Moss has emerged as a notable contender for survival in the harsh conditions of space. Known for its resilience in extreme environments on Earth, moss can thrive in inhospitable locales such as the frigid peaks of the Himalayas and the arid sands of Death Valley. Recent research highlights the remarkable potential of the moss species P. patens, particularly its sporophytes, which demonstrated unparalleled stress tolerance against ultraviolet (UV) light, freezing temperatures, and heat.

In a groundbreaking study, researchers examined three cell types of P. patens at different reproductive stages to evaluate their tolerance levels under extreme conditions. The sporophytes performed exceptionally well, leading to a sophisticated experiment where these samples were subjected to space conditions. The research team stored sporophyte samples outside the International Space Station (ISS) within Japan's Kibo module for approximately nine months in 2022, after which the samples were brought back to Earth.

The results were surprising and encouraging; over 80% of the spores survived the rigorous conditions in space, with many even germinating typically once back on Earth. Professor Tomomichi Fujita from Hokkaido University explained that his team's findings suggest these spores could endure space for as long as 5,600 days, nearly 15 years.

Key findings indicated that the vacuum of space, microgravity, and significant temperature fluctuations did not adversely affect the moss spores. However, exposure to light, particularly high-energy UV rays, proved detrimental. Light damage diminished the levels of essential pigments, like chlorophyll a, crucial for photosynthesis, hindering further growth.

Compared to other plant species studied under similar conditions, P. patens showcased superior resilience, although there were some adverse effects on certain moss samples. Fujita noted that the spongy, protective structure of the spores likely plays a critical role in shielding them from dehydration and harmful UV radiation.

This adaptation may have originated early in land plant evolution, allowing mosses to colonize terrestrial environments successfully. Fujita posited that the spores' success in the extreme conditions of space could signify a crucial step towards establishing ecosystems beyond Earth. While this research primarily focuses on a single moss species, Fujita plans to expand his studies to include other species, providing deeper insight into the capabilities of these resilient life forms under challenging environments.