section_path: Human presence/Crewed flight
section_name: Crewed flight
paragraph_text: Crewed flight
  
  Studies of routes for crewed missions to Mars have since the 1960s proposed opposition missions instead of direct conjunction missions with Venus gravity assist flybys, demonstrating that they should be quicker and safer missions to Mars, with better return or abort flight windows, and less or the same amount of radiation exposure from the flight as direct Mars flights.
  
  Early in the space age the Soviet Union and the United States proposed the TMK -MAVR and Manned Venus flyby crewed flyby missions to Venus, though they were never realized.