The Apollo Lunar Roving Vehicle was an engineering miracle, but It would have collapsed on Earth under the weight of a suited astronaut. That's because it was designed to operate in lunar gravity, which pulls with about 15% as much force as Earth gravity. In the 1960s, engineers at the U.S. Geological Survey's Astrogeology Branch built a near-copy of the Apollo rover that could be used on Earth for astronaut training and lunar exploration planning. They called it Grover the Geologic Rover. The video shows Grover at work in the Cinder Lake crater field and provides a moon rover driving lesson.