Square Kilometer Array (1)

Artistic impression of SKA

Artists impression of SKA

I just had the most interesting conversation with one of the antenna engineers currently working on what is going to be the largest Radio astronomy telescope the world has ever seen, the Square Kilometer Array (SKA). There is so much that can be said about this topic so I decided to break it up into a few blog posts.

The image above is an artists impression of the planned telescope which will consist of a few thousand reflector antennas forming a huge array with a +- 0.01 degree beamwidth, The array will be constantly scanning the sky, ?listening? to whatever signals are coming from outer space. The data collected from each fraction of a degree will be processed to produce ultra-high resolution images of objects in space like in the ones shown below – these are images of the famous Crab Nebula taken by the Palomar radio telescope (left) and the optical Hubble Space telescope (right).

Crab Nebula taken by Palomar radio telescope (left) and Hubble Space telescope (right).

Crab Nebula taken by Palomar radio telescope (left) and Hubble Space telescope (right).

The main drive behind SKA is for scientific researchers to learn what lies beyond the borders of our galaxy, to study dark energy, dark matter and to try and solve the mysterys and questions like what happened ?in the beginning?.

South Africa and Australia are in the run to host the SKA and have started working on smaller demonstration projects like Meerkat and ASKAP. Both these countries?have great locations available for the SKA construction and the final decision of who the host country will beis primarily a political one (the announcement of the host country will be in 2011). Should South Africa win the draw, the center of the array – where most of the antennas will be located is in the Great Karoo (a semi-desert region well known in radio astronomy circles as a ?quiet? spot ? in terms of RF noise) and will stretch over nearly all countries in Africa, south of the equator.

Here are some of the tight specifications for each reflector antenna in the array:

  • 2:1 bandwidth
  • 1 degree main beamwidth
  • practically no backlobe (< 30 dB)

and

Each 2 ton antenna must be kept physically stable despite changes in the elements (Sun, Rain, Wind etc.) to reduce possible noise that might reflect from the ground.

There are numerous other challenges like cooling down the feed, creating affordable vacuums, manufacturing tolerances, data processing etc. which I will touch on in future posts.

Feed of the Meerkat reflector antenna.

Feed of the Meerkat reflector antenna.


12m radio telescope reflector antenna in the Karoo, South Africa.

12m radio telescope reflector antenna in the Karoo, South Africa.

Author: Robert Kellerman

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