Updates on yesterday’s Soyuz failure


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The Russian investigation into yesterday’s Soyuz launch failure has tentatively identified a malfunctioning valve as a possible source of the failure.

“The state commission has tentatively established a malfunction of the fuel dump valve of the rocket’s oxidizer tank:exhaust gas coming from the valve pushes a side section away from the center section. The valve appeared to be defective and failed to function,” the source said.

The valve passed the preflight check, he said. “It was opened before the launch, and closed afterwards consistent with the procedure,” the source said.

Once the rocket is fueled, the valve dumps redundant oxygen. “It is closed several minutes before the launch. It is supposed to open after the side section separates from the central section, but that did not happen,” the source said.

The “side section” refers to the Soyuz’s strap-on boosters. The “central section” refers to its core stage. From this report it appears the failure of the valve has been linked to a collision between the stages at separation.

“There are no final versions but the primary cause is understandable and is related to the collision of a side element making part of the first stage. A collision occurred during the separation of the first and second stages,” the Roscosmos official said.

“A deviation from the standard trajectory occurred and apparently the lower part of the second stage disintegrated. The rocket stopped its normal flight and after that the automatic system did its work,” Krikalyov said.

An element of the booster’s first stage collided with the second stage, Krikalyov said. “This could have been caused by the failure of the system of the normal separation, which should have been activated. We will analyze the causes in detail,” the Roscosmos official said.

This is obviously only a preliminary result, and should be treated with caution. Meanwhile, the investigation has also launched a criminal investigation. This doesn’t surprise me, as the Russians will sometimes consider some things, such as incompetence, as falling under criminal statutes. Considering the discovery of a drilled hole on a launched Soyuz capsule only a few weeks ago, however, I think they are probably even more paranoid than normal.

Update: Russia has decided they will launch a unmanned Soyuz mission before resuming manned flights.

This is definitely going to impact ISS operations, and cancels a December manned Soyuz launch.

The Soyuz capsules attached to ISS have a 200 day lifespan in space. Thus, the crews on board cannot stay past those dates, which means if launches get delayed for a significant period the station might end up without a crew. NASA has said ISS can be operated in this manner, but I also know they want to avoid this if at all possible.

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3 comments

  • Kirk

    Here’s a good video of a 2014 Soyuz launch from Kourou with side-by-side views from an on board camera and one on the ground. The video is worth watching from the start, but the link takes you to 2:10, a few seconds before strap-on booster separation. https://www.youtube.com/watch?v=vHWDNrrfhnI&t=130

  • Michael

    “The valve passed the preflight check, he said. “It was opened before the launch, and closed afterwards consistent with the procedure,” the source said.”

    Every time I cycled a Shuttle valve as part of a pre-flight test I always wondered if that was the last valid operation of said valve.

  • Jim

    Don’t be surprised if you see them suggest using the unmanned Soyuz capsule as the lifeboat. Bring the current (old) capsule back down after the unmanned test flight gets up there to take its place.
    NASA is playing up the capabilities of the ISS to go on unmanned. I don’t believe them. Maybe a month or two. They are doing a lot of maintenance on that thing daily. Without bodies up there and working, I don’t see it lasting very long.
    Does anyone know when the next reboosting is scheduled? I haven’t heard about that in a while.

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