Explorers on the Moon

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Explorers on the Moon
(On a marché sur la Lune)
Wearing space suits, Tintin, Snowy, and Haddock are exploring the surface of the moon, with their rocket ship in the background.
Cover of the English edition
Date 1954
Series The Adventures of Tintin
Publisher Casterman
Creative team
Creator Hergé
Original publication
Published in Tintin magazine
Date of publication 29 October 1952 – 29 December 1953
Language French
Publisher Methuen
Date 1959
  • Leslie Lonsdale-Cooper
  • Michael Turner
Preceded by Destination Moon (1953)
Followed by The Calculus Affair (1956)

Explorers on the Moon (French: On a marché sur la Lune) is the seventeenth of The Adventures of Tintin, the comics series by Belgian cartoonist Hergé. Published in 1954, it carries on the story of the preceding title Destination Moon.


The story continues from Destination Moon. Professor Calculus is taking Tintin, Tintin's dog Snowy, Captain Haddock, and Calculus' assistant Frank Wolff to the Moon in his rocket. However, the detectives Thomson and Thompson come up from the hold, having mistaken the time of the launch (1:34 a.m. instead of 1:34 p.m.) and been left on board while carrying out a final security check, putting the expedition at risk due to the new strain on the oxygen supply, designed for four people and Snowy and now forced to accommodate six.

The mission remains fraught with difficulties. Thomson and Thompson accidentally turn off the nuclear power motor, which stops the artificial gravity and sends everyone floating until Tintin restarts the motor. Haddock has smuggled some whisky aboard in hollowed-out books, becomes drunk, and engages in an unscheduled spacewalk that results in him briefly becoming a satellite of the asteroid Adonis. Despite the extreme danger to himself and the ship, Tintin also dons a space suit to fetch him, and, in a very rare display of temper, berates the Captain for his recklessness. When the rocket engine must temporarily be shut down in order to execute the turnaround maneuver that will enable it to land on the Moon right side up, the momentary lack of artificial gravity also poses problems for Haddock, who has neglected to put on his magnetic boots in time. Additionally, Thomson and Thompson suffer a relapse of the condition caused by their ingestion of the energy-multiplying substance Formula Fourteen (see Land of Black Gold); as a result, they once more sprout thick hair that grows at lightning speed and frequently changes color.

The spacecraft eventually lands safely in the Hipparchus Crater, and by agreement among the crew, Tintin is the first to set foot on the Moon (the first human to do so). Everyone then gets a chance to walk about; even the Captain enjoys it, but upon seeing the Earth, expresses unease over whether they will survive to see it again.

The crew soon starts unpacking the scientific payload—telescopes, cameras, and a battery-powered expedition tank. Calculus decides to reduce the total stay on the lunar surface from fourteen Earth days to six in order to conserve oxygen. Three days later, the Captain, Wolff and Tintin take the battery-powered tank to explore some stalactite caves in the direction of the Ptolemaeus Crater; inside a cave Snowy slips into an ice-covered fissure, damaging his two-way radio, and there is a minor drama in rescuing him when Tintin becomes trapped as his oxygen supply runs low, but they all return to the rocket safely.

Tintin decides to rest up and have lunch with Wolff while the Captain, Calculus, and Thomson and Thompson immediately go out in the tank again on a 48-hour trip to explore the lunar caves in detail, as Calculus suspects they might find uranium or radium deposits there. A sudden turn of events occurs when the spy plot broached in Destination Moon is revealed: Wolff has been working with a secret agent from a foreign power, the brutish and autocratic Colonel Jorgen (whom Tintin had previously encountered and defeated in King Ottokar's Sceptre), who has been hiding in the rocket since it was launched eight days previously (having been smuggled aboard along with technical equipment). When Tintin goes below to fetch some supplies for lunch, Jorgen knocks him out and binds him, as well as knocking out Snowy and pushing him over into the open door hatch to have him fall down a level. He then tries to seize control of the rocket, which he plans to fly back to the country for which he works, leaving the others marooned on the Moon; Wolff protests against what would amount to a death sentence for the rest of the crew, but Jorgen threatens him with his gun. When he finds that engine troubles mean the tank is returning early, he tells Wolff to take off at once.

