A beach ball rover may seem like a strange idea, but it isn't the first time scientists have pondered using a giant ball as a rover. In the late 1970s, a French visiting scientist at the University of Arizona proposed building a giant ball to explore Mars, but the model was motorized and much heftier, weighing more than 1,000 pounds.
Jones and his team have designed a three-wheeled rover that rolls on very fat inflatable wheels. The Inflatable Rover is now being tested for a possible launch to Mars in 2007. And it was actually this rover model that led to the design of the Tumbleweed.
Jones and his team had developed smaller-sized balls as rovers, but when they rolled them out in the Mojave Desert, they found the small balls became snagged behind rocks. Then, while testing the Inflatable Rover in the Mojave Desert, one of the rover's giant wheels spun off and began rolling briskly across the sand. That's when Jones imagined the Tumbleweed.
"We realized, 'Oh! We just have to make the balls bigger!'" he said.
Tumbleweed may be nearly ready in the laboratory, but it's still uncertain whether or not it will ever be launched to the Red Planet. The next robots due for Mars are a pair of twin rovers poised to launch in 2003. These rubber-wheeled rovers are much larger than the 1997 Pathfinder Sojourner and are expected to travel up to 110 yards each Martian day, which is 24 hours, 37 minutes.