Marvels from Mars: Stunning postcards from the Red Planet

The Red Planet, Mars, fascinates us like no other celestial body. We have yet to visit the most Earth-like world in the solar system in person, but since the Sixties a small armada of space probes have poked and prodded the dusty Martian surface.



And, as these astonishing images show, they have taken the most spectacular close-up pictures while orbiting the planet.



Because Mars has so little air, and certainly no substantial running water and no vegetation, the processes of weathering and erosion, so important on Earth, operate differently on Mars.



Valley of mystery: This chasm looks as if water once flowed through it

Jagged edge: The rim of Victoria Crater, home to a field of sand dunes, was caused by erosion

Pink and blue desert: Trails of dune debris blown across the harsh landscape, left, and rock formations look like alien sea creatures, right



The result is that Mars is covered with spectacular, near-vertical cliffs, huge rubblestrewn plains and vertiginous crater edges.



Future tourists, if there are any, will be able to gaze over colossal canyons - one of which, the 2,500-mile-long Valles Marineris, would swallow our Grand Canyon.

What look like ancient river beds snake across the ochre plains - evidence, perhaps, of a warmer, wetter past.



Mars is home not only to the solar system's longest, deepest canyon, but also to the biggest volcano (Mount Olympus, at 89,000ft - three times as high as Everest and with a base bigger than all of Great Britain), the deepest craters, the tallest cliffs and huge seas of sand, built up over countless millions of years by the thin, but relentless Martian winds.



In the groove: Valles Marineris, at more than 100 miles wide, dwarfs the Grand Canyon

Devil's punch bowl? The mouth of Albor Tholus, an extinct volcano, is 30km across

There are oddities on the Martian surface, too; craters that look like hearts, and the famous 'Happy Face' crater in the Nereidum Montes mountains.



Our next-door neighbour: Mars

And around the Martian poles are strange, spider-like formations that may be some sort of 'ice geysers'.



This is indeed an alien world. Ever since the 19th century, scientists have been arguing just how Earth-like Mars is - but by the 1970s, most thought Mars was dead, almost devoid of an atmosphere, perishingly cold and almost certainly not the abode for life.



The first space probes showed a surface more like that of the Moon than Earth, with a thin, parched, whistling atmosphere which would suck your lungs dry in an instant were you to venture onto the surface without a spacesuit.



But now, opinion has swung back to a rather more benign Mars, as a closer look reveals that the Red Planet may not be as hostile as we thought.

The two NASA rovers, Spirit and Opportunity, which have been trundling around the Martian surface since 2004, have discovered ancient rocks which may have been formed in long-dried-up Martian seas.



We have not found life - not even microbes, let alone Little Green Men - but many scientists believe that there may have been life in the past that survives, perhaps buried underground, to this day.



Controversy surrounds the possible existence of liquid water on the Martian surface - a probable prerequisite for life.



Some tantalising pictures, taken by the Mars Global Surveyor probe from orbit, showed what look like small springs or streams gushing down steep cliffs.

Mars is equal in area to the land-surface of the Earth - the planet is smaller than our world and has no oceans. But what no one disputes is that it has a beauty out of this world.

Red crescents: Scalloped sand cliffs ripple across the surface

Cold mountain: Patterns on this range could have been caused by glaciers

Boulders or bacteria? Rocky outcrops at the south pole of the planet, left, and Giant craters scar the planet’s surface, right













