The science-fiction novel “Callisto” is devoted to the question of whether intelligent life is possible on other worlds of the universe. A huge white sphere has landed on the territory of the Kursk Region. The whole world waited to see who would come out of the spaceship. Naive Callistans didn’t suspect that on Earth there are two main social systems. And while the USSR was establishing scientific and human contacts with the aliens, cunning capitalists tried to find out their military and scientific secrets—stopping at nothing. The Earth scientists did everything possible to help the Callistans set off on their return journey. Along with them, the first envoys of Earth set off on the long multi-year flight—young Soviet scientists. Their stay on Callisto and their return to Earth are described in the second book of the series.