Deep Reservoir of Water on Mars Could Support Life

An enticing discovery leaves scientists... enticed

New modeling indicates there’s enough water deep in the interior of Mars to create an ocean 1 mile (1-2 km) deep over the entire surface of the planet. In theory, the underground water could support life, the researchers said today, but there’s no evidence yet for life way down there.

A cutout of the Martian interior beneath NASA’s Insight lander. The top 5 kilometers of the crust appear to be dry, but a new study provides evidence for a zone of fractured rock 11.5-20 km below the surface that is full of liquid water — more than the volume proposed to have filled hypothesized ancient Martian oceans. Credit: James Tuttle Keane and Aaron Rodriquez, courtesy of Scripps Institute of Oceanography

And “way down there” is the operative phrase. The water is locked in pores and cracks in rock from 7 to 12 miles (11.5 to 20 km) beneath the surface, deeper than a typical terrestrial drilling rig can go, too deep and sequestered to naturally bubble to the surface on its own.

The finding, based on seismic data from NASA's Insight lander, are detailed this week in the Proceedings of the National Academy of Sciences.

"Establishing that there is a big reservoir of liquid water provides some window into what the climate was like or could be like," said study team member Michael Manga, a UC Berkeley professor of earth and planetary science. "And water is necessary for life as we know it. I don't see why [the underground reservoir] is not a habitable environment. It's certainly true on Earth — deep, deep mines host life, the bottom of the ocean hosts life. We haven't found any evidence for life on Mars, but at least we have identified a place that should, in principle, be able to sustain life."

How the research was done:

The scientists employed a mathematical model of rock physics, identical to models used on Earth to map underground aquifers and oil fields, to conclude that the seismic data from Insight are best explained by a deep layer of fractured igneous rock saturated with liquid water. Igneous rocks are cooled hot magma, like the granite of the Sierra Nevada.

As with previous reports of water beneath the surface of Mars, and water frozen in polar ice, the new finding is one more place scientists can look, with future missions, for any signs of past or present life on Mars. The analysis also helps researchers better understand the water cycle on Mars, a planet that was once thought harbor rivers and oceans and a legitimate atmosphere—all of which mysteriously disappeared long ago.

A 2018 photo of Mars during a dust storm, snapped by the Hubble Space Telescope. More than 3 billion years ago, the dusty red planet had oceans and rivers, previous evidence has indicated. That water disappeared, leaving only ice on the surface, most of it in the polar caps. Credit: NASA/ESA/STScI

“Understanding the Martian water cycle is critical for understanding the evolution of the climate, surface and interior,” said Vashan Wright, a former UC Berkeley postdoctoral fellow who is now an assistant professor at UC San Diego’s Scripps Institution of Oceanography. “A useful starting point is to identify where water is and how much is there.”

An artist’s concept of the InSight lander on Mars after the lander’s robotic arm deployed a seismometer (domed object to the left of the lander) and a heat probe directly onto the ground. The lander stopped recording data in 2022, but scientists are still mining the data for information about Mars’ interior. Credit: NASA/JPL-Caltech

During its time functioning on Mars, the Insight lander also recorded Marsquakes, meteorite impacts, and volcanic rumblings.