Proposed world's largest single dish, FAST

The collecting area of a radio telescope is a figure of merit of that instrument's capability. A Five hundred meter Aperture Spherical Telescope (FAST) is proposed to be built in the unique karst area of southwest China, and will act, in a sense, as a prototype for the Square Kilometer Array (SKA). It will be over twice as large as Arecibo coupled with much wider sky coverage. Some results from site surveys for such a SKA concept are briefly reported. Technically, FAST is not simply a copy of the existing Arecibo telescope but has rather a number of innovations. Firstly, the proposed main spherical reflector, by conforming to a paraboloid of revolution in real time through actuated active control, enables the realization of both wide bandwidth and full polarization capability while using standard feed design. Secondly,a feed support system which integrates optical, mechanical and electronic technologies will effectively reduce the cost of the support structure and control system. With an overall diameter of 500 m and radius of its spherical surface of 300 m, FAST will be the world's largest single dish.