While Matt Damon relied on potatoes cultivated in crew biowaste to survive in the hit film The Martian, researchers say it is a humble desert moss that might prove pivotal to establishing life on Mars.
Scientists in China say they have found Syntrichia caninervis – a moss found in regions including Antarctica and the Mojave desert – is able to withstand Mars-like conditions, including drought, high levels of radiation and extreme cold.
The team say their work is the first to look the survival of whole plants in such an environment, while it also focuses on the potential for growing plants on the planet’s surface, rather than in greenhouses.
“The unique insights obtained in our study lay the foundation for outer space colonisation using naturally selected plants adapted to extreme stress conditions,” the team write.
Prof Stuart McDaniel, an expert on moss at the University of Florida and who was not involved in the study, suggested the idea had merits.
“Cultivating terrestrial plants is an important part of any long-term space mission because plants efficiently turn carbon dioxide and water into oxygen and carbohydrates – essentially the air and food that humans need to survive. Desert moss is not edible, but it could provide other important services in space,” he said.
Dr Agata Zupanska, of the SETI Institute, agreed, noting moss could help enrich and transform the rocky material found on the surface of Mars to enable other plants grow.
“Otherwise, moss is not tasty and does not make a great addition to the salad,” she said.
Writing in the journal The Innovation, researchers in China describe how the desert moss not only survived but rapidly recovered from almost complete dehydration. It was also able to regenerate under normal growth conditions after spending up to five years at -80C and up to 30 days at -196C, and after exposure to gamma rays, with doses of around 500Gy even promoting new growth.
The team then created a set-up that had similar pressures, temperatures, gases and UV radiation to Mars. It found the moss survived in this Mars-like environment, and was able to regenerate under normal growth conditions, even after seven days of exposure. The team also noted plants that were dried before such exposure faired better.
“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 colonisation and growth in outer space,” the researchers write.
McDaniel noted most plants cannot withstand the stresses of space travel.
“This paper is exciting because it shows that desert moss survives short exposures to some of the stresses that are likely to be found on a trip to Mars, including very high levels of radiation, very cold temperatures, and very low oxygen levels,” he said.
But he added the research had limitations.
“These experiments represent an important first step, but they do not show that the moss could be a significant source of oxygen under Martian conditions, nor do they show that the desert moss could reproduce and proliferate in the Martian context,” McDaniel said.
Zupanska added that, among other problems, the study did not test the impact of particulate radiation.
“In my opinion, we are getting close to growing plants in extraterrestrial greenhouses, and moss certainly has a place in those,” she said. “Implying that moss, or any other pioneering species, is ready to terraform Mars, or any other outer planet, is an exaggeration.”
Dr Wieger Wamelink of Wageningen University, also raised concerns, including that temperatures on the red planet rarely get above freezing, making outdoor plant growth impossible, while the new study did not use Mars-like soil.
“The mosses were treated under Mars circumstances for a maximum of several days and then regrown under Earth conditions on sand,” he said. “This, of course, does not show at all that they can grow under Mars conditions.”
However, Prof Edward Guinan of Villanova University in the US described the study as impressive.
“This extremotolerant moss could be a promising pioneer plant for Mars colonisation,” he said, although he noted the moss would need water to grow.
“We have a long way to go,” he said. “But this lowly desert moss offers hope for making small portions of Mars habitable for humankind in the future.”