A spacecraft will conduct a reconnaissance flyby of Mars 1971

Gaetano Crocco : aviation and rocketry pioneer
"At the Seventh International Astronautical Congress, held in Rome in September 1956, Italian aviation and rocketry pioneer Gaetano Crocco described a manned space mission in which a spacecraft would conduct a reconnaissance flyby of Mars, swing past Venus to bend its course toward Earth, and, one year to the day after departing Earth orbit, reenter Earth’s atmosphere. After Earth-orbit departure, the spacecraft would need no additional propulsion. Crocco told the assembled delegates that an opportunity to commence such a mission would next occur in June 1971."