China Building Huge 500-Meter Radio Telescope

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Official ground-breaking ceremonies took place for a gigantic new 500 meter diameter radio telescope in China which will allow astronomers to detect galaxies and pulsars at unprecedented distances. The $102 million facility, known as the Five-hundred-meter Aperture Spherical Telescope (FAST), will have a collecting area more than twice as big as the 305 meter diameter radio telescope at Arecibo Observatory in Puerto Rico, which has been the world’s largest since it opened in 1964. Not only that, the new telescope will also have the ability to change its shape and move the position its focus.

Like the Arecibo telescope, the new telescope will sit in a natural depression that already is close to the shape of the collecting surface, simplifying the support structure and shielding the telescope from stray human-generated radio waves. The location is quite remote, about 170 km by road from the Guizhou Province’s provincial capital Guiyang, making it unusually radio-quiet, says Nan Rendong, FAST chief scientist and a researcher from the National Astronomical Observatories at the Chinese Academy of Sciences, in an article in Physicsworld.com.

The site’s potential for long, uninterrupted observations — coupled with the telescope’s huge size, which will give it twice the sensitivity of Arecibo — means that researchers there will be able to detect objects like weak, fast-period pulsars that are too faint to be measured accurately by smaller instruments.

“The FAST science impact on astronomy will be extraordinary,” Nan said, adding that although the telescope is located in China, once it is completed in 2014 it will be open to astronomers from around the world.

A system of motors attached to its 4600 panels will allow astronomers to change its shape from a sphere to a paraboloid, making it easier to move the position of the telescope’s focus. This will allow the south-pointing telescope to cover a broad swathe of the sky — up to 40 degrees from its zenith, compared to the 20-degree-wide strip covered by Arecibo.

At first, however, the telescope will only be sensitive to low-frequency radio waves, less than 3 GHz. Arecibo’s bandwidth, by contrast, stretches up to 10 GHz.

A planned second phase of construction will extend FAST’s range to 5 GHz, but a date for the upgrade has not yet been set.

Source: Physicsworld.com