The Chinese officially began searching the stars around noon local time on Sunday using the newly completed FAST radio telescope which has surpassed Arecibo in being the world's largest single aperture telescope. Nestled in the natural Dawodang (limestone) depression in the remote and mountainous Pingtang county, Guizhou province, the Five-Hundred-Meter Aperture Spherical Telescope (FAST) will search the heavens to catalog pulsars, investigate dark matter, gravitational waves, and fast radio bursts, and assist in the search for extraterrestrial life and natural hydrogen in distant galaxies.
The $180 million project has been in development for 14 years with construction beginning in 2011. The massive scientific endeavor required the relocation of several villages and 10,000 people living in the vicinity. Further, the remote area required the telescope to be constructed without the use of heavy machinery and the dish had to be constructed manually. FAST is modeled after the Arecibo observatory in Puerto Rico and uses 4,450 triangular reflector panels supported by a steel mesh suspended over the limestone valley using large steel towers anchored to the surrounding hills. FAST deviates from Arecibo when it comes to reflecting and receiving radio signals, however. While Arecibo uses a 900 ton movable receiver with a complex set of mirrors that make up a sub reflector, FAST uses 2,250 actuators (winches) that pull on up to 300m sections of the dish to create a parabola that can move in real time to track signals as the Earth rotates and reflect them back to the receiver which is reportedly much lighter and can contain more instruments than Arecibo.
While Arecibo, with its 305 meter dish, can track signals up to 20° from the zenith, FAST can track signals up to 26° from the zenith at 300 meter parabola sizes and up to 40° with smaller parabola sizes making it rather versatile. The massive dish combines the benefits of a large single fixed dish and a smaller dish (or dishes which could be combined to provide higher resolution using interferometry) that can tilt and rotate.
Specifically, Dennis Normile quoted experts in saying:
Single dishes excel at observing point sources like neutron stars and at scanning a multitude of frequencies in the search for extraterrestrial intelligence, says astronomer Li Di, a FAST project scientist, who previously worked at NASA’s Jet Propulsion Laboratory in Pasadena, California. Another advantage is that, compared with the multiple dishes in an array, single dishes are “relatively cheap and relatively straightforward to upgrade,” says George Hobbs, an astronomer at CSIRO. “You just keep building better receivers.” (Dennis Normile at Science Magazine)
FAST is quite the accomplishment and I am interested to see what the scientists are able to discover using the world's largest radio telescope. Hopefully it will continue to receive adequate funding!
- World’s largest radio telescope will search for dark matter, listen for aliens (Science Mag)
- Chinese FAST Telescope to Surpass Arecibo (infographic)
- FAST: China's great space telescope begins operations (close-up photos of reflector panels)
- Arecibo Observatory (Wikipedia)