As every space enthusiast knows, we will land people on Mars within 20 years. Of course, we’ve been 20 years away from Mars for the last half-century. Between 1950 and 2000, NASA and various independent groups have come up with more than 1,000 detailed studies for manned Mars missions. Yet not a single one has come very close to fruition. At least on paper, Mars remains an eventual NASA goal, with their latest Curiosity rover seen in some ways as a precursor to human missions. “Today, the wheels of Curiosity have begun to blaze the trail for human footprints on Mars,” said the agency’s administrator Charles Bolden after the rover’s successful landing on Aug. 5. Despite this, Mars is not really on the agency’s radar. After their Mars Atmosphere and Volatile Evolution (MAVEN) probe, set to launch in 2013, NASA has no concrete plans for the Red Planet. “Certainly, nobody’s really serious about sending people to Mars right now,” said historian David Portree, Wired Science’s resident spaceflight history expert and Beyond Apollo blogger. There are still plenty of ideas out there, ranging from the extremely ambitious — such as Elon Musk’s desire to fly to the Red Planet in the next two decades – to the completely bizarre – like the MarsOne reality-show/one-way-suicide-mission combo. Here we take a look at historical Mars plans, both crazy and sane, and the few that really stood a good chance at becoming reality. The von Braun Paradigm The rocket pioneer Wernher von Braun was one of the first people to come up with a detailed manned Mars mission based on sound science and engineering. Before he joined NASA, von Braun wrote a book called Das Marsprojekt, published in West Germany in 1952. In it, he envisioned a grandiose Mars exploration plan with ten 4,000-ton spaceships capable of taking 70 crewmembers to the Red Planet. Once at Mars, several astronauts would descend to the surface on winged spacecraft that landed on skis at the Martian polar ice cap. They would then complete a 4,000-mile overland trek to the equator to build a basecamp and landing pad to allow the others to descend (at least you can’t accuse von Braun of thinking small!). A scaled-down version of this epic mission famously appeared to American audiences in a series of articles between 1952 and 1954 in Collier's magazine. The plans also served as part of the inspiration for Walt Disney’s 1957 ABC program Mars and Beyond, which you can still see in its charming entirety online. Though popularly known, these missions never had any serious support from a space agency and no one knows how much they would have cost. Von Braun estimated in Das Marsprojekt that fuel alone would come to $500 million – about $4 billion in today's currency. They also suffered from a lack of knowledge about interplanetary space; von Braun’s spaceships heavily defended against micrometeoroids but not against radiation. And Mars’ atmosphere is now known to be far too thin to support the type of winged landers in his plans. Image: NASA/Ames Research Center

NASA’s First Plans With Mars making an extra-close approach to the Earth in 1971, many NASA officials and engineers had the Red Planet fixed firmly in their sights during the 1960s. “Probably the golden age of planning at NASA was this era,” said historian David Portree. The earliest mission ideas, coming from Lewis Research Center (now Glenn) in Ohio, set the archetype for most subsequent plans. A nuclear rocket would be assembled in Earth orbit with a crew of seven and fired to Mars. At the target, a two-man descent vehicle would land on the Martian surface. The astronauts would explore for a period of time and return to Martian orbit using a traditional chemically-fueled oxygen-hydrogen rocket, where they would rendezvous with the other crewmembers and return to Earth. But any Mars plans got relegated to the back burner in 1961 when President Kennedy called for NASA to get a man to the moon and return him safely by the end of the decade. Still, the importance of spaceflight during this period spurred interest in manned Mars missions. The Early Manned Planetary-Interplanetary Roundtrip Expeditions (EMPIRE) would have sent a small crew to flyby Mars and then Venus. Though astronauts in these mission ideas would not have landed, they could have released probes to the surface of the planets and returned tremendous data, which until then was severely lacking. The crew could have remote-controlled robots to accomplish tasks they couldn’t do autonomously and even planned to have a sample return from the Martian surface – a prize still coveted by scientists today. Portree thinks that EMPIRE-style missions might have come the closest of any manned Mars mission to actually happening. It could have been done with Apollo-era technology and was seriously considered by the U.S. Congress. But after Apollo 1 suffered a terrible fire in 1967 that killed its three crewmembers, Congress was no longer in the mood to fund elaborate interplanetary schemes. “It’s interesting to think about what could have been if there hadn’t been an Apollo 1 fire,” Portree said. Read More: Manned Mars Surface Missions (1966) Image: Philco Aeronutronic/NASA

