Square kilometre Array Telescope
The Mileura station area of Western Australian has been short listed as one of two potential sites for the construction of the worlds largest radio telescope, the Square Kilometre Array. A $2 Billion dollar project, funded by 19 countries, the Square kilometre array is one of the most ambitious science projects ever devised.
Summary
The Square Kilometre Array (SKA) is the next generation in radio telescopes. Whereas the size of existing individual radio telescopes is measured in tens or hundreds of metres (Arecibo is currently the worlds largest radio telescope at 305m and Australia’s own Parkes radio telescope comes in at 85m), the SKA will have a combined collecting area of one million square meters.
While it is impossible to build a single radio telescope with this diameter, the SKA will use a technology called interferometry to combine the collecting area of thousands of smaller radio dishes into a single synthesised aperture.
The Square Kilometre Array will consist of a central array of radio telescopes linked to a collection of 180 outlying stations at distances ranging from 150KM to 3000KM.
The SKA will be significantly more sensitive than existing radio telescopes and will allow astronomers to “see” all the way back to the birth of the universe including the formation of the first stars and galaxies.
A parsley populated and extremely radio quiet zone is required for the installation of the Square Kilometre Array. Both Western Australia and South Africa (the second short listed site) are able to offer a location which meets the requirements for the installation and operation of the SKA.
The short listed sites are currently under review with the winning site due to be announced in 2011 and construction to begin shortly afterwards. Prior to the construction of the final telescope array, a smaller, but similar telescope array will be constructed on the proposed West Australian site. The Square Kilometre Array Pathfinder Telescope will be a very capable instrument in it’s own right as well as being a pathfinder instrument for the full SKA project.
Locations
Two proposed location have been shot listed for the construction of the Square Kilometre Array, the Mileura station area of Western Australian and the Karoo site in the Northern Cape Province of South Africa. These sites were short listed from a list which also included sites from Argentina, China and the USA.
Western Australia
The Mileura station is located in the mid Western area of Western Australia about six hours drive from Geraldton, the closest major township. With only 100,000 people inhabiting the 5 million square kilometres of Australia’s interior, it offers some of the most radio-quiet locations found on the planet.
The West Australian site offers a number of benefits for the construction of the Square Kilometre Array.
- The full backing of the local communities, state and national government. An area surrounding the proposed site has been designated a radio-quiet zone.
- Low population density resulting in the absence of interfering man-made radio signals.
- Low risk of extreme weather conditions. Low risk of wildland fire and low risk of seismic activity.
- The possibility of installing all outlying SKA stations within the same politically stable country.
- Access to nearby fibre optic cabling infrastructure and ease of installation of new fibre optic cable infrastructure.
- Excellent views of the centre of the Milky Way.
- A society with a strong history of scientific discovery and experience.
- Access to well developed and extensive engineering capabilities.
South Africa
The Karoo area is located in the Northern Cape Province of South Africa. The northern Cape Province of South Africa is the largest and least populated province in the country and is therefore able to meet one of the main selection criteria of being a radio-quiet zone.
South Africa also has a number of benefits for the construction of the Square Kilometre Array.
- Full backing of the Government
- A remote, sparsely populated radio-quiet zone.
- A dry climate
- Low land prices and low operating costs
- Good road, power and telecommunications infrastructure.
Technology
It is anticipated that the Square Kilometre Array will consist of a central station in which radio telescopes with 50% of the collecting area will be located. This central station will be supplemented by outlying stations being located with 150KM of the central site and each consisting of radio telescopes providing a total of 25% of the collecting capacity of the SKA. The remaining 25% of collecting capacity will be installed in outlying stations within a distance of 3000KM of the central station.
The central station will provide ultrahigh brightness sensitivity at arc-second scale resolution to allow the study of structures in the early Universe. While, combined with the central site, the outlining stations will provide high angular resolution capability and will therefore allow imaging of faint emission from the interstellar medium of distant galaxies, as well as the surface of stars, and the active nuclei of galaxies.
For the dishes themselves, both planar phased arrays and reflectors are being considered. The technology must allow for viewing of the sky in more than one direction at once over large areas of sky.
SKA Pathfinder Telescope
The SKA Pathfinder telescope is designed to be both a world leading telescope in it’s own right as well as a test bed for the main Square Kilometre Array telescope.
Consisting of up to 45 dishes working together as single telescope, the pathfinder telescope will be able to detect and image many hundreds of more galaxies than have previously been discovered.
The SKA Pathfinder telescope will be built by the CSIRO in collaboration with leading astronomers and engineers from overseas. The Australian government has committed $100.9 million dollars towards the project and construction is expected to commence between 2008 and 2011.
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