Once a major trading spot with a population of 400,000 as well as advanced technology, warp reactors and subspace transmitters, in 2353 a major solar flare occurred which caused a glacial freeze on the planet's surface. Magnetic storms and extreme levels of radiation followed.
Later, it was theorized that any attempt at an evacuation would have been prevented by the atmospheric disturbances. In any case, there were few survivors. Five members of Viorsa's species who did survive, including the settlements planner, programming their system to wake them in fifteen years when they expected eco-recovery would have commenced. At that time they planned to attempt rebuilding. An automated signal requested that starships coming upon the planet not disturb this plan.
However, nineteen years after the disaster, in 2372, the USS Voyager visited the planet and found that not only the survivors had not waken up, but in fact many of them had died. In fact, due to the pods being placed more than two kilometer underground, at first they did not detect even those lifesigns. (VOY: "The Thaw")