He flew aboard Vostok 4 in August 1962, as part of the first joint space flight, with Vostok 3. The mission ended a day early because Popovich reported seeing thunderstorms over the Gulf of Mexico, forgetting that ‘thunderstorms’ was a code word for returning early because of motion sickness. He also flew aboard the July 1974 Soyuz 14 mission that docked with the Salyut space station. Popovich was selected as a cosmonaut in 1960 and left the programme in 1982.