A human mission to Mars has been the subject of science fiction, engineering, and scientific proposals throughout the 20th century and into the 21st century. The plans comprise proposals to land on Mars, eventually settling on and terraforming the planet, while exploiting its moons, Phobos and Deimos.

Preliminary work for missions has been undertaken since the 1950s, with planned missions typically taking place 10 to 30 years in the future. The list of manned Mars mission plans in the 20th century shows the various mission proposals that have been put forth by multiple organizations and space agencies in this field of space exploration.

The United States has a number of robotic missions currently exploring Mars, with a sample-return planned for the future. One possible means of propulsion for such interplanetary transport ships has been proposed by New Scientist. In its proposal, New Scientist outlines an argon plasma-based VASIMR rocket which the group claims could reduce the interplanetary transit time to less than 40 days. As a training venue for future Mars missions, NASA has used the Haughton impact crater on Devon Island due to the crater's similarity with Martian geology.

• The European Space Agency has sent robotic probes, and has long-term plans to send humans but has not yet built a human-capable launcher. There is a proposal to convert ESA's existing Automated Transfer Vehicle (ATV) for crewed launches. It plans to launch an unmanned mission to Mars, ExoMars, in 2016.

• Russia (and previously the Soviet Union) has sent a large number of probes. It can send humans into Earth orbit and has extensive experience with long-term manned orbital space flight due to its space station programs. A simulation of a manned Mars mission, called Mars-500, was completed in Russia in November 2011.

India successfully placed an unmanned Mars Orbiter Mission (also called Mangalyaan) satellite in Mars orbit on 23 September 2014.

• Japan has sent one robotic mission to Mars, the Nozomi, but it failed to achieve Mars orbit.

• China's mission to Mars, the Yinghuo-1 space probe, was lost with Russia's sample return mission to Phobos, Fobos-Grunt.

• The US Mission to Mars:  Speaking at Kennedy Space Center, President Barack Obama discussed his plans for NASA which includes sending astronauts to a nearby asteroid by 2025 and going to Mars by the mid-2030's. "Let me start by being extremely clear," Obama said. "I am 100 per cent committed to the mission of NASA and its future because broadening our capabilities in space will continue to serve us in ways we can hardly imagine." Obama's plan, which includes the $6 billion in additional funds for NASA over the next five years that was previously announced and using a scaled-down version of the Orion spacecraft as a rescue vehicle for the International Space Station.

Also, Obama committed funds for research now to build a heavy-lift rocket starting in 2015 — or earlier — to launch astronauts and payloads to missions beyond the Moon. "By 2025 we expect new spacecraft designed for long journeys to allow us to begin the first ever crew missions beyond the Moon into deep space," Obama said. "So, we'll start by sending astronauts to an asteroid for the first time in history. By the mid-2030s, I believe we can send humans to orbit Mars and return them safely to earth, and a landing on Mars will follow."

Obama said his program of partnering with commercial space companies allows for more missions launched from Kennedy Space Center, an acceleration of advanced technologies that will allow for better space transportation systems and a shortening of the dependence on Russian rockets. The president made no mention of any extension to the space shuttle program, which was one rumor that floated around before his speech.

Speaking after the President, Norm Augustine – who headed the Augustine Commission review of NASA's future, said that the new program is very close to one of the options his panel offered and this path would be "worthy of a great nation, and be able to transform NASA from transportation to exploration." Augustine also pointed out that we seem more eager to accept current Russian technology than to encourage future of our own private industry.

The White House Chief Science Advisor John Holdren said Obama's plan is a "faster pace to space, with more missions sooner and more affordably." He said it's a more visionary approach as it expands commercial capability and allows NASA to devote its resources to exploring deep space.

Obama discussed his space plan at the Operations and Checkout Building at the Kennedy Space Center, the same building used to build the Orion spacecraft. This is the first time in 12 years a sitting U.S. president has visited KSC. The plan was originally unveiled on Feb 1, 2010, and the proposal to cancel the Constellation program and use commercial companies for trips to LEO was met with harsh criticism from members of Congress and many former astronauts, including a letter from Neil Armstrong, Gene Cernan and Jim Lovell who called the plan "devastating" the legacy of US space leadership. Today, however, before the president's speech, Elon Musk from SpaceX – whose Falcon 9 spacecraft will launch a test flight perhaps next month – issued a statement that lauded Obama's plan to end Constellation. "The President quite reasonably concluded that spending $50 billion to develop a vehicle that would cost 50% more to operate, but carry 50% less payload was perhaps not the best possible use of funds. To quote a member of the Augustine Commission, which was convened by the President to analyze Ares/Orion, 'If Santa Claus brought us the system tomorrow, fully developed, and the budget didn't change, our next action would have to be to cancel it,' because we can't afford the annual operating costs."  "Cancellation was therefore simply a matter of time," Musk continued, "and thankfully we have a President with the political courage to do the right thing sooner rather than later. We can ill afford the expense of an "Apollo on steroids", as a former NASA Administrator referred to the Ares/Orion program. A lesser President might have waited until after the upcoming election cycle, not caring that billions more dollars would be wasted. It was disappointing to see how many in Congress did not possess this courage." By choosing KSC to make his speech Obama hoped to bring home that his program will add more 2,500 jobs compared to plan under previous administration. "We will modernize KSC, creating jobs as we upgrade launch facilities, and bringing the potential for more jobs as companies come here to compete for launch projects. This is an area prime to lead in this competition." Afterwards, NASA Administrator Charlie Bolden said, "It's special when a president talks about you but it's even more special when he comes to visit."

NASA's Mars

Various Technologies May Aid a Human Mission to Mars:

One of the medical supplies that may be needed is intravenous fluid, which is mostly water but contains other things so it can be added directly to the human blood stream. If it can be created on the spot from existing water then it could spare the weight of hauling earth-produced units, whose weight is mostly water. A prototype for this capability was tested on the International Space Station in 2010.

Mars Mission Practice in Canadian Arctic

While it is possible for humans to breathe pure oxygen, a pure oxygen atmosphere was implicated in the Apollo 1 fire. As such, Mars habitats may have a need for additional gases. One possibility is to take nitrogen and argon from the atmosphere of Mars; however, they are hard to separate from each other. As a result, a Mars habitat may use 40% argon, 40% nitrogen, and 20% oxygen.