* One of the most ambitious schemes for a next-generation instrument is the "Square Kilometer Array (SKA)", an array of antennas that will actually have a total kilometer of area, making it two orders of magnitude more sensitive than any previous radio telescope. The SKA will operate at relatively short wavelengths and will be used to probe the distant, early Universe; map the magnetic fields of galaxies; monitor thousands of pulsars to track gravitational waves; and search for intelligent life in the Universe.
The SKA will be cheap for its capabilities, but it will still cost up to about $1.6 billion USD. It is now being promoted as an international collaboration, with the main selling point at present being mapping of galactic and extragalactic neutral hydrogen clouds through the 21 centimeter emission. Of course, the SKA will have other capabilities. It will be able to pick up the signals from carbon monoxide and other cosmic molecules to map out the structures of distant galaxies; examine the violent cores of active galaxies, where supermassive black holes may lurk, using the coherent microwave emissions of clouds of stimulated water molecules called "mega-masers"; and trace out the magnetic fields of nearby galaxies, giving hints of galactic structure.
The SKA is expected to have about 4,000 10-meter dish antennas operating over 1 to 25 GHz, supplemented by a set of fixed planar lowband radio receiver arrays operating over 100 MHz to 1 GHz. Candidate sites have been narrowed down to Mileura in Western Australia and Karoo in South Africa. The nation that hosts the site will be required to control communications emissions to prevent unnecessary interference with the operation of the SKA.
Both nations are building small demonstrator arrays at the proposed sites to evaluate technologies. Detail design of the SKA is expected to begin in 2008. The first SKA elements are expected to be in operation by 2014, with completion of the full array in 2020.
