Scientists have discovered a significant reservoir of liquid water deep beneath the surface of Mars, marking a major breakthrough in our understanding of the Red Planet’s water cycle and potential for habitability

The discovery was made using data from NASA’s Mars InSight lander, which recorded seismic activity on Mars for four years before its mission concluded in December 2022. By analyzing the velocity of seismic waves from Marsquakes, researchers could infer the presence of liquid water in the planet’s rocky outer crust.

Three billion years ago, Mars was covered with oceans and flowing rivers of water. Today, the Red Planet’s landscape is starkly different, with no liquid surface water—just patches of frozen water ice—and rocky channels and dry lakebeds where rivers and lakes once were.

But miles beneath its surface, Mars might contain a massive reservoir of water trapped within the nooks and crannies of porous, volcanic rock, according to a new study published Monday in the journal Proceedings of the National Academy of Sciences. If extracted, researchers say it would be enough water to create a planet-wide ocean about a mile deep...