There are a number of influences and traditions to parse in this novel. Obviously, it’s Golden Age, 1950s hard science fiction, which means rocket ships, other planets, aliens, et cetera. The technical details are explored with relish. Modern literacy research suggests young males are more likely to be reluctant readers than girls, and one solution is to let them read what they want, which is often technical non-fiction about vehicles or space rather than fictional stories about people and emotions. Heinlein apparently already had that figured out 60+ years ago.
Green Man Review will be publishing my coverage of the recent batch of Heinlein novels I requested from Baen, and will be making it an ongoing series. First read my introductory post, then my first review, quoted above, of The Rolling Stones.