Churned-up Martian soil. Image from NASA's Mars exploration rover Spirit of soil in the Columbia Hills that has been churned up by its wheels. This area measures 40 centimetres wide and is nicknamed Paso Robles". The wheels have exposed sulphur- rich rock (grey and light orange). Spirit and sister rover Opportunity were launched in the summer of 2003. Spirit landed on Mars on 3 January 2004. Its mission is to analyse soil and rocks and search for water. Image taken on Spirit's 400th Martian day, 16 February 2005."