🌱 Incredible: this plant survived several months in the vacuum of space

The hostile immensity of space, with its absolute vacuum and deadly radiation, seems to forbid any form of life. Yet, a modest inhabitant of our planet challenges this implacable logic.

Mosses, these ancient plants that carpet forests and walls, possess a survival capacity that defies understanding. Their spores, true biological safes, have just revealed their ability to travel through the cosmos under extreme conditions, opening new perspectives for life beyond Earth.


This discovery comes from work carried out by a team from Hokkaido University, whose research focuses on the evolutionary mechanisms of plants. Their attention turned to Physcomitrium patens, a model moss with a perfectly known genome. Their preliminary laboratory investigations had already highlighted the great resistance of its reproductive structures. But only an in-situ experiment could validate these encouraging observations.

The test of the cosmic vacuum

The experiment took place outside the International Space Station, where spore samples were installed for 283 days. This duration represents prolonged exposure to the most hostile conditions: space vacuum, microgravity, extreme thermal variations, and unfiltered cosmic radiation. The outbound journey took place aboard the Cygnus NG-17 spacecraft in March 2022, while the return to Earth was via the SpaceX CRS-16 capsule in January 2023.

The results exceeded all the scientists' expectations. Over 80% of the spores retained their viability after this prolonged space exposure. Among these survivors, 91% showed an intact ability to germinate once back in the Earth's environment. This observation went against predictions that anticipated near-total destruction of the samples.

Biochemical analysis revealed remarkable stability of the photosynthetic pigments. Only chlorophyll showed a slight decrease of 20%, with no apparent consequence on the vitality of the spores. This overall resistance indicates the existence of particularly effective cellular protection mechanisms against space aggressions.

The secrets of great resistance

The key to this resistance lies in the very structure of the sporophytes, the capsules containing the spores. These protective envelopes act as natural shields against ultraviolet radiation, which is particularly harmful in space. Laboratory tests had demonstrated that encapsulated spores showed UV tolerance a thousand times greater than that of the moss's juvenile cells.

This protection also extends to extreme temperatures. The spores withstood intense cold conditions at -196°C (-321°F) for over a week, as well as sustained heat at 55°C (131°F) for a month. These performances far exceed the survival capabilities of most living organisms, including those of the most resistant bacteria.

Researchers believe these properties represent an evolutionary adaptation dating back 500 million years, which would have allowed bryophytes to colonize terrestrial environments. The protective structure of the spores would constitute a biological innovation that favored the exit from water and the conquest of hostile environments, and then survival through mass extinctions.