I recall hard realtime as being defined by an answer being worthless if it is late. If you are rocketing through the air, you can fire your rockets a few msec late, and as long as you compensate later nothing will break.

Parts of the spacecraft will have hard realtime requirements, but those parts can be modular and controlled by soft-realtime systems

Manufacturing (I believe) (i.e moving production line)

Regular avionics, and stuff in cars