Primary Life Support System
（重定向自Portable Life Support System）
![A Portable Life Support System from the Apollo A7L suit, with its outer cover removed](/Images/godic/202502/03/A7L_plss2748.jpg")
![The interior of the Apollo PLSS.](/Images/godic/202502/03/Apollo_portable_life_support_system2748.jpg")
![Diagram of the A7L PLSS and OPS, with interfaces to the astronaut and the Lunar Module cabin](/Images/godic/202502/03/Plss1002748.jpg")
A Primary (or Portable or Personal) Life Support System (or /Subsystem) (PLSS), is a device connected to an astronaut or cosmonaut's spacesuit, which allows extra-vehicular activity with maximum freedom, independent of a spacecraft's life support system. The PLSS is generally worn like a backpack. The functions performed by the PLSS include: