Photos: Rover prototypes at the Jet Propulsion Laboratory

The NASA Jet Propulsion Laboratory sits at the base of the San Gabriel Mountains in Pasadena, Calif. The federally funded facility, which is managed by the California Institute of Technology, helps develop robotic spacecraft for planetary exploration.

The rover known as Rocky 7 was initially developed to test techniques for grasping rocks and collecting samples. It's also been used as a test bed for software development.

Rocky 8 is roughly twice as large as Rocky 7, giving it more room to carry samples. A center mast holds stereo cameras that help the rover avoid obstacles. Like most of these rovers, Rocky 8 runs on lithium-ion batteries that are recharged by solar panels on its surface.

In the foreground, the FIDO (Field Integrated Design and Operations) rover slowly rolls over a rock in the landscape. Technologically similar to the actual Mars rovers, FIDO is used to test every aspect of the mission. The large bot in the background is the ATHLETE lunar rover.

The All-Terrain Hex-Legged Extra-Terrestrial Explorer is designed for use on Earth's moon. Capable of rolling over rough or steep terrain, ATHLETE's large size will enable it to carry heavy cargo for robotic or human missions.

Open-house visitors had a chance to control this PackBot via a common gaming joystick connected to a ThinkPad laptop. The robot's internal obstacle-avoidance program thwarted nearly all attempts to knock over that stack of cans.

A JPL intern swaps out the battery on the PackBot. The robot is a commercially available model from iRobot, which has been modified with a laser scanner, stereo cameras, and custom computer components.

Behind the sign sits a specialized vehicle designed for the transport of human infants across urban terrain.