"The demonstrated hopping capability of the robots allows the small unmanned ground vehicles to overcome as many as 30 obstacles that are 40-60 times their own size. Hopping mobility has been shown to be five times more efficient than hovering when traversing obstacles at heights under 10 meters, which allows longer station-keeping time for the same amount of fuel." - quoted from original source: http://www.sandia.gov/news/resources/releases/2009/hoppin... (less info)