Certain lichen species can withstand Mars-like conditions with an X-ray radiation dose of 50 Gy (Grays) that is expected on the Mars surface over one year of strong solar activity, according to new research from Jagiellonian University and the Space Research Centre at the Polish Academy of Sciences.
Morphological and anatomical characteristics of Cetraria aculeata (a, d, g, j) and Diploschistes muscorum (b, c, e, f, h, i, k, l). Image credit: Skubała et al., doi: 10.3897/imafungus.16.145477.
Lichens inhabit diverse ecosystems worldwide, but they are particularly crucial in extreme environments like hot deserts and cold polar regions.
They are known as extremophiles, able to survive under extreme temperatures, intense radiation, and prolonged water scarcity.
The remarkable ability of lichens to endure harsh conditions has led to the suggestion that they are well-suited to survive the extreme environment of outer space.
Lichen successful life strategy depends on the symbiotic association between a fungus and an alga or cyanobacteria, which allows them to colonize extreme terrestrial habitats where no other multicellular organism is able to survive.
The key to understanding their impressive resistance lies in their characteristics of ‘stress-tolerant’ organisms, i.e., low metabolic rates, minimal nutritional requirements, and extended longevity, which are further supported by protective mechanisms: radiation screening, thermal dissipation, and antioxidant defense.
Moreover, they can cope with prolonged water scarcity or even a total absence of liquid water.
This is related to the lack of ability to regulate water content, which allows them to survive long periods of severe desiccation without damage in the dormant state, but also to tolerate high levels of ultraviolet/photosynthetic active radiation and temperature extremes associated with drought conditions.
Mars is a primary focus of interest in astrobiology due to the presence of water and the associated potential for life.
The present atmospheric conditions on Mars are inhospitable and thus the potential habitats for existing life are limited.
Nevertheless, habitable environments may exist below or on the surface during more favorable climatic periods.
These niches could act as isolated habitats that protect from harsh conditions.
Despite the atmosphere being mostly composed of carbon dioxide (95%), the effectiveness of greenhouse warming is limited.
The temperature on Mars predominantly remains below the freezing point of water and the atmospheric pressure is c.a. 6 millibars.
Consequently, a considerable part of the existing water on Mars is ice and atmospheric water vapor; however, certain water amounts could be temporarily present as liquid water.
Both ionizing and non-ionizing radiation constantly reach the Mars surface and pass through the atmosphere of Mars much more easily than on Earth.
Since ultraviolet and ionizing radiation are extremely harmful to living organisms, this factor is the most limiting in the context of habitability on Mars.
“In our study, the fungal partner in lichen symbiosis remained metabolically active when exposed to Mars-like atmospheric conditions in darkness, including X-ray radiation levels expected on Mars over one year of strong solar activity,” said Jagiellonian University researcher Kaja Skubała and colleagues.
In their research, the authors focused on two lichen species, Diploschistes muscorum and Cetraria aculeata, selected for their differing traits, exposing them to Mars-like conditions for five hours in a simulation of the planet’s atmospheric composition, pressure, temperature fluctuations, and X-ray radiation.
The findings suggest that lichens, particularly Diploschistes muscorum, could potentially survive on Mars despite the high doses of X-ray radiation associated with solar flares and energetic particles reaching the planet’s surface.
These results challenge the assumption that ionizing radiation is an insurmountable barrier to life on Mars and set the stage for further research on the potential for extraterrestrial microbial and symbiotic survival.
“Our study is the first to demonstrate that the metabolism of the fungal partner in lichen symbiosis remained active while being in an environment resembling the surface of Mars,” Dr. Skubała said.
“We found that Diploschistes muscorum was able to carry out metabolic processes and activate defense mechanisms effectively.”
“These findings expand our understanding of biological processes under simulated Martian conditions and reveal how hydrated organisms respond to ionizing radiation — one of the most critical challenges for survival and habitability on Mars.”
“Ultimately, this research deepens our knowledge of lichen adaptation and their potential for colonizing extraterrestrial environments.”
The findings appear in the journal IMA Fungus.
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K. Skubała et al. 2025. Ionizing radiation resilience: how metabolically active lichens endure exposure to the simulated Mars atmosphere. IMA Fungus 16: e145477; doi: 10.3897/imafungus.16.145477
