An artist’s rendition of the precursor to the SKA, the MeerKAT. (Image: SKA Africa)
In May 2012, when the SKA Organisation announced that South Africa, with Australia, would host the southern hemisphere portion of the Square Kilometre Array (SKA), Brand South Africa chief executive officer Miller Matola said the country was thrilled with the opportunity.
The South African portion of the initial stage of the project, the MeerKAT, is worth R2-billion ($182-million), but total costs will amount to some R3.9-billion. An engineering feat, in which specially designed foundations are laid to support a 19m-high structure, and keep it stable in strong winds, the project is already attracting scientists and engineers from across the globe wanting to collaborate on its construction.
But to truly understand the scale of the SKA, it is important to know what it does and how it works.
Watch: Understanding the Square Kilometre Array
What is the SKA?
The SKA is a series of radio telescopes, which look like large satellite dishes. Radio telescopes are used in radio astronomy, the branch of the science concerned with radio emissions from celestial objects – galaxies, stars and the like – which are used to determine their size, mass and chemical composition. A radio telescope is an invaluable tool when studying the stars; unlike an optical telescope, it cuts through clouds and dust and is even immune to bad weather.
Massive stars and galaxies give off radio signals, much like a radio transmitter; a radio telescope, like a radio, picks up these waves, which are different for each body. Astrophysicists and astronomers tune into the waves to learn more about the universe – and if an alien civilisation wanted to contact Earth, sending a message via radio waves would be a good idea. The movie Contact, starring Jodie Foster, is based on this theory. In the movie, the message was received via the Arecibo telescope in Puerto Rico. It is currently the largest and most sensitive radio telescope in the world.
But while astronomers can get a clearer picture of a celestial body using a radio telescope, it doesn’t have the superior resolution of an optical telescope. To match this resolution, a radio telescope would have to be kilometres across, which is neither possible nor practical.
A single radio telescope also has a limited range of movement and can only receive waves from a small portion of the sky. The SKA aims to resolve this problem through building an array of telescopes, called an interferometer. This approach, called interferometry, links together the individual telescopes to build a bigger picture of the portions of sky being observed.
The SKA will be one of the world’s largest interferometers, and the most sensitive. The majority of the array will be based in South Africa and Australia, with more telescopes in Botswana, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Namibia and Zambia.
In South Africa, they will be built in the Karoo, in Northern Cape. The remote area has clear night skies and very little noise interference, which will boost reception. It is also protected under the Astronomy Geographic Advantage Act of 2007, which bars transmitting more radio waves in the region.
Once the array is completed, the amount of information it collects in just one day would take nearly two million years to play back on an iPod. Construction on the SKA will begin in 2016, and is expected to be completed by 2024.
South African scientists are closely involved in key aspects of the overall project. In an interview with Engineering News, the SKA SA associate director for science and engineering, Professor Justin Jonas, said: “South Africa has concentrated its efforts in the systems engineering aspects of the various consortia, so we will have a significant influence on the design of the various sub-systems and of the instrument as a whole. Assembly, integration and verification form an essential part of systems engineering – hence, our leadership of this work package.”
South Africa already hosts the KAT7 telescope array, an important testing ground for the MeerKAT telescope array, a 64-dish system that will form part of the final SKA array. The array will also be built in Northern Cape.
Each country involved in building portions of the final array is responsible for developing the infrastructure to support the project in their region. This means that South Africa will be responsible for constructing and maintaining buildings dedicated to the SKA as well as facilities for the buildings, including providing electricity, water and waste removal. South Africa will also provide vehicles, cranes and specialist maintenance equipment for the project and will build and maintain the roads to support the SKA.
Matola said the MeerKAT will attract the best scientists and engineers to work in Africa. It will also have other long-term benefits for the nation as a whole. “The SKA funding and infrastructure will encourage our scholars and students to take up science and technology subjects, and a new class of scientists will be developed,” he added.