Desert Lichen Reveals Potential for Life Under Intense Solar Radiation

In a groundbreaking study published on June 12, 2025, in the journal *Astrobiology*, researchers at the Desert Research Institute (DRI) have demonstrated that the common lichen *Clavascidium lacinulatum*, found in the Mojave Desert, can survive prolonged exposure to levels of solar radiation previously deemed lethal. This research, led by Henry Sun, Associate Research Professor of Microbiology at DRI, provides compelling evidence that life forms may exist on exoplanets orbiting stars that emit stronger solar radiation than the Sun.

The study's significance emerges from the inquiry into whether Earth is unique in hosting life, a question that has fascinated scientists for centuries. As astronomers increasingly discover Earth-like planets in habitable zones around other stars, the potential for life in environments with high ultraviolet (UV) radiation becomes a critical area of investigation. The findings from this study suggest that photosynthetic organisms like lichens could indeed survive, and possibly thrive, under such extreme conditions.

Sun and his graduate student, Tejinder Singh, collected lichens from their local desert and exposed them to ultraviolet C (UVC) radiation—a range that is harmful to most known life forms. The experiment revealed that after three months, half of the algal cells within the lichen remained viable and capable of replication upon rehydration. Sun stated, “In order for a microorganism to persist on a planet, it has to last longer than a day.” This prolonged exposure is ecologically significant, challenging earlier assumptions about the limits of life in extreme environments.

The researchers investigated the chemical mechanisms behind this resilience by collaborating with chemists from the University of Nevada, Reno. Their results showed that lichen contains natural protective compounds that function similarly to additives used in plastics to enhance UV resistance. The protective layer of the lichen, which appeared darkened like a suntan, plays a crucial role in shielding the more vulnerable algal cells beneath it from radiation damage.

“This layer acts as a photo stabilizer and protects the cells from harmful chemical reactions caused by radiation,” explained Sun, emphasizing the unexpected nature of this adaptation. The study further examined how atmospheric conditions affect the extent of radiation damage, finding that in an oxygen-free environment, the damage was significantly reduced.

The implications of this research extend beyond Earth, suggesting that similar microorganisms might populate exoplanets that experience high UVC radiation, particularly those orbiting M and F-type stars known for intense solar flares. As stated by Singh, now at NASA Goddard Space Flight Center, “This work reveals the extraordinary tenacity of life even under the harshest conditions, a reminder that life, once sparked, strives to endure.”

In light of the findings, scientists are urged to reconsider the potential habitability of planets exposed to intense solar radiation. The research underscores a critical understanding in astrobiology—life may not only exist in the temperate zones of planets but could also thrive in seemingly inhospitable environments. As technology advances and tools like the James Webb Space Telescope allow for deeper exploration of distant worlds, the possibility of discovering life beyond our planet inches closer to reality.

This study is a pivotal contribution to the field of astrobiology, offering new insights into the resilience of life and the conditions that might support its existence on exoplanets. The future of extraterrestrial research looks promising as scientists continue to explore these uncharted territories.

Reference: Singh, T., Georgiou, C.D., Jeffrey, C.S., et al. (2025). UVC-intense exoplanets may not be uninhabitable: Evidence from a desert lichen. *Astrobiology*. doi: 10.1089/ast.2024.0137.