Large amounts of water can be trapped deep in the crust of Marsscientists said, raising new questions about the possibility of life on the red planet.
Scientists say that more than 3 billion years ago, Mars had not only lakes and rivers, but oceans on its surface – but as the planet lost its atmosphere, these bodies disappeared. All that is visible today is permafrost ice at the planet’s poles.
Although some of the water is thought to have been lost to space, research has suggested that this is not the full story, and that water could be absorbed into minerals, buried as ice, or even in liquid form deep within the planet’s crust could exist.
Now scientists say their calculations indicate that large amounts of liquid water are trapped in rocks about 11.5-20 km below the Martian surface.
“Our estimate of liquid water exceeds the volumes of water that have been proposed to fill 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. .
Write in the Proceedings of the National Academy of SciencesWright and colleagues report how they made calculations based on gravity data for Mars and measurements recorded by Nasa’s InSight lander. The latter reveals how the speed of seismic waves – created by Martian quakes and meteorite impacts – changes with depth in the red planet’s crust.
“A middle 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 site were representative of the entire planet, the amount of water trapped in the rock fractures would fill a 1-2 km deep ocean on Mars.
“On Earth, groundwater infiltrated underground 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.”
While the results do not rule out the possibility that water was also lost to space or trapped in minerals, Wright said the work allowed scientists to estimate the relative contributions of these different mechanisms to past surface water loss on Mars. to reconsider.
The study also raises a tantalizing possibility.
“The presence of water does not mean that there is life, but water is considered an important ingredient for life,” Wright said. “We know that life can exist in the deep underground of the earth, where there is water. The mid-crust of Mars contains at least one key ingredient for habitability and life as we know it.”
Bethany Ehlmann, a professor of planetary science at the Keck Institute for Space Studies, which was not involved in the work, said it is now necessary to make a definitive measurement showing whether or not there is deep liquid water on Mars – and, if so, exactly where it is.
“On Earth, where there is liquid water, there is life, so if liquid water aquifers are now present on Mars, they are a prime target in the search for life,” she added.
Dr Jon Wade of the University of Oxford said he would not be surprised by life on Mars. “Early in its history, Mars would have been as conducive to simple life as Earth, if not more so,” he said.
Dr Steven Banham of Imperial College London added that identifying liquid water in the middle crust would also help geophysicists and geologists to understand the internal structure of Mars and how it behaves.
However, Banham raised doubts that such water could provide a resource for crewed missions to Mars.
“Yes, the amount of water below the crust is potentially large, but it will be difficult to access or utilize,” he said. “It may not make much difference to human exploration, at least initially.”
