Syntrichia caninervis: Moss that survives deep freeze and radiation could live on Mars

A hardy moss found in desert locations around the globe can survive environmental conditions that are lethal to almost all other life forms, suggesting it could be the first possible pioneer species for the colonisation of Mars.

Syntrichia caninervis is widespread in some of Earth’s harshest locations, including Tibet and Antarctica, so Xiaoshuang Li at the Xinjiang Institute of Ecology and Geography in Urumqi, China, and his colleagues decided to subject it to a brutal suite of tests to discover just how much it could survive.

The researchers found that the moss could regenerate after being stored at -80°C for five years or in liquid nitrogen at -196°C for a month. They also bombarded it with doses of gamma radiation and found that up to 500 Gray units (Gy) actually helped the moss regenerate, while only doses over 8000Gy caused severe damage. Most plants can’t cope with radiation above 500Gy, while 50Gy is enough to cause convulsions and death in humans.

Putting this all together, the team put the moss in simulated Martian conditions, including an atmosphere composed of 95 per cent carbon dioxide, temperatures that fluctuated from -60°C to 20°C, high levels of UV radiation and low atmospheric pressure. Even after a week in the simulator, the moss was able to fully regenerate after 30 days.

That said, one environmental factor the team didn’t address was the impact of perchlorates, a toxic, corrosive chemical thought to be widespread in Martian soils.

David Eldridge at the University of New South Wales in Sydney, Australia, says that if the moss is to truly thrive, it will eventually need some relief from extreme cold and desiccation, but on Mars, unlike Earth, such conditions are unrelenting.

“If there is one plant that is capable of living on Mars, it is that moss,” he says. Eldridge suspects, however, that humans could take them to Mars put them on the surface and they would continue to be alive, but barely. “It might survive, but I doubt it would thrive,” he says.

Sharon Robinson at the University of Wollongong, Australia, says that although the plant could survive, it isn’t entirely clear why we would want to take the moss to Mars. “We can’t eat them, although if they were photosynthesising they might be able to make a bit of oxygen,” she says. Alternatively, the moss could be a home for tardigrades, an equally hardy species.