SKA: answering the big questions about the universe

The Square Kilometre Array will feature in the next instalment of Brand South Africa’s Play Your Part TV series, to be aired on Sunday 20 July at 9pm on SABC2.

Once the SKA is up and running, it will be one of the world’s biggest science projects. The MeerKAT project, pictured above, will be integrated into the first phase of the SKA construction in 2018. (Image: SKA South Africa)

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Shamin Chibba

The answers to some of astronomy’s biggest questions may come straight out of the Karoo when construction on the Square Kilometre Array (SKA) begins in 2018.

The SKA is a radio telescope which will scour the universe for information to give scientists more data on dark matter, black holes, energy particles and the formation of stars and galaxies. The final construction will look like a field of giant satellite dishes.

The SKA Organisation, a private non-profit company based in the UK, is running the project. Both South Africa and Australia will host SKA with 70% of the project being based in the Karoo. The first phase of construction is expected to start in 2018 with phase two commencing in 2023 and ending in 2030.

The 64 dishes of the MeerKAT, South Africa’s main component of the colossal Square Kilometre Array telescope, will be integrated into the first phase of SKA’s construction along with 190 more dishes. Australia’s equivalent to MeerKAT – the Australian Square Kilometre Array Pathfinder – will also be absorbed into phase one. In addition, 60 mid-frequency dishes and an as yet undisclosed number of low-frequency aperture arrays will be installed.

The core site in South Africa will be located 100km west of Carnarvon, Northern Cape. It will sit at an altitude of 1 000m, in a remote area free from radio interference. The area is also legally protected by the Astronomy Geographic Advantage Act of 2007, which restricts “activity which might detrimentally impact on astronomy and related scientific endeavours”. This would include transmitting radio waves.

Australia’s core site is at Boolardy, a former sheep station about 100km west of the mining town of Meekatharra, which lies about 770km northeast of Perth in Western Australia.

Outer telescopes will be placed in eight partner countries; Namibia, Botswana, Ghana, Kenya, Madagascar, Mauritius, Mozambique and Zambia.

According to the SKA’s technical development manager, Francois Kapp, scientists from around the world are already involved in the MeerKAT project. “More than 500 scientists are involved, of whom 50 are from South Africa.”

How it works

Unlike other radio telescopes, which are limited in movement and how many frequencies they can receive, the SKA will include an array of telescopes, called an interferometer. It will link the individual telescopes to build a bigger picture of the portions of sky being observed.

Massive stars and galaxies give off radio signals and a radio telescope picks up these waves, which are different for each body. Astrophysicists and astronomers then tune into the waves to learn more about the universe. The more waves picked up, the more information collected.

The SKA will exceed the image resolution quality of the Hubble Space Telescope by a factor of 50 and will be able to capture huge areas of the sky. In South Africa, data gathered from all the receivers will be processed locally. The SKA will have a combined collecting surface of one square kilometre, and will be 50 times more sensitive and 10 000 times faster than anything yet built.

The first phase will be made up of mid-frequency antennae and an array of low-frequency antennae.

According to Justin Jonas, associate director for science and engineering at SKA South Africa, the higher elevation of the Karoo site is an advantage for the mid-frequency telescope, which is why this segment was allocated to them.

The rest of the low-frequency aperture array antennae, as many as 10 times more than in phase one, will be constructed in Australia and New Zealand.

Jonas said scientists should be able to use phase one for research by 2020. “By that time construction on phase two should be underway, with full science operations commencing by 2024.”

In phase two, all the dishes will be built in Southern Africa. This is the stage at which the widely spaced dishes will start to spread into the partner countries, as far as 3 000km or more from the core in the Karoo. A number of flat, 60m-wide mid-frequency aperture arrays will also be built here.

Costs and challenges

Budget for the SKA’s first phase is set at €1.5-billion (R21.6-billion). However, in 2012, South African science and technology minister, Naledi Pandor, had estimated the project to be as much as €2.5-billion (R36.1-billion).

The South African government initially pledged R2-billion for the construction of the MeerKAT.

In March this year, the project received a €120-million (R1.8-billion) injection from the British government. According to Phil Diamond, director-general at the SKA Organisation, the UK’s funding is a big step towards the project’s realisation. “This is solid proof that the project is now really under way. With such a major investment secured, there is no stopping it.”

Despite these contributions, the SKA Organisation is still finding it hard to secure financial support.

Further adding to SKA’s challenges is the €650-million (R9.7-billion) cap, which could limit the project’s design. Director of the SKA Organisation, Bernie Fanaroff, said it would have to be designed to that cost while maintaining scientific excellence.

The funding model for the instrument was still being negotiated at international level, said South Africa’s former minister of science and technology, Derek Hanekom, in October 2013. He said members of the SKA organisation – South Africa, the UK, Australia, Canada, China, Italy, New Zealand and the Netherlands – will all contribute to capital and running costs. Depending on whether new members come on board, these costs may vary.