Millions of years before humans appeared, microbes were thriving here on earth - yet
less than half of one per cent of the estimated
two to three billion microbial species have ever
been identified. Today, the search for new microbes, able to
survive in the world’s most extreme conditions, is
helping us to address one of the last remaining challenges – is there life beyond earth?
Microbes thrive in an extraordinary range of habitats and often where no other life
forms could exist. These include freezing conditions – very
similar to the permafrost of Mars. This could help us prove that life may have
been possible on Mars – and on other planets too
The search for life on Mars is essentially a detective story. It’s about looking for
those tell tale signatures of life, maybe changes to rocks,
maybe parts of microbes left over - those parts of
the evidence that all come together and tell us that Mars once had life or maybe even has
life.
Mars and the earth share many physical similarities. For example, Mars has deserts, glaciers
and polar caps. To help us, we’re looking on the Earth for the most new and different
microbes living in the most extreme environments which are similar to the environments on
Mars, this way we can study signatures the microbes leave behind.
Scientists have found many rocks on Mars that look like they were in contact with water.
And that tells us that there were environments
on Mars that may have been like environments on
earth. Environments that we know contain microorganisms. And this provides us with some
compelling evidence that this is a planet that might once have harboured life.
We’re looking for signs of subsurface microbes living there now or in the past. We’re looking
for key indicators associated with life and these are the building blocks of the cell.
Once we know where to look on earth, we can design and build instruments, which can
search similar environments on Mars. In fact scientists testing equipment in similar
geological conditions to Mars recently discovered a rare and complex microbial community
living in blue ice vents inside the remote and frozen one million-year-old Sverrefjell
Volcano in Norway.
We know that Mars once had water because we can see evidence of old river valleys. But
the radiation from space and makes life there
impossible today. The only place where microbes might still survive, perhaps in pockets of
water, is deep underground – so drilling is the only
option, but it might mean going several meters below the surface.
Studying rocks that have been in contact with water or studying rocks that contain microorganisms
on earth, helps us develop instrumentation to go and look for this life on Mars. So
it’s really about gaining an understanding of where microbes are on earth to help us
look for life on Mars.
This information is helping the development of a Life Marker Chip as part of the ExoMars
Rover expedition in 2018. It’s an instrument incorporated into the rover, travelling across
the surface of the planet, collecting and analysing
soil and rock samples, looking for specific molecules associated with life.
People get terribly excited about the possibility of life on Mars – but we have to remember
it’s just testing a hypothesis – it may be that
we’ll find no evidence of life on Mars in the most
compelling places we think it might have grown. It would be just as remarkable to find no
life on Mars as to find life on Mars because that
would tell us that despite the fact that Mars was
that mars was very similar to Earth in its early history.
something was missing for life.