Believe me, we Earthlings will never colonize Mars! A now very near future in which humans will establish lasting colonies on Mars is something many of us now take for granted. Believing this is part of the optimism to which our faith in science and technology has accustomed us. But in the case of Mars, that compared to the Moon is a world thousand times more distant and equally inhospitable, are we really sure of what we are told every day? Elon Musk thinks Mars is like Earth? But who would like to live in underground tunnels lit by anti-depression lamps, feeding on lettuce grown under UV lights? Who among us would be willing to live in a place where he could no longer breathe the air outside, and where he would have to wear a spacesuit all the time, knowing that out there the slightest accident would be enough to find himself dead in less than a minute? Sure, for an astronaut to walk on Mars would be an amazing and profound experience. But visiting the planet to expand the frontier of our knowledge is very different from living there permanently by forming bases and colonies. Mars is not made for humans. Mars will kill you! And now I will explain why… The Red Planet is a cold, dead place, with an atmosphere about 100 times thinner than Earth’s. The paltry amount of air that does exist on Mars is primarily composed of noxious carbon dioxide, which does little to protect the surface from the Sun’s harmful rays. Air pressure on Mars is only about 0.6 percent that of Earth. You might as well be exposed to the vacuum of space, resulting in a severe form of the bends—including ruptured lungs, dangerously swollen skin and body tissue, and ultimately death. The thin atmosphere also means that heat cannot be retained at the surface. The average temperature on Mars is -63 degrees Celsius, with temperatures dropping as low as -126. By contrast, the coldest temperature ever recorded on Earth was at Vostok Station in Antarctica, at -89 degrees on June 23, 1982. Once temperatures get below -40 degrees, people who aren’t properly dressed for the occasion can expect hypothermia to set in within about five to seven minutes. Mars also has less mass than is typically appreciated. Gravity on the Red Planet is just a third of the Earth’s, which means a 70 kg person on Earth would weigh a scant 25 kg on Mars. While that might sound appealing, this low-gravity environment would likely wreak havoc to human health in the long term, and possibly have negative impacts on human fertility. Yet despite these and many other issues, there’s this popular idea floating around that we’ll soon be able to set up colonies on Mars with ease. Elon Musk is projecting colonies on Mars as early as the 2050s, while astrobiologist Lewis Darnell, a professor at the University of Westminster, has offered a more modest estimate, saying it’ll be about 50 to 100 years before “substantial numbers of people have moved to Mars to live in self-sustaining towns.” The United Arab Emirates is aiming to build a Martian city of 600,000 occupants by 2117, in one of the more ambitious visions of the future. Sadly, this is literally science fiction. While there’s no doubt in my mind that humans will eventually visit Mars and even build a base or two, the notion that we’ll soon set up colonies inhabited by hundreds or thousands of people is pure nonsense, and an unmitigated denial of the tremendous challenges posed by such a prospect. Pioneering astronautics engineer Louis Friedman, co-founder of the Planetary Society, likens this unfounded enthusiasm to the unfulfilled visions proposed during the 1940s and 1950s. “Back then, cover stories of magazines like Popular Mechanics and Popular Science showed colonies under the oceans and in the Antarctic – Friedman told. The feeling was that humans would find a way to occupy every nook and cranny of the planet, no matter how challenging or inhospitable, but this just hasn’t happened. We make occasional visits to Antarctica and we even have some bases there, but that’s about it. Under the oceans it’s even worse, with some limited human operations, but in reality it’s really very, very little.” After the Moon landings, Friedman said he and his colleagues were hugely optimistic about the future, believing we would do more and more things, such as place colonies on Mars and the Moon, but the fact is, no human spaceflight program, whether Apollo, the Space Shuttle Program, or the International Space Station, has established the necessary groundwork for setting up colonies on Mars, such as building the required infrastructure, finding safe and viable ways of sourcing food and water, mitigating the deleterious effects of radiation and low gravity, among other issues. Unlike other fields, development into human spaceflight, he said, “has become static.” Friedman agreed that we’ll likely build bases on Mars, but the “evidence of history” suggests colonization is unlikely for the foreseeable future. NASA and other space agencies are currently working very hard to create and test countermeasures for the various negative impacts of living on Mars. For example, astronauts on the ISS, who are subject to tremendous muscle and bone loss, try to counteract the effects by doing strength and aerobic training while up in space, but we’re not