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Soyuz Failure Narrowed Down to Collision Between Booster and Core Stage

posted by martyb on Monday October 15 2018, @02:00AM   

takyon writes:

Soyuz failure probe narrows focus on collision at booster separation

Russian investigators believe a malfunction during separation of the Soyuz rocket's four liquid-fueled first stage boosters two minutes after liftoff from Kazakhstan led to an emergency landing of a two-man crew heading for the International Space Station, officials said Friday.

Speaking to reporters Friday in Moscow, veteran cosmonaut Sergei Krikalev, head of the Russian space agency's human spaceflight program, said the investigation into Thursday's launch failure has narrowed on a collision between part of the Soyuz rocket's first stage and the launcher's second stage.

Russian cosmonaut Alexey Ovchinin and NASA astronaut Nick Hague were carried away from the failing rocket by an emergency escape system, and they safely landed inside their descent module near Dzhezkazgan, Kazakhstan, around 250 miles (400 kilometers) northeast of the Baikonur Cosmodrome, where the launch originated.

The Soyuz first stage is comprised of four boosters, each powered by a four-nozzle kerosene-fueled RD-107A main engine, that burn for 1 minute, 58 seconds, during launch. Once their engine firings are complete, the boosters are supposed to jettison simultaneously at an altitude of roughly 150,000 feet (45 kilometers) to tumble back to Earth. Krikalev said Friday that one of the boosters did not separate from the Soyuz core stage — or second stage — cleanly.

Previously: Soyuz Crew Vehicle Fails Mid-Flight, Astronauts OK

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Original Submission

• No use of escape rocketNo use of escape rocket (Score: 5, Informative) by pTamok on Monday October 15 2018, @09:18AM (1 child)

  by pTamok (3042) on Monday October 15 2018, @09:18AM (#748916)

  AFAIK the Soyuz OGB SAS was not used. The timeline of a normal Soyuz launch is here:

  RussianSpaceWEb.com: How Soyuz rides into orbit [russianspaceweb.com]

  Milestone................................Elapsed time
  Liftoff..................................0.00 (Note, this is liftoff, NOT engine start)
  Emergency escape rocket, SAS, jettison...114.16 seconds
  Stage I separation.......................117.80 seconds
  Payload fairing separation...............157.48 seconds
  Stage II engine cutoff command, GK-2.....285.05 seconds
  Stage II separation......................287.30 seconds
  Separation of Stage III tail section.....297.05 seconds
  Stage III main engine cutoff.............524.96 seconds
  Stage III - spacecraft separation........528.26 seconds

  You see that the escape rocket is jettisoned before Stage I separation, so if there is a problem with Stage I separation, the escape rocket cannot be activated as it has already gone.

  A video of a successful launch of Soyuz TMA-19M is here: Soyuz TMA-19M successful launch [youtube.com]

  The video of the failed launch of Soyuz MS-10 is here: Soyuz MS-10 failed launch [youtube.com]

  If you compare the two, you can see starting at about 2 minutes 50 seconds into the successful video, the jettison of the escape rocket (OGB SAS), followed by the Stage 1 separation, showing the classic Korolev cross formed by the jettisoned boosters. In the launch failure, you can see a Korolev cross [wikipedia.org] is not formed. If you hunt about on the Internet, you can find a video of the Korolev cross being formed from the vantage point of the Soyuz looking backwards.

  This video starts at the jettison of the escape rocket, which you see as the bright object detaching from the Soyuz: https://www.youtube.com/watch?v=KF_9mVUvl3Y [youtube.com] ; followed by the Stage I separation that went wrong.

  The full launch sequence of MS-10 is here, without the cutaways to the interior of the crew capsule or pre-rendered animations: https://www.youtube.com/watch?v=n5bc3dIn0m4 [youtube.com]

  Lift off at 00:20 +/- 1s
  Escape rocket jettison at 02:15 +/- 1s (elapsed from lift off approx 115 secs)
  Attempted Stage I separation at 02:18 +/- 1s (You see the interruption in the exhaust trail begin to form, followed at least two of the boosters falling away as planned, but it then goes pear shaped cloud shaped.)

  The Russian Space Web website goes into detail on the launch failure here: http://www.russianspaceweb.com/soyuz-ms-10.html [russianspaceweb.com]

  According to Deputy Prime Minister Yuri Borisov, quoted by TASS, the emergency escape system was activated at T+123 seconds in flight. As a result, the escape began after the separation of the emergency rockets (at T+114.6 seconds) and the first stage at T+117.80 seconds at an altitude of around 50 kilometers.

  There are more details on the escape system in the article here: http://www.russianspaceweb.com/soyuz_sas.html [russianspaceweb.com] - Note that the table incorrectly states the SAS was used for MS-10. The article does, however, explain:

  To provide an escape during a short period after jettisoning of the emergency escape rocket, but before the separation of the payload fairing, which previously had no immediate escape scenario, two pairs of solid motors were placed on the fairing. In turn, this upgrade allowed to drop the main escape rocket 123 seconds after the launch, instead of previous 160 seconds, thus compensating for added mass of the new escape system.

  Those rockets are the 'RDG' rockets, not so named, but referred to in the Wikipedia article on Soyuz abort modes. [wikipedia.org]

  From the Apollo-Soyuz Test Project onward, the soyuz spacecraft also had a secondary set of four rocket motors at the top of the fairing that can propel the escape head section away from the rocket during the period between the jettisoning of the SAS at T+115s until fairing deployment at T+157s. In contrast to the SAS these rockets only move the escape head section a small distance away from the rocket, as at these altitudes there is enough time for the landing system to deploy.

  Starting Score:	1		point
  Moderation		+4
  Informative=4, Total=4
  Extra 'Informative' Modifier		0
  Total Score:		5

• Re:No use of escape rocket(Score: 1) by pTamok on Tuesday October 16 2018, @08:17AM

  by pTamok (3042) on Tuesday October 16 2018, @08:17AM (#749438)

  Nice presentation by an enthusiast, giving a plausible explanation of what happened. Uses beer bottle as a prop.

  YouTube: Scott Manley:Soyuz MS-10 Failure - Updates & Answers To Your Questions [youtube.com]

  He states the guaranteed lifetime in orbit of the Soyuz is determined by the rate of self-decomposition of the hydrogen peroxide attitude adjustment fuel of the descent module. Others have linked it to how long the tanks/pipes/valves of the various propulsions systems will resist corrosion by their fuels (mainly nitrogen tetroxide and unsymmetrical dimethylhydrazine). Either way, there's a good reason for the use-by date.

  Parent