The US space agency's Mars rovers Spirit and Opportunity this month mark their fifth anniversary on the Red Planet, where they have endured harsh conditions and revealed a deluge of information.
The twin robots, which landed on Mars three weeks apart in January 2004, were initially expected to have just 90-day missions, but have since sent back to Earth a quarter-million images, toured mountains and craters and survived violent dust storms. The rovers, which along with 250,000 images have sent back to Earth some 36 gigabytes of data, have greatly advanced NASA's understanding of Mars' geology, including peeks into the planet's wet and habitable past. Analysts say the wealth of information data will keep scientists busy for years as they further unravel the vast banks of data.
Since 2004 the machines have covered 21 kilometers (13 miles) of Mars' characteristic red rock desert, driving inch by inch to avoid chasms and rocky obstacles, picking up samples and snapping images to beam back to mission control on Earth.