Moss survived in space for nine months, study finds

For nine months in 2022, moss lived in space.

It wasn’t in a lab aboard the International Space Station, like other gardening experiments conducted in orbit — rather, the moss was attached to the station’s exterior, fully exposed to the harsh environment of the cosmos.

The purpose of the space moss test, reported in a study published Thursday in the journal iScience, was to see if moss — an early land plant capable of thriving in some of the most extreme environments on Earth — could survive long-term exposure to the vacuum of space.

Surprisingly, the researchers found that the moss spores not only endured, they “retained their vitality” and were still capable of reproducing when they eventually returned to Earth.

“Most living organisms, including humans, cannot survive even briefly in the vacuum of space,” Tomomichi Fujita, the study’s lead author and a professor in the department of biological sciences at Hokkaido University in Japan, said in a statement.

“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,” he added.

Mosses are thought to have descended from ancestral plants that started moving out of water to colonize dry land roughly 450 million years ago.

The organisms are known to be extremely hardy, able to grow everywhere from the Antarctic tundra to the peaks of the Himalayas to volcanic lava fields to all manner of aquatic habitats.

Fujita said he was inspired by that impressive resilience.

“I began to wonder: could this small yet remarkably robust plant also survive in space?” he said.

His team started by studying a type of moss known as Physcomitrium patens in simulated space environments in a lab on Earth, including extreme hot and cold temperatures, vacuum conditions and high levels of UV radiation.

They determined that moss sporophytes — encapsulated spores that function as reproductive structures — were the parts of moss most likely to survive in space because they seemed able to endure high levels of UV radiation. The spores were also capable of germinating after being exposed to both scorching temperatures of 131 degrees Fahrenheit for a month and minus 320 degrees F for over a week.

So in March 2022, the researchers sent hundreds of moss sporophytes to the International Space Station aboard a cargo spacecraft made by the aerospace company Northrop Grumman. Astronauts at the orbiting outpost attached the sporophyte samples to the outside of the space station, where they remained for 283 days.

The moss samples were then returned to Earth on a SpaceX cargo mission in January 2023.

The researchers found that over 80% of the spores survived their nine-month stint outside the space station. Of those, almost 90% were able to germinate again in a lab on Earth.

“We expected almost zero survival, but the result was the opposite: most of the spores survived,” Fujita said. “We were genuinely astonished by the extraordinary durability of these tiny plant cells.”

In the study, the researchers said the structure encasing the spores may have acted as protection against the harmful effects of UV radiation. These structures were likely an evolutionary adaptation hundreds of millions of years ago, the study authors wrote, to protect early plants during mass extinction events as they started colonizing dry land.

The scientists said more research is needed, but it’s possible that mosses could survive in space for much longer, perhaps up to 15 years.

They said the findings could be used to develop future agricultural systems in space and to explore whether extraterrestrial soils can grow viable plants.

“Ultimately, we hope this work opens a new frontier toward constructing ecosystems in extraterrestrial environments such as the Moon and Mars,” Fujita said.

This article was originally published on NBCNews.com