To ask if you could live outside the International Space Station (ISS) is rhetorical at best but could any living organism on Earth manage it?

One unassuming toughie did, and provided at least rough proof of concept that life could exist on Mars.

Lichen from Antarcticas McMurdo Dry Valleys survived 18 months on a platform attached to the outside of the ISSs Columbus module, Futurism reported. Though they emerged in worse shape than temperate lichens tested separately in Mars-like conditions, many still survived.

The International Space Station. Photo: NASA

The study authors focused on the success of the species in the Martian simulation.

The most relevant outcome was that more than 60% of the cellsremained intact after exposure to Mars, said Rosa de la Torre Noetzel of Spains National Institute of Aerospace Technology (INTA) and co-researcher on the project.

Survival in outer space itself was lower. Only around 35% of these lichens cells retained their membranes throughout the experiment.

Nevertheless, this is strong evidence that lichen is tougher than anything alive by many orders of magnitude.

For carbon-based life forms, outer space is in a word unsurvivable. In no particular order, space is:

However, repeated experiments have proven lichens resistance to these conditions.

In 2005, researchers placed lichens aboard a rocket and then attached them to a European Space Agency module outside a Russian satellite. They left them for 16 days, then brought them back home.

All exposed lichens, regardless of the optical filters used, showed nearly the same photosynthetic activity after the flight, the study said. These findings indicate that [most lichen cells] can survive in space after full exposure to massive UV and cosmic radiation, conditions proven to be lethal to bacteria and other microorganisms.

Read more:

Lichen Survives on Outside of International Space Station Explorersweb - ExplorersWeb