Yuri Vasilievich Kondratyuk (real name Aleksandr Ignatyevich Shargei) (1897—1942) was an engineer, one of the legendary Russian theorists who developed the concept of interplanetary travel. He is considered to be the founder of cosmonautics and rocket science. In 1922 he released a book For those who will read to construct. In this book, he derived the equation of the rocket motion, introduced the description of four-stage rocket ship working on the oxygen-hydrogen propellant. In 1929 he released a book Conquest of Interplanetary Space. There he discussed the issue of space colonization, the problems connected with the propellant. In the early20th century he calculated the optimal trajectory from the Earth to the Moon. NASA used his calculations in their Apollo lunar program The trajectory proposed by the scientist in 1916 was later named the Kondratyuk’s route.