The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC), is an observatory in Arecibo, Puerto Rico owned by the US National Science Foundation (NSF).
The observatory’s main instrument was the Arecibo Telescope, a 305 m (1,000 ft) spherical reflector dish built into a natural sinkhole, with a cable-mount steerable receiver and several radar transmitters for emitting signals mounted 150 m (492 ft) above the dish. Completed in 1963, it was the world’s largest single-aperture telescope for 53 years, surpassed in July 2016 by the Five-hundred-meter Aperture Spherical Telescope (FAST) in China. Following two cable breaks supporting the receiver platform in the prior months, the NSF stated on November 19, 2020 it was decommissioning the telescope for safety concerns, but before controlled demolition could be conducted, the remaining cables failed on December 1, 2020, causing catastrophic structural failure to the telescope.
