The idea of sending humans to Mars has been the subject of aerospace engineering and scientific studies since the late 1940s as part of the broader exploration of Mars. Long-term proposals have included sending settlers and terraforming the planet. Currently, only robotic landers, rovers and a helicopter have been on Mars. The farthest humans have been beyond Earth is the Moon, under the U.S. National Aeronautics and Space Administration (NASA) Apollo program which ended in 1972.
Conceptual proposals for missions that would involve human spaceflight started in the early 1950s, with planned missions typically expected to take place between 10 and 30 years after they were drafted. The list of crewed Mars mission plans shows the proposals put forth by multiple organizations and space agencies in this field of space exploration. These plans have varied—from scientific expeditions, in which a small group (between two and eight astronauts) would visit Mars for a period of a few weeks or more, to a continuous presence (e.g. through research stations, colonization, or other continuous habitation). Some have also considered exploring the Martian moons Phobos and Deimos. By 2020, virtual visits to Mars, using haptic technology, had also been proposed.