Mars is sometimes put forward as offering a "new home" if we poison the Earth's environment or damage its weather systems. But is this something that could happen or is it all material for Hollywood blockbusters? Here we look at the potential and ask: Can the Martian environment provide a home for humanity?
The make-up of the Martian atmosphere and nature of its environment is a key consideration in humanity’s plans to colonise Mars. If human life is to be sustainable on the red planet, scientists will have to command a complete knowledge of its environment, and develop the know-how to deal with it.
In September, Elon Musk – founder and chief executive of SpaceX – publicly announced the company's long-term plan for regular transport to Mars. Musk believes we can send people to the planet in about 10 years. By then the SpaceX team will have analysed and assessed a huge amount of data concerning the planet's environment, atmosphere, and weather.
But according to Kevin Nolan, the author of Mars: A Cosmic Stepping Stone and a lecturer at Tallaght Institute of Technology, it is entirely unclear how a settlement on Mars could become a reality any time soon.
"As challenging as it is to get a human-rated vehicle to the surface of Mars, it is nothing compared to the challenge of developing on-surface habitats, " says Nolan.
The average temperature on the planet is estimated to be –55 degrees, with surface temperatures reaching highs of about 20 degrees at the equator, and lows of –150 degrees at the poles. Nevertheless, Mars has an atmosphere more similar to Earth than any other planet in the solar system. For example, like Earth, Mars has seasons, meaning seasonal changes in its atmosphere and weather.
But the Martian atmosphere is much thinner than Earth’s, meaning atmospheric pressure is so low that the blood of any unprotected visitor would boil.
“Mars’s atmosphere is only 1 per cent as dense as the Earth’s, and unless terraformed, likely taking hundreds of years, all human habitats on Mars will be in enclosures,” Nolan says.
However, the atmospheric composition does provide a boon for those wishing to return home.
“Mars’ atmosphere, as thin as it is, is mostly carbon dioxide, so it will be very useful for manufacturing methane as fuel,” Nolan says.
This will be important when considering the extreme cost of each kilogram sent into space. In fact Nasa’s current plans for Mars do not include fuel for a return trip; rather “astronauts will have to manufacture tons of methane as their fuel to get back off the surface”.
Dust devils and storms
The Martian atmosphere is also too thin to maintain a stable temperature, meaning strong winds can quickly develop as temperatures fluctuate dramatically. The winds on Mars raise the red dust from the surface, which – by becoming suspended in the atmosphere for long periods of time – cause the planet to be a very dusty place.
"This can have a devastating effect on solar power, and indeed on all operations on the planet," says Nolan. "Nasa sees dust management as among the toughest challenges for human missions to the surface."
On the surface, dust devils – whirlwinds of dust – are generated in areas where the land is sufficiently heated by the sun. Some of these are taller than Mount Everest, and can be triggered even more rapidly than tornadoes on Earth.
But much more worrying are Martian dust storms, similar to those seen in the movie The Martian, which begin as smaller dust devils and can become global monsters in scale.
According to Nolan, “These dust storms arise frequently and can cover huge regions of the planet for months or years on end.”
Because of the size of these storms and their associated effects, like blocking out the sun and dramatically lowering surface temperature, they will be a major concern for future visitors and inhabitants of the planet.
Another key issue for human life will be water supply and agriculture. Because the boiling point of water depends on atmospheric pressure, any liquid water on the surface of Mars boils instantly.
“Mars’s thin atmosphere means that water cannot exist for any length of time in the liquid state,” says Nolan. “Any water on Mars – and there’s more than enough water there – is stored as ice under the surface,” he says.
So, however quickly humanity manages to begin sending people to Mars, it looks like overcoming the challenges for sustainable life on its surface will require much more time.
“Even with everyone engaged – including billionaires – we’re probably looking at 2100 before the first truly permanent presence on the planet is established,” Nolan says.
Conor Purcell PhD is a science and nature writer who regularly writes for The Irish Times. He can be found on twitter @ConorPPurcell and some of his other articles at cppurcell.tumblr.com.
MARTIAN AGRICULTURE
Plants need light, carbon dioxide, heat, water and nutrients to grow healthily using the process of photosynthesis. On Mars there is an abundance of sunlight and carbon dioxide. Heat can be sourced near the equator, or in an enclosure powered by solar energy, and water can be artificially extracted in liquid form. But the lack of nutrients will prove to be a real issue.
On Earth, plants take nutrients from the soil in which they grow. But on Mars “the soil is completely lifeless, with no nutrients, and is mostly a super-peroxide which would kill all organic material that comes into contact with it”, says Kevin Nolan. “So it is totally useless for agriculture.”
Because of this all Martian soils will have to be chemically altered, he says, “and it is likely that all agricultural soils used in early colonies will be shipped from Earth”.
And even in the case that all of these requirements for plant life are satisfied, there still remains the problem that Mars has no magnetic field.
Unlike Earth, Mars’s surface is not protected from very harmful cosmic and solar radiation, Nolan says. “And hence a range of hitherto unforeseen problems will arise on the genetic and cellular level, potentially impacting on soil nutrition and vegetation health.”
This radiation issue will probably take decades to solve, and will require research that cannot be carried out on Earth alone.