This rover will be able to drill two metres below the surface of the planet and may be our best bet so far of finding proof of life on the planet. In 2018, the ExoMars rover will launch out of the Earth’s atmosphere on its mission to Mars. Photograph: Michael Putland/Getty The actual scientific answer to how you prove life on Mars His question ‘Is there life on Mars?’ didn’t go far enough. So, the preliminary answer to the question how do you prove there’s life on Mars is: very, very carefully.ĭavid Bowie in 1973 on his Ziggy Stardust Tour. But the rover isn’t sterile and so is not allowed to visit protected regions of Mars, lest it bring with it any bugs from Earth that might contaminate the area and bugger up the most-likely potential eco-system outside our planet. The Curiosity rover could just trundle over to the streaks of water that have been found – though they are on a slope, which the rover may not be able to handle – and dig up some dirt for analysis.

The “dark streaks” of flowing water could act as a big X on a map, telling scientists where to dig if they want to find microbial treasure, but now what do they do? This is a pressing problem for Nasa in light of this week’s announcement. Who could tell when microbes were genuinely Martian, or simply earthly contaminants? The problem of contamination He claimed his work didn’t prove there were no Martian fossils in the rock, but he did raise the question of how anyone could really be sure. However, a British scientist came along to rain on their parade when he discovered that bacteria from Earth had contaminated the Mars rock, sneaking their way in through cracks in the rock.

In 1996, scientists at the Johnson Space Center in Houston, Texas, believed that they had found a rock from Mars which contained “microfossils” – that is, fossils caused by ancient Martian microbes. Microbial life, unassuming as it is, is still quite difficult to prove. Once you’re over the disappointment of the fact we’re looking for microbes rather than colonies of scaly green puppies, you’re still left with a tricky problem. Listen to our favourite songs about Mars, and add your own to the Spotify list Spotify How would you “prove” microbial life? As Nasa scientist Ashwin Vasavada told CNN last year in a tone of someone trying hard to take a ridiculous question seriously (a tone I imagine he has to adopt often): “We have no evidence of Martian iguanas or rats at this time.” Dammit. Sadly, this is apparently very far from the type of life we might find on Mars today. Could this skeleton of an alien be real? Wouldn’t it be great if it were? We know that probably the first life that’s found on Mars will be single-celled and only visible under a microscope, but is it so crazy to wish that instead of that we could have the Martian Crabzilla? Or even just a sneaky Mars rat? I mean, that would be awesome right? Which is why even the most reasonable among us get a little frisson when we see extremely spurious photographs of supposed life on Mars. We’ve been fed on a televisual diet of little green men, of humanoid aliens we can fight if they’re evil or rescue and befriend if they’re not. Is there life on Mars, and if so, how do we prove it? Adjust your expectations

It seems David Bowie’s question does not go far enough. These discoveries have raised questions that non-scientists rarely have to think about: what constitutes proof of life on another planet? Assuming an alien isn’t about to streak in front of a Mars rover, which if we’re honest is what we’re all secretly hoping for, what do you look for? And how do you find and send back evidence of life to Earth without contaminating that evidence with life – microbes, bacteria etc – that you’ve brought from Earth? ‘Now this is the plan: get your ass to Mars.’ Arnold Schwarzenegger begins his mission in Total Recall.

Markers around the face of mars