Pierre Kohler (born 1945) is a French astronomer and science journalist. A specialist in orbital dynamics at the Meudon Observatory and then a CNRS researcher, he completed a 1975 doctoral thesis on the lifespan of artificial satellites under Evry Schatzman. He later turned to science journalism, heading RTL's science desk and the magazine Ciel & Espace, and produced a prolific body of popular science (more than eighty books) on astronomy, space and the Earth sciences, including Von Braun contre Korolev. Here he provides the French adaptation of Ryabchikov's book.