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Data from a retired NASA mission has revealed evidence of a subterranean water reservoir deep beneath the surface of Mars, according to new research.
A team of scientists estimate that there could be enough water, trapped in tiny cracks and pores of rock in the center of the Martian crust, to fill oceans on the planet’s surface. Groundwater would likely cover all of Mars to a depth of 1 mile (1.6 kilometers), the study found.
The data came from NASA’s InSight lander, which used a seismometer to study the interior of Mars from 2018 to 2022.
Future astronauts exploring Mars would face many challenges if they tried to access the water, as it lies between 7 and 12 miles (11.5 and 20 kilometers) below the surface, according to the published study. Monday in the journal Proceedings of the National. Academy of Sciences.
But the finding reveals new details about the geological history of Mars – and suggests a new place to look for life on the red planet if water could ever be found.
“Understanding the Martian water cycle is critical to understanding the evolution of the climate, surface and interior,” said lead study author Vashan Wright, assistant professor and geophysics at the University of California, San Diego’s Scripps Institution of Oceanography, in statement. “It’s a useful starting point to identify where water is and how much there is.”
The search for ‘lost’ water on Mars
Mars was likely warmer and wetter billions of years ago, based on evidence of ancient lakes, river channels, deltas and water-altered rocks studied by other NASA missions and observed by orbiters. But the red planet lost its atmosphere more than 3 billion years ago, effectively ending the wet period on Mars.
Scientists are still not sure why Mars lost its atmosphere, and many missions have been developed to learn about the history of the planet’s water, where it went, and whether water ever created habitable conditions for life on Mars. Although water is still trapped as ice by the planet’s polar ice caps, researchers do not believe that is the cause of the planet’s “lost” water.
Current theories offer several possible scenarios for what happened to Martian water after Mars lost its atmosphere: Some hypothesize that ice formed or was lost to space, while others suggest that it was formed incorporated into minerals below the planet’s surface or leached into deep aquifers.
The new results suggest that water on Mars has filtered down into the Martian crust.
InSight, short for Inland Exploration using Seismic, Geodesy and Thermal Investigations, was a stationary lander. But it collected unprecedented data about the thickness of the red planet’s crust and the temperature of its mantle, as well as the depth and composition of the core and atmosphere. The lander’s seismometer detected the first tremors on another planet, known as marsquakes.
Although earthquakes occur when tectonic plates shift, move and grind against each other, the Martian crust is like one giant plate with faults and fractures as the planet continues to shrink and cool over time. As the Martian crust stretches, it cracks, and the InSight seismometer was able to detect more than 1,300 marsquakes as they plunged from hundreds of thousands of miles away.
Scientists studying the InSight data were able to study the speed of ocean currents as they traveled through the planet, which could serve as an indicator of the substances that exist beneath the Martian surface.
The speed of seismic waves depends on what the rock is made of, where there are cracks and what fills those cracks, Wright said.
The team used this data and fed it into a mathematical model of rock physics, which is used on Earth to map oil fields and underground aquifers.
The results showed that the InSight data best match a deep layer of undulating or volcanic rock filled with liquid water.
“Establishing a large reservoir of liquid water provides several windows into what the climate was or could be like,” said study coauthor Michael Manga, professor of earth and planetary science at the University of California, San Francisco. Berkeley, in a statement.
“And water is essential to life as we know it. I don’t see why it (the underground reservoir) is not a habitable environment,” Manga added. “It’s certainly true on Earth – deep, deep mines host life, and the bottom of the ocean hosts life. We have not found any evidence for life on Mars, but at least we have identified a place that should, in principle, be able to support life.”
If the crust of Mars is similar across the planet, there could be more water within the mid-crustal zone than the “volumes hypothesized to have filled ancient Martian oceans,” the authors wrote in the study.
Rocks help capture information about a planet’s history, and understanding a planet’s water cycle can help researchers unlock the evolution of Mars, Wright said.
Although the analysis of the data cannot reveal any information about life, past or present, if it existed on Mars, a wet Martian crust could be habitable in the same way that deep groundwater on Earth is hospitable your microbial life, he said. said.
But even drilling holes just half a mile (1 kilometer) or deeper on Earth is a challenge that requires energy and infrastructure, so drilling that deep would require bringing massive amounts of resources to Mars, Wright said.
The team was surprised to find no evidence to suggest that there was a frozen layer of groundwater beneath Insight because that part of the crust is cold. The researchers are still trying to find out why groundwater is not frozen at shallower depths above the middle crust.
Windows in Martian history
The findings add a new piece to the Martian water puzzle.
The idea that liquid water could exist deep under the Martian surface has existed for many years, but this is the first time that real data from a Mars mission can confirm such speculation, said Alberto Fairén, an interdisciplinary planetary scientist visiting and astrologer within the Department. astronomy at Cornell University. Fairén was not involved in the study.
He said the water was probably “a kind of deep underground mud”.
“These new results show that liquid water exists in the Martian subsurface today, not in the form of isolated and isolated lakes, but as liquid sediments soaked in water, or as aquifers,” said Fairén. “On Earth, the subsurface biosphere is truly vast, containing most of the prokaryotic diversity and biomass on our planet. Some investigations even show the origin of life on Earth precisely deep in the subsurface. Therefore, the astrobiological implications of finally confirming liquid water habitats kilometers below the surface of Mars are truly exciting.”
The result is “exactly the kind of thing I hoped we would get out of InSight,” said Bruce Banerdt, principal investigator of the InSight mission.
“I was hoping that we would get data that was good enough to do these kinds of studies where we are really looking at the details of the interior of Mars related to geological questions, questions about Martian habits, questions about evolution. of Mars,” he said.
Banerdt, who was not involved in the research, said that while the interpretation of the data presented in the paper is strongly supported by good arguments, he also believes that it is somewhat speculative and that there is almost always another way to explain a certain set. of data.
“I was very impressed by the fact that Wright et al introduced mineral physics concepts to interpret seismic data,” said Banerdt.
Both Banerdt and Wright expressed interest in the potential to send more seismometers to Mars and other planets and moons within our solar system in the future. While one InSight seismometer collected critical data, spreading it out across Mars would reveal variations within the planet and provide a better window into its varied and complex history, Banerdt said.
“Just as on Earth, where groundwater is connected to the surface through rivers and lakes, this was certainly the case on early Mars as well,” Wright said. “The groundwater we see is a record of the past.”
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