What function do the two large, chunky red valves on the center of the Soyuz control panel have? They are located in the lower middle of this image, just above the Vizor periscope. I wish to know what each one does, and how and when they are used by the cosmonauts during a flight. The more detail the better :)
The crew ops manual contains a couple procedures involving them - e.g. closing them to determine presence of leaks.