Overview
- A peer-reviewed iScience study reports that more than 80% of Physcomitrium patens spores endured 283 days on the ISS exterior and later germinated in the lab.
- Samples were launched on Cygnus NG-17 in March 2022, mounted on Japan’s Kibo exposure facility, and returned to Earth on a SpaceX cargo flight in January 2023 for analysis.
- Lab and flight data point to the encasing sporophyte structures as the main defense, with prior tests showing roughly 1,000-fold greater UV tolerance than other moss tissues.
- Returned spores showed mostly normal development with about a 20% reduction in chlorophyll a, indicating some UV impact without obvious growth defects.
- Using the results, researchers modeled a tentative survival span of about 5,600 days in similar conditions, cautioning that low Earth orbit differs from deep space and that longer, off-ISS trials are needed.