What does discovery of liquid water on Mars actually mean?

26 Jul 2018

Image: Dotted Yeti/Shutterstock

The discovery of liquid water just beneath the surface of Mars confirms a long-suspected theory, but could it hold life?

In 2015, the appearance of Mars as a desolate, dry, lifeless planet was significantly challenged after a team of researchers announced it had discovered evidence of running liquid water on its surface.

Just two years later, this claim was refuted with evidence appearing to show the alleged water flows are actually just granular flows of dust.

But now, hope for the potential confirmation of microbial life on Mars has been boosted significantly following the discovery of what appears to be a pool of liquid water buried beneath layers of ice at the planet’s southern pole.

Given that the ghostly shadows of Mars’ watery past cover the planet, the existence of liquid water beneath its surface had long been suspected by scientists. On top of that, the presence of salts on Mars made it ideal to keep any water liquid, even at freezing temperatures.

A big salty pool

Now, new evidence from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument aboard the European Space Agency’s Mars Express satellite has helped confirm it for the first time.

The investigation showed that the south polar region of the Red Planet is made of many layers of ice and dust down to a depth of 1.5km in an area 200km wide.

After analysing the results, a particularly bright 20km-wide spot was found, which was interpreted to be a stable body of liquid water, laden with salty, saturated sediments.

Liquid water on Mars radar scan

This image shows an example radar profile for one of 29 orbits over the 200x200km study region in the south polar region of Mars. The brightest reflections from the base layer – close to the centre of this image – is interpreted as a pond of liquid water. Image: ESA/NASA/JPL/ASI/Univ Rome; R Orosei et al 2018

A ‘thrilling’ discovery

“This is just one small study area; it is an exciting prospect to think there could be more of these underground pockets of water elsewhere, yet to be discovered,” said Roberto Orosei, principal investigator of the MARSIS experiment and lead author of the paper published to Science.

These findings open up the door again to the possibility of the existence of the hardiest known lifeforms – extremophiles – on the Red Planet as the pool draws considerable comparisons with life found at Lake Vostok 4km below Antarctica.

The possibility of life on Mars, either now or historically, is still the greatest question left to answer about our nearest planetary neighbour, and it will now be up to future missions – such as the current European-Russian ExoMars orbiter and future rover – to analyse it up close.

Dmitri Titov, ESA’s Mars Express project scientist, added: “This thrilling discovery is a highlight for planetary science and will contribute to our understanding of the evolution of Mars, the history of water on our neighbour planet and its habitability.”

Colm Gorey was a senior journalist with Silicon Republic