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The Square Kilometre Array (SKA) is a proposed radio telescope which is intended to have a collecting area of approximately one square kilometre.^[1] It is planned to operate at frequencies of 0.10–25 GHz, with a goal of 0.06–35 GHz, and its size will make it 50 times more sensitive than current instruments. It may incorporate multiple independent fields of view, allowing several radio astronomers to observe at once, or to look at different areas of the sky simultaneously. The SKA will create images of distant radio sources using aperture synthesis. Construction of the SKA is scheduled to begin in 2010, with initial observations in 2015. It is intended to be fully operational by 2020. It will easily be the most sensitive radio instrument ever conceived, being able to detect every active galactic nucleus (AGN) out to a redshift of 6, when the universe was less than 1 billion years old. It will have the sensitivity to detect Earth-like radio leakage at a distance of several hundred to a few thousand light years.

Design

An international consortium is working on the telescope design, to be decided in 2008. The interferometric array is expected to be composed of many elements spread over an area of several thousand kilometres. The reference design calls for a compact core of elements containing about 20% of the collecting area within a 1km-diameter region, 50% of the collecting area within an area 5 km across, 75% of the collecting area within 150 km, and the remaining elements spread up to a few thousand kilometres away.

Location

The final decision on the site will be made in 2008 or 2009. The two shortlisted candidates for the core of the array are:

South Africa: The core site is located at an elevation of about 1000 metres in the Karoo area of the arid Northern Cape Province, with distant stations in Ghana, Kenya, Madagascar, and Mauritius.

Australia: The core site is located at Boolardy in Western Australia, west of Meekatharra on a flat desert-like plain at an elevation of about 460 metres. The most distant stations will be located in New Zealand. ^{[2] [3]}

A preliminary list of 4 candidate host countries also included a site in the Karst Region of Guizhou in southwest China as well as a site at high elevations in a National Park in Argentina.

Funding

The SKA is expected to cost US$1.6bn,^[2], with funding coming from many international sources. Preliminary plans call for 1/3 of the funding from the United States, 1/3 of the funding from Europe, and the remaining 1/3 from the rest of the world. The distribution of radio time is still a contested issue, with some countries advocating that the amount of radio time any country is given should be proportional to the amount of funding donated. Others advocate a "free skies" policy, in which the best scientific proposals are given radio time regardless of national boundaries.

See also

• List of radio telescopes
• LOFAR (the Low Frequency Array, currently under construction in The Netherlands)
• Mills Cross (historical connections with the SKA development in Australia)

References

External links

• "Australia may host Square Kilometre Array", Cosmos magazine, September 2006
• Australian SKA Planning Office Newsletter. CSIRO (10, April 2007). Retrieved on 2007-03-19.
• SKA South Africa web site