An ambitious private manned mission to Mars aims to launch a two-person crew to fly around the Red Planet and return to Earth in 501 days, starting in January 2018.

This bold undertaking is planned by the Inspiration Mars Foundation, a non-profit company founded by millionaire and space tourist Dennis Tito that was officially unveiled on Feb. 27 after early details leaked. Though the spacecraft would not land humans on Mars or even put them in orbit, it would bring people within a few hundred kilometers of the Martian surface – roughly the same distance between the International Space Station and Earth – and represent a major milestone in human spaceflight. If successful, the mission would go down in history as the first time a private company accomplished something government agencies were unable to do in space.

The mission is extremely ambitious, well beyond anything previously accomplished by the private sector and it faces plenty of obstacles. The company has an aggressive schedule to keep if it wants to hit its 2018 mark and needs to make sure the necessary technology is developed and well-tested. Despite its deep-pocketed backer, the mission has nowhere near the funding it needs to launch and will require raising greater sums than have ever been done for a private space endeavor. Its designers also need to figure out exactly how to keep the crew healthy, both physically and psychologically, for the 501-day duration of the flight as they face dangers from radiation, bone and muscle loss, fatigue, and depression. Mission designers will have to ensure they can get the crew safely to the ground when the capsule returns to Earth at a screaming 30,000 mph.

Yet despite these hurdles, of all the bold announcements from private spaceflight companies in recent years, this one seems the most achievable.

“The reason this entire thing is possible is because it’s actually a very simple mission,” said Jane Poynter, president of the Paragon Space Development Corporation, which makes life-support systems and has partnered with Inspiration Mars. “We’re not trying to land, we’re going to fly by and we’re using extant technologies that NASA and the space industry have been developing for years.”

Inspiration Mars isn’t looking to sell a product in an unknown market, like the asteroid-mining Planetary Resources or the national-moon-ferrying Golden Spike Company, and doesn't have incredibly aspirational aims, like the planet-colonizing Mars One. It hopes to undertake a straightforward mission that could spur innovation, inspire young scientists and engineers, and move human spaceflight forward.

“You have to have a reasonable degree of skepticism and realism,” said Taber MacCallum, who co-founded Paragon with Poynter (and is also her husband). “We might run into some insurmountable obstacle 18 months in. But with proper engineering, support, and a good mess of luck, we could see this done.”

Now all they have to do is actually fly to Mars.

. Bottom: Jane Poynter. Courtesy NASA

As currently outlined, the Inspiration Mars mission would be departing on what’s known as a “fast free return trajectory,” which both minimizes the amount of time spent in space and the amount of fuel required. A spacecraft would fire its rockets for a single burn to set off to Mars, make a few course corrections on the way, circumnavigate the Red Planet, and then slingshot back home using Mars’ gravity, negating the need for another burn. Because of the positions of Earth and Mars, opportunities for such quick flybys happen only every 15 years and, if they miss the 2018 deadline, the next chance won't come until 2031.

Paragon estimates that the mission would need to launch a 10-ton spacecraft with roughly 33 cubic meters of volume, equivalent to the space in the back of a large moving van. About half that volume would be taken up with water tanks, food, and life support, leaving a cramped living space with an area barely bigger than a parking space. That means putting two people in a room for 1.4 years that's probably smaller than your bathroom.

The crew would process urine and flush water to recycle about 75 percent of it as drinkable water. They would carry the bare minimum of personal provisions, such as clothing and hygiene items. An initial feasibility study co-authored by Poynter, MacCallum, Dennis Tito, and others didn’t make allowances for privacy, separate sleeping quarters, or even showers (just sponge baths) in the habitat, but it remains to be seen how these ideas would evolve for a real mission.

No existing launch vehicle is large enough to get such a mass into space, though SpaceX plans to have its Falcon Heavy rocket ready within a few years. If SpaceX is unable to meet that deadline, the mission could use two smaller existing launch vehicles, one to bring the tank carrying the rocket engines and necessary fuel and another to launch the crew habitat, which complicates the mission and could make it more expensive.

The number one danger during the journey will be radiation. Whether charged particles streaming from the sun or galactic cosmic rays accelerated by distant sources, space is chock full of radiation. Humans on Earth are protected from this fallout by our magnetic field, which also shields astronauts on the ISS. But out in deep space, the crew of a 500-day trip would be exposed to total radiation roughly equal to the dose an astronaut that flew five or six times to the ISS would expect to receive over their career.

Among other things, radiation damages DNA thereby raising the risk of cancer, and lowers blood cell counts. The effect would be like smoking a pack of cigarettes a day during the whole mission, MacCallum said.

The most severe event to watch out for would be a solar flare or mass ejection, where the roiling surface of the sun produces a burst of charged particles and radiation. If exposed to such an occurrence, a crew might experience nausea, vomiting, blistering, and potentially death. Apollo astronauts were spared a potentially fatal flare in 1972 that occurred between Apollo 16 and 17 but the Inspiration Mars mission would be out in space for a long time, raising the odds of getting hit.

