For decades, Mars has teased us with signs that it was once awash in water. Now, a new discovery suggests the Red Planet might still be hiding a huge ocean beneath its surface, Mars’ Hidden Ocean.
Scientists have been poring over Marsquake data from NASA’s InSight lander. They have found evidence of vast amounts of liquid water. This water is trapped deep below the Martian crust.
This discovery raises tantalizing questions about life. It also raises questions about future exploration. In this feature, we’ll break down what was found. We’ll explain how it connects to Mars’ watery history. We’ll also discuss what it means for the ongoing search for life. This includes our dreams of one day living on the Red Planet.
The Eternal Hunt for Mars’ Hidden Ocean
Mars exploration is guided by a simple mantra: “follow the water.” There is a good reason for this. Almost every mission to Mars has uncovered clues that water once flowed on this now-arid world. Spacecraft have photographed dried-up river channels and ancient lakebeds etched into the Martian surface
Rovers have explored rocks and minerals that only form in the presence of water. These include the “blueberry” hematite spheres found by the Opportunity rover and clay minerals examined by Curiosity. Scientists have amassed a growing body of evidence that the Red Planet was once dominated by water, much like Earth today
In fact, researchers believe that billions of years ago, Mars had rivers and lakes. It even had a vast ocean covering much of its northern hemisphere.
To appreciate the new finding, it helps to recall some milestones in Mars’ water story:
- 1970s: NASA’s Viking orbiters photographed branching valleys and flood channels, the first hints of ancient rivers. The Viking landers even scooped the soil in search of signs of life (though results were inconclusive).
- 2001: NASA’s Mars Odyssey orbiter mapped enormous quantities of hydrogen just below the surface. These findings were interpreted as thick deposits of water ice frozen in the Martian soil. This is especially true near the poles.
- 2004: The Spirit and Opportunity rovers confirmed past water activity. Opportunity found minerals like hematite and gypsum that form in liquid water. This indicates its landing site was once a salty sea or mud flat.
- 2008: Phoenix lander touched down in the arctic plains of Mars. It directly dug up water ice inches beneath the ground. The lander watched the ice slowly sublimate (turn to vapor) in the thin air.
- 2012-Present: The Curiosity rover found ancient streambeds and clay-rich rocks in Gale Crater. This discovery proved a long-lived freshwater lake existed there billions of years ago. Perseverance, which landed in 2021, is currently exploring an ancient river delta in Jezero Crater. It is hunting for signs of fossilized microbial life.
- 2021: China’s Zhurong rover found signs that its landing area (Utopia Planitia) sat on the shore of an ancient ocean. It detected telltale patterns in underground layers. These included sloping, sand-rich deposits like those on beaches. This offers “the clearest evidence yet” that Mars once had a massive ocean.
All these missions built a picture of a Mars that was once much warmer and wetter than today. But about 3.5 billion years ago, Mars’ climate drastically changed – the rivers and lakes dried up as the planet lost most of its atmosphere
Where did all that water go?
Some of it froze into the polar ice caps. Some of it likely escaped into space when Mars’ magnetic field faltered.The new discovery of Mars’ Hidden Ocean suggests that a large portion of Mars’ water may have gone underground. It could form a hidden reservoir deep beneath the surface.