Working as a mechanic, Kondratyuk completed the manuscript of a book titled The Conquest of Interplanetary Spaces, dealing with rocket motion and issues concerning the colonization of space. He also suggested using a gravitational slingshot trajectory to accelerate a spacecraft.[8] In 1925, Kondratyuk made contact with Moscow-based scientist Vladimir Vetchinkin and sent him the manuscript. Up to that time, he and his work were unknown to rocketry enthusiasts.