Despite intense UV radiation and temperature swings, most spores remained viable when returned to Earth. Their protective casing acts as a natural shield, enabling resilience even scientists didn’t expect. The results open doors to using hardy plants for future off-world agriculture.

Moss Resilience From Earth to Space
Mosses are known for their ability to flourish in some of the harshest locations on the planet, from high mountain ranges like the Himalayas to the scorching terrain of Death Valley, as well as the frozen Antarctic tundra and even the cooling surfaces of active volcanoes. Their remarkable toughness inspired researchers to send moss sporophytes, which are reproductive structures that contain spores, into what may be the most inhospitable environment of all: outer space. The study, published in iScience today (November 20), reported that more than 80% of the spores endured 9 months outside the International Space Station (ISS) and returned to Earth still able to reproduce. This marks the first documented instance of an early land plant surviving long-term direct exposure to space.

“Most living organisms, including humans, cannot survive even briefly in the vacuum of space,” says lead author Tomomichi Fujita of Hokkaido University. “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.”

Fujita first began considering the idea of testing moss in space while examining plant evolution and development. Mosses seemed exceptionally capable of settling in places that challenge most forms of life. “I began to wonder: could this small yet remarkably robust plant also survive in space?”