Martian surface. False colour image from the panoramic camera on NASA's Mars exploration rover Opportunity of a large wind-blown ripple known as Scylla. Blue areas are thought to be due to the presence of basaltic sands mixed with haematite-rich inclusions. Opportunity and its sister rover Spirit were launched in the summer of 2003. Opportunity landed on Mars on 24th January 2004. Its mission is to analyse soil and rocks and search for water. Image taken on Opportunity's 644th Martian day, 15th November 2005.