I is called a "Stall"
capsules.
It's called a Compartment.
Stable isotopes of elements are called stable because they do not radioactively decay.
cab
It depends of the compartment of course, some are more important than others, but a general compartment I believe might be termed a 'berth.'
it is called a stable
The home of a horse is called a barn or a stable, and they sleep in a stall which is in the barn or stable.
In some areas they are still called Stable boys or Lads even if they're women. In other areas they're called Stable hands or just a groom.
farm hand, stable boy, ranch hand
The Caboose
The compartment under a hot air balloon is called the gondola or basket. It is where passengers and the pilot stand during the flight.
The stable isotope produced by radioactive decay is called a daughter isotope.