Prisoners of the Sun
Hergé first devised the idea of sending Tintin on a mission to the Moon while he was working on "Prisoners of the Sun" (1949). His decision to move into the field of science fiction might have been influenced by his friendly rivalry with his colleague Edgar P. Jacobs, who had recently had success with his own science fiction comic, "The Secret of the Swordfish" (1950–53). He decided that it would be a two-volume story arc, as had proved successful with his earlier arcs, "The Secret of the Unicorn" (1943) and "Red Rackham's Treasure" (1944), and "The Seven Crystal Balls" (1948) and "Prisoners of the Sun". He had initially intended on beginning this story after the culmination of "Prisoners of the Sun", but both his wife Germaine Remi and his close friend Marcel Dehaye convinced him to proceed with "Land of Black Gold" (1950), a story that he had previously left unfinished, instead.