SpaceX founder Elon Musk on Tuesday unveiled his vision for "making humans a multiplanetary species." It may be the most ambitious and fraught endeavor ever proposed by man.
Humans have placed robots on the surface of the red planet and flown satellites around it, providing high-resolution analysis of its surface and a sense of its geology. But it'll take more than a decent map to find our way. Despite the phenomenal resources and record Musk brings to the enterprise, there remain a few planet-size holes in his plan.
In short, a lot of things need to be invented before mankind can even make it to Mars -- never mind establish a colony.
The most basic component of the complicated mission is the one Musk is in the best position to provide: a heavy-lift rocket. The billionaire's vision calls for a vehicle capable of launching more than 100 people at a time. SpaceX's utterly massive Interplanetary Transport System (ITS), unveiled in concept earlier this week, would measure 400 feet nose-to-tail when fully loaded and be powered by 42 of the company’s newly tested Raptor engines.
It just so happens that NASA is building a heavy-lift rocket of its own, though it’s a bit more modest. The Space Launch System is expected to carry just six astronauts.
Another critical need is the money to pay for such a rocket. Funding for space exploration has eroded significantly since the heydey of NASA's Apollo program in the 1960s and '70s. Musk joked that his fundraising list included stealing underpants and Kickstarter. He said the enterprise was likely to succeed with a sizable partnership among governments and the private sector.
Say everything goes according to plan. Let's hypothetically give Musk the money, the rocket, and everything else he needs.
The biggest remaining problem isn’t even the $10 billion, one-way ticket price that Musk half-joked about on Tuesday. What’s needed most are humans capable of withstanding the rigors of space.
Simply put, bodies deteriorate after too much time off earth (unfortunately, they also deteriorate after too much time on earth).
At the conclusion of a four-minute video SpaceX released showing how the company would carry people from Earth to Mars, helmeted passengers look outside their spacecraft as the door opens, but don't step out onto the surface.
"There’s a good reason why," said Ariel Waldman, an adviser to NASA's Innovative Advanced Concepts program and member of a National Academy of Sciences committee that reported on human spaceflight in 2014. Mars has 37 percent of earth's gravity, which is a lot more force than zero-gravity space travel. "After a flight to Mars, you’re not going to be able to walk," because of the atrophying of your muscles, she explained.
But weak limbs are a temporary issue that could be fixed with some bed rest. The other physiological concerns of life on Mars are far more serious.
|After an eight-month trip to Mars, NASA says muscle atrophy will make it difficult to walk.
Image: The Martian/ 20th Century Fox
The risk of cancer tops the list. Martian settlers would be exposed to large amounts of solar and galactic cosmic radiation, which affects people differently depending on their age and sex. Men and older astronauts can afford more days in space than women and younger astronauts before hitting safety thresholds. While it would be weird to minimize radiation risk by just sending up teams of only, say, older men, nonetheless "there are risk factors to be taken into consideration," Waldman said.
Engineers may be able to solve the problem of shielding spacecraft from radiation to protect astronauts. If so, once on Mars, living in underground habitats would help reduce exposure.
Musk acknowledged—but minimized—the radiation risk during his presentation, possibly because blowing up on the launchpad tends to focus the mind more vividly.
"The first journey will be very dangerous, and the risk of fatality will be very high," Musk said. "Are you prepared to die? Then you are a candidate for going."
Life in zero-g isn't pleasant. Astronauts lose about 1 percent of their bone minerals each month; shifting fluids interfere with eyesight; and they’re "likely to experience motion sickness," according to NASA. The space agency is researching ways to overcome the various risks from gravity, isolation, artificial habitats, and radiation, but they have yet to be solved.
"These are very real issues that need to be solved before the human race is able to reach destinations beyond the earth and the moon," Scott Kelly, the NASA astronaut who spent 340 days at the International Space Station before returning to earth in March, told the U.S. House Committee on Space, Science, and Technology in June.
The limitations of the human body, ultimately, aren’t Musk's problem. His problems are that there’s no rocket big enough to go to Mars and not enough people with the resources and know-how who are as excited about it as he is. So he'll build a huge rocket, and then see who emerges to help surmount the myriad obstacles that stand in his way.