Nasa has celebrated 10 years since it successfully landed two robotic explorers on Mars - and one of them still works.

The Spirit Mars Rover landed on the Red Planet via its innovative "bouncing ball" landing system on January 4 2004, with the Opportunity Rover following it a few weeks later on 24 January.

Both Rovers landed successfully using their 'rolling airbag' cushions, which deployed automatically as they descended to the surface. Both rovers were subsequently able to send back hugely important data about the composition of the planet, and the chance that liquid water and potentially even life once existed on its surface.


Above: Artist's impression of how the rovers looked as they landed on the surface

While Spirit worked for six years and eventually gave up the ghost, Opportunity has vastly outlasted original estimates of its useful lifespan, and is still rolling across the surface sending back data to Nasa's team of researchers.

While it has since been superseded technologically by the Curiosity rover, its presence in a difference part of the planet gives Nasa a vital resource which it says it will exploit as long as it can.

Loading Slideshow...
  • This Aug. 9, 2011 image provided by NASA shows a view from the Mars Rover Opportunity from the Western rim of the Endeavour Crater.

  • This undated image provided by NASA shows the Mars rover Opportunity looking back at an outcrop where it spent the Martian winter in 2012.

  • This image provided by NASA shows a rock that the NASA Mars rover Opportunity examined in 2012.

  • This image provided by NASA shows a shadow self-portrait taken by NASA’s Opportunity rover on the Martian surface.

  • This image provided by NASA shows a panoramic view from NASA's Mars Exploration rover Opportunity of "Solander Point."

  • This image provided by NASA shows the late-afternoon shadow cast by the Mars rover Opportunity at Endeavour Crater. The six-wheel rover landed on Mars in January 2004 and is still going strong. (AP Photo/NASA)

  • Handout photo issued by NASA Wednesday 21 January 2004 of a image mosaic taken by the panoramic camera onboard the Mars Exploration Rover Spirit.

  • Nasa undated computer generated image of what the it's Spirit rover would look like on the surface of Mars.

  • This magnified image taken by the Mars Rover Opportunity shows evidence of past flowing water.

  • This magnified image taken by the Mars Rover Opportunity shows evidence of past flowing water.

"Ultimately, it's not only how long the rovers work or how far they drive that's most important, but how much exploration and scientific discovery these missions have accomplished," said Nasa's John Callas, who has worked on the Spirit and Opportunity missions for more than 13 years.

"Opportunity is still in excellent health for a vehicle of its age. The biggest science may still be ahead of us, even after 10 years of exploration."

As part of its celebrations Nasa has published a gallery of images taken by the rovers over the last 10 years

  • © NASA/JPL/University of Arizona
    Audaciously called Inca City because of its rectangular, geometric shapes evoking vestiges of habitats, these terrains have nothing reminiscent of a city or of the Inca. Their size—several kilometers—is the best proof of that. The nature of this polygonal network, unique on Mars, remains poorly understood, but seems to be linked to volcanic dykes covered by eolian sand. These terrains are close to the South pole and undergo springtime defrosting in dark patches that become progressively larger as temperatures climb.
  • © NASA/JPL/University of Arizona
    The sedimentary strata are mostly composed here of ice from water and not carbonic ice. The fractures that traverse these strata come from strong, seasonal thermal variations that can reach close to 100° C (212° F).
  • © NASA/JPL/University of Arizona
    The zones at lower latitudes (between 40° and 60°) contain very large proportions of ice, notably in the form of glaciers. In the present case, the glacier flows toward the lower-left part of the image—as the nearly parallel lines, all running in the same direction, indicate. A detailed viewing allows even smaller lines perpendicular to this direction to be perceived. These are fractures or crevasses similar to the crevasses that are formed on the glaciers of the Alps, notably when the glacier rolls down the sides of the reliefs.
  • © NASA/JPL/University of Arizona
    The dark traces that converge come from a multitude of fractures are linked to the sublmation of a layer of carbonic ice. This forms geysers because the evaporation of ice proceeds more rapidly beneath the thin layer of ice.
  • © NASA/JPL/University of Arizona
    Hundreds of black-sand dunes of basaltic composition have accumulated on the floor of the Proctor crater. In winter, because of the relatively high latitude (47° south), these dunes are covered by frost and carbonic ice, in particular on the polar flanks deprived of sunlight, thus creating a sharp contrast in tone.
  • © NASA/JPL/University of Arizona
    A labyrinth of canyons hollowed out by outflows on a volcanic plateau near the Elysium Mons volcano. During a volcanic action that traverses a region containing ice, albeit subterraneously, a chain of processes is set off from explosions called phréatogmatiques or lahars, those muddy or doughy outpours that, on Earth, flow down snow-covered volcanoes. The nature of these outflows, at the same time muddy, rocky, and fluid, is not precisely known, but these have probably been brief and are not directly connected to climatic conditions. The volcanismon Marsis a source of heat that can explain the local presence of liquid water in a climate that remains very cold.
  • © NASA/JPL/University of Arizona
    The terrains of carbonic ice of the southern vault have been eroded, leaving circular depression, by sublimation—except when the terrains are heterogeneous and inclined, in which case arabesques of small cliffs are formed. The orientation of the terrains, had they been moderately inclined in relation to the pale Sun, low on the horizon at the poles, isin fact fundamental to this process.