The Case for Mars After the successful manned moon landing, many at NASA and elsewhere thought the agency would move on to the next logical step: Mars. Yet throughout the 1970s, exactly the opposite happened. NASA’s last manned Mars plans came in 1971 and the agency pivoted to low-Earth orbit with ideas for the Space Shuttle and a space station. “It was very career-limiting in the 1970s to talk of anything beyond the station and shuttle,” Portree said. Congress was interested in funding what was right in front of them. Going to the moon had been done for political reasons and, lacking anything comparable for Mars, they had no time to go to the Red Planet. For a decade, few Mars missions were proposed. So folks took it upon themselves to brainstorm ideas outside of NASA. In 1981 engineers working with NASA and calling themselves the “Mars Underground” began organizing a series of conferences that met every three years to plan for a permanent Mars base. In 1983, the Planetary Society — a non-profit space advocacy group – created one of the most detailed Mars mission ideas since the ‘60s. The plan required 18 space shuttle launches to build a four-person vehicle that would spin to provide one-quarter Earth gravity during the trip to Mars. Three crewmembers would descend to the surface to conduct experiments and explore. All would return to Earth 18 months later. But the 1986 Challenger accident put to rest the idea that people would be using shuttle technology to create manned Mars plans. The misfortune came as a big blow to many advocates who thought the shuttle would create easy and constant access to space. Read More: Visions of Spaceflight Circa 2001 (1984) Image: A spinning spaceship like this one could have provided artificial gravity for astronauts. NASA

NASA’s Wildest Plan Renewed interest in manned Mars missions outside of NASA pushed the agency to come up with their own detailed plans starting in the late 1970s. Unfortunately, they ended up putting possibly the worst person in charge of the effort: former administrator Thomas Paine. “I think Paine had watched a little too much Star Trek,” Portree said. “He had such grandiose ideas that he scared everybody.” Paine’s plan started with re-conquering and industrializing the moon with new vehicles such as nuclear space tugs and fully reusable space shuttles. Hundred-man space stations would have floated in Earth orbit, and astronauts would have been ferried back and forth to a moon base on the new spaceships. When one vehicle reached the end of its lifetime, it would be launched off to Mars to be used for building a space station and infrastructure there. This elaborate scheme would have required 20 Saturn V launches a year (each at a cost of $500 million) and needed many more billions to fully complete its vision. “It helped create the idea that sending people to Mars has to be huge and costly,” Portree said. Even Werner von Braun, with his own ambitious Mars plans thought Paine’s ideas were over the top. When the long and detailed report came in 1984, the Reagan administration gladly accepted it and then put it on a shelf, never to be looked at. Read More: Integrated Program Plan “Maximum Rate” Traffic Model (1970) Images: 1) Nuclear rockets such as this could have taken people to Mars. NASA/Glenn Research Center 2) An overview of Paine’s ambitious plan. NASA Marshall Space Flight Center

Sally Ride’s Mission to Earth Former astronaut Sally Ride – the first American woman in space – headed a NASA commission in the 1980s charged planning the agency's future. Her “Leadership and America’s Future in Space” gave NASA one thing it has seriously lacked since Apollo: a vision. “I really like the Ride plan, which did not invoke nuclear propulsion or other new technology,” Portree said. “It’s very pragmatic.” Ride’s idea was not a detailed blueprint, instead acknowledging that NASA’s priorities and technology development cannot always be foreseen 20 years in the future. She offered a flexible guide with options that leaders could choose from. The first and cheapest option was called the Mission to Planet Earth and outlined a program to use satellites and robots to better understand our planet and its changes. Slightly more expensive and ambitious would be plans to send out robotic missions to explore the solar system. An evolutionary outpost on the moon could be an additional step. Finally, Ride suggested a series of manned round trips to the surface of Mars that would not be a political stunt like Apollo but a genuine plan to establish a Martian base. These four potential schemes were independent of one another and could be ramped up or down in a variety of ways. Depending on funding and public and political will, some could be executed while others could be left on the shelf. Read More: Piloted Split/Sprint Mission to Mars (1987) Image: NASA/Glenn Research Center

Bush and the Space Exploration Initiative The early 1990s saw renewed interest in Mars. The first President Bush surprised many when he called for a Space Exploration Initiative to revitalize NASA. The president may have been naive in hoping for a Kennedy moment and made his bold declaration calling for a return to the moon and Mars mission without fully preparing everyone. “Most people seemed stunned,” Portree said. “I think the only one who looked really happy about it was Barbara [Bush].” The Space Exploration Initiative uprooted a lot of the established plans and started over from scratch. Johnson Space Center took over mission planning and began generating new ideas. A space station was called for by 2000, followed by a lunar base, and a Mars expedition after 2010. The manned Mars mission plans that came from this era would require three different expeditions. Each would build on the capabilities of the last and generate an eventual Martian base. In addition, astronauts would set up a propellant station on Mars’ moons Phobos and Deimos to help future travelers “That was an interesting time and a lot of interesting work got done,” Portree said. But the Bush plans were more about giving defense contractors something to do after the end of the Cold War rather than about truly exploring the solar system. The $440 billion price tag also scared many members of Congress. In the end, the Space Exploration Initiative was forgotten almost as quickly as it was put together. Image: NASA/Glenn Research Center