The prince's home, "Asteroid B-612", was likely derived as a progression of one of the planes Saint-Exupéry flew as an airmail pilot, which bore the serial number "A-612". During his service as a mail pilot in the Sahara, Saint-Exupéry had viewed a fennec (desert sand fox), which most likely inspired him to create the fox character in the book. In a letter written to his sister Didi from the Western Sahara's Cape Juby, where he was the manager of an airmail stopover station in 1928, he tells of raising a fennec that he adored.