Posted on March 25, 2020
It was decided that henceforth, cosmonauts would wear pressure suits for launch and the return to Earth. Also, a system was installed to automatically pump air into the descent module in the event of decompression. Additionally, the ventilation valves were modified so a premature opening would cause them to re-close automatically. Of course these changes meant the spacecraft could only accommodate two cosmonauts.
Simplified Depiction of Ventilation Valve 2Ventilation Valve 1 with Manual Shutter OpenUpdated Soyuz 7K-T for 2 CosmonautsExcerpt from Apollo 8 Press KitApollo 15 Suit Wearing ScheduleExcerpt from Apollo 15 Flight Journal
P3-Revised2CosSoyuz-1
P6-A15FlightJour
P5-A15SuitSchd
P4-A8PressKit
P2-Valve1SimplifiedDepiction
P1-Valve-2
P3-Revised2CosSoyuz
P2-Valve-2
P1-Valve1SimplifiedDepiction
