Curiosity is the latest in an evolving range of rovers designed by NASA. This photograph shows three generations of rovers in the Mars Test Yard at NASA\(***)s Jet Propulsion Laboratory. Front and left is the flight spare for the first Mars rover, Sojourner, which landed on Mars in 1997 as part of the Mars Pathfinder Project. The Mars Exploration Rover Project test rover, left, is a working sibling to Spirit and Opportunity, which landed on Mars in 2004. Finally there is a test version of Curiosity itself, right.