Could there be life on Mars

What do rocket fuel, gold mine-loving bacteria and antifreeze have to do with finding life on Mars? Lisa from our Live Science Team fills us in. 

This week is World Space Week, meaning it’s time to celebrate all things space! We thought we’d take a look at one of the most exciting and cutting edge space stories of 2015: the discovery of liquid water on Mars. 

So what’s the big deal? Every few months it seems that there’s a new story about water on the Red Planet. Up until now we were confident that there’s frozen water on Mars, and that there used to be liquid water too – maybe even oceans like on Earth. However, this new data proves that Mars has flowing, liquid water on it right now. All life as we know it needs liquid water to survive, so the latest discovery gives Mars a serious level-up on the list of places we might find alien life.

Except… there’s a slight hitch. You might have heard that Mars isn’t exactly the warmest spot in the Solar System, clocking in at an average temperature of -55˚C. So the only reason this water we’ve found isn’t frozen is because it contains salts. We know that salt lowers the freezing point of water – that’s why we put salt on the roads when they get icy. The salts that scientists have found in Martian water are perchlorate salts – or rocket fuel to you and me. So is that really much progress in the search for life?

Well, life as we know it is actually weirder than you might think. Living things are surprisingly good at getting everywhere, and surviving in the most extreme conditions you can imagine. One example of this that seems to be particularly trendy in the world of science reporting at the moment is the Tardigrade. These 8-legged critters measure up at around 0.5mm and can survive deadly ionising radiation, temperatures over 100˚C and under -200˚C, nearly 6000 times atmospheric pressure at sea level and the vacuum of outer space. Now that sounds impressive… but when we’re looking at candidates for an alien life lookalike there’s a sneaky word that can throw us off: survive. We can probably all agree that there’s a difference between living and simply surviving. Tardigrades don’t particularly like to live in those extreme conditions, but they will if they have to.

However, if we delve into the world of microbiology, we find that there are single celled organisms that just love living in extreme conditions. They’re imaginatively called extremophiles (literally “extreme-loving”) and come in all shapes and sizes. If you can think of a completely inhospitable environment, there’s probably a microbe that loves living there.

There’s one extremophile in particular that scientists think might be the closest thing to alien life down here on Earth. It’s named Desulforudis audaxviator, which is more poetic than it sounds. Audax Viator means “bold traveller” in Latin, a reference to Jules Verne’s book Journey to the Centre of the Earth – appropriate seeing as it was found 2.8km down a gold mine. It’s not easy to please, with a preference for radioactive rocks at temperatures around 60˚C, a severe aversion to oxygen, and a diet of sulphates and CO2. These picky requirements are great for the microbe – it’s got the place all to itself as the only living thing in its environment. However, the one thing it does have in common with us, and all other life that we know about, is that it needs liquid water to survive.

So, our antifreeze water on Mars is starting to look more hospitable. In fact scientists have already found bacteria on Earth that can process perchlorate salts, so why not on Mars? This is certainly an exciting time in the search for life beyond Earth, so keep an eye on the news!