Season 2 answers your “how do they get the fuel to travel everywhere” questions in a neat and tidy package, and in a closer-to-reality way than any FTL drive / impulse power idea. It’s rooted in scientific theory, presuming a few equations get solved and processes get optimized. According to interviews, I think it was a variant of D20 Modern that Ty Franck ran for Daniel Abraham, his wife, and a few friends when they lived in Albuquerque. Based on the experience, Dan then approached Ty with the idea of turning it into a full blown novel series. The two of them together are “James S.A. Corey”. As for where books coincide with seasons:| Book 1 ends in the middle of Season 2 Book 2 ends in the middle of Season 3 Book 3 ends at the end of Season 3 (thinking that they would have to end the series after SyFy cancelled them) Book 4 is Season 4 (the first one Amazon bankrolled) Book 5 elements are previewed in Season 4 and then make up all of Season 5. And as you might expect, later books sprinkle details into earlier seasons to round them out narratively, and a few characters are combined/shifted around to fit the television format. At no point is the show “ahead” of the books actually being written, unlike GoT.