Moss on Mars: Aquatic Plants for Space Life Support & Radiation Shielding

Mosses in Space: Aquatic Plants Show Promise for Long-Duration Missions

Long-duration space missions present significant challenges for life support. Maintaining breathable air, potable water, and managing waste require closed-loop systems capable of regeneration, and recycling. Recent research, led by the University of Naples Federico II and supported by the European Space Agency (ESA), explores the potential of aquatic mosses – commonly found in aquariums – to combine oxygen production with water filtration in compact, low-maintenance systems. The findings, published in Frontiers in Plant Science, suggest these unassuming plants could play a crucial role in future human spaceflight.

Beyond Higher Plants and Microalgae

Bioregenerative Life Support Systems (BLSSs) are central to sustaining human crews on extended missions. Traditionally, higher plants and microalgae have been the focus of research. However, both approaches have limitations. Higher plants demand complex and large cultivation systems, while microalgae face challenges like biofilm formation, contamination, and uneven light distribution within photobioreactors. Aquatic mosses offer an intriguing alternative due to their simple structure, minimal input requirements, and established effectiveness as biofilters.

‘Moss on Mars’ Project: A Comparative Analysis

The ‘Moss on Mars’ project, as it was dubbed, examined three aquatic moss species – Taxiphyllum barbieri, Leptodictyum riparium, and Vesicularia montagnei – under controlled conditions designed to mimic space habitat environments. “This project included two important novel elements,” explains Principal Investigator Dr. Chiara Amitrano, a researcher at the University of Naples Federico II. “The first one is exploring the possibility of integrating aquatic mosses into space research as biofilters and bioregenerators. And the second one is investigating the physiological apparatus, the photosystem II of these mosses. All the published papers about aquatic mosses are about biofiltration and phytoremediation.”

The team compared the three species, assessing photosynthetic performance, pigment concentrations, antioxidant activity, and biofiltration efficiency for heavy metals and nitrogen compounds. Both T. Barbieri and L. Riparium demonstrated effective biofiltration, successfully removing copper, lead, and zinc from contaminated water. However, T. Barbieri consistently outperformed the others, exhibiting the highest rates of net photosynthesis and pigment accumulation.

Unexpected Resilience to Radiation

Building on these initial findings, the researchers investigated the response of T. Barbieri to ionizing radiation, a significant hurdle for any organism in space. “Studying the effect of ionising radiation on aquatic mosses was a first for us and also in literature,” notes Amitrano.

Moss samples were exposed to three doses of X-rays – 1, 10, and 30 Gray (Gy) – and their recovery was monitored over 63 days using a custom setup that continuously measured carbon dioxide and oxygen levels. The results were unexpected. Mosses exposed to 1 Gy of radiation actually outperformed non-irradiated controls, displaying higher net photosynthesis, greater electron transport rates, and increased chlorophyll concentrations. This phenomenon, known as radiation hormesis, suggests that low-dose radiation can stimulate beneficial physiological responses.

Even at higher doses, the mosses demonstrated remarkable resilience. Radiation altered the moss morphology, resulting in denser branching and reduced branch length. These changes could potentially increase surface area for gas exchange and filtration, enhancing the plant’s overall effectiveness.

Implications for Future Space Missions

“We really think we can include these aquatic mosses in the space environment,” says Amitrano. “They are radiation-resistant biofilters. They can support resource recycling, and they don’t need very much input to grow. And they have a good photosynthetic apparatus, producing oxygen and removing carbon dioxide.”

Moritz Fontaine, Discovery & Preparation Officer and ESA’s lead for the project, echoed this sentiment, stating that the University of Naples’ work demonstrates how mosses could help keep astronauts alive on Mars by filtering water, refreshing air, and resisting radiation. These findings represent a crucial piece of the puzzle for future human spaceflight.

ESA’s support through the Discovery programme was instrumental in enabling this research. “The funding was fundamental for us to set up the experiment, starting with the three species and then trying the ionising radiation of these mosses,” Amitrano explains.

The project originated through ESA’s Open Space Innovation Platform (OSIP) and was funded by the Discovery element of ESA’s Basic Activities.

With a second paper on the radiation experiments currently in preparation, the team envisions a range of applications for aquatic mosses, from biofilters in water recycling systems to biomaterials and potential radiation shielding. While further research is needed, this project highlights the potential of these versatile, low-maintenance organisms to perform multiple ecological functions in resource-constrained environments – not only in space, but also for terrestrial water treatment applications.