For over ten years, NASA engineers have been kicking around the idea of a tumbleweed-inspired Mars rover. This “tumbleweed rover” would be a rugged but lightweight ball, with sensors and other electronics securely suspended inside. It would move about simply at the mercy of the Martian wind, much like its botanical namesake. Until now, the only way of testing such rovers has been to build a prototype, then set it loose here on Earth and watch the fun. That could be about to change, however. Researchers at North Carolina State University have developed a computer model that can test tumbleweed rover designs before they’re ever built.