Outside, from the Moon tank, the Captain, Calculus, and Thomson and Thompson watch, horrified, as the rocket begins to take off, but comes crashing back down and coming to rest. Jorgen wrongly accuses Wolff of sabotaging the launching gear and nearly shoots him, but Tintin stops him. Tintin has freed himself and succeeded in foiling the plot, but in order to do so had been forced to sabotage the rocket to prevent Jorgen's attempted liftoff. Snowy has meanwhile broken a leg from his ordeal, but is bandaged. Wolff, deeply ashamed, reveals to the stunned group his history of gambling debts, which Jorgen's employers have used to blackmail him into aiding them involuntarily. After the group interrogates Jorgen and Wolff, they are restrained with rope and Tintin locks them in the hold. Calculus determines that the crew needs at least four days to repair the damaged rocket, while the remaining oxygen supply will last at most four days.

Due to the strain on the oxygen supplies, the crew decides to abandon most of the equipment and to cut short the lunar stay. The repair work is completed slightly ahead of schedule after three days, and the rocket cleared for lift-off. Even so, shortly before lift-off, the Captain becomes the first among them to experience a bout of dizziness due to build-up of carbon dioxide. The lift-off is successful, but the rocket is put off course, and by the time the crew awake from the liftoff-induced blackout and correct it, they have lost additional time and thus consumed more oxygen.

Halfway back to Earth, Jorgen escapes after overpowering the detectives, who have attempted to secure the prisoners more thoroughly with handcuffs. When Jorgen declares his intention to kill Tintin and the others, Wolff intervenes and the two struggle over the gun; it goes off, killing Jorgen. However, even without Jorgen there isn't enough oxygen to make it home. Overcome with guilt, Wolff sacrifices himself by opening the airlock, after jury rigging it so it would not automatically shut off the engine, and going out into space while the others are unconscious, leaving behind a moving farewell note that asks for forgiveness.

The rest of the group continues towards Earth as their oxygen runs low. Everyone soon falls unconscious, but Tintin barely manages to set the rocket up to land on auto-pilot. After the ship lands, firemen cut a doorway through the hull. On the tarmac, everyone is revived, except for the Captain. A doctor is giving a prostrate Haddock oxygen, but fears that his heart is worn out because "It seems he was a great whisky drinker." Suddenly roused by the sound of the word "whisky", Captain Haddock wakes up with a start.

Everyone rejoices and a ground crew member returns with a bottle of whisky. In the bliss of the moment, Calculus joyfully announces that "we will return" to the Moon (referring to mankind in general), whereupon Haddock furiously declares that he will never be seen inside a rocket again. He then promptly walks away, only to trip and a fall over a stretcher in the midst of declaring that "Man's proper place ... is on dear old Earth!"

Scientific accuracy and inaccuracy[edit]

Destination Moon and Explorers on the Moon were written more than 17 years before the 1969 Apollo 11 Moon landing and several years before manned space flight. Hergé was keen to ensure that the books were scientifically accurate, based on ideas about space flight then available.


The rockets bear a striking physical resemblance to V-2 rockets, the only rockets to have struck popular imagination by the early 1950s. The similarity even goes as far as including the checkerboard pattern on the hull, which the V-2 designers used to measure the roll rate of a rocket during test flights.[1]

No separate lunar lander is shown: The whole ship turns about on its axis, lands tail-down, and returns intact. This is in stark contrast to the real-life Saturn V moon rockets, which, like virtually all modern rockets, were disposable, multistage rockets, and as such would separate into progressively smaller segments during ascent in order to save weight. The approach taken by Tintin's rocket is what NASA called a "direct ascent". Such a mission profile was studied, and discarded by NASA engineers. In Tintin's case, it is made possible by the rocket's extremely efficient propulsion which, more than half a century later, remains much more capable than any real-life rocket propulsion system.

