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While it has since been superseded technologically by the Curiosity rover, its presence in a difference part of the planet gives Nasa a vital resource which it says it will exploit as long as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