An Ocean’s Worth of Water May Be Trapped Beneath Surface of Mars, New Study Says

View of the last selfie taken by NASA's InSight Mars lander on April 24, 2022. (NASA/JPL-Caltech/Handout via Reuters)

Scientists suggest that liquid water may still exist on Mars, potentially concealed deep within the planet’s rocky outer crust.

The conclusion, published Aug. 12 in the journal Proceedings of the National Academy of Sciences, is based on a new analysis of data collected by NASA’s “InSight” lander. The three-legged, $814 million robot touched down at a plain just north of the red planet’s equator in 2018 and remained active for the next four Earth years, or two Martian years.

The lander carried a seismometer to listen to and record rumblings—popularly known as Marsquakes—from deep inside the planet. As seismic waves travel through or reflect off material in Mars’s crust, mantle, and core, they change in ways that seismologists can examine to determine the composition of these layers.

By analyzing four years of Marsquakes, researchers said they found seismic signals that could be “best explained” by a big reservoir of water.

According to the paper, the Martian “mid-crust”—located 6 to 12 miles below the surface—appears to be composed of igneous rock with thin fractures filled with water.

“Understanding the Martian water cycle is critical for understanding the evolution of the climate, surface, and interior,” Vashan Wright, a geophysicist at the University of California at San Diego and the paper’s leading author, said in a statement. “A useful starting point is to identify where water is and how much is there.”

How Much Water Could Mars Have?

The surface of Mars is known to be scarred with channels and gullies. Scientists believe that around 3 billion years ago, the planet had abundant oceans, lakes, and rivers.

However, during this period, the planet is believed to have lost most of its atmosphere, rendering it unable to sustain stable bodies of liquid water on its surface. The ancient surface water may have been incorporated in minerals, buried as ice, sequestered as liquid in deep aquifers, or lost to space.

If the area studied is representative of other regions across the planet, the Martian mid-crust could contain “more than the water volumes proposed to have filled hypothesized ancient Martian oceans,” the study said.

Wright and his colleagues estimate that the amount of water locked in the pores of the mid-crust could cover the entire planet to a depth of about a mile.

Could the Water Be Harvested?

Unfortunately, the location of this Martian groundwater might not be good news for anyone trying to tap into it to supply a future Mars colony, given how difficult it would be to drill 6 to 12 miles deep into the crust.

“It would be challenging to access liquid water in the Martian water mid-crust,” Wright said. “For example, drilling in the Earth subsurface often involves using some fluid to make the drilling process easier. Such a fluid is not readily available on Mars.”

The deepest hole humans ever dug is the Kola Superdeep Borehole in the Russian Arctic Circle, which reached a depth of about 7.6 miles when the costly project was abandoned in 1989. It took the Soviet scientists almost 20 years to drill that far.

The latest findings on Mars could also provide a direction for the ongoing search for evidence of life on the Red Planet. While Mars’s underground reservoirs might not be necessarily harboring some form of life, they are likely habitable environments.

“The presence of water does not signify that there is life, but water is thought to be an important ingredient for life,” Wright said. “We know that life can exist in deep subsurface of the Earth, where there is water present.”