Spaceports are buildings that facilitate the loading and unloading of ships on asteroid surface. Shuttles and Heavy Transports must utilize a Spaceport in order to land on an asteroid. Many ships can be stored in a single Spaceport, potentially belonging to many different crews, if the Spaceport owner allows access.
They call it ‘landing’, but really it’s more of a matter of lashing down the ships so they don’t just kinda drift off. I’ve seen more than one dockworker accidentally launch a cargo container into space just by lifting it too roughly. Microgravity’s a hell of a thing.