Moss has been shown to survive one of the harshest environments imaginable: the exterior of the International Space Station (ISS).
Researchers sent three different types of moss structures to the orbital outpost: protonemata, or juvenile moss; brood cells; and sporophytes, or encapsulated spores. The juvenile moss didn’t survive the experience. Some of the brood cells made it, but 80 percent of the spores were still capable of reproducing after a nine-month stint outside the outpost.
“We expected almost zero survival, but the result was the opposite: most of the spores survived,” said Tomomichi Fujita of Hokkaido University. “We were genuinely astonished by the extraordinary durability of these tiny plant cells.”
The idea of sending moss into space came to Fujita during studies of plant evolution and development. Mosses thrive in some of the harshest environments on Earth, and can be found anywhere from the peaks of mountains to the lava fields of active volcanoes.
However, the exterior of the ISS was another matter entirely. As well as wildly varying temperatures – between -196°C and 55°C – there are also high levels of radiation to deal with.
Samples were loaded onto the Cygnus NG-17 freighter and exposed to space for a total of 283 days on a facility attached to Japan’s Kibo module. The samples were then returned on a SpaceX vehicle for researchers to study.
While the ISS is host to all manner of organisms within the outpost, including its crew, the exterior makes an interesting testbed to investigate just how hardy some species can be. Scientists reckon the encased spores could have survived for as long as 15 years, though this is a rough estimate. As with so much in science, more research is needed.
Famously, the Surveyor 3 camera, liberated from the lander by the Apollo 12 crew, was thought to have had some microbes on it that had somehow survived in the lunar environment before being detected on Earth.
While the thought of a technician accidentally sneezing on the camera’s lens and the resulting residue going to the Moon and back is enticing, the truth is likely more mundane. The contamination could easily have occurred during processing following its return to Earth. Modern techniques are much stricter.
The discovery by Fujita and his team has implications for agriculture in space. Fujita said: “Ultimately, we hope this work opens a new frontier toward constructing ecosystems in extraterrestrial environments such as the Moon and Mars. I hope that our moss research will serve as a starting point.” ®