What is the SKA?

The Square Kilometre Array Radio Telescope - or SKA - will be the world's biggest telescope - and one of the biggest scientific projects - ever!

Why is it called the "Square Kilometre Array"?

It is called an array because it will be made up of many large antennas (and other types of radio wave receivers) that will be linked together via optic fibre cables. The total surface area of all the antennas together will add up to approximately one square kilometre.

What makes the SKA so special?

Its sheer size and power! Thousands of antennas - spread over 3 000 km - will work together as one gigantic, virtual instrument - creating a radio telescope at least 50 times more powerful, and 10 000 times faster than any other radio telescope currently in existence.

What will the SKA cost to build?

About R20 billion.

Who is building the SKA?

Many different countries are working together to build - and pay for - the SKA. At least 13 countries and close to 100 organisations are already involved, and more are joining the project.

Who is working on the SKA project in South Africa?

Dr Bernie Fanaroff is the Project Director of the South African SKA Project. Dr. Fanaroff has a PhD in radio astronomy from Cambridge University. In addition to the scientists and engineers working on South Africa's bid for the SKA, there are also about 100 engineers and radio astronomers designing and building South Africa's 64-dish radio telescope - MeerKAT. The South African SKA Project is funded by the Department of Science and Technology via the National Research Foundation. South Africa's Minister of Science and Technology - Mrs Naledi Pandor - has been a champion for South Africa's bid to host the SKA, and continues to support this project as one of the flagship projects in her department.

What will the SKA look like

The SKA will be made up of three different kinds of receiving technologies:

  • The mid-frequency dish array - which look like DSTV dishes, but much bigger - will be about 15 m in diameter. The dish array of the SKA is the most well known of the three receiver types, and make up the majority of the SKA.
  • Large, flat disk-shaped receivers - each about 60 m wide (known as the dense aperture array), which will operate at mid frequencies.
  • Small upright radio receivers - about 1,5 m high (known as the sparse aperture array), which will operate at low frequencies.

How will the SKA work?

Radio telescopes work in much the same way as your radio. As you tune your radio to different frequencies, the receiver in your radio picks up different music stations. Radio telescopes do pretty much the same thing. However, they collect radio waves from objects millions or billions of light years away from Earth. If you heard what was being received however, it would sound like static hiss. These radio signals are then processed by computers that can interpret the signals, to form images that give us snapshots of the Universe.

What will the SKA be used for?

Radio astronomers will use the SKA to understand how stars and galaxies formed, and how they evolved over time, what the so-called "dark-matter" is that occupies 95% of the Universe, how magnetic fields formed and evolved in the Universe and how they influence astrophysical processes, to investigate the validity of Einstein's theory of relativity, and perhaps detect life elsewhere in the Universe. The SKA will also discover new aspects of the Universe that we had not preducted, and will generate more questions that need to be answered.

Where will the SKA be built?

The majority of the SKA - the full dish array and the dense aperture array - will be built in Africa. The core - i.e. the region with the highest concentration of receivers - will be constructed in the Northern Cape Province, about 80 km from the town of Carnarvon (the same site as where the MeerKAT is being constructed). The sparse aperture array (low frequency array) will be built in Western Australia.

Why build the SKA in Africa and Australia?

On 25 May 2012 the SKA Organisation announced that the SKA would be shared between both countries, but with a majority share coming to South Africa. Following a competitive bidding process, South Africa and Australia were both shortlisted in 2006 as potential sites for building the SKA. Both countries have invested a huge amount in this project - including building pathfinder radio telescopes with associated physical infrastructure, and developing capacity with the skills and expertise to build and use the SKA. Phase 1 of the SKA (about 10% or the full Phase 2 implementation) will make optimal use of the existing infrastructure and telescopes already built by the two countries.

Why is the SKA built in such remote locations?

Radio telescopes must be located as far away as possible from man-made electronics or machines that emit radio waves that will interfere with the faint radio signals coming from the distant Universe. The site should also be as high and dry as possible, because some radio waves are absorbed by the moisture in our atmosphere.

When will the SKA be built?

Over the next four years, teams of radio astronomy scientists and engineers from around the world will work together to scope and finalise the design of the SKA. They will decide on the design of each receiver type, the configuration of the antennas, and the design of all the other antenna elements:

  • SKA Phase 1 construction is scheduled to begin in 2016.
  • SKA Phase 2 should be built from 2019 to 2024.

How does the MeerKAT telescope fit into all of this?

South Africa's MeerKAT telescope is an SKA precursor or 'pathfinder' telescope. It will consist of 64 dish-shaped antennas and will be the most powerful radio telescope in the southern hemisphere. MeerKAT (and the Australian SKA Pathfinder, called ASKAP) will become part of SKA Phase 1. MeerKAT will form 25% of the Phase 1 dish array in South Africa.

What is KAT-7?

South Africa has already built seven dishes (KAT-7), as an engineering prototype for the MeerKAT. It is the world's first radio telescope with dishes made of composite materials (fibre glass). KAT-7 has already produced its first scientific images, and radio astronomers are using the data from KAT-7 as part of their research work.

What spin-offs can be expected from the SKA?

The technologies and systems required for the SKA will require engineers to work at the cutting edge of design and innovation. There will certainly be technology spin-offs for more generic and commercial applications. For example, the SKA will collect and process significant amounts of data, which will require advances in high-performance computing; while producing thousands of antennas within short time scales will lead to new manufacturing and construction techniques. The most important spin-off, however, will be the generation of new knowledge and knowledge workers - young scientists and engineers with cutting edge skills and expertise in a wide range of scarce and innovative fields.

How can young scientists and engineers get involved?

The SKA has an active bursary and capacity development programme ranging from artisan and in-service training programmes to advanced studies at postgraduate level. About 400 students have received SKA bursaries since 2005.

Cool SKA facts and figures


  • The data collected by the SKA in a 24-hour period, would take nearly two million years to play back on an iPod.
  • The SKA will generate enough raw data every day to fill 15 million 64 GB iPods.
  • The SKA central computer will have the processing power of about one hundred million PCs.
  • The SKA will use enough optical fibre to wrap twice around the Earth.
  • The dishes of the SKA will produce 10 times the current global internet traffic.
  • The aperture arrays will produce more than 100 times the current global internet traffic.
  • The SKA super-computer will perform 1018 operations per second - equivalent to the number of stars in three million Milky Way-size galaxies. This is needed to process all the data that the SKA will produce.
  • The SKA will be so sensitive that it will be able to detect an airport radar on a planet 50 light years away.
  • The SKA will contain thousands of antennas with a combined collecting area of about one square kilometre (that's one million square metres).

Last Modified: Wed, 15 Jan 2020 16:09:37 SAST