Figure 15-9 Radio Telescope Used for SETI The Arecibo Observatory’s radio telescope, with a diameter of 305 m (1000 ft), is the largest single-aperture telescope in the world. It is located in Arecibo, Puerto Rico. In the past decade, it has been used in an all-sky survey, along with an antenna located in the Mojave Desert in California, to search for extraterrestrial intelligence. In 1996, an antenna in Canberra, Australia, joined the network.