The Starset SocietyBy: Rhodilee Jean Dolor
Researchers from the Jagiellonian University in Poland and the Space Research Center of the Polish Academy of Sciences have found a symbiotic life form that can potentially survive and function in the harsh environment of extraterrestrial worlds.
In a new study, Kaja Skubała, from the Jagiellonian University, and colleagues showed that certain lichen species can withstand and thrive in simulated Mars-like conditions, including exposure to damaging amounts of ionizing radiation.
Space Radiation
Mars lacks a magnetic field so its surface is exposed to high radiation levels. According to the National Aeronautics and Space Administration (NASA), space radiation poses significant health risks to humans, including increased lifetime risk for cancer, central nervous system effects and degenerative diseases.
“Ionizing radiation is like an atomic-scale cannonball that blasts through material, leaving significant damage behind. More damage can also be created by secondary particles that are propelled into motion by the primary radiation particle,” NASA says.
Astronauts are exposed to ionizing radiation with effective doses ranging from 50 to 2,000 mSv, but studies on people exposed to radiation, including survivors of atomic bombings and radiotherapy patients, show increased risk for cancer at doses above 100 Milli-Sievert (mSv). Researchers likewise found that individuals exposed to lower doses of radiation between 50 and 100 mSv also have high risk for cancer.
Amid ambitious plans to bring humans to Mars in the future, Skubała and colleagues say that exposure to ionizing radiation is one of the most critical challenges for survival and habitability on the planet.
Resilient Life Form
Studies are now being conducted on organisms that could hold clues on how humans can thrive beyond Earth. Researchers are taking a closer look at those that demonstrate the ability to weather extreme environments.
Skubała and colleagues wanted to find out whether metabolically active organisms can function under the harsh conditions of extraterrestrial worlds with high levels of ionizing radiation.
For their study published in the journal IMA Fungus on March 31, they exposed two lichen species, Diploschistes muscorum and Cetraria aculeata, to Mars-like conditions for five hours, simulating the arid world’s atmospheric composition, pressure, temperature fluctuations and X-ray radiation.
X-rays and energetic particles—including galactic cosmic rays (GCR) and solar energetic particles (SEP)—are the sources of cosmic ionizing radiation on the Red Planet.
Lichens are composed of two or more separate organisms that live together as one. This complex life form is a symbiosis between a fungus and an algae and/or cyanobacteria that is known to thrive in diverse climates and habitats.
Lichens are also called “extremophiles” because of their ability to survive in extreme conditions on Earth from hot dry deserts to freezing polar regions.
Skubała’s team found that the fungal partner in the symbiosis remained metabolically active despite exposure to Mars-like atmospheric conditions and X-ray radiation levels representing over one year of strong solar activity on the planet.
“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,” Skubała said. “Ultimately, this research deepens our knowledge of lichen adaptation and their potential for colonizing extraterrestrial environments.”
The researchers also discovered that the D. muscorum lichen species is in particular able to withstand the high doses of X-ray radiation associated with solar flares and energetic particles that hit the Martian surface.
“Diploschistes muscorum was able to activate defense mechanisms effectively. In contrast, increased oxidative stress and associated damage were not effectively balanced in C. aculeata, which does not support the melanin’s radioprotective function in this species,” the researchers wrote. “The heavy crystalline deposit on D. muscorum thallus might offer protection enhancing lichen resistance to extreme conditions.”
Skubała and colleagues say that the findings of the study offer a better understanding of lichen adaptation and the potential of this symbiotic organism for colonizing extraterrestrial environments.
“Our study is the first to demonstrate that the metabolism of the fungal partner in lichen symbiosis was active while being in an environment similar to the surface of Mars in the darkness,” they wrote in their paper. “[T]he high doses of X-rays associated with solar flares and SEPs reaching the surface of Mars should not affect the potential habitability of Mars by lichens.
Based on the result of the experiment, the researchers recommend D.muscorum as a promising candidate for further astrobiological research.
“Further long-term studies investigating the impact of chronic radiation exposure on lichens have been recommended, as well as experiments assessing their survival in real Martian environments,” Skubała said.
Space Survival Tips from Organisms
In 2014, researchers also sent lichens to the International Space Station (ISS) and exposed these life forms to the extreme conditions in low Earth orbit, including ultraviolet radiation, cosmic rays, and the vacuum of space for 1.5 years.
Some of the lichen samples were also subjected to simulated Martian environments. In their paper published in the International Journal of Astrobiology, the researchers reported that 71% of the lichens remained viable when these were sent back to Earth.
Another organism that draws attention from the scientific community is the tardigrade. In an experiment conducted aboard the ISS in 2021, researchers found that this microscopic, eight-legged animal can withstand the vacuum of space, cosmic rays and solar ultraviolet radiation.
NASA says that these organisms are helping researchers find ways to help humans survive in hostile extraterrestrial environments.
“Understanding how they tolerate extreme environments – including the one astronauts experience in space, with microgravity and elevated radiation levels – can better guide research into protecting humans from the stresses of long-duration space travel.”
