Update:

I need to clarify that beast modes should be chosen based on where you're going; I'm uncertain if beast modes were a thing prior to the events of the original series, it seemed implied that it was a new and unusual thing, but since y'all are going to an alien ecosystem anyway,  there's a lot more creative choices you can get away with,  and that's just if you don't make something up entirely.

So, you won't immediately have beast modes,  but the one you pick at character creation should be on the alien planet,  not Earth,  otherwise how did you get that in the first place?