'Project Arcturus' is the code name for a secret plot developed by super villain, Hank Scorpio , in the second episode of season 8, You Only Move Twice.
While details of Project Arcturus remain nebulous throughout the episode, aspects include the development germ warfare capabilities, a nuclear powered "doom's day" device, and a weather machine. These armaments are used by Scorpio to ransom the U.N. for "gold" with the threatened destruction of a European power and the actual destruction of the 59th Street Bridge, leading ultimately to Scorpio's seizure of the East Coast of the United States.