NASA and Elon Musk’s SpaceX are both planning to put humans on Mars in the next 20 years – but a key hurdle is making the atmosphere breathable.
Now, scientists in China say a promising species of plant could convert the Red Planet’s rich atmosphere of carbon dioxide into breathable oxygen.
Steppe screw moss, also known as Syntrichia caninervis, is found in extreme desert landscapes like like Tibet and Antarctica.
Lab experiments show that it can survive freezing temperatures and lethal rays of radiation – typical conditions on the Martian surface.
According to the experts, the moss is even more resilient than tardigrades – the microscopic organisms described as ‘indestructible’.
Mars is the fourth planet from the sun – a dusty, cold, desert world with a thin atmosphere. Pictured, Mars captured by the Hubble telescope
Lab experiments show that the moss, called Syntrichia caninervis, survive freezing temperatures and powerful rays of radiation
The experts, from the Chinese Academy of Sciences in Beijing, aren’t suggesting that humans eat S. caninervis on Mars to stay alive (like Matt Damon’s character ate potatoes in ‘The Martian’).
That’s because the plant is not edible and would provide little nutritional value if we did eat it (although it’s not toxic).
However, if it could proliferate on the Red Planet, it could convert Martian carbon dioxide (CO2) to oxygen to help create a breathable atmosphere.
One of the many obstacles to ‘terraforming’ Mars is its atmosphere – around 95 per cent of which is made up of CO2, which is too high for humans to breathe.
‘Many plans to establish human settlements on other planets focus on adapting crops to growth in controlled environments,’ the team say.
Pictured, the team’s graphical abstract showing the plant’s ability to turn Martian CO2 into breathable oxygen – while withstanding radiation and freezing temperatures
The experts aren’t suggesting that humans eat S. caninervis on Mars to stay alive, because the plant is not edible. Pictured, Matt Damon as Dr Mark Watney growing potatoes on Mars in the 2015 film ‘The Martian’
‘Our study shows that the environmental resilience of S. caninervis is superior to that of some of highly stress-tolerant microorganisms and tardigrades.’
S. caninervis – already well known for its ability to tolerate drought conditions – is found in Tibet, Antarctica and the circumpolar regions of Eurasia and North America.
Given the moss’s ability to survive extreme environmental conditions, the researchers decided to test its limits in the lab.
They stored the plant at -112°F (-80°C) in an ultra-cold freezer for up to five years and at -320°F (-196°C) in a liquid nitrogen tank for up to 30 days.
In all cases, the plants regenerated when they were defrosted, although their rebound was less rapid compared to control specimens that had been dehydrated but not frozen.
It’s unclear how the researchers would expect the moss to be defrosted when constantly exposed the the frigid Martian conditions, however.
In lab tests, the plants regenerated when they were defrosted, though their rebound was less rapid compared to control specimens that had been dehydrated but not frozen
In the lab tests, the moss also demonstrated the ability to survive gamma radiation exposure that would kill most plants, typical of what the Martian surface is exposed to.
Amazingly, powerful doses of radiation at 500 Gray (Gy) even seemed to promote the plants’ growth – namely, ‘the regeneration of new branches’.
For comparison, humans experience severe convulsions and death when exposed to around 50 Gy of radiation.
Finally, the experts tested the moss’s ability to endure Mars-like conditions using the Chinese Academy of Sciences’ Planetary Atmospheres Simulation Facility, a ultra-high-vacuum (UHV) simulation chamber.
The simulator’s Martian conditions included air composed of 95 per cent CO2 (the same as on Mars) and fluctuating temperatures that went above and below freezing, as well as high levels of UV radiation and low atmospheric pressure.
Steppe screw moss (Syntrichia caninervis) waiting for rain among lichens in Hackberry Canyon of Hovenweep National Monument, Colorado, US
Dried moss plants achieved a 100 per cent regeneration rate within 30 days after being subjected to the Martian conditions for one, two, three, and seven days.
Hydrated plants, which were only subjected to the simulator for one day, also survived, though they regenerated more slowly than their desiccated counterparts.
The team caution that their study does not prove that the moss could be transported to Mars or even explain how it would be planted there.
However, the study identifies S. caninervis as ‘a pioneer plant for growth’ on the Red Planet, as space agencies work towards ‘self-sufficient habitats’ there.
‘Looking to the future, we expect that this promising moss could be brought to Mars or the moon to further test the possibility of plant colonization and growth in outer space,’ they say.
‘Our results indicate that S. caninervis is among the most radiation-tolerant organisms known.’
The study has been published in the journal The Innovation.
