Sisko returns from a trip to Bajor with the blueprint for an ancient space vessel that operates like a sailboat, using solar pressure for propulsion. According to legend, the Bajorans used these ships to explore their star system 800 years ago, even going as far as Cardassia. Sisko decides to build one himself to see if this was possible, and painstakingly recreates the vessel, determined to prove the design was spaceworthy.