A fleet of pint-size bulldozers may one day do the dirty work on Mars, engineers at NASA's Jet Propulsion Laboratory report. Needless to say, they are a far cry from the Fisher-Price variety. Lightweight, solar-powered and intelligent, these robotic vehicles could aid in the search for life on the Red Planet or help support a human presence there.

"If water sources, such as hot springs, layers of ice or groundwater reservoirs are discovered on Mars, a network of these rovers could conduct scientific investigations and excavate the site piece by piece, just as humans would on an archaeological dig," JPL robotics engineer Brian Wilcox explains. "Rovers like these may also play a role in establishing a space outpost for eventual human occupancy. They may be used to create buried habitats or utility trenches and to excavate resources to support life."

Part bulldozer and part dump truck, each eight-pound rover has arms that carry a tiny scoop to a bucket overhead (see image). Equipped with the same processor and software as a nanorover originally designed for a Japanese asteroid mission, the bulldozer rovers would work in groups coordinated by a central control tower. "We think a greater amount of terrain can be excavated if the workload is shared among several smaller vehicles," Wilcox comments. "Smaller, solar-powered vehicles have a higher power-to-weight ratio than bigger vehicles, yet together perform the same tasks as a large vehicle."

So far, four working prototypes of the bulldozer rovers exist, and developers are working to determine which size best suits excavation tasks. "When people hear about the work we do, they sometimes think we are just talking science fiction," JPL scientist Wayne Schober remarks, noting that in fact, he and his colleagues have developed a number of sophisticated robots used on various space missions. "We are not all fun and games. We mean business."