Arecibo Observatory - The Arecibo radio telescope. It search for Extraterrestrial signals from the space. The huge 'dish' is 305 m (1000 feet) in diameter, 167 feet deep, and covers an area of about twenty acres. The surface is made of almost 40,000 perforated aluminum panels, each measuring about 3 feet by 6 feet, supported by a network of steel cables strung across the underlying karst sinkhole. It is a spherical (not parabolic) reflector suspended 450 feet above the reflector is the 900 ton platform