In 2018, scientists made the incredible discovery that they had found a "stable body of liquid water" on Mars. A new study takes that one step further and suggests that the water thought to be responsible for dark streaks on the Red Planet may be coming from well below the surface.
The new study, published in Nature Geoscience, suggests that the recurring slope lineae (RSL) may have a "deep underground origin" and not flows of water either on or just underneath the surface, as previously thought.
"We suggest that this may not be true," the study's co-author, Essam Heggy, said in a statement. "We propose an alternative hypothesis that they originate from a deep pressurized groundwater source which comes to the surface moving upward along ground cracks."
The study's lead author, Abotalib Abotalib, added that by studying the deserts on Earth, the researchers were able to suggest the same is true for our celestial neighbor.
"The experience we gained from our research in desert hydrology was the cornerstone in reaching this conclusion," Abotalib added in the statement. "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."
"Spatial correlation between recurring slope lineae source regions and multi-scale fractures (such as joints and faults) in the southern mid-latitudes and in Valles Marineris suggests that recurring slope lineae preferably emanate from tectonic and impact-related fractures," the researchers wrote in the study's abstract. "We suggest that deep groundwater occasionally surfaces on Mars in present-day conditions."
The researchers were able to look at imagery from NASA's Mars Reconnaissance Orbiter, which found the RSL 8 years ago. From there, they looked at 3 specific craters and streaks in the Valles Marineris complex and found a correlation between the RSL and faults, according to Space.com.
The depths of the underground water could be significant, nearly half-a-mile (2,460 feet) deep, according to Heggy. "Such depth requires us to consider more deep-probing techniques to look for the source of this groundwater versus looking for shallow sources of water, " he added in the statement.
If the water is as deep as Heggy and Abotalib believe, that could indicate more similarities between Mars and Earth, with Heggy going so far as to say it might suggest "they have a similar evolution, to some extent."
The researchers believe that if they are able to understand how the groundwater formed on Mars, its precise location and how it moves, it could help us further understand our own planet and if we're undergoing the same changes to the climate that Mars experienced over the past 3 billion years
"Understanding Mars' evolution is crucial for understanding our own Earth's long-term evolution and groundwater is a key element in this process," Heggy said.