A team of researchers from Japan tested protenema (juvenile moss), brood cells (specialized stem cells that arise under stress), and sporophytes (encapsulated spores) of model moss species. Open Fiscomitrium in a simulated space environment by identifying the spores as the most resistant and subsequently exposing them to the space environment outside the International Space Station (ISS). After nine months in space, more than 80% of the spores survived, retaining the ability to germinate. These results demonstrate surprising robustness Open Fiscomitrium spores in space and reveal the ability of land plants to withstand extreme conditions.
Open Fiscomitrium The spores survive in simulated space conditions with high resistance. Image credit: Maeng etc.., document number: 10.1016/j.isci.2025.113827.
As Earth's environment has undergone rapid changes in recent years, it has become increasingly important to explore new possibilities for the survival of life beyond our planet.
Understanding the resilience of terrestrial organisms to extreme and unfamiliar environments, such as the space environment, is an important step towards expanding human habitats beyond Earth, such as the Moon or Mars.
Studying the limits of survival of living organisms in both terrestrial and space environments will not only improve our understanding of their adaptability, but also help us prepare for the challenges of maintaining ecosystems.
“Most living organisms, including humans, cannot survive even briefly in the vacuum of space,” said Dr. Tomomichi Fujita, a researcher at Hokkaido University.
“However, the moss spores remained viable after nine months of direct exposure.”
“This provides striking evidence that life that evolved on Earth has internal mechanisms at the cellular level to withstand the conditions of space.”
In their study, Dr. Fujita and his colleagues subjected Open Fiscomitriumof a well-studied moss, commonly known as spreading ground moss, in simulated space environments, including high levels of UV radiation, extremes of high and low temperatures, and vacuum conditions.
They tested three different structures from Open Fiscomitrium – protonemas, brood cells and sporophytes – to find out who is more likely to survive in space.
“We expected that the cumulative effects of space, including vacuum, cosmic radiation, extreme temperature fluctuations and microgravity, would cause much more damage than any single stress,” Dr. Fujita said.
The researchers found that UV radiation was the most difficult element to survive, and the sporophytes were by far the most resilient of the three parts of the moss.
None of the young mosses survived high levels of ultraviolet light or extreme temperatures.
The brood cells had a higher survival rate, but the spores they contained were 1,000 times more resistant to UV radiation.
The spores were also able to survive and germinate after being exposed to temperatures of minus 196 degrees Celsius for more than a week, as well as after living in temperatures of 55 degrees Celsius for a month.
Scientists hypothesized that the structure surrounding the spore serves as a protective barrier, absorbing ultraviolet radiation and coating the interior of the spore both physically and chemically to prevent damage.
This is probably an evolutionary adaptation that allowed bryophytes – a group of plants to which mosses belong – transitioned from aquatic to terrestrial plants 500 million years ago and have since experienced several mass extinctions.
In March 2022, the authors sent hundreds of sporophytes to the ISS aboard the spacecraft. Spaceship Cygnus NG-17.
Upon arrival, the astronauts attached the sporophyte samples to the outside of the ISS, where they remained in space for a total of 283 days.
The moss then traveled back to Earth. SpaceX CRS-16 in January 2023 and was returned to the laboratory for testing.
“We expected the survival rate to be almost zero, but the result was the opposite: most of the spores survived,” Dr. Fujita said.
“We were truly amazed by the extraordinary longevity of these tiny plant cells.”
More than 80% of the spores survived intergalactic travel, and all but 11% of the remaining spores were able to germinate back into the laboratory.
The team also tested chlorophyll levels in the spores and found normal levels for all types, except for a 20% decrease in chlorophyll A, a compound that is particularly sensitive to changes in visual light, but this change did not appear to affect the health of the spores.
“This study demonstrates the remarkable resilience of life that originated on Earth,” said Dr. Fujita.
Curious about how long the spores could survive in space, the researchers used data obtained before and after the moss expedition to create a mathematical model.
They predicted that the spores contained within could survive up to 5,600 days—roughly 15 years—in space conditions.
However, they stress that this number is only a rough estimate and that a larger data set is needed to make more realistic predictions about how long moss can survive in space.
“Ultimately, we hope that this work will open new horizons in the creation of ecosystems in extraterrestrial environments such as the Moon and Mars,” Dr Fujita said.
“I hope our research on moss will serve as a starting point.”
The results are described in paper in the magazine iScience.
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Eighty etc.. Extreme ecological tolerance and space survival of moss, Open Fiscomitrium. iSciencepublished online November 20, 2025; doi: 10.1016/j.isci.2025.113827
