Researchers have uncovered evidence of a massive underground reservoir of liquid water on Mars, using data from seismic activity recorded by NASA’s Insight lander. This reservoir, estimated to contain enough water to cover the entire planet with an ocean 1 to 2 kilometers deep, offers new insights into the history of water on Mars.
The seismic data allowed scientists to locate the reservoir, which is trapped in tiny fractures and pores within the rock of Mars’ mid-crust, lying between 11.5 and 20 kilometers below the surface. Despite its vast size, the reservoir is inaccessible for future Mars colonists due to its extreme depth. Even on Earth, drilling to such depths presents significant challenges.
While this discovery may not immediately benefit future human settlers on Mars, it does pinpoint a promising location in the search for potential Martian life. The existence of such a deep water reservoir could provide clues about the planet’s geological history and its past climate.
“Understanding where water exists on Mars and how much there is crucial to unraveling the planet’s climatic and geological evolution,” said Vashan Wright, assistant professor at UC San Diego’s Scripps Institution of Oceanography and former postdoctoral fellow at UC Berkeley. Wright, along with Michael Manga of UC Berkeley and Matthias Morzfeld of Scripps, published their findings in this week’s Proceedings of the National Academy of Sciences.
The researchers utilized a rock physics model, similar to those used on Earth to identify underground aquifers, to analyze the seismic data from Insight. Their analysis suggests that the most likely explanation for the data is a deep layer of fractured igneous rock, saturated with liquid water. Igneous rocks, like the granite found in the Sierra Nevada, are formed from cooled magma.
“This discovery of a significant liquid water reservoir gives us insight into Mars’ past climate and its potential for sustaining life,” said Michael Manga, UC Berkeley professor of earth and planetary science. “On Earth, we find life in deep mines and at the bottom of the ocean, so there’s a possibility that this reservoir could host life on Mars as well.”
Manga, who served as Wright’s postdoctoral advisor, noted the substantial evidence supporting the theory that water once flowed on Mars, such as river channels and lake deposits. However, this wet period ended more than 3 billion years ago when Mars lost its atmosphere. While much of Mars’ water is now frozen in the polar ice caps, this new discovery suggests that a significant amount may have seeped into the planet’s crust.
NASA’s Insight lander, which arrived on Mars in 2018, was instrumental in this discovery. The mission, which concluded in 2022, provided valuable data on the Martian crust, mantle, core, and atmosphere, far exceeding the expectations of the scientific community.
“The Insight mission has been incredibly successful,” Manga said. “By analyzing the seismic data collected, we’ve been able to determine the thickness of the Martian crust, the depth of its core, and even some of the mantle’s temperature.”
Insight recorded Mars quakes up to magnitude 5, along with meteor impacts and volcanic activity, which helped scientists probe the planet’s interior. An earlier study suggested that the upper crust above a depth of 5 kilometers likely lacks water ice, indicating that accessible frozen groundwater may be limited outside the polar regions.
The latest study focused on the deeper crust and concluded that the best explanation for the data is a water-saturated mid-crust beneath the lander’s location. If similar conditions exist across Mars, the amount of water in this mid-crust zone could surpass the volumes thought to have once filled Mars’ ancient oceans.
This discovery reshapes our understanding of Mars’ water history and opens new avenues in the search for extraterrestrial life, even though the water itself remains out of reach for now.
