Space‑Resilient Moss: Spores Exposed on the ISS Survive Nine Months with >80% Viability

02:11 AM, 11/22/2025

The study found that moss spores mounted on the exterior of the International Space Station survived a nine‑month exposure to space, with more than 80% remaining capable of reproduction after return to Earth. Lead author Tomomichi Fujita called the results "striking evidence" that cellular material from Earth can endure harsh space conditions. The unexpected high viability suggests implications for planetary protection, panspermia research and the development of biological elements for future off‑world systems.

Researchers exposed spores of a hardy terrestrial moss on the exterior of the International Space Station for nine months. When the samples were returned to Earth and examined, more than 80% of the recovered spores remained viable and were able to reproduce, according to a study published in iScience.

"Most living organisms cannot survive even briefly in the vacuum of space," said Tomomichi Fujita, lead author and professor of plant biology at Hokkaido University. "These results provide striking evidence that, at least at the cellular level, material from Earth can endure the harsh environment beyond our atmosphere."

The spores endured vacuum, extreme temperature swings and elevated radiation while mounted outside the station. Previous space biology experiments emphasized larger plants and various bacteria; this work highlights the exceptional resilience of microscopic spores and their capacity to withstand direct exposure to space.

Before the experiment the team expected an "almost zero survival" rate, but the outcome was the opposite. Although the findings do not imply that whole ecosystems could survive unaided in space, they raise important questions about planetary protection, the possibility of natural interplanetary transfer of life (panspermia), and the future use of robust biological materials for off‑world habitats and life‑support systems.

The researchers plan follow-up studies to identify the mechanisms of resistance, test additional species and exposure durations, and assess the long‑term reproductive fitness of survivors.

Space‑Resilient Moss: Spores Exposed on the ISS Survive Nine Months with >80% Viability

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