Wanted: men and women to leave the birthplace of humanity and the only safe haven in the solar system for an interminable voyage in a cramped container with people you will probably learn to hate. Destination: the freezing, airless, highly irradiated and irredeemable wasteland we call Mars. Must be willing to live in a pressurised pod, drink crewmates’ recycled urine and endure disgraceful broadband service.
Hollywood has a knack for bringing excitement to Mars, but the foundation of any tension invariably lies in the fact that anyone who goes wants to come back, because it’s downright hostile and Earth was never that bad, that dangerous, or that doomed in the first place. Visionaries such as Stephen Hawking and Elon Musk want us to colonise other planets to safeguard the future of the species. They have a point. But if we can’t survive on the planet we evolved to live on – the only life-nurturing planet we know – it’s hard to see us making a great fist of it elsewhere. Another hitch: we’re nowhere near ready to leave.
As the crow flies, the shortest distance from Earth to Mars is 55m km, but Mars missions fail as often as they succeed. In the past, spacecraft have crashed into the surface, burned up in the atmosphere or barrelled on by. Instead of taking the shortest route, they typically follow more efficient trajectories that take about eight months one-way. That’s a long time to be cooped up with a bunch of strangers.
Aware of the potential for things to go wrong, space agencies have run several simulated missions to Mars by locking would-be spacefarers into pretend spaceships and watching how they cope. A 520-day European Space Agency simulation found that some men developed sleep problems, particularly on the long “return” leg, despite having plenty of music, books, DVDs and computer games for entertainment. It didn’t help that communications to the outside world have a 30- to 40-minute delay. But it’s the boredom that hurts the most, apparently. In Mary Roach’s Packing for Mars, a retired cosmonaut confesses to the mind-numbing boredom of space station life. “I wanted to hang myself,” he said. Which, he goes on to point out, isn’t that easy in weightless conditions.
Life on Earth is protected against the intense radiation of the solar wind and cosmic rays by the planet’s magnetic field. Once Mars-bound travellers pass through the field, they must be shielded by other means. Some of the most harmful radiation is in the form of high-energy protons, which can be stopped by hydrogen-rich substances, such as water and polyethylene. In principle, a spacecraft’s water tanks – topped up with filtered urine – and even the crew’s waste food packaging could be used as shielding in transit. But more sophisticated materials are on the horizon. Nasa is developing hydrogenated boron nitride nanotubes that can be woven into threads, potentially to make suits that absorb the damaging particles. They are an ever-present danger that would cause radiation sickness and cancer in those exposed.
The first humans to set foot on Mars will likely stay for a month or so. For such short visits, living and working spaces could be lightweight, pressurised inflatable shelters that can be deployed and covered with Martian soil to beef up radiation shielding. Once inside, people could ditch their space suits and breathe the air. As with the space station, more modules could be added over time to give people more room to move around and mingle. For brief spells, it would do.
Nasa’s latest plans for hurling humans to Mars involve testing the agency’s Orion spacecraft in lunar orbit before slating the first Mars missions in the 2030s. The best contender in the private sector is Elon Musk’s SpaceX, which is banking on its Interplanetary Transport System to ferry people straight to Mars as early as the next decade. Other private missions have been proposed but do not inspire much confidence: Mars One is a reality TV-based venture described in an Massachusetts Institute of Technology report as “not feasible”. Meanwhile Dennis Tito, the world’s first space tourist, wants to slingshot a married couple around Mars and bring them home without ever touching down. Both will need to buy rockets made by others.
Before humans can spend years on the red planet, they must invent a suite of new machines to take them there. Nasa opened a competition in 2015 for companies to come up with ways to 3D print Martian habitats from crew waste and Martian materials. But more serious breakthroughs are needed for Mars settlers to be self-sufficient. A colony would need equipment to extract water from subsurface ice, and oxygen from carbon dioxide in the thin Martian atmosphere. Mars is farther from the sun than Earth is and the temperature can plunge to -125ºC in the winter, calling for large fields of solar arrays to capture enough of the sun’s rays to generate electricity for power and heating.
In The Martian, Matt Damon opts for bags of human poo to grow potatoes in, and after analysing the red planet’s soil with its long-defunct Phoenix lander, Nasa agreed that some kind of fertiliser would probably be necessary to farm plants on Mars. Any crops would have to be grown indoors, however, to protect them from radiation, and under lamps, to make up for the feeble sunlight that reaches the surface. From first footfalls, it could take many decades to establish a functioning colony on Mars. And even if it became self-sufficient, it would still be reliant on supplies from Earth for equipment and parts: a colony can only do so much.
What would become of humans on Mars? Without a hefty exercise regime, they would become weak and feeble. Mars is a small planet with only one third the gravity of Earth. To stand would take less leg muscle; to pump blood to the brain, less heart. And what about the politics? At the outset, the first settlers would doubtless be revered as brave pioneers. Would that attitude hold as the novelty wore off? Or might Mars settlers find themselves out of sight and out of mind; resented for their need of support? Isaac Asimov anticipated as much in The Martian Way.
Humans on Mars would be the first to be neither on Earth nor able to see the planet as a life-sustaining marble in the blackness of space. Astronauts have found the view back to Earth enormously helpful for their mental wellbeing. What happens when, as seen from Mars, the Earth appears insignificant, no more than a tiny pale dot?
So, yes, given the right technology, humans can live on Mars. The question is do we want to?