An air lock in a space craft is a door used to move between the sealed environment of a space craft to the vacuum of space (or other craft) with minimal impact to the sealed environment.

I always think of airlocks on space craft, like cabin doors in the Alaskan bush, never physically locked. If you have managed to get to the door alive, and you want in, come on in.

Are any airlocks actually locked (circa 2016)?

  • 2
    $\begingroup$ "Locked", or just "not trivially openable from the outside"? Big difference. Especially because before you can even think about opening them in space, you need to rendezvous with the craft. $\endgroup$ – user Mar 19 '16 at 16:03
  • $\begingroup$ IIRC, for the first docking of a Soyuz and an Apollo casule during the Cold War, neither the Soviets or the U.S. were willing to share the specs of their docking ports, so an intermediate docking bell was developed. $\endgroup$ – Joe L. Mar 19 '16 at 18:26
  • 1
    $\begingroup$ That comment dpesn't make much sense because the "bell" still had to interface with both systems...and somebody had to build it. $\endgroup$ – Organic Marble Mar 19 '16 at 21:39
  • 1
    $\begingroup$ @Joe L. The docking bell was necessary because the Soyuz and Apollo used very different atmospheres and they needed an airlock between them. The airlock was equipped with the APAS docking system at the 'Soviet' end. APAS was developed jointly for this mission. The Soviets replaced the standard Soyuz docking mechanism with APAS for this mission. $\endgroup$ – Hobbes Mar 20 '16 at 12:51
  • $\begingroup$ See this question: space.stackexchange.com/questions/14524/… $\endgroup$ – Hobbes Mar 20 '16 at 12:57