Pavel Popovich was selected as one of the first group of twenty air force pilots that would train as the first cosmonauts for the Soviet space program and was considered as a strong candidate for the second spaceflight.
He was considered as a strong candidate for the first spaceflight  but while Yuri Gagarin was ultimately chosen for the Vostok 1 flight, Popovich served as the flight's capcom. From May to August 1961, he trained to fly on spacecraft "Vostok-2" in a group of astronauts, followed (between September and November 1961) with training to fly "Vostok-3". This flight was cancelled. 
