Mars underground lakes, prospects of life on Mars.
THE prospects of life on Mars have been boosted by the discovering of the first geological evidence of a system of ancient interconnected lakes which once lay deep beneath the Red Planet’s surface.
Lead author Francesco Salese of Utrecht University, the Netherlands, said: “Early Mars was a watery world, but as the planet’s climate changed this water retreated below the surface to form pools and ‘groundwater. We traced this water in our study, as its scale and role is a matter of debate, and we found the first geological evidence of a planet-wide groundwater system on Mars. Mr Salese and colleagues explored 24 deep, enclosed craters in the northern hemisphere of Mars, with floors lying roughly 4000 metres below Martian ‘sea level’, based on elevation and atmospheric pressure).
They found features on the floors of these craters that could only have formed in the presence of water. Many craters contain multiple features, all at depths of 4000 to 4500 m – indicating that these craters once contained pools and flows of water that changed and receded over time.
Features include channels etched into crater walls, valleys carved out by sapping groundwater, dark, curved deltas thought to have formed as water levels rose and fell, ridged terraces within crater walls formed by standing water, and fan-shaped deposits of sediment associated with flowing water.
The water level aligns with the proposed shorelines of a putative martian ocean thought to have existed on Mars between three and four billion years ago.
Co-author Gian Gabriele Ori, director of the Università D’Annunzio’s International Research School of Planetary Sciences, Italy added: “We think that this ocean may have connected to a system of underground lakes that spread across the entire planet.”
“These lakes would have existed around 3.5 billion years ago, so may have been contemporaries of a martian ocean.”
The history of water on Mars is a complex one, and is intricately linked to understanding whether or not life ever arose there – and, if so, where, when, and how it did so.
The team also spotted signs of minerals within five of the craters that are linked to the emergence of life on Earth: various clays, carbonates, and silicates.
The finding adds weight to the idea that these basins on Mars may once have had the ingredients to host life.
Exploring such sites may therefore reveal the conditions suitable for past life, and are therefore highly relevant to astrobiological missions such as ExoMars – which is a joint ESA/Roscosmos project.
While the ExoMars Trace Gas Orbiter is already studying Mars from above, the next mission will launch next year.
It comprises a rover – recently named after Rosalind Franklin – and a surface science platform, and will target and explore martian sites thought to be key in the hunt for signs of life on Mars.
Dmitri Titov, ESA’s Mars Express project scientist, said: “Findings like this are hugely important.
“They help us to identify the regions of Mars that are the most promising for finding signs of past life.
“It is especially exciting that a mission that has been so fruitful at the Red Planet, Mars Express, is now instrumental in helping future missions such as ExoMars explore the planet in a different way. It’s a great example of missions working together with great success.”
Scientists have been increasingly optimistic about the possibility of find life on Mars in recent years.
Speaking after NASA’s Mars Curiosity Rover identified evidence of organic molecules on Mars, Professor Vladimir Airapetian, a senior astrophysicist at Heliophysics Science Division at Goddard Space Centre, who was not involved in the latest research, told Express.co.uk: “This research study has provided a couple of “Lego” pieces to the whole picture of the past habitability of Mars.
“The compounds that they identified including carbon-bearing molecules and methane variations in the Martian atmosphere add to the previously identified nitrates in Gale crater area.
“This discovery may suggest that we should dig deeper into the Martian surface to study where more complex molecules associated with life can be found.”