Astro-geeks (and Matt Damon fans) are all talking about The Martian, which hits cinemas around the world this week (a release date that seems to sync up a little too conveniently with recent news that scientists have discovered water on the Red Planet … but we digress). The film, based on the book by Andy Weir, follows the plight of astronaut and botanist Mark Watney as he struggles to survive while stranded on Mars.

And struggle he should. The Red Planet is right outside the “Goldilocks Zone”, the region around the sun where life as we know it could exist. Climate is a major concern here, with temperatures ranging from -50°C to 23°C (-50°F to 73°F) – but the weather isn’t the only challenge. Mars has a "miniscule atmosphere", meaning low oxygen and low pressure; hanging out on the surface of Mars is the equivalent of being 35 kilometres above the Earth, an altitude that only the highest "air-breathing" airplanes can reach. 

Of course, things can get pretty crazy down here on Earth too, and that craziness can teach us a lot about what life on Mars would be like. These three creatures survive in extreme environments on our Pale Blue Dot ... so how do their adaptations match up with the Red Planet? We gave them a “Watney Rating” based on how well they’d do there (Watney did say things should be named after him given what he's been through).


Nematode The Martian 2015 10 02
Original image: Scot Nelson; Space suit: Colin

These tiny worms are some of the most common multicellular animals on Earth. There are nearly 20,000 species in the phylum Nematoda. However, some nematodes are more extreme than others. A handful of species, including Halicephalobus mephisto, have been discovered in mines and caves, living deeper than scientists previously thought possible for a multicellular organism.

Living deep down (some as far as a kilometre, or 1.6 miles, underground) means living far away from rich surface nutrients, sunlight and oxygen. But as long as nematodes can find bacteria, they can survive. Unfortunately for these extreme critters, intergalactic travel will have to remain a pipe dream for now. As far as we know, Mars doesn’t include anything that could feed these guys (and they’re not smart enough to grow their own potatoes). Even if they managed to find something to munch on, they wouldn’t stand up to the cold, dry Martian soil. However, the discovery of these "goldmine worms" prompted researchers to start questioning whether life could exist below the surface of Mars.


Tardigrade The Martian 2015 10 02
Original image: Don Loarie; Space suit: Colin

Tardigrades, also known as water bears, are the toughest microscopic animals you’ll never see. They're nearly impossible to kill. When faced with hostile conditions, they enter a state known as cryptobiosis, or suspended hibernation. There isn’t a habitat on Earth these guys couldn’t deal with; they’ve been found anywhere from the polar ice caps to the deep oceans to the tropics. They’ve even spent time in the vacuum of space ... and came back alive!

The only thing working against tardigrades is their need for water. Without it, they enter cryptobiosis until more water is found – and that would be a problem on Mars. However, NASA announced this week that they’ve officially discovered liquid saltwater on Mars (yay!), so perhaps there’s hope for our tiny tardigrade friends (they have, after all, been known to live in saltwater down here on Earth).


Cyanobacteria The Martian 2015 10 02
Original image: Nat Tarbox; Space suit: Colin

Cyanobacteria are some of the oldest forms of life on Earth, so they can live through almost anything – and they’ve already been tested for Martian survivalist skills. Scientists at the German Aerospace Center created a chamber that simulates the environment on Mars, complete with Martian soil, and they placed cyanobacteria inside to see how well they'd fare.

The bacteria not only survived the 34-day-long test, but actually thrived! And it’s no wonder: cyanobacteria have the perfect adaptations on their side. Because of the thin Martian atmosphere, light from the sun doesn’t really get filtered out. Instead, the surface is hit with harsh UV and infrared radiation. For most species, this would be a disadvantage – those harsh rays can blast through cells and destroy genetic material. But cyanobacteria are prokaryotes, so they don’t have a central nucleus full of genetic material. Instead, they’re filled with chlorophyll, which means they can use harsh sunlight as food – and what's more, that process creates much-needed oxygen! In fact, cyanobacteria are responsible for most of the oxygen on Earth, a fact that has some scientists wondering if we could use cyanobacteria to terraform Mars.