Moss survived 283 days in space, shocking biologists
In a groundbreaking study published in *iScience*, a team from Hokkaido University in Japan has revealed that moss, specifically the species *Physcomitrium patens*, has astonishing resilience, surviving an extended exposure to the harsh conditions of space. In March 2022, the researchers sent moss reproductive structures known as sporophytes aboard the Cygnus NG-17 spacecraft, where they remained outside the International Space Station (ISS) for 283 days. Remarkably, over 80 percent of the spores returned to Earth capable of germination, highlighting the extraordinary adaptability of this seemingly humble plant. Tomomichi Fujita, a biologist and co-author of the study, emphasized the significance of these findings, noting that while most life forms struggle to survive even briefly in space, the moss spores demonstrated remarkable vitality after nine months of exposure to the vacuum and radiation of space.
The research stemmed from Fujita’s interest in how moss has evolved to thrive in Earth’s most extreme environments, from the icy peaks of the Himalayas to the scorching sands of Death Valley. The team meticulously prepared the moss for its space journey by subjecting it to simulated space conditions, including high levels of ultraviolet (UV) radiation and extreme temperature fluctuations. Their experiments revealed that sporophytes exhibited a thousandfold greater tolerance to UV radiation compared to juvenile moss and brood cells. This resilience is attributed to a protective structure surrounding the spores, which acts as a barrier against environmental stresses. The successful survival of these spores in space not only showcases the robustness of life on Earth but also opens new avenues for future research into agricultural systems that could support human life in extraterrestrial environments, such as Mars and the Moon.
Fujita and his team are optimistic that their findings will inspire further exploration into how mosses and other resilient organisms can contribute to sustainable ecosystems beyond our planet. Their mathematical model suggests that the spores could potentially survive in space for up to 15 years, although they caution that more extensive research is needed to confirm this estimate. The implications of this study are profound, as it could pave the way for developing agricultural systems that utilize hardy plants like moss to cultivate food and other resources in space, ultimately aiding humanity’s quest for extraterrestrial colonization. As Fujita aptly put it, this research represents a new frontier in understanding how life can adapt and thrive beyond Earth, potentially transforming our approach to living in space.
While it may appear humble, Earth’s
moss
is built darn tough. It
thrives in extreme environments
–from the bitter cold, low-oxygen air of the Himalayas, down to the parched sands of Death Valley. Some species even make their home among the
lava fields of active volcanoes
. It can now add
space
to its list of homes.
In March 2022, a team from Hokkaido University in Japan sent several moss reproductive structures called
sporophytes
into space aboard the
Cygnus NG-17 spacecraft
. Over 80 percent of the spores survived for nine months outside of the
International Space Station
(ISS). The spores even returned to Earth still capable of reproducing. The findings are detailed in a
study published today in the journal
iScience
.
“Most living organisms, including humans, cannot survive even briefly in the vacuum of space,”
Tomomichi Fujita
, a study co-author and biologist at Hokkaido University,
said in a statement
. “However, the moss spores retained their vitality after nine months of direct exposure. This provides striking evidence that the life that has evolved on Earth possesses, at the cellular level, intrinsic mechanisms to endure the conditions of space.”
A reddish-brown sporophyte can be seen at the top center of a leafy gametophore. This capsule contains numerous spores inside. Mature sporophytes like these were individually collected and used as samples for the space exposure experiment conducted on the exposure facility of the International Space Station.
Image: Tomomichi Fujita.
Readying the moss
For Fujita, the idea for space moss struck while he was studying plant
evolution
and was interested in how the plant colonized Earth’s harshest environments. He began to wonder, “could this small yet remarkably robust plant also survive in space?”
To see, Fujita’s team turned to
Physcomitrium patens
, a well-studied species moss commonly called spreading earthmoss. They put the moss into a simulated space environment with high levels of ultraviolet (UV) radiation, extreme high and low temperatures, and vacuum conditions.
Next, the team tested three different structures from the moss–juvenile moss (called protenemata), the specialized stem cells that emerge under stressful conditions called
brood cells
, and the reproductive sporophytes that enclose the spores. Testing these three helped them determine which moss structure had the best chance of surviving in space.
The space exposure unit used for the experiment next to a 100-yen coin for scale.
Image:
Tomomichi Fujita.
“We anticipated that the combined stresses of space, including vacuum, cosmic radiation, extreme temperature fluctuations, and microgravity, would cause far greater damage than any single stress alone,” said Fujita.
The UV radiation proved to be the toughest element, but the sporophytes were the most resilient of the three moss parts. All of the juvenile moss died from the UV levels or extreme temperatures. While the brood cells had a higher survival rate than the juvenile moss, the sporophytes still exhibited about 1,000 times more tolerance to UV radiation. The spores could even survive and germinate after being exposed to temperatures of −320 degrees Fahrenheit for over one week, as well as after living in temperatures as high as 131 degrees for a month.
According to the team
, the structure surrounding the spore appears to serve as a protective barrier. It absorbs UV radiation and physically and chemically covers the inner spore to prevent damage. This coating is likely an evolutionary adaptation that allowed the group of plants that moss belongs to (bryophytes) to transition from aquatic to terrestrial plants 500 million years ago. Moss has survived several mass extinction events ever since.
Moss goes to space
To put this huge evolutionary advantage to another test, the team sent the spores beyond the stratosphere and to the ISS. Once there, astronauts attached the sporophyte samples to the outside of the space station. The samples were then
exposed to space for 283 days
. In January 2023, the moss headed back to Earth on SpaceX CRS-16 and was returned to the lab for testing.
“We expected almost zero survival, but the result was the opposite: most of the spores survived,” said Fujita. “We were genuinely astonished by the extraordinary durability of these tiny plant cells.”
Over
80 percent
of the spores survived their intergalactic journey. All but 11 percent of the remaining spores were able to germinate in the lab. The team also tested the
chlorophyll
levels of the spores. The levels were mostly normal except for a 20 percent reduction in chlorophyll a.
Chlorophyll a
is particularly sensitive to changes in visual light, which could explain why those levels dropped. Even with the reduced chlorophyll a, this change did not appear to impact the health of the spores.
“This study demonstrates the astonishing resilience of life that originated on Earth,” said Fujita.
How long could moss survive in space?
To see how much longer the spores could have survived, the team used the data from before and after the moss’s expedition to create a mathematical model. Based on this model, the spores could have survived for
up to 15 years (or 5,600 days) under space conditions
. However, they caution that this is just a rough estimate based on one experiment, and that a larger data set is necessary for more realistic predictions of how long moss could survive in space.
The team hopes that this moss experiment helps advance research on how extraterrestrial soils can plant growth and inspires more exploration of how mosses could develop
agricultural systems in space
.
“Ultimately, we hope this work opens a new frontier toward constructing ecosystems in extraterrestrial environments such as the Moon and Mars,” said Fujita. “I hope that our moss research will serve as a starting point.”
The post
Moss survived 283 days in space, shocking biologists
appeared first on
Popular Science
.
