Series of five science-fiction short stories by Creator/JohnWCampbell, published in ''Thrilling Wonder Stories'' between 1936 and 1938, and collected in book form in 1966 as ''The Planeteers''.

Ted Penton and Rod Blake have fled Earth in their nuclear-powered spaceship, the ''Ion'', after a mishap involving their illegal research on [[ILoveNuclearPower atomic power]] (it involved destroying 300 square miles of Europe in an atomic explosion). Since nobody else on Earth is willing to use atomic power, nobody can catch up with them; and so while their lawyers try to sort things out on Earth, Penton and Blake bide their time exploring the Solar System and having adventures.

We first meet up with our heroes on Mars, where they encounter centaurs and parasitic [[{{shapeshifting}} shapeshifters]]. Penton learns telepathy from the centaurs, which will prove useful in future dealings with intelligent aliens. After Mars, the pair proceed towards the outer system, where they start a revolution, fight {{blob monster}}s, learn alien languages, encounter high gravity and extreme cold, solve problems with the power of chemistry, etc.

The stories are:
* "The Brain Stealers of Mars"
* "The Double Minds"
* "The Immortality Seekers"
* "The Tenth World"
* "The Brain Pirates"

The Penton and Blake stories are remembered today for their influence on Creator/IsaacAsimov's more famous stories about the robot field-testers [[Literature/IRobot Powell and Donovan]].

Not to be confused with [[WesternAnimation/CaptainPlanetAndThePlaneteers those other planeteers]].

!! This work provides examples of:
* AlienLunch: The alien food ''stragath'' creeps Blake out because it tends to move around while you're trying to eat it.
* AllPlanetsAreEarthlike: Venus, Mars, Ganymede, Callisto, and the Tenth World's satellite Pornan all have breathable air.
* AlmostOutOfOxygen: In "The Tenth World", Penton and Blake visit a planet that is too cold to have gaseous oxygen. They're trapped away from their spaceship by alien monsters, and find that they're using up oxygen faster than expected because of the planet's high gravity.
* AsYouKnow: Penton and Blake often spend the first few paragraphs of a story recapping what has happened to them so far.
* BizarreAlienBiology
* BlobMonster: The ''grethlanth'' and the ''shleath'' in "The Double Minds". (A ''shleath'' is like a ''grethlanth'', only fifty feet in diameter.)
* DrivesLikeCrazy: In "The Brain Pirates", Terruns and all the residents of the tenth world's satellite come off as crazy drivers to the Terrestrial heroes. It's mentioned that their vehicles only go about twenty miles an hour, but thanks to the high gravity there's a lot of traction, and stopping can be very abrupt.
* ExpressiveHair: In "The Brain Stealers of Mars", Rod Blake's hair "[rises] very slightly from his head" when he finds out about the thushol's tendency to KillAndReplace the other Martians.
* FutureSlang
* GetAHoldOfYourselfMan: In "The Brain Stealers of Mars", Rod Blake starts laughing hysterically after encountering an alien disguised as Ted Penton. The real Ted Penton cracks him across the face to snap him out of it.
* {{Heavyworlder}}: Penton and Blake, when they visit worlds with sub-Earth gravity.
* IntoxicationEnsues: Twice in "The Tenth World". It's mentioned that when Penton and Blake were on Venus, they got drugged out of their minds after mistaking sodium bromide for sodium chloride. Later, Blake gets drunk on excess oxygen when his spacesuit malfunctions, and his resulting irrational behavior ends up saving the day.
* ISayWhatISay: A variant in "The Brain Stealers of Mars": Penton and Blake encounter shapeshifting aliens who impersonate them, and they have to spot the imposters; because the aliens can read minds, they can flawlessly imitate what Penton or Blake would say. It's not long before all twelve Pentons start speaking and acting in unison. Blake, on the other hand, is more uncertain, and the Blakes argue with and contradict one another despite all having access to the same mind.
* ItWasHereISwear
* ManEatingPlant: A man-eating Venusian plant is mentioned as having almost killed one of the heroes in "The Brain Stealers of Mars".
* MistakenForAnImposter: In "The Brain Stealers of Mars", Blake encounters a {{shapeshifting}} alien plant-thing that disguises itself--poorly--as Penton. He shoots it and it turns into a bat and flies away. He's still in the grip of hysteria when another Penton-thing shows up, and Blake shoots at it too. Of course, this one is real.
* NoBiochemicalBarriers: Usually played straight; Penton and Blake are able to eat Callistan jelly fruit and ''stragath'' (although the latter creeps Blake out because it tends to move around while you're trying to eat it). Averted in "The Brain Pirates", though, when Penton and Blake become stranded on the outer-system satellite Pornan and fear starvation because all the food there is full of heavy metals.
* OhMyGods: The characters do use "My God", but Penton also swears by multiple gods. Including, on one occasion, "By the Nine Gods of the Nine Worlds, and the multiple deities of space!"
* {{Omniglot}}: Penton, thanks to Martian telepathic techniques.
* OrganicTechnology: "The Double Minds" is set on Ganymede, where electricity was never discovered. Light bulbs are powered by fluorescent bacteria and cars have muscles instead of motors. Unlike most examples of Organic Technology, the story clearly states that Ganymedian gadgets are a poor substitute for electric-powered technology. A bit of an UnbuiltTrope, considered that it was written in 1937.
* PepperSneeze: In "The Brain Stealers of Mars", Rod Blake sneezes when exposed to pepper. This clues Ted Penton into the fact that he is the real Rod Blake, since he figures that the shapeshifting aliens couldn't have spontaneously imitated such a complicated reflex as sneezing.
* PerceptionFilter
* {{Shapeshifting}}
* SpeakInUnison: In "The Brain Stealers of Mars", Ted Penton and Rod Blake encounter {{shapeshifting}} aliens who impersonate them, and they have to {{spot the imposter}}s. Because the aliens can read minds, they can flawlessly imitate what Penton or Blake would say, and it's not long before all twelve Pentons start speaking and acting in unison. (Blake, on the other hand, is more uncertain, and the Blakes argue with and contradict one another despite all having access to the same mind.)
* SpeaksInShoutOuts: In "The Immortality Seekers", Penton and Blake encounter a Callistan [[AllAnimalsAreDogs dog-like creature]] who speaks telepathically by repeating things she's heard people say or think--a living phonograph machine, they call her. She has an editorial ability, though, and only repeats thoughts that are appropriate to a given topic or situation.
* SpotTheImposter: In "The Brain Stealers of Mars", the ''thushol'' are Martian shapeshifting parasites who impersonate the heroes. They're also mind-readers, so that a duplicate has all the knowledge of the original, and the heroes can't find out who is the real one by questioning each other.
* TelepathicSpacemen: Penton and Blake encounter several species of telepathic aliens. Also, at the beginning of the series, the Martians teach Penton their telepathic techniques so that ''he'' becomes a telepathic spaceman, and he uses the skill to instantly learn languages on other planets.
* TwoOfYourEarthMinutes: Weirdly averted in "The Brain Pirates".
* UniversalDriversLicense
* VocalDissonance: Near the beginning of "The Brain Stealers of Mars", Rod Blake meets something on the surface of Mars that looks like Ted Penton--but it's new to imitating humans, and when it first speaks, it speaks in Rod Blake's voice.