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The desert moss that could help terraform Mars

AI generated image of Mars in the process of being terraformed. Credit: Image Creator

Mars is currently not very hospitable to life, although it may have been billions of years ago. Many Mars settlement advocates and science fiction writers dream of the turning the Red Planet green by terraforming its atmosphere to make it more Earth-like. Even partially changing smaller regions, i.e. para-terraforming, would be a good first step.

To get things started it would be helpful if there were organisms that could survive the frigid temperatures, low ambient pressure and harsh radiation on Mars while helping to boost the oxygen levels in the atmosphere and assisting with soil fertility. Fortunately, there is a desert moss called Syntrichia caninervis that fits the bill. In a report in the journal The Innovation a team* of Chinese researchers present results of a study that demonstrate the extremotolerance of this plant to conditions on the Red Planet. This hardy organism can withstand temperatures down to a frosty -197°C, has extreme desiccation tolerance recovering within seconds after losing 97% of its water content and is super resistant to gamma radiation.

S. canivervis is a pioneering organism that has wide distribution in extreme biomes on Earth, from the Gurbantunggut Desert in China to the Mojave Desert in the California . It plays a key role in development of biological soil crust, a type of widespread ground cover which is the precursor of fertile soil. A major source of carbon and nitrogen in arid regions, these so called “living skins of the Earth” are responsible for a quarter of the total nitrogen fixation of terrestrial ecosystems. As stated in the paper, this resilient moss “…has evolved several morphological mechanisms to adapt to extreme environments, including overlapping leaves that conserve water and shield the plant from intense sunlight and white awns at the tops of leaves that reflect strong solar radiation and enhance water utilization efficiency.”

To test the desiccation tolerance of S. caninervis the researchers subjected the organism to air-drying treatment followed by measurements of plant phenotypes, water content, photochemical efficiency and changes in leaf angle. The mosses exhibited an exceptional ability to recover rapidly after being dehydrated. Incredibly, the plants were observed to be green when hydrated, turned black as water was gradually extracted, then returned to green only after 2 seconds upon rehydration.

Extended low temperature tolerance was tested by placing two samples of the plants in a freezer set at -80o C for 3 and 5 years, respectively. Short duration extreme cold was studied by subjecting the samples to -196o C in a liquid nitrogen tank for 15 and 30 days. The plants were then cultivated normally to determine their ability to regenerate. Remarkably, in the 3 and 5 year long duration freezer cohorts, both sample branch regeneration rates recovered to approximately 90% of that observed in the control group after 30 days of growth. Similar results were noted for the plants subjected to the 15 and 30 day -196o C treatment with 95% regeneration rate when compared to the controls.

For radiation resistance, samples of S. caninervis were subjected to gradually increasing levels of gamma radiation from 500 Gy up to 16000 Gy. At the upper end of the range the plants died. However, the organism survived exposures up to 2000 Gy with regeneration of branches slightly delayed when compared to controls with no radiation exposure (most plants can’t tolerate more than 1000Gy). A surprising result was noted when exposure to 500 Gy actually increased the regeneration of branches vs no exposure. Humans are sickened by exposure to 2.5 Gy and die upon exposure to 50 Gy. These results demonstrate that S. caninervis has exceptional radiation tolerance.

Finally, simulated Mars conditions were tested by placing S. caninervis in an environmental chamber called the Planetary Atmospheres Simulation Facility operated by the Chinese Academy of Sciences. Parameters were set in the chamber to mimic Mars conditions in mid-latitude regions with temperatures dipping down to −60oC at night and rising to +20oC during the day; atmospheric pressure pegged at 650 Pascals ( 0.09 PSI); Martian atmospheric gasses set to match Martian conditions ( 95% CO2, 3% N2, 1.5% Ar, 0.5% O2); and the expected ultraviolet radiation flux tuned across the UVA, UVB, and UVC wavelength bands. The treatments were applied for 1, 2, 3, and 7 days and then regeneration of branches was measured and compared to control samples. The results showed that S. caninervis can survive in a simulated Mars environment regenerating branches after 15 days of recovery. This hardy moss, having evolved to colonize extremely dry, cold environments on Earth make it ideally suited as a pioneer species to start the process of greening Mars, helping to establish an ecosystem through oxygen production, carbon sequestration, and generation of fertile soil.

Graphical illustration depicting extremotolerant properties of the moss Syntrichia caninervis showing superior desiccation and freezing tolerance, radiation resistance and pioneering benefits for terraforming Mars (slight modifications made to text of Public Summary). Credits: Xiaoshuang Li et al., under creative commons license CC BY-NC-ND 4.0

Of course terraforming Mars may take many years, perhaps centuries. In the near term, an ancient farming method called intercropping could help boost the yields of vegetables grown on Mars to sustain a healthy settler’s diet. The technique coordinates the cultivation of two or more crops simultaneously in close proximity. In a research article in PLOS ONE scientists at the Wageningen University & Research in the Netherlands describe the method of soil based food production using Martian regolith simulate. The researchers acknowledge that some processing of Martian regolith will be required to remove toxic components such as perchlorates. Research on these techniques is already underway. The study found that intercropping “…shows promise as a method for optimizing food production in Martian colonies.”