Rocket engine[edit]

Hergé's rocket has two propulsion systems — a conventional liquid-fueled chemical rocket engine for launching (and also for deceleration upon landing), and an engine for the spacebound part (>800 km altitude) of the journey, described as being nuclear powered. The depicted rationale for this solution is to avoid contaminating takeoff and landing sites with radioactive exhaust products. Today, nuclear power is not widespread in space propulsion because of another safety risk, namely that of the reactor core or other radioactive materials falling back to Earth upon accidental or programmed destruction of the spacecraft. Real-life nuclear thermal rocket designs such as the NERVA engine were briefly tested in the United States in the 1960s. One of the reasons for cancelling the NERVA programme was the danger of radioactive particles being released in the rocket exhaust, i.e. the same concerns that Hergé had.

The book shows on-board artificial gravity of one earth gravity being generated through the constant acceleration of the moon rocket throughout the voyage to the Moon. NERVA or a similar engine using nuclear fission (where the nuclear reactor is used to heat up working mass (hydrogen or ammonia) propellant which is ejected at ~8–9 km/s velocity, accelerating the rocket through conservation of momentum) cannot run for any prolonged amount of time at one earth gravity acceleration before running out of propellant. The "fuel economy" can be increased by raising the reactor temperature and hence exhaust velocity (see gas core reactor rocket) but doing so will melt the engine unless the thrust is reduced. The only known propulsion system that combines high exhaust velocity with continuous high thrust is Robert Zubrin's controversial nuclear salt water rocket proposal.[2] The idea is to store the nuclear fission fuel as a solution in water. The fuel tanks (narrow pipes) are coated with a neutron damping material to prevent a chain reaction. To start the engine, the fuel is injected into a long cylindrical plenum pipe of large diameter, which terminates in a rocket nozzle. Free of the neutron damper, a critical mass of uranium soon develops. The energy release vaporizes the water, and the blast of steam carries the still reacting uranium out the nozzle. Zubrin claims the resulting heat and radiation would not damage the rocket as most of the nuclear reaction occurs outside the reaction chamber.

Space travel[edit]

When the rocket is turned around halfway through the journey (to decelerate), the crew experiences weightlessness for a short time, and the effects of this weightlessness are correctly portrayed, including floating liquid held into a spherical shape by surface tension.

There is a glaring flaw in the configuration of the rocket's acceleration couches, in which the explorers lie face-down. In reality, all launches have passengers lie on their backs, and the only worse position for a human being to endure acceleration than face-down would be heads-down. Hergé took the cue from the diagram of the Wernher von Braun moonship, without realizing that the crew members who need to monitor the controls are prone, but everybody else in their acceleration stations are properly on their backs.[3] The liftoff acceleration also seems to be significantly higher than that of existing real-life manned spacecraft: The crew passes out due to the tremendous G-forces.

The reader is given the impression that the journey to and from the Moon is undertaken in just a few hours, whereas the Apollo Moon journey took about three days to reach the Moon from Earth. However, if the rocket accelerated constantly at one gravity for the first half of the trip and decelerated at the same rate for the second half, as the author implies, the flight from Earth to the Moon could have taken as little as three and a half hours.[citation needed]

Finally, the mission is allowed to continue unabated even when it is discovered that extra passengers are aboard, resulting in increased oxygen consumption. In reality, space missions are terminated as soon as possible if it is believed that oxygen supplies may be inadequate. This occurred during the Apollo 13 mission when a faulty wire in one of the spacecraft's oxygen tanks caused it to explode. Although the explosion occurred too late for the mission to turn back, the actual Moon landing did not occur and the astronauts returned to Earth as soon as was feasible.

