The SS Artemis was a Federation colony ship, launched in 2274, that was scheduled to transport colonists to the planet Septimus Minor.
Once underway, however, the vessel suffered a major failure in its navigation systems, sending it off course, ultimately settling around Tau Cygna V. The vessel disappeared off Federation sensors and numerous searches failed to located any survivors.
The fate of the Artemis was finally discovered when the Tau Cygna colony was discovered in 2366 by the Sheliak, who demanded the planet be evacuated per the Treaty of Armens with the Federation. (TNG: "The Ensigns of Command")