At first glance this hilly desert landscape appears to show
islands of trees casting shadows on reddened soil.
But this strange winter wonderland of dusty dunes, icy rivulets and dark
outcrops lies 62 million miles away on Mars. And the 'trees,' pictured by a
Nasa probe, are actually trails dislodged sand.
In winter a layer of carbon dioxide ice covers the dunes but this evaporates
in spring causing dark material to streak down the slopes.
A small plume of dust is even visible to the centre left of the image, which
was kicked up by the falling debris.
Candy Hansen from Nasa added: 'The colour of the ice surrounding adjacent
streaks of material suggests that dust has settled on the ice at the bottom
after similar events.'
The picture was taken by the powerful HiRISE camera on board the Mars
Reconnaissance Orbiter - a probe that has been circling the Red Planet since
The orbiter was commissioned to search for evidence that water persisted on
the surface of Mars for a substantial period of time - long enough to
provide a habitat for life.
For that reason it has focused much of its attention on the cold polar
Mars, like Earth, is believed to have experienced global climate changes
over the past few million years.
The layered deposits in the polar regions of Mars should hopefully have
recorded these changes over millions of years.
Changes in the tilt (relative to the Sun) of the rotation axes of both
planets are thought to have influenced their climates, but these changes
were larger in the Martian case.
For this reason and because of the apparent lack of recent oceans and life
on Mars, it should be simpler to determine the causes and history of climate
changes on Mars.
So HiRISE is returning images of the polar layered deposits on Mars that
have the potential to help to unravel Mars? climate history.
The orbiter is also used to analyse more active regions. Nasa released a
stunning image yesterday that showed the youngest flood lava on Mars.
The region is in Athabasca Valles, in the Elysium Planitia region of
equatorial Mars. Although the dramatic image resembles the patterns made by
an oil slick, the colour variations are from the bright layered deposits on
Researchers have found the deposits contain opaline silica and iron
sulfates, which you would expect to find if acidic water once flowed over
basaltic materials in low temperatures.
Scientists believe water activity affected this plateau after the formation
of the nearby canyons. Although the source of water and sediment remains