Plant Identified That Could Grow on Mars

A future civilization on Mars could be accompanied by one very special and resilient little plant.

A type of moss found in the desert—named Syntrichia caninervis—may be able to survive and grow in the harsh environment of Mars, according to a new paper in the journal The Innovation.

This moss can grow in freezing temperatures as cold as -320.8 degrees Fahrenheit, and can survive levels of gamma radiation that would kill most other plants and life forms.

The plant can also withstand incredibly dry conditions, as well as a combination of dryness, heavy radiation, and cold weather in a simulation of the conditions on the Red Planet.

“Our study shows that the environmental resilience of S. caninervis is superior to that of some of highly stress-tolerant microorganisms and tardigrades,” the researchers wrote in the paper. “S. caninervis is a promising candidate pioneer plant for colonizing extraterrestrial environments, laying the foundation for building biologically sustainable human habitats beyond Earth.”

Mars has a range of conditions that make it challenging for potential human exploration and habitation, with a thin atmosphere composed primarily of carbon dioxide, with small amounts of nitrogen, argon, and trace amounts of oxygen and water vapor. The atmospheric pressure on Mars is less than 1 percent of Earth’s, averaging about 6 millibars, compared to Earth’s 1,013 millibars at sea level, and the average surface temperature is about -80 degrees F, but can range from about -195 degrees F during winter at the poles to 70 degrees F during summer at the equator.

Additionally, water on Mars exists mostly as ice, with polar ice caps composed of water and dry ice (frozen carbon dioxide). Mars also does not have a global magnetic field like Earth, meaning that anything on its surface is exposed to high levels of cosmic radiation that would pose a significant risk for human explorers and anything being grown in its soils.

This is the first time that a whole plant has been tested for its ability to withstand conditions in space or on another world. Syntrichia caninervis is found across the world growing in harsh environments, ranging from Tibet to Antarctica, making it the perfect candidate for testing under Mars conditions.

In the paper, the researchers describe how the moss was stored at -112 degrees F for three or five years, and at -320 degrees F for 15 and 30 days. After being defrosted, they discovered that the plants were able to regenerate and grow. They also found that if the moss had been dehydrated prior to freezing, they recovered faster.

They also tested the plant under varying radiation doses, finding that it survived and even thrived at levels of up to 500 Gray (Gy)—humans, for comparison, usually die after exposure to about 8 Gy.

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

The researchers then combined all of these Martian environmental factors, exposing the plant to fluctuating temperatures of between -76 and 68 degrees F, low atmospheric pressure, air made up of 95 percent CO2, and high levels of ultraviolet radiation. They found that if the moss had been dried prior, it had a recovery rate of 100 percent 30 days after exposure, while hydrated plants also recovered, but much more slowly.

“S. caninervis represents a promising candidate as a colonist to facilitate terra-
forming efforts on Mars or other planets. This is not only because S. caninervis
is a land plant with extreme multiple stress tolerance but also because it could
serve as a pioneer species and the basis for the establishment and maintenance
of the ecosystem by contributing to oxygen production, carbon sequestration,
and soil fertility,” the researchers wrote. “Thus, S. caninervis can help drive the atmospheric, geological, and ecological processes required for other higher plants and animals while facilitating the creation of new habitable environments conducive to long-term human settlement.”

They continued: “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.”

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