Using seismic data from the InSight mission, scientists have found evidence that seismic waves slow down in a layer between 5.4 and 8 kilometers below the surface of Mars. This may be due to the presence of liquid water at these depths.
The mystery of the missing Martian water
Mars was not always the barren desert we see today. Billions of years ago, rivers flowed across its surface, flowing into lakes and seas. When the planet’s magnetic field weakened and the atmosphere thinned, much of the surface water disappeared. Some of the water went into space, some of it froze in the polar caps, and some of it became bound up in minerals, where it remains to this day.
But evaporation, freezing and rocks can’t fully explain all the water that existed on Mars in the distant past. Calculations show that the “missing” water is enough to cover the planet with an ocean at least 700 meters deep, and possibly up to 900 meters deep.
One hypothesis says that the missing water seeped into the crust. During the Noachian period (4.1 billion to 3 billion years ago), Mars was subjected to heavy asteroid bombardment, which may have created cracks that carried it into the planet’s interior. There, the higher temperatures would have kept the water in a liquid state, unlike the frozen layers closer to the surface.
InSight mission data
The InSight rover landed on Mars in 2018. One of its main tasks was to study the interior of the Red Planet using a highly sensitive seismometer. It collected data for nearly four years.
The research team decided to use them to find an answer to the question about the possibility of the existence of a hidden water layer. To achieve this, they analyzed data collected by InSight during two meteorite impacts in 2021 and 2022. They generated seismic waves that swept across the crust of the Red Planet like circles on water.
By studying the pattern of wave propagation, the scientists found a significant underground anomaly: a layer at a depth of 5.4 to 8 kilometers where they moved more slowly. This “low-velocity layer” is likely a liquid water-filled, highly porous rock, like a moisture-soaked sponge. As an analogy, terrestrial aquifers are where groundwater seeps into the pores of rock.
Calculations show that the “aquifer” on Mars could contain enough water to cover the planet with a global ocean 520-780 meters deep. This is several times more than in Antarctica’s ice sheet.
According to scientists, if there were ecosystems on Mars in ancient times, its relics may well have found refuge in these subsurface bodies of water. They could also make it much easier for humanity to colonize and terraform the planet, becoming a source of drinking water as well as rocket fuel components.
Earlier we reported on the results of another study, the authors of which came to similar conclusions about the existence of the subsurface ocean of Mars.
According to Phys.org
