At last, Earth has its revenge on Mars. For decades, ever since Orson Welles panicked the United States with his radio adaptation of H. G. Wells’ War of the Worlds, Hollywood has plagued the planet with tentacled, horned and bug-eyed Martians. Now, courtesy of Australian billabongs, Mars is set to be invaded by creepy-crawlies from Earth. University of Melbourne researchers are designing robots based on the native freshwater crayfish Cherax destructor to crawl across the red planet for the American space agency NASA.