Why does the Soyuz cover its main engine?

[Ganesh Ujwal]

As seen in Gravity, and also in this youtube video: , the Soyuz main engine is covered by a metal plate that it mechanically moved out of the way before firing. What is the function of this covering?

 

[DaveC426913]

That's a 20 minute video. I don't suppose you'd care to narrow down the segment in question?

 

[Bandersnatch]

(8:13)

My naive guess would be a micrometeorite cover.

 

[DaveC426913]

(8:13)

My naive guess would be a micrometeorite cover.

That was my thought too. Lots of things you wouldn't want getting into your handbasket-to-home. Bolts, wrenches, vapour, huge temperature gradients.