Moss is already known to handle harsh radiation, dehydration, and prolonged periods of freezing. Now scientists have taken their spore capsules even further by exposing them to open space for nine months, and most of them have survived.
The team did the work of spreading soil (Physcomitrium patents), a small moss species widely used by researchers as a plant model. Capsules containing its spores were installed outside the International Space Station (ISS), where they experienced direct solar radiation, vacuum conditions, and sharp temperature fluctuations during each orbit.
Under those circumstances, cells usually break down quickly. So the researchers were surprised by what came back. “We expected almost zero survival, but the result was the opposite,” says Tomomichi Fujita, a biologist at Hokkaido University. More than 80 percent of the spores continued to germinate even after returning to Earth.
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The team detected a small decline in chlorophyll a, but other pigments remained stable. The spores grew normally in follow-up tests, and showed no signs of major stress during their time in orbit.
This type of toughness fits with the evolutionary history of mosses. Bryophytes – the group that includes mosses, liverworts and hornworts – were among the first plants to move from water to land about 500 million years ago. Their spores had to withstand desiccation and direct sunlight long before soil existed, which may explain why their protective structures persist so well today.
The result has been pairing the algal spores with some of the organisms known to tolerate direct space exposure, including tardigrades and some microbes. Their existence also figures into ongoing discussions about what types of life can tolerate extreme environments beyond Earth.
According to the researchers, this stability could have implications for future experiments on the Moon or Mars. Mosses require very little soil and can draw nutrients directly from rock, making them candidates for preliminary ecosystem tests in extraterrestrial settings.
“Ultimately, we hope this work will open a new frontier toward building ecosystems in extraterrestrial environments such as the Moon and Mars,” says Fujita. “I hope our moss research will serve as a starting point.”
The research was published in iscienceRead the study here,