First evidence of ancient groundwater system found on Mars: Scientists

Last year European Space Agency's Mars Express mission detected a pool of liquid water beneath the planet's south pole.

Business Standard : Scientists say they have found the first geological evidence of a system of ancient interconnected lakes that once lay deep beneath the surface of Mars, five of which may contain minerals essential for life.

According to researchers from Utrecht University in the Netherlands, Mars appears to be an arid world, but its surface shows compelling signs that large amounts of water once existed across the planet.

Last year European Space Agency's Mars Express mission detected a pool of liquid water beneath the planet's south pole.

A new study, published in the Journal of Geophysical Research: Planets, reveals the extent of underground water on ancient Mars that was previously only predicted by models.

"Early Mars was a watery world, but as the planet's climate changed this water retreated below the surface to form pools and 'groundwater'," said Francesco Salese from Utrecht University.

"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," Salese said in a statement.

The researchers explored 24 deep, enclosed craters in the northern hemisphere of Mars, with floors lying about 4000 metres below martian 'sea level' -- a level that, given the planet's lack of seas, is arbitrarily defined on Mars based on elevation and atmospheric pressure.

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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 metres -- 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.