Puerto Rico is the home of the world’s largest, most sensitive radio telescope. The Arecibo Observatory has been measuring the motions of galaxies for more than 40 years, mapping the surface of Venus, studying pulsar physics and listening for signals from extraterrestrial life.
The 1,000-foot-wide dish, resting in a natural sinkhole, consists of 40,000 panels of aluminum forming a radio-reflective surface. The panels collect radio waves from the sky and focus on a feed antenna that amplifies the signals and sends them to a control room that analyzes the data.The antenna hangs from a 900-ton platform with 18 cables connected to three concrete towers suspended 450 feet above the dish. 26 Electric motors target the telescope and change its focus.
Besides studying distant stars and galaxies, scientists are using the Arecibo telescope to detect and track objects moving near to Earth. Observations here helped astronomers refine the expected course of the Apophis asteroid, which will miss our planet narrowly in April 2036. The new trajectory announced last autumn indicates that the likelihood of impact this year is very low, about 1 in 250000.
Last year, Arecibo benefited from the transition to digital television, which opened up astronomical observations to a 100-megahertz frequency band. A new receiver gives access to that bit of radio spectrum that astronomers are hoping to intensively study through mid-2011. At that time , commercial broadcasts would most likely dominate the bandwidth once more.