Lunar exploration[edit]

When the comic was created, nobody had actually visited the lunar surface, so the drawings were based on Chesley Bonestell's illustrations for Willy Ley's book The Conquest of Space and Collier's "Man Will Conquer Space Soon!" series.[4]

The spacesuits are rigid and have fishbowl-like helmets made of glass-like "multiplex," with bulky integrated backpacks that permit radio communications with the ship and other astronauts. The main differences from the suits worn by the Apollo astronauts are that they are apparently rigid, rather than soft, are orange rather than white, and the helmets lack sun-shielding visors. Hergé had initially designed space helmets very similar to the ones used in real life, however he designed the Perspex 'goldfish bowl' type of helmet so that the characters could be identified more easily.[5] Even the oxygen feed into the suits is apparently a pipe; Haddock reminds Tintin to be mindful of damaging it on a rocky wall during their rescue of Snowy.

Hergé accurately represented the methods of movement on the Moon: the reduced gravity makes Tintin and friends hop in huge jumps.[6]

In order to explore the surface of the Moon away from their landing site, Tintin and his crew bring a rover vehicle. This is similar to the last three Apollo missions, which also brought along a Lunar Roving Vehicle (LRV). However, whereas the Apollo vehicle was extremely light, open, and seated two, Tintin's rover is actually more akin to a tank, is pressurized, which means the occupants can remove their spacesuits once inside, and seats four. A real-life Space Exploration Vehicle (SEV) similar to Tintin's tank would later be developed in 2010 by NASA.

Tintin admits to have had no training in driving such a vehicle, a rather odd neglect, and it is only when they first try it out on the Moon that they decide that crash helmets should be worn while travelling in it.


In one part of the story, Tintin and Snowy accidentally discover frozen water beneath the surface of the Moon. When the Moon landings were completed, many experts felt the Moon was bone dry,[citation needed] so this would have been an inaccuracy. In 2009, however, evidence has shown a strong probability that water ice does exist in certain lunar regions.


Notable failings in Hergé's story include the representation of the Earth as seen from space (there are no clouds), and the lunar landscape, which is represented as craggy, unlike the smooth, undulating hills of reality.[7]

The asteroid Adonis is a real object, but despite being classed as a near-Earth asteroid, it never comes between the Earth and the Moon. However, its exact orbit was not known in the early 1950s. The choice of Adonis as the passing body is not made by chance: this notable Earth-approaching asteroid was discovered from Belgium by Delporte in 1936.[citation needed]

Tintin stated that the stars appear, "frozen ... they don't twinkle like how they do on Earth." This is quite accurate because there is no atmosphere on the Moon, so stars cannot twinkle.

Hergé was delighted to have predicted the lunar mission fairly accurately, given the limited knowledge at the time, and later he produced a four-page comic of Tintin, Haddock, Calculus and Snowy greeting Neil Armstrong on the Moon. Shown for instance as an illustration in this.[8]


Various merchandise has been released about this book. In the United States, a pop-up-version was made. A View-Master set was also released. The Moon rocket has been used on various merchandise.



  1. ^ "V2ROCKET.COM - Operation Backfire at Cuxhaven/Altenwalde". v2rocket.com. 
  2. ^ Chung, Winchell. "Nuclear Salt Water Rocket". Project Rho. Retrieved 3 September 2014. 
  3. ^ "Deck Plans - Atomic Rockets". projectrho.com. 
  4. ^ "The Space Review: A comic book, the Cold War, and the Moon". thespacereview.com. 
  5. ^ Thompson, Harry: "Tintin: Hergé & His Creation", page 146. Hodder and Stoughton, 1991.
  6. ^ Compare with video from Apollo 16 on YouTube and video from Apollo 17 on YouTube
  7. ^ See for instance the Apollo 15 landing site
  8. ^ Explorers on the Moon (login required)


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