Desert Moss Shows Potential for Terraforming Mars

Syntrichia caninervis, a desert moss, shows great promise for Mars colonization due to its remarkable ability to survive in harsh conditions that are lethal to most other life forms.

Although moss can withstand drought conditions well, researchers have discovered that it can withstand high levels of gamma radiation, freezing temperatures as low as -196 °C, and combined Martian conditions simulating all three stressors.

The study was published in the journal The Innovation. In every instance, pre-dehydration appeared to aid the plants in coping.

The researchers wrote, “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 is a promising candidate pioneer plant for colonizing extraterrestrial environments, laying the foundation for building biologically sustainable human habitats beyond Earth.”

This is the first study to test entire plants against the harsh conditions of Mars or space; a few earlier studies have tested the resistance of microorganisms, algae, lichens, and plant spores.

The common moss species Syntrichia caninervis is found all over the world. As a component of the biological soil crust—a common and hardy kind of ground cover frequently found in arid regions—it grows in remarkably harsh desert environments, such as Tibet, Antarctica, and the circumpolar regions. The moss can withstand harsh environmental conditions, so the researchers decided to push it to the limit in a lab setting.

The researchers kept the plants for three and five years at −80 °C (in an ultra-cold freezer) and for 15 and 30 days at −196 °C (in a liquid nitrogen tank) to test the moss’s ability to withstand cold. Plants that were not dehydrated before freezing rebounded more slowly than plants that were dried and then frozen, but overall, the plants recovered when they were defrosted, albeit at a slower rate than control specimens that had been dehydrated but not frozen.

The moss also showed that it could withstand exposure to gamma radiation, which would normally be fatal to most plants. Doses of 500 Gy of radiation appeared to encourage the growth of the plants. In contrast, exposure to approximately 50 Gy causes severe convulsions and death in humans.

The researchers wrote, “Our results indicate that S. caninervis is among the most radiation-tolerant organisms known.”

Lastly, the researchers used the Planetary Atmospheres Simulation Facility at the Chinese Academy of Sciences to test the moss’s resilience to Mars-like conditions. The Martian conditions replicated in the simulator were low atmospheric pressure, high UV radiation, temperatures ranging from −60 °C to 20 °C, and air made up of 95% CO₂.

After being exposed to Martian conditions for 1, 2, 3, and 7 days, dried moss plants reached a 100% regeneration rate in just 30 days. Even after only one day of exposure to the simulator, hydrated plants were able to survive, albeit at a slower rate of regeneration than their desiccated counterparts.

The researchers concluded, “Although there is still a long way to go to create self-sufficient habitats on other planets, we demonstrated the great potential of S. caninervis as a pioneer plant for growth on Mars. 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.”