Three person crew will fly to Mars for three years

"The first flight to Mars of the TMK-1 was planned to begin on June 8, 1971.
The 75 metric ton TMK-1 spacecraft would take a crew of three on a Mars flyby mission. After a 10½ month flight the crew would race past Mars, dropping remote-controlled landers, and then be flung into an Earth-return trajectory. Earth return would happen on July 10, 1974, after a voyage of three years, one month, and two days."