Rocky IV is a prototype for a robotic planetary exploration vehicle. It contains a color camera, a scoop to take soil samples and a chipper to examine the weathered covering of rocks, seen extended toward the rock in this photo. The rover can place a seismometer on the surface. Rocky IV is smaller and lighter than its predecessor, Rocky III, also a prototype for the study of planetary rovers. Rocky IV is 61.5 centimeters (24 inches) long, 38.4 centimeters (15 inches) wide and 36 centimeters (14 inches) high. Rocky IV weighs 7.5 kilograms (16.5 pounds) compared with Rocky III's 25.4 kilograms (56 pounds). Rocky IV is the latest in a family of robotic vehicles identified by a unique suspension system which uses no springs. The suspension is called "rockerbogey," and is connected by a differential between the left and right sides which can operate independently of each other. Also, each stainless steel wheel has a motor in its hub.
