Being a real space buff, and watching most launches, I missed the action on this one.
Glad they made it safely home.
Speculation time. The Russian rocket uses 4 liquid boosters on the side of the first stage. I am not sure of the exact time these are jettisoned,
but it is around 2:30 into flight. At just about that exact moment the camera is showing inside the craft, looking at the astronaut/cosmonaut. You
can see them jerk wildly, about 6 times before the camera cuts back to external view.
That is not normal. A single thump as the boosters let go all at the same time is expected. Something went wrong with the booster separation.
Cutting back to the external view, we should have seen what is known as the Korolev Cross. The 4 boosters falling away, and the rocket in the center.
Instead there looks to be more than 4 pieces. Possibly as many as 7 or 8 main ones, hard to tell from the video.
They report the emergency as a "booster failure" about 2:45 into the flight, about 15 seconds after the side booster separation.
To me, and this is all speculation, it seems there was a problem at the side booster separation. Possibly one did not detach fully, and was ripped
apart. Main booster goes down within 15 seconds, meaning that pieces could have struck the center booster engine, causing it to fail.
The jerking/shudder we see inside could be from the main booster in it's death throws. Surging multiple times after being damaged, until it shut down
Edit/Revision: After watching the video numerous times, something caught my eye. When the video cuts back to the outside view after separation of
the side boosters, take a look at the booster on the right. Instead of falling away and tumbling, it looks like it is swinging back and forth wildly.
Like maybe fuel hoses, or straps did not detach it all the way. So it was kind of dragging it along, swinging, possibly banging into the main engine
which caused it's failure.
This would also explain the jerking we see inside. The hard side to side movements of a swinging part below the craft, creating sudden
edit on 11-10-2018 by MrRCflying because: (no reason given)