Solar particle events like these happen randomly, though in 2018 the sun will be closer to the minimum part of its activity cycle, lessening the chances of a large event. In the case of a major event, sun-observing satellites would provide some warning and the crew could retire to a storm shelter built from vehicle hardware. But a large event or even several smaller ones could weaken astronauts’ immune systems, said radiobiologist Ann Kennedy of the University of Pennsylvania, who works on the effects of radiation for the National Space Biomedical Research Institute.

With the sun at minimum the crew would be exposed to a higher rate of galactic cosmic rays than normal, and the chronic low-dose of ionizing radiation "can not be shielded against with current technology," said radiation physicist Jeff Chancellor, also of the NSBRI.

Even surrounding the spacecraft with a huge, thick shield, something like five or six times what the ISS has, would not significantly lower galactic cosmic ray exposure, he added. In fact the more shielding you have, the worse, because the charged particles can interact with molecules in the material to produce further harmful radiation.

The crew can help counteract some of the radiation's effects with drugs for nausea and vomiting and pills or supplements to provide the daily recommended doses of vitamins.

“My gut feeling is there’s a good chance they can do this mission, but there’s a lot left to be seen,” Chancellor said. Space travel is always risky, he added, though there is hope that further research can provide a crew with effective radiation countermeasures before 2018.

Beyond radiation, the main biomedical problem will be muscle and bone deterioration, which occurs to the human body during extended stays in microgravity. To counteract this, Poynter said it would be of the utmost importance for the crew to have an exercise machine that they use daily for several hours.

NASA/JPL/MSSS

The other main crew danger will come from themselves. The tight accommodations coupled with being so far from Earth with no hope of aborting the mission once started, as well as an ever-increasing time delay could put tremendous strain on the crew psychologically. Similarly extreme isolation is rare but has occurred in overwinter crews in Antarctic base stations or simulations such as Mars500.

“In cases like that, they managed to successfully complete their mission, but it wasn’t all roses,” said Poynter. Some training could be given to handle the conditions, but the crew selection would require individuals to be resilient and upbeat for the duration of their flight.

MacCallum and Poynter favor sending a man and woman as the pair, possibly to balance out personalities but also because the crew will have a symbolic value as representatives of humanity. Given the cramped quarters, the lack of privacy, the need for cooperation and experience under similar conditions, and the dangers from radiation, the ideal crew would be “an older married couple," said MacCallum.

When I pointed out that, with their previous experience in the Biosphere-2 experiment, he and Poynter happened to fit that description to a T, they both laughed.

“We have talked about it,” said Poynter. “And when the right time comes, I think we’ll put our hat in the ring.” But she and MacCallum added that they would be happy to be part of the mission in any way, even as ground support.

As it stands, Inspiration Mars is looking to work with NASA on their undertaking. The agency can provide a great deal of information and experience from decades of spaceflight. The company has already signed a partnership with NASA to research development of the mission’s heat shield and reentry strategy. Given that Inspiration Mars sees its mission as an important stepping stone for NASA’s long-term goals, the agency might even be able to help the mission financially, if there was enough support from the public and Congress. (Though the effects of the sequester later this week could constrain NASA's finances.)

Currently, Tito is committed to funding the first two years of putting the Mars trip together no matter what. But even he doesn’t have unlimited money and is in talks with other potential backers. Yet so far, donors haven't been quick to open their checkbooks and put money in private space ventures.

Though plans have yet to be finalized, MacCallum said that given the mission’s relative simplicity, he expected it would cost less than NASA’s $2.5 billion Curiosity rover, possibly putting it in the hundreds of millions or even billion-dollar range. Raising that kind of money for a private space mission has never been done before and that figure might be somewhat optimistic.

With its seven minutes of terror and Rube Goldberg landing sequence, getting Curiosity to the surface of Mars was one of the hardest engineering feats over done in space. Having humans land would be harder by an order of magnitude or more, said engineer Bobby Braun of the Georgia Institute of Technology, who was formerly NASA's chief technologist.

“I’d say having humans circumnavigate Mars and return safely to Earth is somewhere in between what Curiosity already did and having humans walk on Mars,” he said.

Braun thinks that the Inspiration Mars idea is great, and he accepts that the private sector can accomplish things for less money than governments. But “it’s also a very bold plan, particularly doing it in the timeline they want, and there’s a good deal of challenges," he said. "I would love to see them make that 2018 launch date, but it’s pretty darn quick.”

As is continuously pointed out in articles regarding different private company plans, space is hard. Initial estimates tend to be hopeful and delays can almost always be expected. Historically, there have been many ambitious space announcements – both from public and private organizations – that were unable to deliver on their huge promises.

New ideas are always welcome. “I think this announcement is going to stop and make people reconsider the possibilities,” said Braun, but the question is whether “they will be able to have the proper follow through.”

Braun added that Inspiration Mars need not confine itself to their 2018 deadline. With slightly more fuel, the company could try for missions at many of the two-year intervals where Earth and Mars get closer.

The main goal of Inspiration Mars is to inspire a younger generation. Taber and MacCallum sound like they are hoping to create a new “Kennedy moment” that would encourage people to think big. The mission would provide scientific data sorely lacking on long-term human spaceflight. If the company were somehow able to pull it off, independent researchers would be particularly interested in the information generated from this undertaking.

“As a professor, surrounded by undergrad and graduate engineering students, something like this would light their fire,” said Braun. “It would be very exciting for science and engineering students around the country and around the world.”