Mars' surface water: We finally know what happened: study

An international study co-led by Simon Frser University (SFU) researcher Brendan Dyck has revealed that the sun may not have evaporated away all of Mars' surface water after all.

Instead, the surface water on Mars was absorbed by its crust over time, leaving the planet essentially dry.

"The public's infatuation with finding life on Mars stems from the many characteristics both Earth and Mars share," says Dyck. "Early on, both planets had similar potential to sustain life, but as time evolved, Mars lost its surface water along with its potential to sustain complex multi-cellular life."

In the study, published in Nature, Dyck and his collaborators calculated the volume of water that could be held in the minerals that make up Mars' crust. By modelling the reactions of water with the crusts of early Earth and Mars, they found that the Martian crust can hold more than twice the amount of water as Earth, effectively drying out the surface of Mars.

Their findings suggest that approximately 300 meters of surface water on Mars could have been absorbed into its crust and is now locked-up in microscopic mineral structures.

"It would be very difficult to sustain life as we know it on Mars even if surface water existed on the planet for a couple million years. Owing to the long time-scales of evolution, surface water would have to exist for billions of years before the evolution of complex multi-cellular life could take place."

This study shows that the composition of a rocky planet's crust plays an important part in determining whether water will remain on a planet's surface over deep time.