there yet… is still not enough. In his latest book, On the Future: Prospects for Humanity, cosmologist and astrophysicist Martin Rees addressed the issue of colonizing Mars rather succinctly: “Don’t ever expect mass emigration from Earth. It’s a dangerous delusion to think that space offers an escape from Earth’s problems. We’ve got to solve these problems here. Coping with climate change may seem daunting, but it’s a doddle compared to terraforming Mars. No place in our solar system offers an environment even as clement as the Antarctic or the top of Everest. There’s no ‘Planet B’ for ordinary risk-averse people”. By terraforming, scientists are referring to the hypothetical prospect of geoengineering a planet to make it habitable for humans and other life. For Mars, that would mean the injection of oxygen and other gases into the atmosphere to raise surface temperature and air pressure, among other interventions. A common argument in favor of colonizing Mars is that it’ll allow us to begin the process of transforming the planet to a habitable state. But, as Friedman told, “that’s thousands of years in the making at least.” To be clear, terraforming is not necessarily an impossibility, but the timeframes and technologies required preclude the possibility of sustaining large, vibrant colonies on Mars for the foreseeable future. Until such time, an un-terraformed Mars will present a hostile setting for venturing pioneers. First and foremost there’s the intense radiation to deal with, which will confront the colonists with a constant health burden. There are many other big challenges to colonizing Mars, with radiation exposure being one of them. This is an “issue that a lot of folks, including those at SpaceX, aren’t thinking about too clearly. Living underground or in shielded bases may be an option, but we have to expect that cancer rates will still be “an order of magnitude greater” given the added exposure over time. We could quantify the risks for about a year, but not over the super long term. The problem is that you can’t stay underground or in bases forever. As soon as you go outside to do anything, you’re in trouble! In principle, we could create artificial environments on Mars, whether by building domes or underground dwellings, and so the radiation problem may be solvable, but the problems are still huge, and in a sense anti-human. Life in a Martian colony, in fact, would be miserable, with people forced to live in artificially lit underground bases, or in thickly protected surface stations with severely minimized access to the outdoors. Life in this closed environment, with limited access to the surface, could result in other health issues related to exclusive indoor living, such as depression, boredom from lack of stimulus, an inability to concentrate, poor eyesight, and high blood pressure – not to mention a complete disconnect from nature. And like the International Space Station, Martian habitats will likely be a microbial desert, hosting only a tiny sample of the bacteria needed to maintain a healthy human microbiome. “Hey guys, just a moment before we continue… BE sure to join the Insane Curiosity Channel… Click on the bell, you will help us to make products of ever-higher quality!” Another issue has to do with motivation. As Friedman pointed out earlier, we don’t see colonists living in Antarctica or under the sea, so why should we expect troves of people to want to live in a place that’s considerably more unpleasant? It seems a poor alternative to living on Earth, and certainly a major step down in terms of quality of life. A strong case could even be made that, for prospective families hoping to spawn future generations of Martian colonists, it’s borderline cruelty. And that’s assuming humans could even reproduce on Mars, which is an open question. Casting aside the deleterious effects of radiation on the developing fetus, there’s the issue of conception to consider in the context of living in a minimal gravity environment. We don’t know how sperm and egg will act on Mars, or how the first critical stages of conception will occur. And most of all, we don’t know how low gravity will affect the mother and fetus. The issue of human gestation on Mars is a troublesome unknown. The low gravity may also “confuse” the gestational process, delaying or interfering with critical phases of the fetus’ development. On Earth, bones, muscles, the circulatory system, and other aspects of human physiology develop by working against gravity. The human body might adapt to the low-gravity situation on Mars, but we simply don’t know. A strong case can be made that any attempt to procreate on Mars should be forbidden until more is known. Enforcing such a policy on a planet that’s 34 million miles away at its closest is another question entirely, though one would hope that Martian societies won’t regress to lawlessness and a complete disregard of public safety and established ethical standards. Astronauts who return from long-duration missions have a rough go for the first few days back on Earth, experiencing nausea, dizziness, and weakness. Some of them, like NASA’s Scott Kelly, never feel like their old selves again, including declines in cognitive test scores and altered gene function. The recovery time is