 During the rest of the mission the crew would perform astronomical studies of the Sun and Mercury, which they would approach within 0.3 astronomical units.A variation of the Soviet Union's TMK mission planning for a manned mission to Mars involved a flyby of Venus on the return voyage, and was given the code name "MAVR" (MArs - VeneRa), meaning Mars - Venus.However, the TMK program was cancelled after the N1 rocket that was needed to loft the mission failed to fly successfully.