The moon is a satellite

Passage:

Because of its proximity, Earth's only natural satellite -- the Moon -- became the first celestial body to be visited by humans (in 1969).

Represented so far:

Because of its proximity, Earth's natural satellite -- the Moon (a celestial body) -- was visited by a human first.

Instructions for downloading

The addition of this node led me to think about the relationship of the node at the end of the rel arc and the node at the end of the object arc in a possessor-rel-object case frame. Is it the case that that the object will always be a member of the class that is pointed to by the rel arc (or a subclass of the superclass pointed to by the rel arc)? Might there be some background knowledge about this?