What's the absolute minimum time in which spacecraft docking can be achieved?
This question isn't so much about the time to match orbits as it is about the time it takes to maneuver into the proper orientation and execute the individual docking steps.
For a better example than my original one -- suppose you have a Dragon V2 approaching the ISS when they suddenly realize that their CO2 scrubbers have failed. They need to dock as rapidly as possible; every second counts. The capsule is already on a course which will take it right up into alignment for docking, but it will still have to be oriented, mated, and so forth. If they act as rapidly as they possibly can, how long will it take before they can breathe fresh air again (ignoring the remaining time it takes to close the distance with the ISS)?
Obviously there would be redundancies in place for the failure of the CO2 scrubbers (if the Dragon V2 even has those). This scenario is just for the sake of discussion.