The findings, if confirmed by future observations, would be the most significant discovery of liquid water on Mars to date.
Water was not only present on Mars in the past but is still flowing in some capacity today.
What's more, tantalizing clues have continued to imply the existence of liquid water on Mars today.
This new discovery of a subterranean water deposit, outlined in a new paper in Science, suggests water is indeed underneath the red sands of Mars.
Since then, MARSIS has been studying Mars with radar signals to learn more about the planet's interior structure and composition.
The strong radar echoes in 2007 wound up being the result of a layer of icy carbon dioxide on the surface of Mars rather than liquid water beneath.
"CO 2 ice is very transparent and is able to let the radar pulse penetrate into the ice much better than pure water ice," Orosei says, which is why it mimicked the signal one would expect from underground liquid water. »