Discussing Mars as a “once wet” world might soon be a thing of the past, because if a new study turns out to the correct then Mars is still a relatively wet world today - and not just at the poles, but at the equator too where it permeates up to the surface through cracks found in craters.
Earlier this month, scientists suggested Mars once had an ancient planet-wide system of channels that connected underground lakes with an extensive ocean that covered much of the martian surface. Impressive as this sounds, it might only be half of the story.
If there is one type of terrain on Earth that could be used as an analogy for what might be currently occurring on the Red Planet, then a dry and arid desert comes pretty close. An idea that two researchers at the University of Southern California (USC) Arid Climate and Water Research Center (AWARE) have already latched on to.
Using their experience gained from research in subsurface aquifers and groundwater flow movement found in arid environments on Earth, Essam Heggy and co-author and colleague Abotalib Z. Abotalib, both from USC, compared features found in the North African Sahara and in the Arabian Peninsula with similar geological patterns on our nearest terrestrial neighbour.
The features they examined are called recurring slope linea – sharp and distinct linear features – that are found lining the sides of crater walls all over the martian surface. Scientists previously thought these streaky rock carvings were affiliated with surface water flow or close subsurface water flow, says Heggy, who recently published their work in Nature Geoscience.
"We suggest that this may not be true. We propose an alternative hypothesis that they originate from a deep pressurised groundwater source which comes to the surface moving upward along ground cracks," Heggy says.
The analysis of the crater walls was made using hi-resolution optical images and via modelling to infer that groundwater was responsible for the features and, say the duo, it could stretch as far down as 750 metres beneath the surface. But we’re not talking about long-past aquifer processes that occurred millions or billions of years ago, but springs that leak occasionally onto the surface in present times, I.e water on Mars is active right now.
"The experience we gained from our research in desert hydrology was the cornerstone in reaching this conclusion,” said Abotalib. After seeing the same mechanisms on this planet, it helped us explore the same mechanism on Mars, he added.
With a big push by NASA to head to Mars, knowing that water could be easily accessible would be hugely advantageous, but this particular study is not about colonisation. For Heggy, these rare and puzzling water flows on Mars are of big interest to the science community.
"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. 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. "