OMG, is this where Tribbles and Bones-speak come from? A tribute to Heinlein? Well certainly the Tribbles part; Wikipedia confirms it. And one of the characters keep saying, "Confound it" to the point that my brain fills in with "Jim."
Written as 'juvenile' sci-fi in the early 50s, I am really enjoying the story because it is adventure and not suspense. The story is basic enough but it is so old that it was written before we even figured out how to escape earth's gravity let alone accept JFK's challenge to put a man on the moon. Fascinating how close Heinlein was on some of the details that he made up.