Enabling & Support
11/02/2026
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Long-duration space missions will require closed-loop life support systems that can regenerate oxygen and purify water while recycling waste. A recent ESA Discovery project led by the University of Naples Federico II explored whether aquatic mosses – often found in aquariums – could combine oxygen production with water filtration in compact, low-maintenance systems.
Bioregenerative Life Support Systems (BLSSs) rely on living organisms to sustain human crews during extended missions. Higher plants and microalgae have been studied extensively, but each has limitations. Higher plants require large and complex cultivation systems, while the challenges facing microalgae include biofilm formation, contamination, and uneven light distribution in photobioreactors.
Aquatic mosses present an intriguing alternative. These non-vascular plants have simple structures, require minimal inputs, and are already known as effective biofilters. However, their potential for space applications had never been systematically investigated.
A New Approach
The ‘Moss on Mars’ project examined three aquatic moss species – Taxiphyllum barbieri, Leptodictyum riparium, and Vesicularia montagnei – under controlled environmental conditions mimicking those in space habitats.
“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 all three species under two environmental conditions, assessing photosynthetic performance, pigment concentrations, antioxidant activity, and biofiltration efficiency for both 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 emerged as the clear frontrunner, exhibiting the highest rates of net photosynthesis and pigment accumulation.
Radiation Resistance
Based on these results, the team selected T. barbieri for further tests exploring its responses to ionising radiation, a key challenge for any space-based organism.
“Studying the effect of ionising radiation on aquatic mosses was a first for us and also in literature,” notes Amitrano.
The researchers exposed moss samples to three doses of X-rays – 1, 10, and 30 Gray (Gy) – then monitored their recovery over 63 days using a custom setup with continuous carbon dioxide and oxygen sensors.
The results proved surprising. Rather than showing damage, mosses exposed to 1 Gy radiation outperformed non-irradiated controls, exhibiting higher net photosynthesis, greater electron transport rates, and increased chlorophyll concentrations. This phenomenon, known as radiation hormesis, suggests low-dose radiation may stimulate beneficial physiological responses.
Even at higher doses, the mosses demonstrated resilience. The radiation altered moss morphology, creating denser branching while reducing branch length – changes that could potentially enhance surface area for gas exchange and filtration.
Future Applications
“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.”
“The University of Naples has demonstrated within this Discovery activity that mosses could help keep astronauts alive on Mars by filtering their water, refreshing their air, and shrugging off radiation in the process,” says Moritz Fontaine, Discovery & Preparation Officer and ESA’s lead for the project. “These findings are an important puzzle piece for future human spaceflight.”
ESA’s support through the Discovery programme proved essential. “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 idea originated through ESA’s Open Space Innovation Platform (OSIP), which seeks promising new concepts for space research, and was funded by the Discovery element of ESA’s Basic Activities.
The project has already produced one peer-reviewed publication in Frontiers in Plant Science, with a second paper on the radiation experiments in preparation. Looking ahead, the team envisions applications ranging from biofilters in water recycling systems to biomaterials and potential radiation shielding.
Although significant work remains, this project demonstrates the potential of aquatic mosses as versatile, low-maintenance organisms capable of performing multiple ecological functions in resource-constrained environments – both in space and for terrestrial water treatment applications.
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