Installation 09 was one of the Rings that was created to cleanse the Galaxy of life to prevent the Flood spreading. It was warped to the edge of the Force Galaxy during the Monitor Civil War and was not seen for millions of years.
Upon being rediscovered, it appeared to be destroyed. It was fractured in half, and the blame initially fell on the Death Star. However, surveys of the ring soon discovered it was destroyed way before the Death Star was even built. There is no evidence on the ring itself to hint as to what actually destroyed it.
This mystery has baffled the League's think tanks, and they are currently investing much of their resources into solving it. Survey teams litter the rings surface, but the question remains unanswered: What did destroy Installation 09?