High Quality Content by WIKIPEDIA articles! The list of manned Mars mission plans in the 20th century is a listing of formal proposals, studies, and plans for a human manned mission to Mars during the 20th century. It is limited to serious studies done with engineering and scientific knowledge about the capabilities of then current technology, typically for high-budget space agencies like NASA. Mission profiles included manned flybys, manned landers, or other types of Mars system encounter strategies. A manned Mars lander, often called a Mars Excursion Module (MEM), enabled Mars orbit rendezvous or flyby rendezvous. For 21st century mission and later plans; see Manned mission to Mars.