proportionate to the length of the mission – the longer the mission, the longer the recovery. Disturbingly, we have no data for microgravity exposure beyond a year or so, and it’s an open question as to the effects of low gravity on the human body after years, or even decades, of exposure. With this in mind, it’s an open question as to how Martian colonists might fare upon a return visit to Earth. It might actually be a brutal experience, especially after having experienced years in a partial gravity environment. Children born on Mars (if that’s even a possibility) might never be able to visit the planet where their species originated. Finally, there’s the day-to-day survival to consider. Limited access to fundamental resources, like food and water, could place further constraints on a colony’s ability to grow and thrive. Establishing stable resources to live off for a long period of time is possible, but it’ll be tough. We’ll want to be close to water and water ice, but for that we’ll have to go pretty far north. But the further north you go, the rougher the conditions get on the surface. The winters are cold, and there’s less sunlight. Colonists will also need stable food sources, and figure out a way to keep plants away from radiation. The regolith, or soil, on Mars is toxic, containing dangerous perchlorate chemicals, so that also needs to be avoided. To grow crops, colonists will likely build subterranean hydroponic greenhouses. This will require specialized lighting, genetically modified plants designed specifically for Mars, and plenty of water, the latter of which will be difficult to source on Mars. Technological solutions to these problems may exist, as are medical interventions to treat Martian-specific diseases. But again, nothing that we could possibly develop soon. And even if we do develop therapies to treat humans living on Mars, these interventions are likely to be limited in scope, with patients requiring constant care and attention. As Martin Rees pointed out, Mars and other space environments are “inherently hostile for humans,” but as he wrote in his book, we (and our progeny here on Earth) should cheer on the brave space adventurers, because they will have a pivotal role in spearheading the post-human future and determining what happens in the twenty-second century and beyond. By post-human future, Rees is referring to a hypothetical future era in which humans have undergone extensive biological and cybernetic modifications such that they can no longer be classified as human. So while Mars will remain inaccessible to ordinary, run-of-the-mill Homo sapiens, the Red Planet could become available to those who dare to modify themselves and their progeny. A possible solution is to radically modify human biology to make Martian colonists specially adapted to live, work, and procreate on the Red Planet. As Rees wrote in On the Future: This might be the first step towards divergence into a new species. Genetic modification would be supplemented by cyborg technology – indeed there may be a transition to fully inorganic intelligence. So, it’s these spacefaring adventurers, not those of us comfortably adapted to life on Earth, who will spearhead the posthuman era. Indeed, modifying humans to make them adaptable to living on Mars will require dramatic changes. Our DNA would have to be tailored specifically to enable a long, healthy life on Mars, including genetic tweaks for good muscle, bone, and brain health. These traits could be made heritable, such that Martian colonists could pass down the characteristics to their offspring. In cases where biology is not up for the task, scientists could use cybernetic enhancements, including artificial neurons or synthetic skin capable of fending off dangerous UV rays. Nanotechnology in the form of molecular machines could deliver medicines, perform repair work, and eliminate the need for breathing and eating. Collectively, these changes would result in an entirely new species of humans – one built specifically for Mars. Like some of the other solutions proposed, this won’t happen any time soon, nor will it be easy. And it may not even happen. Which brings a rather discouraging prospect to mind: We may be stuck on Earth. As Friedman pointed out, this carries some rather heavy existential and philosophical implications. If humans can’t make it to Mars, it means we’re destined to be “a single-planet species,” he said. What’s more, it suggests extraterrestrial civilizations might be in the same boat, and that the potential for “intelligent life to spread throughout the universe is very, very gloomy.” “If we can’t make it to a nearby planet with an atmosphere, water, and a stable surface – which in principle suggests we could do it – then certainly we’re not going to make it much beyond that – said Friedman – But if we’re doomed to be a single-planet species, then we need to recognize both psychologically and technologically that we’re going to have live within the limits of Earth.” Which is a good point. That we may eventually become an interplanetary or interstellar species remains an open question. We must work to make this futuristic prospect a reality, but until then, we have to make sure that Earth – the only habitable planet we know of – remains that way.