Mars Spirit rover. Computer illustration of the Spirit rover on the surface of Mars. This is one of two identical rovers sent to Mars in 2003. It is designed to study the history of the Martian climate and to search for evidence of ancient water. It will study the composition and formation of soil and rocks. It has a panoramic camera on the white pole at upper centre which will allow interesting areas to be chosen for study. It will travel up to 100 metres in each Martian day (sol; 24 hours 37 minutes). It is hoped it will operate for over 90 sols. Spirit landed successfully on Mars in January 2004.