China building world’s biggest radio telescope
Since its completion in 1963, the Arecibo Observatory in Puerto Rico, with a diameter of 305 m (1,000 ft) and a collecting area of 73,000 square meters (790,000 sq ft), has been the largest single-aperture radio telescope ever constructed. But Arecibo is set to lose its title with construction now underway in Guizhou Province in southern China of the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Upon its expected completion in 2016, FAST will be able to see more than three times further into space and survey the skies ten times faster than Arecibo.
FAST was first proposed by China for the Square Kilometer Array (SKA), which has since opted to combine the signals of thousands of smaller antennae spread over a distance of more than 3,000 km (1,864 miles), combining for a total collecting area of approximately one square kilometer (0.38 square miles). The SKA will be built in the southern hemisphere with South Africa and Australia currently vying for the right to host the project.
Despite this, an international review and advisory conference on the science and technology of FAST held in Beijing in 2006 concluded FAST was feasible. In the following year funding for FAST was given the green light and the approved budget now sits at CNY700 million (approx. US$107.9 million). Construction in the Dawodang depression in south Guizhou commenced in March.
Unlike Arecibo, which has a fixed spherical curvature focusing radio waves into a line above the dish where they are focused to a single point by more mirrors, FAST's cable-net supporting structure will be able to deform the surface in real time through active control. As PopSci explains, this will allow a subset dish's 4,400 triangular aluminum panels to form a parabolic mirror anywhere within the larger bowl that is nearly the size of the entire Arecibo dish.
Using FAST's unparalleled sensitivity and high surveying speed, the project is expected to enable the surveying of neutral hydrogen in the Milky Way and other galaxies, the detection of new pulsars (both galactic and extragalactic), the search for the first shining stars, and of perhaps most interest to many people, the search for extraterrestrial life. It is expected to be able to detect transmissions from over 1,000 light years away.
With a construction period of 5.5 years, FAST is due to be completed in 2016.