NASA's Mars rover, Opportunity just celebrated its 12th anniversary on Mars; a mission that was originally meant to last just 90 days. Although recently eclipsed in the news by its bigger brother Curiosity, Opportunity is still going strong and making valuable scientific discoveries. Launched into space in 2003, Opportunity bounced to a hole-in-one landing in a small crater on Mars' Meridiani Planum on January 25, 2004. It has since spent 4,270 Martian days, or sols, on the surface, slowly moving from target to target, exploring craters, meteorites, unusual rock formations, and finding evidence of past water activity. Over the past 144 months, Opportunity has taken more than 200,000 images, and driven a total of 26.50 miles (42.65 kilometers) across Mars; not bad for a mission designed to last only three months.