China races SETI to first contact. @Andersen

Nov 11, 2017, 05:24 AM

11-10-2017 (Photo:The world's largest filled-aperture (i.e. full dish) radio telescope is the Five hundred meter Aperture Spherical Telescope (FAST) completed in 2016 by China.[7] The 500-meter-diameter (1,600 ft) dish with an area as large as 30 football fields is built into a natural Karst depression in the landscape in Guizhou province and cannot move; the feed antenna is in a cabin suspended above the dish on cables. The active dish is composed of 4450 moveable panels controlled by a computer. By changing the shape of the dish and moving the feed cabin on its cables, the telescope can be steered to point to any region of the sky up to 40° from the zenith. Although the dish is 500 meters in diameter, only a 300-meter circular area on the dish is illuminated by the feed antenna at any given time, so the actual effective aperture is 300 meters. Construction was begun in 2007 and completed July 2016[8] and the telescope became operational September 25, 2016.[9]

The world's second largest filled-aperture telescope is the Arecibo radio telescope located in Arecibo, Puerto Rico. Another stationary dish telescope like FAST, whose 305 m (1,001 ft) dish is built into a natural depression in the landscape, the antenna is steerable within an angle of about 20° of the zenith by moving the suspended feed antenna. The largest individual radio telescope of any kind is the RATAN-600 located near Nizhny Arkhyz, Russia, which consists of a 576-meter circle of rectangular radio reflectors, each of which can be pointed towards a central conical receiver.

The above stationary dishes are not fully "steerable"; they can only be aimed at points in an area of the sky near the zenith, and cannot receive from sources near the horizon. The largest fully steerable dish radio telescope is the 100 meter Green Bank Telescope in West Virginia, United States, constructed in 2000. The largest fully steerable radio telescope in Europe is the Effelsberg 100-m Radio Telescope near Bonn, Germany, operated by the Max Planck Institute for Radio Astronomy, which also was the world's largest fully steerable telescope for 30 years until the Green Bank antenna was constructed.[10] The third-largest fully steerable radio telescope is the 76-meter Lovell Telescope at Jodrell Bank Observatory in Cheshire, England, completed in 1957. The fourth-largest fully steerable radio telescopes are six 70-meter dishes: three Russian RT-70, and three in the NASA Deep Space Network. As of 2016, the planned Qitai Radio Telescope will be the world's largest fully steerable single-dish radio telescope with a diameter of 110 m (360 ft).

A typical size of the single antenna of a radio telescope is 25 meters. Dozens of radio telescopes with comparable sizes are operated in radio observatories all over the world. The 305 meter Arecibo Observatory, Puerto Rico (1963) ) Twitter: @BatchelorShow

China races SETI to first contact. @Andersen

We set off again, making our way through a string of small villages, beep-beeping motorbike riders and pedestrians out of our way. Some of the buildings along the road were centuries old, with upturned eaves; others were freshly built, their residents having been relocated by the state to clear ground for the new observatory. A group of the displaced villagers had complained about their new housing, attracting bad press—a rarity for a government project in China. Western reporters took notice. “China Telescope to Displace 9,000 Villagers in Hunt for Extraterrestrials,” read a headline in The New York Times. The search for extraterrestrial intelligence (seti) is often derided as a kind of religious mysticism, even within the scientific community. Nearly a quarter century ago, the United States Congress defunded America’s seti program with a budget amendment proposed by Senator Richard Bryan of Nevada, who said he hoped it would “be the end of Martian-hunting season at the taxp...