In a book that travels from Earth to Mars and back, it's not surprising that Heinlein writes in third-person omniscient. This point of view means that Heinlein will not keep his story limited to the views of one character (what we call third-person limited; see The Strange Case of Dr. Jekyll and Mr. Hyde for an example of that)—instead, the story is told by an outside narrator who knows everything. (Like Shmoop.)
Heinlein has access to many different characters' perspectives. Occasionally, he'll switch perspectives between multiple characters in the same chapter. Other times, he pulls back to give us a cosmic view of what's happening in the universe—in which case we get the information from the perspective of a nondescript narrator.
Why all this jumping around? We can find out with a little investigative work. Try this: focus your attention on the specific events taking place in one particular chapter and consider why Heinlein chose the character(s) he did to be the perspective character.
For example, we see the World Federation conference from Jubal's perspective. Why? Well, even though it is Mike's butt on the line, he's still innocent in the ways of human politics. Jubal, on the other hand, is well-versed in law and government, so he can give the reader information that Mike just couldn't. Got the hang of it?
Each chapter will have the perspective character it does for a specific reason. Take a few seconds out after reading each chapter and consider why. Yes, the ever-elusive why. But really, you might see the chapter—and the book—in a whole new light.