The Arias expedition was a year-long scientific expedition carried out by Starfleet in 2356-57. The USS Al-Batani, under the command of Admiral Owen Paris, was assigned to perform the expedition. (VOY episode: "Caretaker")

While officially, the Arias Expedition was a study of massive halo objects, the mission was actually a spy mission along the Cardassian border. The mission was to study the area 600-light-years beyond Deep Space 7. The mission was not without risk to the Al-Batani's crew, as six months into the voyage, Admiral Paris and Ensign Kathryn Janeway was captured by Gul Camet. Fortunately, both officers were rescued by Lieutenant Justin Tighe. (VOY novel: Mosaic)