Moss in space: spores survive nine-month ride on outside of ISS | Biology
Matt Damon grew potatoes to survive in The Martian, but researchers say moss could one day help turn dust and rocks from other planets into fertile soil.
Physcomitrella patensor spread moss on the ground, is already known as a pioneer species – even though it was one of the first plants to appear in arid mud areas. Researchers have found that moss spores can survive for at least nine months stuck on the outside of the International Space Station (ISS) and continue to reproduce once they return to Earth.
Although the plant is not edible, the researchers say the results could be important for space exploration.
Lead study author Dr Tomomichi Fujita, from Hokkaido University in Japan, said: “While moss may not be on the menu, its resilience offers insight into the development of sustainable space survival systems. Moss could help with oxygen generation, humidity control or even soil formation.”
This is not the first time that researchers have highlighted the remarkable survival abilities of mosses or sent such species to the ISS. Indeed, These plants are known to tolerate a multitude of extreme conditions on Earth, while scientists have discovered that desert moss species Syntrichia caninervis can withstand Mars-like conditions in experiments on Earth.
In the journal iScience, Fujita and colleagues report how they exposed three different foam structures to a simulated space environment on Earth. They found that moss spores enclosed in a structure called a sporangium were the most resilient and were able to germinate after exposure to UVC radiation levels exceeding 100,000 joules per square meter.
Further testing suggested that these enclosed spores were also resistant to vacuum conditions, freezing, high temperatures, and vacuum radiation.
The researchers then sent enclosed spores to the ISS aboard the Cygnus NG-17 spacecraft. These were attached outside the ISS in sample holders with different filter settings and left for nine months.
After the samples were returned to Earth, the researchers found that all had high germination rates, noting that even those that had been fully exposed to UV rays in space had an 86% germination rate, compared to a 97% germination rate for the spores that remained on Earth. However, one type of chlorophyll present in the samples exposed in space showed signs of degradation.
“If such spores can withstand long-term exposure during interplanetary travel and then successfully resurrect after rehydration and warming, they could one day contribute to the establishment of basic ecosystems beyond Earth,” Fujita said.
He noted that the study focused only on survival in space conditions. “The question of whether moss can germinate and grow in various extraterrestrial conditions – including different gravity levels, atmospheric compositions and radiation levels – remains open,” Fujita said.
Dr Agata Zupanska of the Seti Institute, who was not involved in the work, welcomed the study but said it was already known that dormant, desiccated biological forms such as spores or seeds showed significantly greater resistance to environmental extremes than hydrated cells or tissues. She said similar seed exposure experiments, including space crop seeds, had already been conducted outside the ISS.
Zupanska also pointed out that the external environment of the ISS, although harsh, did not fully represent the complexity of true deep space conditions, including those on the Moon or Mars.
“The value of space plants is only realized if they can actively grow and thrive far from Earth,” she said. “While spore resilience is important, it represents only a first step toward the broader goals of growing plants in extraterrestrial environments.”
