Well,
In principle, since the Lords and Spirits of Orhan can get to Kulthea, and get back, there must be some sort of route. Since the Charon Gods do not travel to Kulthea with the same ease, there is potentially a difference between the Essaence bridge between Orhan and Kulthea and Charon and Kulthea. If there is some route, it could be taken - in principle.
In practice, I don't think so. There's a little GM note on p.24 of my old Master Atlas (I think it's first edition) saying that: " Access to Orhan by PCs should not be possible under any but the most bizzare circumstances - the moon should be considered a place of great power and mystery..."
I think this counts for nearly all NPCs, too.
Orhan is certainly protected by Essaence manipulation that is capable of controlling who gets on it and who doesn't. And the Gods (in my opinion) won't have the slightest sympathy for some member of an organization whose main goal is obscene profits (and not for his passengers either).
Remember that the Lords were capable of shrouding their moon against the Altha, who were a lot more powerful than any current civilization - and they were the creators of the compasses. Since it can be assumed that the Gods now pretty well how the compasses work, they can divert them with ease.
Charon is a different matter - since the Dark Gods aren't organized, and some might even be happy to get a navigator in their hands (he he). But since the Dark Gods have so much problems getting to Kulthea, I think the main problem for a Navigator would be to find a way to get there at all. And then, Charon is not a very nice environment: Even with a compass, its not easy to get through the coating, and underneath, you have to navigate through all these caverns.
Than, there's the question how the navigator wants to do it practically ?
There are in my opinion only two (perhaps three) spells capable of achieving this goal: "Flow Rider" and
"Jump Mastery". "Jumping" is IMO not a possibility since the caster cannot really "see" his destination.
"Flow Rider" is theoretically possible, but there is nothing said in its description about life preservation in outer space...
"Jump Mastery" says the caster must have a vague idea where to go. Now that depends a bit on how you define vague idea, but I would count "somewhere on Orhan".
So for Orhan it's a definitive no, for Charon, any Navigator within his right mind would say: "It's not advisable to go there now" (perhaps with a cocked eyebrow pointing to the absurdity of the question).
As to the other moons, I don't even know if they support life.
Hope that helped.
