For nearly six decades, the Arecibo Observatory has served as a beacon for breakthrough science… And now it will go dark. Following the collapse of two structurally important support cables, an engineering assessment has found that damage to the Arecibo Observatory cannot be stabilized without risk to construction workers and staff at the facility. With that, the U.S. National Science Foundation (NSF) will begin plans to decommission the 305-meter telescope, which for 57 years has served as a world-class resource for radio astronomy, planetary, Solar System, and geospace research.