Moss spores survived in outer space for a majority of 2022, and could even reproduce as usual when they were eventually returned to Earth, according to a new study from researchers who say their findings "reveal the potential of terrestrial plants to endure extreme environments" — including the extraterrestrial kind.
"Climate change highlights the importance of understanding life's survival limits for addressing global challenges and supporting future human habitation beyond Earth," reads the introductory text of the study, conducted by scientists at Hokkaido University in Japan. "Understanding the resilience of Earth-born organisms in extreme and unfamiliar conditions, such as the space environment, is a crucial step toward expanding human habitats other than Earth like the Moon or Mars."
The full text was published Thursday in the online journal iScience. It describes a pioneering effort to study bryophyte plants, such as moss, with the intent to learn more about the limits of their survival skills and gauge their adaptability. Although the plants' resilience was already well-known in environments on Earth, research on their survival limits more widely is still in its early stages, the study's authors said.
For nine months, moss withstood the markedly harsh conditions of space — which very few Earthly creatures have ever done — while affixed to the outside of the International Space Station. While the spores' chlorophyll, which gives them their green color, did degrade during the experiment, scientists said more than 80% of them retained their viability after nine months outside of the space station.
Different types of moss spores had individual strengths, like one that may protect against ultraviolet rays, heat and intensive light stresses, and another that "could be used for planetary greening and life support systems," the authors said.
Bryophytes have existed on Earth since at least 500 million years ago, when they began to advance from water onto land, scientists say. The plants continue to exist today despite the fact that Earth has changed considerably, and they have become known for their tolerance to desiccation, freezing and radiation, all of which made them good candidates to be studied in an extraterrestrial setting.
In addition to surviving the 9-month period, the spores could still germinate after the experiment ended and scientists returned them back down to Earth, according to the study.
