Mars may be not as dry as it seems, say researchers

Researchers believe they have found the answer as to what happened to all the water that was once on Mars.

Much of it, they proposed Wednesday, may be locked up in stone.

"The results revealed that the basalt rocks on Mars can hold approximately 25 percent more water than those on Earth, and as a result drew the water from the Martian surface into its interior," said a statement from Oxford University, where scientists took part in the study.

Previous studies had suggested that the water was swept into space by powerful solar winds when the planet's magnetic field collapsed, while some was captured in sub-surface ice.

But this did not account for all the missing water.

A landscape image of Mars captured by NASA's Curiosity rover.

To try to track down the rest, an international team of researchers puts scientific modeling to the test.

As on Earth, chemical weathering and hydrothermal reactions can change minerals in rock from dry to water-bearing, study co-author Jon Wade of Oxford told reporters.

But Martian rock, because of a different composition, is much better at doing so.

Such rocks would have reacted with the surface water on Mars, locking some of it up in their mineral structure, Wade said in an email.

Another recent study by Northern Illinois University showed how much water once flowed on Mars based on present-day geography and geology.

"It is not liquid anymore but physically bound in the mineral," he said – which means the only way to release the water would be to melt the rock.

On an infant Earth, water-bearing rocks formed in a similar way would have floated on the planet's super-hot surface until they melted, releasing water back to the surface as they did.

But on Mars, not all the rock would have melted and some of the water would have remained trapped in rock that sank straight to the mantle.

"In essence, Mars was doomed by its geochemistry!" Wade said.

Many organizations are now planning colonies on Mars, including Nasa, Elon Musk and Mars One.

Liquid water is a prerequisite for life as we know it. And although it is dry and dusty today, the Earth's neighbor is thought to have been a wet planet once.

In 2015, NASA said almost half of Mars's northern hemisphere had once been an ocean, reaching depths greater than 1.6 kilometers (one mile).

Later that year, a study announced the discovery of "water" remaining on the fourth rock from the Sun, in the form of super-salty brine streaks running down steep slopes.

The latest findings were published in the journal Nature .

(AFP)