From that point on, the trip is still plagued with difficulties: the Thompsons accidentally turn off the nuclear motor, leading to microgravity hijinks; Haddock gets drunk on some smuggled whiskey, goes on an impromptu space walk and starts orbiting around an asteroid, forcing Tintin to rescue him and the Thompsons are still suffering occasional relapses of the bizarre condition caused by their ingestion of Formula Fourteen. Despite all this, the rocket successfully lands on the Hipparchus Crater and Tintin becomes the first man to walk on the moon.
They quickly proceed to unpack their scientific payload and explore Earth's natural satellite. Unfortunately the trip has to be cut short not only because of the oxygen issue but due to a far graver development: the spy subplot of the previous book comes to a head when Colonel Jorgen is revealed to have stowed away on the rocket with a gun, and Wolff is revealed as his accomplice and the foreign power's mole in the center. Wolff, who was informed that Jorgen was simply there to observe the expedition is horrified when he finds out Jorgen's plan is to steal the rocket for his employers and maroon everyone else on the Moon. Wolff is forced to launch the rocket at gunpoint but Tintin manages to sabotage it and foil the plot. After interrogating the two, they are locked in the hold but Tintin's move had a grave price: the rocket will have to be repaired while the oxygen supply quickly dwindles.
After leaving the Moon in haste and an incorrect trajectory which causes them to waste even more time and oxygen, Jorgen manages to break free and regain his gun, intending to kill the rest of the crew. He and Wolff struggle causing Jorgen to shoot himself in the heart, killing him instantly. Eventually, Wolff decides to sacrifice himself by leaving the rocket without the others' knowledge so that they have enough oxygen to make it to Earth, leaving a note asking for forgiveness.
The rocket lands on autopilot in Syldavia, with the entire crew unconscious from lack of oxygen. Despite a brief scare with Haddock, everyone has survived. Calculus makes a grand speech claiming that man will return to the moon prompting an enraged Haddock to vow never to enter a rocket again, claiming that "Man's proper place...is in dear old Earth!"
- Alcohol-Induced Idiocy: Under the influence of whiskey, Haddock attempts to go back to Earth by going on an unassisted spacewalk, without metal boots also. Fortunately, Tintin rescues him back into the rocket, before (as Calculus described it) asteroid Adonis gets a new satellite named Haddock.
- Almost Out of Oxygen: The biggest problem during the book, beginning with the discovery that the Thompsons accidentally found themselves on board during liftoff... and even that doesn't cover the extent of the stowaways on board. It's solved in part by the decision to stay on the Moon for a shorter time, and partly by the Heroic Sacrifice of The Mole.
- Artificial Gravity: Which of course gets accidentally switched off just when the Captain breaks out his hidden bottle of whisky, allowing for some early sight gags before the book's tone turns sour.
- Artistic License Military: Discovering there were two accidental stowaways (which is by itself a jarring circumstance) would have been enough to abort a real life space mission and force them to return to Earth. In this particular case, with their fictitious spaceship being a nuclear-powered SSTO, the decision would have been even more reasonable given that the logistic expenses of a brief return and a second takeoff would have been minimal, if any. But that, of course, would have removed all the drama from the story.
- Artistic License Physics: The book portrays the Moon landing as producing exactly the same amount and direction of pressure they all suffered in the takeoff, that is, vertical and downwards. Going without mentioning that an inverse acceleration should intuitively produce pressure in the opposite direction (upwards), a free descent gently decelerated by the main engine acting as a retrorocket would generate infinitely less vertical acceleration than a takeoff, unless they wanted to get propelled into space again instead of performing a landing.
- Ascended Extra: Colonel Jorgen. In his first appearance in King Ottokar's Sceptre he was a pretty minor character who disappeared halfway through the book and was never mentioned again. In this volume, he proves himself to be one of Tintin's most out-and-out heartless and dangerous foes.
- Backhanded Apology: In the French version, Haddock has to apologize to the Thompsons for saying that a circus (actually a Moon crater, called a circus in French) needed two clowns, and that they would suit perfectly. He then proceeds to "apologize" by saying that the circus does not need two clowns, therefore they would not suit perfectly. One of the Thompsons tries to ponder on what that actually implies, but the other is perfectly happy with this. The English version changes the confusion to the Thompsons thinking the Sea of Nectar is the seaside, and Haddock claims that they're looking for two Punch and Judy men on the pier, for which they would suit perfectly. The apology goes about the same way, with Haddock "explaining" that they're not hiring after all, which doesn't address the insult at all.
