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The Square Kilometre Array will be the world’s largest and most sensitive radio telescope.

The SKA or Square Kilometre Array is one of the largest scientific projects in existence, aiming to create the largest radio telescope ever constructed.

Thousands of linked radio antenna will be located in Australia and in Southern Africa. Combining the signals from the antennas in each region will create a telescope with a collecting area equivalent to a dish with an area of about one square kilometre.

Artist’s impression of the SKA dishes.

 

The SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how galaxies have evolved since then, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth.

 

 

 

 

All about the SKA (From the SKA Wikipedia Entry)

The Square Kilometre Array (SKA) is a radio telescope in development in Australia and South Africa which will have a total collecting area of approximately one square kilometre.

It will operate over a wide range of frequencies and its size will make it 50 times more sensitive than any other radio instrument. It will require very high performance central computing engines and long-haul links with a capacity greater than the current global Internet traffic.

 It will be able to survey the sky more than ten thousand times faster than ever before.

With receiving stations extending out to distance of at least 3,000 kilometres (1,900 mi) from a concentrated central core, it will continue radio astronomy’s tradition of providing the highest resolution images in all astronomy. The SKA will be built in the southern hemisphere, in Sub-Saharan states with cores in South Africa and Australia, where the view of the Milky Way Galaxy is best and radio interference least.

With a budget of €1.5 billion (approx $1.6 Billion USD), construction of the SKA is scheduled to begin in 2016 for initial observations by 2019 and full operation by 2024. The headquarters of the project are in Manchester, in the UK.

The SKA will combine the signals received from thousands of small antennas spread over a distance of more than 3000 km to simulate a single giant radio telescope capable of extremely high sensitivity and angular resolution.

The SKA will also have a very large field-of-view (FOV) with a goal at frequencies below 1 GHz of 200 square degrees and of more than 1 square degree (about 5 full Moons) at higher frequencies. One innovative development is the use of Focal Plane Arrays using phased-array technology to provide multiple FOVs.

This will greatly increase the survey speed of the SKA and enable multiple users to observe different pieces of the sky simultaneously. The combination of a very large FOV with high sensitivity means that the SKA will transform the exploration of the Universe.

The SKA will provide continuous frequency coverage from 70 MHz to 10 GHz in the first two phases of its construction. A third phase will then extend the frequency range up to 30 GHz.

  • Phase 1: Providing ~20% of the total collecting area at low and mid frequencies by 2019.
  • Phase 2: Completion of the full array at low and mid frequencies by 2024.
  • Phase 3: Building of the high frequency array from 2022.

The frequency range from 70 MHz to 10 GHz, spanning more than two decades, cannot be realised using one design of antenna and so the SKA will comprise arrays of three types of antenna elements that will make up the SKA-low, SKA-mid and dish arrays:

  1. SKA-low array – A phased array of simple dipole antennas to cover the frequency range from 70 to 200 MHz. These will be grouped in 100 m diameter stations each containing about 90 elements.
  2. SKA-mid array – This is likely to be a phased array of “tiles” to cover the medium frequency range from 200 to 500 MHz. The 3 metre x 3 metre tiles will be grouped into circular stations, 60 m in diameter.
  3. Dish Array – several thousand dish antennas to cover the frequency range 500 MHz to 10 GHz. It is expected that the antenna design will follow that of the Allen Telescope Array using an offset Gregorian design having a height of 15 metres and a width of 12 metres. It is hoped that the parabolic dishes will be equipped with focal plane arrays at their focus. This would allow the dishes to observe over a far wider field of view than that achieved with a single element feed. Prototypes of such multiple element feeds are now under development for the pathfinder arrays described below.

The area covered by the SKA – extending out to ~3000 km – will comprise three regions:

  1. A central region containing 5 km diameter cores of dish antennas, SKA-mid stations and SKA-low antennas. This central region will contain approximately half of the total collecting area of the three SKA arrays.
  2. A mid region extending out to 180 km. This will contain dishes and pairs of SKA-mid and SKA-low stations. In each case they will be randomly placed within the area with the density of dishes and stations falling off towards the outer part of the region.
  3. An outer region from 180 km to 3000 km. This will comprise five spiral arms along which dishes, grouped into stations of 20 dishes, will be located. The separation of the stations increases towards the outer ends of the spiral arms.

 

 

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