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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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Space development on the Moon, Mars and beyond featured in 2023 NIAC Phase I Grants

Conceptual illustration of an oxygen pipeline located at the lunar south pole. Credits: Peter Curreri

This year’s list of NASA Innovative Advanced Concepts (NIAC) Phase I selections include a few awards that look promising for space development. For wildcatters (or their robotic avatars) drilling for water ice in the permanently shadowed craters at the lunar south pole and cracking it into hydrogen and oxygen, Peter Curreri of Houston, Texas based Lunar Resources, Inc. describes a concept for a pipeline to transport oxygen to where it is needed. Clearly oxygen will be a valuable resource to settlers for breathable air and oxidizer for rocket fuel if it can be sourced on the Moon. The company, whos objective is to develop and commercialize space manufacturing and resources extraction technologies to catalyze the space economy, believes that a lunar oxygen pipeline will “…revolutionize lunar surface operations for the Artemis program and reduce cost and risk!”.

Out at Mars, Congrui Jin from the University of Nebraska, Lincoln wants to augment inflatable habitats with building materials sourced in situ utilizing synthetic biology. Cyanobacteria and fungi will be used as building agents “…to produce abundant biominerals (calcium carbonate) and biopolymers, which will glue Martian regolith into consolidated building blocks. These self-growing building blocks can later be assembled into various structures, such as floors, walls, partitions, and furniture.” Building materials fabricated on site would significantly reduce costs by not having to transport them from Earth.

A couple of innovations are highlighted in this NIAC grant. First, Jin has studied the use of filamentous fungi as a producer of calcium carbonate instead of bacteria, finding that they are superior because they can precipitate large amounts of minerals quickly. Second, the process will be self-growing creating a synthetic lichen system that has the potential to be fully automated.

In addition to building habitats on Mars, Jin envisions duel use of the concept on Earth. In military logistics or post-disaster scenarios where construction is needed in remote, high-risk areas, the “… self-growing technology can be used to bond local waste materials to build shelters.” The process has the added benefit of sequestration of carbon, removing CO2 from the atmosphere helping to mitigate climate change as part of the process of producing biopolymers.

Graphical depiction of biomineralization-enabled self-growing building blocks for habitats on Mars. Credits: Congrui Jin

To reduce transit times to Mars a novel combination of Nuclear Thermal Propulsion (NTP) with Nuclear Electric Propulsion (NEP) is explored by Ryan Gosse of the University of Florida, Gainesville.

Conceptual illustration of a bimodal NTP/NEP rocket with a wave rotor enhancement. Credits: Ryan Gosse

NTP technology is relatively mature as developed under the NERVA program over 50 years ago and covered by SSP previously. NTP, typically used to heat hydrogen fuel as propellant, can deliver higher specific impulse then chemical rockets with attractive thrust levels. NEP can produce even higher specific impulse but has lower thrust. If the two propulsion types could be combined in a bimodal system, high thrust and specific impulse could improve efficiency and transit times. Gosse’s innovation couples the NTP with a wave rotor, a kind of nuclear supercharger that would use the reactor’s heat to compress the reaction mass further, boosting performance. When paired with NEP the efficiency is further enhanced resulting in travel times to Mars on the order of 45 days helping to mitigate the deleterious effects of radiation and microgravity on humans making the trip. This technology could make an attractive follow-on to the NTP rocket partnership just announced between NASA and DARPA.

Finally, an innovative propulsion technology for hurling heavy payloads rapidly to the outer solar system and even into interstellar space is proposed by Artur Davoyan at the University of California, Los Angeles. He will be developing a concept that accelerates a beam of microscopic hypervelocity pellets to 120 kilometers/s with a laser ablation system. The study will investigate a mission architecture that could propel 1 ton payloads to 500 AU in less than 20 years.

Artist depiction of pellet-beam propulsion for fast transit missions to the outer solar system and beyond. Credits: Artur Davoyan

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Martian in situ manufacturing using chitosan biolith

Illustration of three applications of chitosan derived Martian biolith cast into different geometries including a wrench, freeformed material or an additive manufactured habitat model. Credits: Ng Shiwei, Stylianos Dritsas, Javier G. Fernandez via PLOS ONE

Working with simple chemistry suitable for an early Martian settlement, a team of researchers in Singapore has demonstrated that Martian biolith using chitosan derived from shrimp, with minimal energy requirements, could be used for rapid manufacturing of objects ranging from basic tools to rigid shelters. Ng Shiwei, Stylianos Dritsas, and Javier G. Fernandez publish their results in a paper in PLOS ONE.

Chitosan is chemically derived from chitin, the organic matrix produced by biological organisms incorporating calcium carbonate into rigid structures. Chitin would be a byproduct of food production in a closed-loop life support system on Mars.

Chitosan can form transparent objects similar in appearance and mechanical properties to plastic, which would be lacking in early stage Mars settlements. When processed with Martian regolith, the resulting Chitosan biolith produces a material with good mechanical properties and general utility for manufacturing on Mars.