What have I missed?

Options for gaining Space from the Imperial book include Clan (Loughton) and Education (IIT or Babbage). Oddly, there doesn't seem to be any Primary Careers that offer Space, not even Ship Crew.

I figured I missed something. THe ship crew thing though is really weird.

Yeah, now I remember. The issue with Ship Crew as a career is that Vacuum, Gunnery, and Space are all Advanced Skills (it's why I scrapped that skill division as soon as I had any say), which get awkward if you don't have the associated General Skill, and Vacuum felt most important for the purposes of Ship Crew, because crew doesn't necessarily mean "helmsman". That said, while I understand why I put Gunnery there, I didn't include Ranged Weapons, which is odd. I'll get that put in the errata to put Space instead of Gunnery in the Elective Skills, and instead of Pilot in the Signature skills.

And, as noted by HappyDaze (who I'm sure I've crossed paths with in other game communities over the years), there are several educations - both general ones, and Imperial-specific - that grant Space.