SpaceX plans to send humans to Mars by 2024 and establish a Martian city by 2050 but how plausible is this? Here’s why it’s going to take a little more than a billionaire’s cash stash to populate the red planet…
In July next year, NASA’s Mars 2020 space lander will begin its 38 million-mile journey to the red planet’s Jezero crater. Once there, the rover will collect rock and soil samples, test oxygen production and identify past microbial life. The mission is part of NASA’s long term objective: gaining enough understanding of Mars to be able to send humans there by the 2030s.
But NASA isn’t alone in its quest. Government-backed space agencies in China, India, Russia and the UAE all plan to launch either Mars-bound orbiters or landers in the next five years. Private companies have also joined the race. Some have dropped out – the Dutch organisation Mars One went bankrupt earlier this year after receiving millions of dollars from investors – while South African entrepreneur Elon Musk thinks he can pip NASA to the post by sending commercial flights to Mars in the mid 2020s.
As outlined in his highly entertaining research paper, Making Humans a Multi-Planetary Species, Musk’s company, SpaceX, is planning to send two unmanned cargo ships to Mars in 2022. The ships’ objectives include confirming water resources, identifying hazards and putting in place power, mining and life support infrastructure. A second, manned mission, is planned for 2024. And after that? Well, Musk’s ultimate plan is to neutralise the harsh conditions of the Red Planet by terraforming it. So, is this even scientifically plausible?
Mars has an incredibly thin atmosphere, around 0.6% of that of Earth, meaning any human on its surface would be unprotected from the sun and its harmful radiation. NASA estimates that for a six-month journey to Mars, an astronaut would be exposed to 300 milliSieverts of radiation, the equivalent of 24 CAT scans.
As with most things Elon says there is a kernel of viability, however the required technology is somewhat distant and so when you look that far into the future you can say almost anything is possible
While Musk has said that he thinks the risk of cancer from radiation would be “relatively minor”, Peter Read, Professor of Physics at the University of Oxford, says: “Martian astronauts probably have to be prepared for some significant exposure to radiation levels higher than found on Earth – this is especially the case also for the journey to and from Mars, which may be even more hazardous from radiation exposure than on the surface.”
Wieger Wamelink, exobiologist at the Wageningen Environmental Research centre in the Netherlands, says: “Cosmic radiation reaches the surfaces making plant life, and human life, impossible. Therefore we will have to live in either caves and then still in pressurized domes or below ground.”
Earth’s atmosphere not only protects us from radiation, but retains a steady temperature night and day. Mars’ lack of atmosphere, on the other hand, means it does not retain heat from the sun as effectively – its average global temperature is around -60°C.
Thickening the Martian atmosphere to more closely resemble the one we have on Earth is, as amazing as it sounds, an idea that has been mooted – not only to protect us from radiation, but to heat up the planet to ensure we don’t instantly freeze to death. This would also melt the most prominent potential source of water on the planet – the polar ice caps. Releasing greenhouse gases, such as CO2, into the Martian atmosphere could be the solution.
Dr Jonathan Fellows at the University of Bristol’s School of Physics says: “In principal you could add more [CO2] to get something thick enough to walk around in. The problem is that you would need an awful?lot of CO2 to achieve this.
“You would need about two and a half quadrillion tonnes of CO2 to give Mars the same atmospheric pressure at ground level that we have on Earth,” he says. “I don’t know that there is that much CO2 available to release on Mars.”
Neither does NASA. Its MAVEN spacecraft, which it launched in 2013, led it to determine that processing all sources on Mars would only create enough CO2 to increase atmospheric pressure to about 7% of that on Earth – not enough for the greenhouse warming required.
Undeterred, Musk is adamant that there is enough CO2 on Mars. He says that Martian polar caps and soil are sources of CO2 and water that could be released upon heating to thicken the atmosphere. Never one for half measures, his proposed methods to do this include firing nuclear weapons at the planet to create tiny pulsing suns that would direct concentrated rays of heat. Strong infrared absorbing substances, such as ammonia or chlorofluorocarbons, could also enhance greenhouse warming and help heat up the planet.
But pumping out masses of CO2 is not conducive to creating a breathable Martian atmosphere. Mars is made up of 95% carbon dioxide, 2.7% nitrogen and only 0.13% oxygen, compared to 21% on Earth. A trip to Mars would therefore require an inexhaustible supply of oxygen. So, an alternative to carrying massive O2 tanks on board would be to create an oxygen-generating source once we’re there – one that could also feed us…
An abundance of CO2 on Mars would make for ideal conditions for plant growth – if it weren’t for a lack of sunlight and water and, as we’ve established, lethal radiation levels.
Nightly temperatures of around -73°C means plant crops would be obliterated outside of carefully monitored conditions, such as heated growth chambers.
But technologies for sustaining crop growth are promising. NASA’s plant researchers have experimented with crops grown under specially controlled lights and temperatures with success. And last year, the German Aerospace Center’s simulation of the polar conditions on Mars in a greenhouse in the middle of Antarctica led to successful harvests of 150kg of vegetables.
But part of the quest to terraform Mars means making use of the resources that are already there, including soil. Luckily, NASA says Martian soil contains the essential nutrients plants need to survive, although it is thought to contain salts known as perchlorates, which are toxic to humans and would need to be leached out. Fertilizers, such as human waste, may also need to be added.
Nathaniel Szewczyk, Professor of Space Biology at the University of Nottingham, says it’s almost certain that crops will grow on Mars.
