Tyra III was the third planet in the Tyra system. In 2374, the crew of the USS Argus rescued survivors from the Seventh Fleet, which was destroyed by Dominion forces. The Argus crew also found a Preserver temple, powered by Omega molecules, under the command of Jem'Hadar soldiers. An Argus team, led by Katherine Sheridan, used a Tantalus field to eliminate the Jem'Hadar. Argus commanding officer Captain Jonozia Lex ordered the temple shut down, but the Tantalus field's power source went critical, causing the Argus to evacuate the system. The resulting explosion was small, however. (Star Trek: The Adventures of Argus: "Trial By Fire")