Methane on Mars
Closer to home, there might be life right on our doorstep – and it might even be making its presence known. The Martian atmosphere contains a not-insignificant amount of methane, and on Earth 90 per cent of our methane comes from living organisms. Is the same true on the Red Planet?
To find out for sure, the European Space Agency (ESA) currently has a spacecraft in orbit around Mars called the Trace Gas Orbiter (TGO). It is going to try and map the methane on Mars, and see where it is concentrated. The idea is that microbial life, either living or dead, could have released methane into the atmosphere. This methane could have been left frozen on the surface of Mars, and is being released today as the ice evaporates.
However, the methane could also have been produced by geological processes, such as the oxidation of iron or by volcanic eruptions. We might be able to find out by measuring whether the carbon and hydrogen that makes up the methane on Mars is similar to that on Earth. If it is, well, it points towards a biological origin.
But, we may not truly know the answer to that until we send more advanced landers, or humans, to the surface of Mars.