MS, all engines are the same
Accordingly, in case of failure of the main collector, the ship switches to the backup and continues to fly.
Questions and answers
Let's try to answer the most obvious questions.
Was there an accident at all?
Judging by the NASA-TV broadcast, there was a signal about the accident, because the cosmonauts reported about it. The Roscosmos informational message acknowledges that a reserve collector was prepared, but not sufficiently informative to unequivocally say what exactly happened. For example, a signal could turn out to be false or disappear after some time. Negotiations in the broadcast blocked NASA-TV speakers, and what happened next is unknown.
How dangerous was that?
The scenario “the brake engine of the spacecraft failed, and it cannot return to Earth” is deadly, so engineers laid down emergency systems in this case at the dawn of cosmonautics. The Soviet Vostoki launched into an orbit from which they would descend within a reasonable time even in the event of a complete failure of the brake propulsion system, the American Mercury carried three solid-fuel brake motors that were reliable due to simplicity, and their total impulse was chosen with a large reserve - the ship would return even in case of failure of two engines out of three. Specifically, in the case of Soyuz-MS, the ship nominally brakes the SKD main engine (pictured below at the center, closed with a lid), and in case of its failure, there are still two sets of DPO-B engines.
In addition, the Union Soyuz MS-11 has already managed to perform a brake maneuver on the SKD main engine. The mooring and orientation engines would in any case be dropped together with the aggregate compartment in twenty minutes, and after separation of the compartments, the descent vehicle was controlled by its own orientation engines. Another confirmation that the flight program did not break down - the ship sat in the regular area at the expected time. In case of problems, the automation of the descent vehicle goes into ballistic descent mode, and the ship lands with a large undershoot, in the reserve landing area. So the general conclusion - there was no danger for the astronauts.
Have there been similar incidents in the history of astronautics?
In 2015, the docking of the Soyuz TMA-19M spacecraft with the ISS was obtained only from the third attempt and in manual mode, because one of the DPO engines did not betray full traction. On the "Union of MS" a similar accident would have no effect on the docking, because the automation would be switched to the backup manifold engine.
On September 6, 1988, a rather unpleasant situation arose on the Soyuz TM-5. The uncertain operation of the orientation sensor was perceived by the on-board computer as a failure, and braking at the estimated time was blocked. Orientation was restored after 7 minutes, and I had to turn off the manually started computer engines in order not to sit down in China. After two turns, the on-board computer began to execute the erroneously loaded docking program, and it was necessary not only to turn off the engine manually, but also urgently to block the activated automatic separation, so as not to remain in orbit without engines and oxygen supply. The astronauts had to wait a day without a toilet (the household compartment was planned to be dropped in advance), but the landing the next day, September 7, passed without problems.
On April 10, 1979, problems arose with the main engine of the Soyuz-33. The astronauts successfully returned to the backup. This modification of the ship still had two main engines and a separate DPO circuit on another fuel. The unified fuel system for SKD and DPO appeared in 1986 on the Unions of TM.
Conclusion
In general, it should be noted that a huge number of space flights, which remained in history as “full-time”, in reality, faced with various problems, too small to get on the pages of encyclopedias. This is normal - space technology is complex and can never be 100% reliable.
And, finally, stories like the one that happened on June 25 are being told, however paradoxical it may seem, about the reliability of the Soyuz and the fact that they were well designed.
PS At the end of May, Hiktre turned the hubs of the former Giktays into non-core ones. Together with the changes in the rules that resolved the repost, in my opinion, it looks like a direct recommendation “try to write to specialized publications, and then you can repost here.” I am grateful to Habra for a good and pleasant platform, and accept the fact that time passes and everything changes. By a happy coincidence, along with this news representatives of several resources came out to me, so I didn’t even have to throw a cry in social networks, “Does anyone need a space columnist?” ordered to live long, and now the materials will be released without any timetable.
Source: https://habr.com/ru/post/457658/
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