(Web Desk) - Despite once being home to lush oceans of liquid water billions of years ago, any traces of H2O on Mars today are well hidden.
Now, scientists have discovered two miles of water buried beneath the surface in an area of the planet's equator, known as the Medusae Fossae Formation (MFF).
The water is frozen as ice in a layer measuring over two miles (3.7km) thick, according to new data from the Mars Express spacecraft.
If melted, the water would cover the whole of Mars in a layer of liquid up to 8.8 feet (2.7 metres) deep, and would be enough to fill Earth's Red Sea.
Although melting the ice may require an ambitious drilling operation when astronauts land on Mars, it could potentially be used for drinking or growing crops.
The top of any ice-rich layers is at least 1,000 feet (300 metres) below the surface, but perhaps as much as 2,000 feet (600 metres) below the surface.
A paper about the new research by a group of international experts will be published in the journal Geophysical Research Letters.
'An ice-rich MFF deposit has important implications for the paleoclimate of Mars and could be potentially of great value to future human exploration of Mars,' said study author Thomas R. Watters at the Smithsonian Institution's Center for Earth and Planetary Studies in Washington, DC.
'The MFF deposits are located at the Martian equator along the boundary between the northern lowlands and the heavily cratered highlands – an ideal landing spot for spacecraft as the lower elevation provides more atmosphere to slow a spacecraft’s decent.'
The MFF is a large geological formation of volcanic origin, around a fifth of the size of the mainland United States.
From satellite imagery it appears as smooth and gently undulating, but is partially wind-sculpted into ridges and grooves.
These wind-sculpted features measure hundreds of miles across and several miles high.
More than 15 years ago, Mars Express found massive deposits up to 1.5 miles (2.5km) deep at the MFF – but it wasn't clear what the deposits actually were.
Now, new observations by the legendary spacecraft finally reveals an answer – frozen water.
'We've explored the MFF again using newer data from Mars Express's MARSIS radar and found the deposits to be even thicker than we thought – up to 3.7 km [2.2 miles] thick,' said Thomas Watters of the Smithsonian Institution.
Initial observations from Mars Express in 2007 showed MFF was low in density and didn't really reflect back radar waves – both characteristics typical of icy deposits beneath the surface.
However, at the time, scientists couldn’t rule out the possibility that subsurface features were deep accumulations of windblown dust, volcanic ash or sediment.
Now, the new radar data from Mars Express shows that the density of the features are too low for this – suggestive of water ice.