With the help of the European Space Agency's ExoMars Trace Gas Orbiter (TGO), a team of scientists has made a fascinating discovery: a huge deposit of water at the bottom of the Valles Marineris, one of the planet's deepest canyon systems and which is ten times as long and five times as deep as the Grand Canyon.

The orbiter's Fine Resolution Epithermal Neutron Detector (FREND) instrument mapped the amount of hydrogen in the topsoil covering the Martian surface down to a depth of about three feet — and struck pay dirt.

It's an unusual place spot water. Most discoveries of water on Mars to date have been found near the planet's polar regions in the form of ice.

"With TGO we can look down to one meter below this dusty layer and see what’s really going on below Mars’ surface," said Igor Mitrofanov, researcher at the Russian Academy of Sciences and lead author of the study accepted into the journal Icarus, in an ESA statement.

"FREND revealed an area with an unusually large amount of hydrogen in the colossal Valles Marineris canyon system: assuming the hydrogen we see is bound into water molecules, as much as 40 percent of the near-surface material in this region appears to be water," he added.

The area is absolutely massive, about the size of the Netherlands according to the statement, making it a highly promising place to look for even more water in the future.

"We found a central part of Valles Marineris to be packed full of water — far more water than we expected," coauthor Alexey Malakhov said in the statement. "This is very much like Earth’s permafrost regions, where water ice permanently persists under dry soil because of the constant low temperatures."

There's still a chance much of the water deposits are trapped inside minerals, but there is cause for optimism.

"Overall, we think this water more likely exists in the form of ice," Malakhov argued.

"This finding is an amazing first step, but we need more observations to know for sure what form of water we’re dealing with," the ESA's Håkan Svedhem, coauthor who used to be on the TGO team, said in the statement, calling the finding a "large, not-too-deep, easily exploitable reservoir of water in this region of Mars."

The discovery could allow us a better understanding of the early evolution of the Red Planet, and allow us to get a much better idea of where to look for signs of ancient life — or even places we could one day inhabit.

READ MORE: ExoMars discovers hidden water in Mars’ Grand Canyon [ESA]

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