Bykovsky set a new space endurance record when he spent five days in orbit aboard Vostok 5 in 1963, and although this record has been long surpassed, to this day, it remains the space endurance record for a solo flight.
Bykovsky was to have commanded the original Soyuz 2 mission, which was cancelled due to problems with Soyuz 1. After the parachutes failed on that mission, killing Vladimir Komarov, the same problem was found with the Soyuz 2 capsule, which meant if the mission had flown, Bykovsky and his crew would also have been killed.
Many of his later years in the space programme were involved with promoting the Intercosmos programme amongst the world's Socialist nations. He retired in 1988 and then spent three years as the Director of the House of Soviet Science and Culture in Berlin.