The Square Kilometre Array: Engineering opportunities

The Square Kilometre Array (SKA) is an international radio telescope for the 21st century which will have a total collecting area of approximately one square kilometre. Similar to present-day radio interferometers, the SKA will consist of many antennas which are spread over a large area. The signals are combined in a central computer (correlator). The resolving power is proportional to the frequency and to the largest baseline between the outermost antennas and hence it will be about ten times more sensitive than the largest single dish telescope (305 m diameter) at Arecibo (Puerto Rico), and fifty times more sensitive than the currently most powerful interferometer, the Expanded Very Large Array (EVLA, at Socorro/USA). The SKA will continuously cover most of the frequency range accessible from ground, from 70 MHz to 10 GHz (corresponding to wavelengths of 3 cm to 4 m) in the first and second phases, later to be extended to at least 25 GHz (1.2 cm). Another major improvement is the enormously wide field of view, ranging from 200 square degrees at 70 MHz to at least 1 square degree at 1.4 GHz. The speed to survey a large part of the sky, particularly at the lower frequencies, will hence be ten thousand to a million times faster than what be possible today.