The Arias Expedition was a Starfleet mission undertaken in the 24th century.

The USS Al-Batani took part in the expedition, under Captain Owen Paris. Kathryn Janeway served as science officer during the mission. (VOY: "Caretaker")

The specifics of the Arias Expedition are further explored in the 1996 Jeri Taylor novel Mosaic. In the novel, the Arias Expedition was publicly a scientific mission to study massive compact halo objects. In fact, this was merely a cover for the Al-Batani's true mission - to conduct espionage along the Cardassian border.
According to, Arias was either a planet, a star, or "other object on an expedition".
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