Collapsed 300-foot Green Bank radio telescope, 1988. On the night of 15 November 1988, the 300-foot telescope at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia, USA, collapsed. The operator in the building below heard a crack and a rumbling noise as the ceiling above him buckled under the weight of the debris. He hit the telescope's emergency stop and managed to escape. The extent of the damage was not known until the Sun rose the next morning to show a ruin of folded steel. Investigations revealed that the dish had been slowly failing for days, before stress cracked a key steel support element, resulting in catastrophic failure and collapse.