In reading through the construction rules for building satellites, as well as the provided example, there's no indication that standard satellites require the environmental sealing chassis modification. Mentions of crewed satellites are minimal, and while there's nothing to contraindicate that environmental sealing isn't required, I wanted to confirm that this was, in fact, the case.
Do crewed satellites require the environmental sealing chassis modification, or is this considered part and parcel of being a satellite in general, and that specific chassis modification is for other support vehicle types listed in Tactical Operations and Technical Manual?