Have you ever heard of the Commander’s Lock?
Have you ever heard of the Commander’s Lock?

arstechnica.com
What happens when an astronaut in orbit says he’s not coming back?

An interesting story about a rarely discussed feature of the Space Shuttle, that lives on in the commercial crew capsules, to prevent travelers from killing everyone onboard.
After a Space Shuttle astronaut threatened to not come back unless he had more time to work on his experiment, NASA put a padlock on the airlock door and only the mission commander had the key.