The original comic book was published in 1950 and, for its day, it was considered quite accurate (although with obvious simplifications) in terms of the physics and technology involved in spaceflight. Author Hergé wanted to make the story as realistic as possible ("no moonmen, no monsters, no incredible surprises") and extensively researched rockets and space travel.
Hergé has an animated cameo a little over seven-and-a-half minutes in as a blonde worker near the top of the rocket model. He is looking away from the rocket and facing another worker.
He appears later as a man in a tie with rolled-up sleeves working with the villains to take control of the rocket model.
He appears later as a man in a tie with rolled-up sleeves working with the villains to take control of the rocket model.