Desert moss could hold the key to terraforming Mars, according to a recent study by Chinese scientists.
Due to its extraordinary resilience, Syntrichia caninervis (S. caninervis), a moss species found in extreme deserts from Tibet to Antarctica, is being touted as a ‘pioneer plant’ for creating a habitable environment on MarsScientists believe that this plant could enrich the rocky surface of the planet, thus enabling the growth of other plants.
A few studies have explored alternative possibilities for these terraforming seeds, such as algae and lichens. “However, plants such as mosses offer important advantages for terraforming, including stress tolerance, a high capacity for photoautotrophic growth, and the potential to produce significant amounts of biomass under challenging conditions,” the team of the new study wrote in the paper.
It is believed that mosses were the first true land plants SoilThis allowed them to develop a tolerance for extreme stress, allowing them to survive in the very harsh conditions of our planet.
But how extreme is that?
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The moss trials
The scientists exposed whole S. caninervis plants to conditions typical of Mars: high doses of gamma radiation, low oxygen, extreme cold, and drought. They report that the plants were able to withstand a combination of these conditions, even losing more than 98 percent of their water content and flourishing again within seconds — “drying without dying,” is the term used. Perhaps even more astonishing is the plant’s ability to recover and grow new branches after being stored for five years in a freezer at -80 degrees Celsius (-112 degrees Fahrenheit) or for a month in liquid nitrogen (-195.8 degrees C; -320.44 degrees F).
“Unique morphological features of S. caninervis, such as twisted leaves, conserve water by minimizing surface area and reducing transpiration, and the awns provide efficient photoprotection against intense UV radiation, extreme temperatures, and water loss,” the team wrote. “Meanwhile, the cell wall, cell membrane, and chloroplast and membrane structure remain intact even in a completely dehydrated state.”
Under stress, S. caninervis enters a state of “selective metabolic dormancy,” conserving strategic key metabolites — products of cellular metabolic pathways — needed for rapid recovery. “For example, S. caninervis plants retain high levels of sucrose and maltose following stress; these sugars serve as osmotic agents and protectors that help maintain and stabilize cellular architecture,” the scientists wrote. “The sugars then provide the energy needed for rapid recovery following relief from stressful conditions.”
Stress also activates genes that code for photoprotective proteins and enzymes that help clean up harmful reactive oxygen species generated under radiation. “The multi-layered tolerance [provides] “It provides protection under stressful conditions and ensures rapid cell repair and recovery of physiological activity when conditions are suitable for growth,” the team said.
These findings, the scientists continue, lay the foundation for building sustainable human habitats beyond Earth. Whether this claim is overblown depends on future experiments—and may not even be feasible in our lifetimes—but one key element missing from the discussion is not the feasibility of the science, but the ethics behind it.
Do humans belong on Mars?
This concept of terraforming another planet is not new and has its roots in science fiction. And while the concept has been romanticized and bandied about in the media of late, there are serious concerns about the extraterrestrial-scale social implications of completely transforming an entire planet for human habitation.
In her essay entitled The Prickly Ethics of Planetary Engineering, for example astrophysicist and NASA Researcher Erika Nesvold puts the dilemma very clearly: “The goal of terraforming is to deliberately create an entire ecosystem on a global scale, which would most likely destroy any existing ecosystem,” she wrote. “Terraforming technology might even become feasible before we have definitively determined whether alien life exists on the planet or moon we hope to transform.
“But suppose we find evidence of existing microbial life on a planet like Mars,” she continued. “Should that disqualify Mars as a target for terraforming? Should we avoid settling Mars altogether?”
The study was published on July 1 in the magazine The Innovation.