“In terms of growing traditional crops and livestock, this is, perhaps surprisingly, not something that much work has been done on,” he said. “[But] if you look at the diversity of life on Earth, life can adapt – it would be shocking if it couldn’t adapt to Mars.”
At the Wageningen Environmental Research centre, scientists have been conducting experiments into the suitability of Martian soil to develop a sustainable agricultural system for life on Mars. Using soil simulants from NASA, they have been able to produce more than a dozen different crops, including tomatoes, rye, cress, rocket, carrots, peas and potatoes.
Professor Wamelink says that fruits rich in vitamin C and E could help protect us against radiation, while Earthworms (which would, presumably, have to be rechristened Marsworms) could help recycle dead plant matter to produce compost. A Martian diet could also consist of fish, which may play a role in purifying water sources, he says.
All this sounds highly promising, so could Elon really be on to something? It may be worth bearing in mind, however, that a Martian settlement will need at least 20,000 square meters of photosynthesis-producing surface area for 100 humans to be able to breathe – which could make a crop failure lethal.
As Mars has less mass than Earth, surface gravity is 38% of that on our home planet. While this would give humans the ability to jump 9ft into the air, which could come in handy, it would mean our limbs aren’t working as hard, causing muscle atrophy and adverse effects on the immune system.
Maggie Lieu, research fellow at the European Space Agency, says: “Without gravity, blood will surge to your eyes and brain, the change in pressure affects the heart and also leads to sight loss – these are things that are still needing to be solved.”
Although the drop in gravity on Mars would be less severe than that on the ISS, regular exercise would still be vital to keep our blood circulating and our bones from demineralising. This is because the human heart is designed to pump against gravity, so blood and other fluids would accumulate upwards.
This has been considered such a problem that as a way of tackling poor circulation on Mars, research students at Curtin University in Australia suggested amputating our arms and legs and replacing them with bionic limbs before we move to Mars could be a more viable way of tackling the issue of poor circulation.
If this doesn’t tempt you, NASA-funded research at the Medical University of South Carolina found that microgravity causes astronauts’ brains to become squashed near the top of the skulls, putting pressure on vital neural areas. MUSC scientists have since called for more time and efforts to understand the impact of prolonged space travel and microgravity on our brain.
“Exposure to the space environment has permanent effects on humans that we simply do not understand,” according to MUSC neuroradiologist?Donna Roberts.
Musk admits there is a “good chance of death” on Mars, but of course, this is part of the challenge of advancing human endeavour in space. The reality is that the fundamental rules that govern how our body functions are turned on their head once we’re on a different planet.
The question remains, therefore, how much a manned crew can achieve in their efforts to set up a civilisation before being debilitated, and possibly killed, by the adverse effects of microgravity.
NASA says terraforming Mars is impossible due to the need for technologies that simply don’t exist. Its more conservative estimate for putting humans on Mars is in the 2030s.
Scientific, practical and ethical considerations of doing so are numerous, from the consistent water supplies, to dust storms that could ruin machinery, transfer of Earth-borne contaminants, to the effects on our astronauts. Would using a group of human guinea pigs in the name of science, however willingly, constitute the greater good if it meant damaging physical and psychological effects or even certain death?
Professor Read says: “The psychology of sustaining a small, tight-knit team of astronauts confined to small quarters for long periods of time and isolated from Earth is still quite challenging.
“The ISS has provided some experience of maintaining a group of astronauts in space for many months, but they are always close to Earth and can be relatively easily supplied or evacuated back to Earth at short notice,” he says. “This wouldn’t be the case for a Martian colony.”
Since the Mars One fiasco, it’s ever more important to take Musk’s predictions with a healthy deal of scepticism. On the other hand, SpaceX is being funded out of Musk’s own pocket. Unlike Mars One, this project seems to be born from genuine love for space, not money.
So is the mid-2020s estimate at all feasible? Professor Chris Done at Durham University’s Department of Physics thinks not. “Not even if he threw a shedload of cash at it. If he had a working, tested design now it would take a few years just to put it together, but no-one has such a design – so he needs to develop technology first.”
Professor Wamelink says: “More likely we will go for the first time between 2030 and 2040 – and maybe this will only be a flyby.”
Daniel Brown at Nottingham Trent University’s School of Science & Technology says: “A general manned mission to Mars could be achieved if sufficient resources are allocated and we see ‘to Mars’ in a wider, looser term. Proposals include to not go directly to Mars, but arrive in an orbital position, for example on one of the moons.
“A long-term idea of a Martian base would require a far more extended preparation period and involve a period of unmanned missions providing more information and depositing supplies.”
Malcolm Macdonald, space technology engineer at the University of Strathclyde, says: “As with most things Elon says there is a kernel of viability, but the required technology is somewhat distant and so when you look that far into the future you can say almost anything is possible.
“However, that doesn’t overcome the ethical questions around such drastic vandalism of a planet we barely understand and whether we should because we might one day be able to.”
Mars’ geological features suggest the planet had an active hydrological cycle about 3-4 billion years ago. Solar wind and radiation has stripped Mars of most of its atmosphere, changing the climate from warm and wet to dry. If Mars was ever home to extra-terrestrial life, it was billions of years ago, and this dusty death desert of a space rock is all that is left – a reminder of former life and irreparable changes to an entire planet.
Andy Young, Senior Physics Lecturer at the University of Bristol, says: “Elon Musk’s plans to set up a Mars base, even without terraforming, are really exciting. But maybe not as a plan B we can rely on instead of looking after our own planet.”