[4] Heinlein had already had success as a writer of short fiction for the sci-fi pulp magazines; the juveniles established him as a novelist for major publishers.
[11] Jack Williamson wrote: "The books, taken together, tell an epic story of the expansion of mankind across the planets of our own Sun and the stars beyond.
The last, Have Space Suit—Will Travel, ends with the triumphant return of its young hero from the Lesser Magellanic Cloud... Nobody has written a more convincing and inspiring future human epic.
"[10] Another reviewer explains: There’s a distinct story arc that follows the books; in Rocket Ship Galileo, a friendly scientist puts together a spaceship in his backyard and takes the neighbor’s kids to the moon ... As the stories move on, often in the same "Future History" universe, and never clearly out of it, we see humanity spread out into the solar system (Space Cadet, Farmer in the Sky, Red Planet, Between Planets) and eventually the stars (Time for the Stars, Starman Jones, Tunnel in the Sky) and space-faring humanity goes through its own voyage to adulthood, from explorer to colony to free nation, and finally to come into contact/conflict with galactic civilization (Have Spacesuit Will Travel) to have our maturity as a species challenged.
"[12] Jack Williamson wrote: "[An] inspiring theme of space conquest unifies the dozen Scribner's titles.
"[10] A literature review in 1985 called the juvenile books "classics in their field" that "have stood the test of time," continuing "even more than a quarter of a century after they were written, these novels are still 'contemporary,' and are still among the best science fiction in the YA range.
"[13] A Wall Street Journal reviewer said in 2014 that Heinlein "lavished so much skill and imagination on these books that today they are regarded as defining elements of old-school sci-fi.
Heinlein told his agent that he wrote it "omitting all cleavage and bed games, such that Miss Dalgliesh can offer it in the same list in which she has my other books.
I feel that I was treated in a very shabby fashion, and I regard him as in part responsible and do not wish to place any more stories with his firm.
So I offer a thirteenth book...and it is turned down with a brisk little note which might as well have been a printed rejection slip, for it was just as cold and just as informative.
The story, a first-person tale featuring Maureen "Puddin'", appeared under the byline "R. A. Heinlein" in Calling All Girls magazine.
Heinlein wrote, "I grew so fond of Maureen [from the Puddin' stories] that I helped her to get rid of that excess weight, changed her name to 'Podkayne', and moved her to Mars (along with her unbearable kid brother).
The Mars of Red Planet seems to be the Mars of Stranger in a Strange Land; Jack Williamson wrote, "The Martians in this story have a special interest, because they are the educators of Valentine Michael Smith [and] they display the same appalling powers that Smith brings back to Earth.
Neither does the Arachnid War from Starship Troopers, nor the appearance of the advanced civilization in the Lesser Magellanic Cloud from Have Space Suit—Will Travel.