Either planned or not. Two (or more) people fighting physically (punches, kicks, or other physical attacks at close distance) with at least one serious blow landed (equivalent to a punch in boxing or more). Guns, knives, swords, projectiles, water, electricity, robots, psychic, exotic don't count. Only trad earth style fighting (adjusted for possible lack of gravity). Primitive weapons count if melee (eg clubs made of even modern things from the ship). Primitive projectiles don't count (eg thrown bolts).

Fighting aliens counts if at least one human involved and aliens are intelligent. Fighting earth or alien animals doesn't.

Either space or another planet (not on earth)

Planes flying above earth don't count unless in zero g

Rockets do count as long as they've launched (not sitting on the surface of Earth) whether or not they have gravity. Space stations count.