Mars too dry to host life: study

The surface of Mars is incredibly dry, and has been that way for millions of years, say scientists who suggest that it would be difficult for life to exist on the red planet today.
The lack of liquid water on the surface of Mars has been demonstrated by scientists.
In a study led by the University of Stirling in the UK, an international team of researchers found the lack of rust on the meteorites which indicates that Mars has been dry for millions of years.
The discovery provides vital insight into the planet's current environment.
Mars is a primary target in the search for life outside Earth, and liquid water is the most important pre-requisite for life.

"Evidence shows that more than 3 billion years ago Mars was wet and habitable. However, this latest research reaffirms just how dry the environment is today," said Christian Schroder, from the University of Stirling.

"For life to exist in the areas we investigated, it would need to find pockets far beneath the surface, located away from the dryness and radiation present on the ground," Schroder said.
Previous research had suggested that very salty liquid water might be able to condense in the top layers of Martian soil overnight.
"But, as our data show, this moisture is much less than the moisture present even in the driest places on Earth," said Schroder.

Using data from the Mars Exploration Rover Opportunity, scientists examined a cluster of meteorites at Meridiani Planum - a plain just south of the planet's equator and at a similar latitude to Gale crater.
Researchers have for the first time calculated a chemical weathering rate for Mars, in this case how long it takes for rust to form from the metallic iron present in meteorites.
This chemical weathering process depends on the presence of water.
It takes at least 10 and possibly up to 10,000 times longer on Mars to reach the same levels of rust formation than in the driest deserts on Earth and points to the present-day extreme aridity that has persisted on Mars for millions of years.

The study was published in the journal Nature Communications.