"Traveling in space in our game, I want to say it's like flight in the '40s, like it's dangerous," said Howard. "It's still dangerous to go and explore, even though lots of people do it."
That's pretty much the end of the Starfield details, though the comparison to early flight is somewhat interesting. There were a lot of crashes in the '40s (partially because of that one war).
Howard also said he visited Musk's SpaceX headquarters as part of an effort to bring "authenticity" to Starfield, and mentioned that Helium-3—a speculative fuel for nuclear fusion—could be the isotope used to fuel Starfield's ships, or at least is something to be debated.
Starfield shouldn't be confused for a rocket engineering sim, though. "We have to gamify it some," said Howard, "so that it's not as punishing as actual space travel."
My impression is that, while it's an RPG and not a sim, Starfield's setting and fiction will lean toward 'hard sci-fi'—speculative, but grounded in present-day theory. As for when we'll see more, Howard repeated that we'll need to be patient.