Is there life on Mars? Could humans survive on the Red Planet? These age-old questions have prompted many missions to Mars, and this informative manual covers the development, design, and engineering of three generations of Mars rovers. The Sojourner, which landed in 1997, was the size of a microwave. Spirit and Opportunity, both the size of a shopping cart, followed in 2004. Curiosity, the size of a car, landed in 2012. With this illustrated guide, readers will learn how these machines work as well as what they have found and hope to discover, and about the possibility that humans may set foot on Mars.