‘Active system’ of flowing water may be hidden underneath Mars surface, scientists say

Discovery could shed light on the Earth, as well as the red planet

There may be a vast and active system of water running underneath the surface of Mars, scientists have said.

Groundwater on Mars may run much deeper than previously thought, with streams flowing invisibly under the surface, a new study has found.

The discovery may help fundamentally change our understanding of the red planet, as well as informing our search for life.

Last year, scientists working with the Italian Space Agency found the presence of a dee-water lake on Mars, under its south pole. The new study suggests that groundwater could still be flowing in active system, and that it could lead to streams flowing on the surface in parts of the planet near the equator.

The researchers found the groundwater probably exists in areas much broader than the plus and that the system could run as deep as 750 meters.

The researchers made the discovery after analysing the characteristics of the Mars Recurrent Slope Linea, which are like dried, short streams of water that appear on the walls of some of the planet's craters.

Previously, researchers thought those features were the result of flowing water across the surface or just underneath it. But now the researchers believe they are actually coming up from a deep pressurised source from where water is pushed up.

"We propose an alternative hypothesis that they originate from a deep pressurised groundwater source which comes to surface moving upward along ground cracks," said Essam Heggy, one of the co-authors on the new paper.

Researchers came to the conclusion after seeing similar mechanisms at work on Earth.

"The experience we gained from our research in desert hydrology was the cornerstone in reaching this conclusion. We have seen the same mechanisms in the North African Sahara and in the Arabian Peninsula, and it helped us explore the same mechanism on Mars," said Abotalib Z. Abotalib, the paper's first author.

Some of Mars craters have fractures in, and the scientists say those allow water springs to rise up to its surface, pushed up by the pressure deep below. Those springs then leak out onto the surface, which leads to the clear features that can be seen in images of the walls of those creators.

That would explain why the water features seem to fluctuate according to Mars' seasons, the researchers say as part of the new study published in Nature Geosciences.

Scientists should consider those exposed parts where the water springs out as primary candidates when looking to explore Mars and understand how habitable it could be, the researchers say. Water of this kind is likely to key to the question of whether Mars could support life – either future human exploration, or basic life that could have lived there in the past or even survive now.

New probing methods would allow scientists to explore those fractures and understand any potential water system that is lurking beneath the surface, the scientists write in the study.

As well as shedding light on the possibility of living on the planet, the new findings are convincing evidence that Mars has important similarities to our own Earth.

"Groundwater is strong evidence for the past similarity between Mars and Earth – it suggests they have a similar evolution, to some extent," said Heggy.

That could help shed light on our own planet and its evolution, as much as the red planet itself.

"Understanding how groundwater has formed on Mars, where it is today and how it is moving helps us constrain ambiguities on the evolution of climatic conditions on Mars for the last three billion years and how these conditions formed this groundwater system," said Heggy in a statement.

"It helps us to understand the similarities to our own planet and if we are going through the same climate evolution and the same path that Mars is going. Understanding Mars' evolution is crucial for understanding our own Earth's long-term evolution and groundwater is a key element in this process."