BFI:
In the wording it gives the save against "any hits inflicted
by the enemy". This should be extended by "or celetial phenomena" or fixed by ending the sentence with "incflicted". (Are torpedoes from a friendly ship attacking me "the enemy" when I fly into the salvo ?

)
I´m sure nearly everybody already played it this way, but it is not covered by the wording of the rules at the moment.
Does a Space Hulk have a low Orbit ?
I don´t think so, it has a gravity well but no atmosphere. Anything with a low Orbit can not fire it´s surface weapons on other ships in the gaming table, unless it is a low orbit table, so Space Hulks can´t have a low orbit.
I heard there are some scenarios out there in which a Space Hulk has a low Orbit, but I never came across one myself, so I doubt any official ones exist.