Researchers are exploring the potential of a unique extremophile microbe, known as Chroococcidiopsis—or more conveniently, Chroo—to survive in harsh extraterrestrial environments and produce oxygen. A recent study led by Daniella Billi from the University of Rome Tor Vergata highlights the remarkable capabilities of this cyanobacterium, suggesting it may play a crucial role in future space exploration.
Chroo is discovered in extreme environments on Earth, including deserts across Asia, North America, and Antarctica. Its rugged resilience has made it a subject of interest for astrobiologists investigating how life might endure on other planets. The paper, published in pre-print form in Acta Astronautica, discusses how Chroo serves both as a valuable research organism and a potential life-supporting tool in extraterrestrial habitats.
Survival Tests in Space
Significant experiments conducted on the International Space Station (ISS) have tested Chroo’s endurance against the harsh conditions of space. Two notable experiments, the BIOlogy and Mars EXperiment (BIOMEX) and the Biofilm Organisms Surfing Space (BOSS) experiment, exposed Chroo to space for approximately 18 months. BIOMEX focused on individual cells, while BOSS examined the behavior of biofilms.
Both studies revealed that UV radiation posed the greatest threat to Chroo. Protective measures significantly improved survival rates; BIOMEX utilized a thin layer of rock to shield individual cells, while BOSS relied on the upper layer of cells in the biofilm to protect those beneath. Remarkably, when Chroo samples returned to Earth, scientists found that their DNA repair mechanisms could effectively mend damage incurred during exposure to space radiation, with no increase in mutations in subsequent generations compared to a control strain.
Earth-Bound Experiments and Future Missions
In addition to space studies, Chroo has undergone various Earth-based tests. In one experiment, researchers exposed Chroo to nearly 24 kGy of gamma radiation—an amount lethal to humans—yet the microbe survived. In another, higher doses resulted in death, but biomarker residues indicated that Chroo could provide insights into the search for extinct life on planets like Mars.
Further studies demonstrated that Chroo can survive freezing temperatures akin to those found on extraterrestrial bodies such as Europa and Enceladus. When subjected to temperatures as low as -80°C, Chroo entered a dormant state, effectively vitrifying until conditions improved.
Chroo’s capabilities extend beyond survival; it can thrive on Lunar and Martian soil, utilizing photosynthesis to produce oxygen. Notably, it can withstand high levels of perchlorates, commonly found in Martian soil, by up-regulating its DNA repair genes to mitigate damage.
Upcoming missions are set to investigate additional aspects of this remarkable organism. The CyanoTechRider mission will explore how microgravity affects Chroo’s DNA repair processes, while BIOSIGN will assess the potential of using far-infrared light to power Chroo’s photosynthesis—an ability that could broaden our understanding of life in diverse cosmic environments.
With its extraordinary resilience and capacity for oxygen production, Chroo stands at the forefront of astrobiological research. As scientists continue to study this super-cyanobacterium, its role in future space missions could prove essential for sustaining life beyond Earth.