- Bowdlerization: In the Belvision version, Captain Haddock isn't drunk when he is pulled into orbit - instead, his feet hurt, so he takes his metal boots off.
- Burial in Space: It doesn't occur on the page, but the heroes jettison Jorgen's body into space. And, of course, Wolff's fate is comparable, although chosen himself.
- Cold Equation: Since oxygen becomes a problem fairly soon in this story, this dilamma pops up in the second part of the book. Jorgen wants to solve it by eliminating everyone except Wolff and him, Tintin is dead set against it even if it means their deaths, and Wolff sacrifices himself for this very reason.
- Dead Man Writing: Wolff leaves a letter explaining his suicidal action and asking for forgiveness.
- Delayed Reaction: It takes one of the Thompsons a few panels to realise that Haddock insulted them by comparing them to clowns (Punch and Judy men in the English versions). It takes also some time for him to realise that Haddock did not apologise (see Backhanded Apology above), but he is interrupted before he can complete his thought.
- Easily Forgiven: Played with regarding Wolff, after the reveal he was The Mole; the characters react differently to his betrayal, with Calculus expressing shocked disbelief, Tintin forgiving him after he stopped Jorgen from shooting them, and Haddock being infuriated, only forgiving him after his Heroic Sacrifice.
- Exact Words: Haddock, not trusting Wolff, orders Thomson to keep an eye on him and inform them of anything he might be doing in their back. Thomson does just that- but fails to actually prevent Wolff from doing anything funny.
- Good Is Dumb: Indirectly invoked by Jorgen when he escapes on the return trip, pointing out that while Tintin's morals may not have allowed disposing of him and Wolff, he himself has no compunctions about executing the rocket crew in order to ensure that he makes it home alive.
- Heroic Sacrifice: Frank Wolff leaves the rocket so that the others have enough oxygen to survive the trip back home.
- Hypocritical Humor: Haddock snarkily comments that the Thompsons always need to find some way to get noticed when they begin exhibiting the symptoms from their poisoning from Tintin: Land of Black Gold. This happens mere minutes after Tintin managed to save him after he decided to leave the rocket while drunk, putting his and the whole crew's lives in danger.
- I'm Not Doing That Again: When Calculus proposes making a return trip to the moon, Captain Haddock absolutely refuses to take part.Haddock: May I be turned into a bollard, blistering barnacles, if I so much as set foot in your flying coffin again! Never, d'you hear? You interplanetary goat, you! Never!!
- In Space, Everyone Can See Your Face: Hergé was well aware that the space suits would require opaque helmets much like the astronauts we see today, but then the readers wouldn't be able to tell who was Haddock and who was Tintin. So, for their convenience he made the helmets transparent and more fish bowl shaped.
- Karma Houdini: Miller, due to none of the characters even knowing about his involvement.
- Kick the Dog: Jorgen breaks Snowy's leg.
- Killed Offscreen: Jorgen and Wolff died outside the view of the reader.
- The Load: Thomson and Thompson are easily the most incompetent they've ever been here. Not only do they accidentally stow away on-board the rocket (leading to the oxygen crisis), unwittingly release Jorgen and generally make a nuisance of themselves throughout the storyline, at no point do they ever do anything that even vaguely helps the mission, unless you count Thomson's not stopping Wolff when he sneaks out to eject himself into space (and even then Thomson failed at the job he was actually given).
- Mocking Music: The gang listens to Radio-Klow while working to repair the ship... and as soon as it comes on, the announcer says they'll be playing Schubert's "The Gravedigger".
- Never Speak Ill of the Dead: Haddock regrets his harsh words against Wolff once he learns of his Heroic Sacrifice.
- Pragmatic Villainy: While Jorgen clearly has no qualms about the prospect of marooning Haddock, Calculus and the detectives on the moon, he isn't motivated so much by revenge — especially considering that he never met the detectives in his debut story, while Haddock and Calculus didn't make their own debuts until later — as the simple fact that were he and Wolff to take them prisoner, they'd be trying to sustain seven people on oxygen supplies meant for four, and wouldn't have a prayer of making it back to Earth alive.
- Prat Fall: Haddock when he says his final line, so he's lying on the ground.
