Recent experiments conducted by researchers at Hokkaido University in Japan reveal that spores from the moss Physcomitrium patens can survive for extended periods in the harsh conditions of space. The study, published in the journal iScience, tested the resilience of the moss in various stages of development – protonemata, brood cells, and sporophytes – under simulated and actual space environments, including exposure outside the International Space Station (ISS). Over 80% of the spores survived nine months in space, retaining their ability to germinate, demonstrating an extraordinary capacity for endurance.
Why This Matters: Expanding Life Beyond Earth
This discovery isn’t merely a botanical curiosity; it has significant implications for the future of space exploration and potential off-world settlements. As Earth faces increasing environmental challenges, and as humanity looks toward establishing a presence on the Moon, Mars, or beyond, understanding how terrestrial organisms can adapt to extreme conditions is crucial.
The study highlights that even without genetic modification, some life forms possess inherent mechanisms for surviving in environments previously thought uninhabitable. This challenges assumptions about the limits of life and opens doors for designing self-sustaining ecosystems on other planets.
The Experiment: From Lab to Orbit
Researchers subjected Physcomitrium patens to simulated space conditions, including vacuum, extreme temperatures (from -196°C to 55°C), and high levels of UV radiation. The sporophytes—encapsulated spores—proved far more resilient than juvenile moss or brood cells, demonstrating 1,000x greater tolerance to UV radiation.
To validate these findings, hundreds of sporophytes were sent to the ISS in March 2022 and exposed directly to space for 283 days. Upon return to Earth in January 2023, over 80% of the spores were still viable, with nearly 90% able to germinate back in the lab.
Evolutionary Origins: A Legacy of Survival
The researchers suggest that this resilience is rooted in the evolutionary history of bryophytes, the plant group to which mosses belong. Their protective spore structure likely evolved as an adaptation to transition from aquatic to terrestrial environments 500 million years ago, allowing them to withstand extreme conditions and survive mass extinction events. The spore’s outer shell acts as a barrier, shielding the inner cell from damaging radiation.
Long-Term Viability: Predicting Survival in Space
Based on the experimental data, the team developed a mathematical model predicting that these spores could potentially survive in space for up to 5,600 days—roughly 15 years. While this remains an estimate, it indicates a remarkable degree of stability under extreme conditions.
“This study demonstrates the astonishing resilience of life that originated on Earth,” said Dr. Tomomichi Fujita, lead researcher at Hokkaido University. “I hope that our moss research will serve as a starting point.”
The findings suggest that future research should focus on how this resilience can be harnessed to develop sustainable life-support systems for long-duration space missions and potential extraterrestrial habitats.
The next step is to test whether the spores can survive even longer periods in space, and how they might interact with other organisms in a closed ecosystem. This work opens the door for a new era of astrobiology and the search for life beyond Earth.
