Scientists say vast amounts of water may be trapped deep within the Martian crust, raising new questions about whether life could exist on the red planet.
Scientists say that more than three billion years ago, Mars had not only lakes and rivers, but also oceans on its surface – however, when the planet lost its atmosphere, these objects disappeared. All that is visible today is permanent ice at the planet’s poles.
While some water is believed to have been lost to space, research suggests that this is not the whole story, and that water may have been incorporated into minerals, buried as ice, or even found in liquid form deep within the planet’s crust.
Scientists now say their calculations indicate that there are vast amounts of liquid water trapped inside rocks between 11.5 and 20 kilometers below the surface of Mars.
“Our estimate of liquid water is larger than the volumes of water suggested to have filled the ancient Martian oceans,” said study co-author Dr. Fashan Wright of the Scripps Institution of Oceanography at the University of California, San Diego.
Writing in Proceedings of the National Academy of SciencesWright and his colleagues say they based their calculations on gravity data on Mars and measurements taken by NASA’s InSight lander, which reveals how the speed of seismic waves—generated by Martian earthquakes and meteoroid impacts—changes with depth inside the Red Planet’s crust.
“The middle crust, which is made up of fractured rocks and filled with liquid water, better explains the seismic and gravity data,” Wright said.
If the measurements at InSight’s landing site were representative of the entire planet, the amount of water trapped in rock cracks would fill an ocean 1-2 kilometers deep on the Martian surface, Wright added.
“On Earth, groundwater seeped up from the surface, and we expect that this process happened on Mars. The seepage must have happened at a time when the upper crust was warmer than it is today,” he added.
Although the results do not rule out the possibility that water was also lost to space or trapped in minerals, Wright said the work has allowed scientists to reevaluate the relative contributions of these different mechanisms to past surface water loss on Mars.
The study also raises an interesting possibility.
“The presence of water does not mean the presence of life, but water is thought to be an important ingredient for life,” Wright said. “We know that life can exist in the interior of the Earth, where there is water. The middle crust of Mars contains at least one essential ingredient for life as we know it.”
Bethany Ehlman, a professor of planetary science at the Keck Institute for Space Studies, who was not involved in the work, said it is now necessary to make a definitive measurement that will show whether there is liquid water deep on Mars — and if so, where exactly.
“On Earth, where there is liquid water, there is life, so if layers of liquid water exist on Mars now, it is a prime target in the search for life,” she added.
Dr John Wade of Oxford University said he would not be surprised to find life on Mars. “Early in its history, Mars was as suitable for simple life as Earth, if not more so,” he said.
Dr Stephen Banham of Imperial College London added that identifying the presence of liquid water in the middle crust would also help geophysicists and geologists understand the internal structure of Mars and how it behaves.
However, Banham expressed doubts about the feasibility of providing such water as a resource for manned missions to Mars.
“Yes, the amount of water in the Earth’s crust is likely to be enormous, but it will be difficult to access or utilize. It may not make much difference to human exploration, at least initially,” he said.
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