- Properly Paranoid: Subverted; Haddock doesn't trust Wolff even after Tintin gave him back his post in the crew, and asks the Thomsons to keep an eye on him should he attempt anything behind their back. As it turns out, he does- namely, a Heroic Sacrifice.
- Redemption Equals Death: Wolff throws himself out the airlock so that the rest of the explorers will have enough oxygen to get back to Earth. Considering that they just barely make it back alive (and still need supplemental oxygen administered), his sacrifice probably did make the difference.
- Reentry Scare: Good lord, yes. Admittedly, the tension involved doesn't really concern the condition of the spacecraft itself so much as the condition of its crew, but all the same, both taking off and landing the craft are consistently depicted as extremely uncomfortable and frightening experiences. One imagines that these sequences alone may have freed more than a few goggle-eyed youngsters in multiple generations from their "I wanna be an astronaut!" phase.
- Sneaky Departure: Frank Wolff has to go about his Heroic Sacrifice in a stealthy manner, lest the others wake up and try to dissuade him. Of course, Thomson wakes up and, showing the presence of mind expected of the twins, permits him to go down into the hold anyway.
- Space Clothes: Enormous bulky amber-colored spacesuits, representing a very endearingly retro vision of lunar operations (the book was published in 1954, a good fifteen years before Neil Armstrong's historic jaunt). When suited up, the characters look like fat C-3PO units.
- Space Suits Are SCUBA Gear: Notably averted, however, despite how classically retro the spacesuit design looks otherwise. There are no vulnerable oxygen tubes on the exterior of the suit.
- Space Is an Ocean: Hinted at when the nautical-minded Captain Haddock threatens to maroon the Thompsons on a desert star while in space.
- Space Is Noisy: Deliberately refuted in the original comic. The animated version by Belvision embraced this trope, however: while the meteor was silent in the original comic, in the cartoon there is a meteor shower that makes a lot of noise!
- Spared by the Adaptation: Both Jorgen and Wolff survive in the Belvision adaptation of the story. Averted in the Nelvana adaptation, however.
- Tech Marches On: The rocket operates by the "direct ascent" model of the whole rocket landing and later leaving on the moon in one piece. Later, NASA concluded that they could never make such a vehicle land tail down safely and went with the method of "Lunar orbit rendezvous," having the rocket traveling in ejecting stages and using a separate lander to land on the moon with the command capsule waiting in orbit to link back up and return to Earth.
- More an inversion in this case: a direct ascent (SSTO = single stage to orbit) and landing requires either much more efficient rockets or MUCH bigger spaceships: both are as much out of reach now as they were then. In fact, a manned landing on the moon is impossible today or in the foreseeable future - but wasn't 50 years ago...
- Threw Himself Out The Airlock: Wolff decides to leave the rocket and let himself wander in space until his death as a Heroic Sacrifice to ensure the others can get to Earth alive.
- Tragic Villain: Frank Wolff was the first character in the Tintin universe who wasn't particularly good, but not particulary bad either. He sides with Colonel Jorgen to sabotage the flight, but is more or less manipulated by him. When Jorgen wants to shoot everybody Wolff protests and interferes, killing Jorgen accidentally with his own gun. Wolff is forgiven by Tintin, but later feels remorse and decides to commit suicide by throwing himself out of the rocket so that the others can safely travel home again.
- Unexpectedly Dark Episode:
- While people have been killed in a number of Tintin stories, this is the first to cover the topic of suicide, excluding Mitsuhirato's suicide near the end of The Blue Lotus.
- The vast majority of characters who die during the series are spared by the Nelvana animated adaptation. Neither Jorgen nor Wolff is afforded that treatment in the adaptation of this story, making it seem much darker than the rest of the series.
- Villain Has a Point: While Jorgen's actions are firmly villainous, his reasoning proves entirely correct; with three more passengers than planned, plus the various delays encountered, the characters are running out of oxygen, and it's pretty clear that despite Tintin's best effort, they cannot hope to survive in the current situation. In the end, only after Jorgen's Accidental Murder and Wolff's Heroic Sacrifice do they manage to survive the trip, and even then they only barely make it.
- Vile Villain, Saccharine Show: Downplayed example, since the comic isn't especially lighthearted, but Jorgen does stand out among other villains. He puts all the recurring cast into life-threatening danger, not just Tintin; and is played completely seriously, not facing any of the series' usual Slapstick comedy.