The next great search for life on Mars

The hunt for life on Mars is on again. NASA’s fifth rover, Mars 2020, will scour the Martian surface for signs that the Red Planet might once have been not only inhabitable, but inhabited.

Once the Mars 2020 rover arrives on the Martian surface in 2021, it will get to work hunting out interesting rocks. The rover is looking for those most likely to contain biosignatures – chemicals like water or hydrocarbons, which suggest that life could have existed on the Martian surface, and perhaps still does.

But rather than examining promising looking rocks in an onboard lab as its predecessor Curiosity did, Mars 2020 will create caches of samples, then leave them on the surface so a future mission will be able to retrieve the rock and return it to Earth. There, the scientists can use the world’s most sophisticated laboratories to analyse every aspect of the samples searching for biosignatures. With analysis no longer limited by what can fit on a rover, it could be possible to find fossil – or perhaps even living – microbes hidden deep within the rock.

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As well as searching out possible past and present life, the rover will aid in bringing future life to Mars by testing tools that could support humans on the Red Planet. Mars 2020 will test a technique to strip oxygen out of the carbon dioxide in the Martian air. Not only can astronauts use this to breathe, but it could also be used as rocket fuel.

Diving into the deep

2020 will see not one, but two rovers heading towards Mars. ExoMars is a joint mission between the European and Russian space agencies – both of who have tried, and failed, to land on Mars before.

Like Mars2020, ExoMars will look for signs of Martian life. But rather than scraping at the surface, it will use a 2m drill to burrow down to where any organic material would be protected from the surface radiation that would otherwise destroy it.

The rover will seek out rocks with a high water content, because on Earth where you find water, you find life. Once a sample has been drilled, the onboard laboratory will sniff out any organic molecules. While these aren’t necessarily biological in origin they are the fundamental building blocks of life as we know it. Curiosity has previously found traces of organics, but ExoMars should help to pin down exactly what they are, and what they mean for potential life on Mars.