Scientists have proposed that vast amounts of water may be trapped deep within Mars' crust, reigniting questions about the potential for life on the red planet. According to research, over three billion years ago, Mars had lakes, rivers, and even oceans on its surface. However, as the planet lost its atmosphere, these bodies of water disappeared, leaving only permafrost ice at the poles.

While some of Mars' water is believed to have escaped into space, recent studies suggest this isn't the full story. It's possible that the water was absorbed into minerals, buried as ice, or may even exist in liquid form deep beneath the planet's crust.

New calculations indicate that substantial quantities of liquid water might be trapped within rocks, located 11.5 to 20 kilometers below the Martian surface.

“Our liquid water estimate is more than the water volumes proposed to have filled possible ancient Martian oceans,” said Dr. Vashan Wright, a co-author of the study from Scripps Institution of Oceanography at the University of California San Diego.

Hypothesis of presence of life on Mars 

In a study published in the "Proceedings of the National Academy of Sciences", Wright and his colleagues detail their calculations, which are based on gravity data from Mars and measurements from NASA’s InSight lander. The InSight lander provided crucial data on how seismic wave speeds, generated by Marsquakes and meteorite impacts, vary with depth within the planet's crust.

This information was instrumental in their analysis, leading to the hypothesis that significant amounts of water could be trapped deep below Mars' surface. “A mid-crust whose rocks are cracked and filled with liquid water best explains both seismic and gravity data,” Wright said.

Wright added that if the measurements at the Insight lander location were representative of the whole planet, the amount of water trapped in the rock fractures would fill a 1-2km-deep ocean on Mars.

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“On Earth, groundwater underground infiltrated from the surface, and we expect this process to have occurred on Mars,” he said. “The infiltration must have happened during a time when the upper crust was warmer than it is today.”

Wright noted that while their findings do not eliminate the possibility that water was lost to space or trapped in minerals, the research enables scientists to reassess the relative contributions of these various mechanisms to the disappearance of water from Mars' surface. This new perspective helps refine our understanding of how the red planet’s once-abundant surface water may have been redistributed or lost over time.

“The presence of water does not signify that there is life, but water is thought to be an important ingredient for life,” said Wright. “We know that life can exist in the deep subsurface of the Earth, where there is water. The mid-crust of Mars at least contains a key ingredient for habitability and life as we know it.”