National Science Foundation

The 305-metre-wide radio telescope at Arecibo, Puerto Rico is permanently closing. Engineers cannot find a safe way to repair it after two cables supporting the structure suddenly and catastrophically broke, one in August and one in early November.

"Even attempts at stabilization or at testing the cables could result in accelerating the catastrophic failure," said Ralph Gaume, the NSF's head of astronomy, at a 19 November media briefing.