* Authors of the Report The extremotolerant desert moss Syntrichia caninervis is a promising pioneer plant for colonizing extraterrestrial environments:

Xiaoshuang Li 1, Wenwan Bai 1 2, Qilin Yang 1 2, Benfeng Yin 1, Zhenlong Zhang 3, Banchi Zhao 3, Tingyun Kuang 4, Yuanming Zhang 1, aoyuan Zhang 1
1 – State Key Laboratory of Desert and Oasis Ecology, Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China
2 – University of Chinese Academy of Sciences, Beijing 100049, China
3 – National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China
4 – Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China

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Making Martian regolith safe for agriculture

AI generated image of crops growing in sealed enclosure within a radiation protected lava tube on Mars. Credits: Microsoft DALL-E Image Creator

Agriculture on Mars is problematic. Even if radiation exposure could be solved (perhaps by locating greenhouses in lava tubes) and sufficient sources of water secured, there is that pesky perchlorate in the soil. Not to worry. The Interstellar Research Group has us covered. IRG, who’s mission is to assist in building a technological, philosophical, and economic infrastructure that advances the goal of establishing outposts throughout the Solar System and, finally, achieving a pathway to the stars, has initiated MaRMIE – the Martian Regolith Microbiome Inoculation Experiment. An informative summary of the project is provided by Alex Tolley over on Centauri Dreams.

SSP has addressed the biological remediation of perchlorates in Martian regolith previously. The research paper linked in that article examined phytoremediation which uses aquatic plants for perchlorate removal and microbial remediation processes utilizing microorganisms and extremophiles. IRG focused on the latter but noted that since the contaminants are water soluble, simply rinsing of the Martian regolith may be a potential solution for removal of the contaminants if sufficient sources of water can be found.

Perchlorates are only one piece of the puzzle to create fertile soil on Mars. So IRG expanded the scope of this initiative to design an experiment to simulate crop growth under the extreme conditions we can expect on Mars, taking into account the composition and pressure of the atmosphere, temperature extremes and high levels of ionizing radiation. The group envisioned a framework of research that would include five phases. The first phase would address the perchlorate issue experimenting with a variety of bacterial and microfungal agents applied to simulated Martian regolith mixed with perchlorates.

In the next phase, the simulated regolith would be conditioned by creating a microbiome to inoculate the regolith. This would include evaluation of pioneer plant species under Martian environmental conditions to transition the regolith into fertile soil.

The third phase would then attempt to grow crops in the mock soil under Martian lighting and atmospheric conditions with increasing ambient pressures until plant growth is satisfactory.

In the fourth phase, the experiment would be repeated with the same settings as in the third phase but decreasing the temperature to find when plant grow tapered off to unacceptable levels. This approach would home in on the optimum conditions for crop growth in the prepared Martian soil.

Finally, the infrastructure to create a farm implementing these conditions on the surface of Mars with appropriate protection from radiation would be defined.

It is not the intention of IRG to actually run these experiments. The output of the effort would be a published paper documenting the known issues and providing an outline of the required studies. Tolley explains that “IRG hopes that this framework will be seen and used as a structure for designing experiments and building on the results of previous experiments, by any researchers interested in the ultimate goal of viable large-scale agriculture on Mars.”

Others are undertaking similar studies. Researchers at the University of Naples Federico II are studying the use of lunar and Martian regolith simulates for plant growth in a paper published last year in Frontiers of Astronomy and Space Science.

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Mars as breadbasket for the outer solar system

Artist’s rendering of a farming settlement on Mars. Credits: HP Mars Home Planet Rendering Challenge via International Business Times.

Space settlement will eventually require space farming to feed colonists and to provide life support. It’s clear that we will replicate our biosphere wherever we go. In that spirit, Bryce L. Meyer envisions Mars as the breadbasket of the outer solar system. In a presentation at Archon 45, a science fiction and fantasy convention held annually by St. Louis area fans, he makes the case for why the fourth planet would be the ideal spot to grow crops and feed an expanding population as part of the roadmap to agriculture in space.

Carbon dioxide and subsurface water ice are plentiful on Mars, critical inputs for crop photosynthesis. There is also evidence of lava tubes there which could provide an ideal growing environment protected from radiation, micrometeorite bombardment and temperature extremes. The regolith should provide good nutrients and there is already research on methods to filter out perchlorates, a toxic chemical compound in the Martian soil.

Image of Lava tubes on the surface of Mars as photographed by ESA’s Mars Express spacecraft. Credits: ESA/DLR/FU Berlin/G Neukum / NewScientist

Another advantage that Mars holds as a food production hub for the asteroids and beyond is its placement further out in the solar system. Since it is higher up in the sun’s gravity well, Meyer calculates that it would take less than 43% of the fuel needed to transport goods from Mars outward than from Earth. He even suggests that with its lower gravity and recent advancements in materials research, a space elevator at Mars could be economically feasible to cheaply and reliably transport foodstuff off the planet.

Meyer keeps a webpage featuring space agriculture, terraforming, and closed cycle microgravity farming where he poses the question “Why settle space?” I like his answer: “Trillions of Happy Smiling Babies!!!”

Basic input/output diagram of an environmental control and life support system like what would be expected in a space farm. Credits: Bryce L. Meyer

Meyer is the founder and CEO of Cyan React, LLC, a startup that designs compact photobioreactors and provides expertise in closed-cycle farming and life support especially for space settlement and space habitats. He is also a National Space Society Space Ambassador doing his part to educate the public about the potential benefits to humanity through the use of the bountiful resources in space. In a presentation at this year’s International Space Development Conference, he describes his research on bioreactors explaining how settlers will grow food and recycle waste sustainably on the high frontier.

Diagram depicting the flow of materials in a closed space farm habitat utilizing bioreactors. Credits: Bryce L. Meyer

Complete closure and stability of an environmental control and life support system (ECLSS) is challenging and not without limitations. As launch and space transportation costs come down in the near future and off-Earth supply chains become more reliable, complete closure will not be required at least initially. In situ resource utilization will provide replacement of some ECLSS consumables where available for colonists to live off the land. As missions go deeper into space reaching the limits of supply chain infrastructure and even out to the stars, closure of habitat ECLSS and resource planning will become more important. Meyer has done the math for farms in space to provide food and air for trillions of smiling babies…and their families as they move out into the solar system.