Science and technology

Africa vies for Square Kilometre Array

South Africa is currently competing against Australia to host the world's most powerful radio telescope, the €1.5-billion Square Kilometre Array.

The international science funding agencies and governments involved in the international SKA consortium will announce the winning bidder in 2012, with construction likely to start in 2014 and take place in phases over several years, with completion by about 2022.

'Time machine'

At between 50 to 100 times more sensitive than any existing radio telescope, the SKA will be able to probe the edges of our universe, and help us to answer fundamental questions about the laws of nature and physics, including the study of so-called "dark energy" and "dark matter".

It will subject Einstein's theory of general relativity to its most stringent tests yet, and will search for gravitational waves, which have been predicted but never detected.

It will be a powerful virtual time machine, enabling scientists to "go back in time" to explore the origins of the first galaxies, stars and planets. If there is life somewhere else in the Milky Way galaxy, the SKA will help us find it.

According to the South African SKA project office, the operations and maintenance of a large telescope normally cost about 10% of the capital costs per year, meaning the international SKA consortium would be spending approximately €100-million to €150-million a year on operating and maintaining the telescope.

"It is expected that a significant portion of the capital, operations and maintenance costs would be spent in the host country," says SKA South Africa's Kim de Boer.

The SKA in Africa

The major component of the SKA telescope receptor will be an extensive array of approximately 3 000 antennas, half of which will be concentrated within a five kilometre diameter of the central region, with the rest distributed up to 3 000km from this central concentration. These antennas will be 12-15 metre diameter dishes.

South Africa proposes that the core of the telescope be located in an arid area of the country's Northern Cape province, with about 90 antennas in neighbouring Namibia, 120 in Botswana and about 30 each in Mozambique, Mauritius, Madagascar, Kenya and Zambia. Added together, the combined collecting area of these antennas will be roughly one square kilometre.

The antennas would be connected via a super-fast data communications network to an extremely large and powerful computer in the Northern Cape, and the telescope would be controlled and operated remotely from Cape Town, where the operations and science centre would be located.

De Boer says the SKA will be one of the largest scientific research facilities in the world and, if awarded to South Africa, would consolidate the southern African region as a major international hub for astronomy and cutting-edge technology.

It would attract the best scientists and engineers to work in Africa, and would provide unrivalled opportunities for scientists and engineers from African countries to work on cutting-edge research and collaborate in joint projects with the top universities in the world.

"Winning the SKA bid would be a major step forward for the government's Astronomy Geographic Advantage Programme," says De Boer. "Other major astronomy facilities in the region include the Southern African Large Telescope (SALT) in the Karoo, and the HESS gamma ray telescope in Namibia."

Why the Northern Cape?

The Karoo region of South Africa's Northern Cape province is ideal for radio astronomy, because it is remote and sparsely populated, with a very dry climate. There is minimal radio frequency interference from man-made sources such as cellular phones and broadcast transmitters, which is crucial for radio astronomy, as radio interference would "blind" the telescope.

In 2007, South Africa's Parliament passed the Astronomy Geographic Advantage Act, which declares the Northern Cape an "astronomy advantage area", giving the Minister of Science and Technology powers to protect the area from future radio interference.

An area of 12.5-million hectares around the proposed core of the SKA will be protected as a radio astronomy reserve, with regulations controlling the generation and transmission of interfering radio signals in and around the area around.

MeerKAT: world-class SKA precursor

South Africa is currently building the Karoo Array Telescope (MeerKAT), which is a precursor instrument for the SKA, but will in its own right be among the largest and most powerful telescopes in the world. MeerKAT is being constructed adjacent to the site proposed for the SKA, near the small town of Carnarvon in the Northern Cape.

Following the successful building and testing of a single prototype dish at the Hartebeesthoek Radio Astronomy Observatory near Johannesburg, the MeerKAT team is now working on KAT-7, a seven-dish prototype interferometer array in the Karoo.

The construction and commissioning of the full MeerKAT array, consisting of 80 dishes, will follow at the same site proposed for the SKA, with a high-speed data network linking the telescope site in the Karoo to the control centre in Cape Town. The telescope will be commissioned in 2013.

Scientific programmes

MeerKAT will be the most sensitive centimetre-wavelength radio telescope in the Southern Hemisphere, and will make significant contributions to both galactic and extragalactic astronomical research.

"MeerKAT will explore phenomena such as how cosmic magnetism came about, how galaxies and clusters of galaxies have developed and evolved over the 14-billion year age of the Universe, the influence of dark matter on galaxies and clusters, and the nature of transient radio sources," De Boer explains.

According to the local SKA project office, the scientific programme will be a mixture of "blind" and "directed" surveys conducted by large project teams, and smaller experiments designed by individual principal investigators or small teams. These teams and principal investigators will be international in their composition, and will include participants from Africa.

The scientific productivity of MeerKAT will be enhanced by combining its results with those obtained by instruments operating at other wavelengths, for instance infrared and X-ray satellite data.

Site preparation

The local SKA project office says that the access roads, workshops and accommodation at the MeerKAT site at Losberg are already complete, while the power lines and optical fibre will follow soon. A 12-metre dish mould has been prepared inside the dish assembly shed. An adjacent building will house six radio frequency interference-shielded containers for computers and other equipment.

A hybrid power transmission line to the site and the underground optical fibre cables will connect this facility to a control centre in Cape Town.

"Following the renovation of an existing building, the SKA South Africa Support Base at Klerefontein, about 80km from the site, now has offices, workstations, a mechanical laboratory, a boardroom and an entertainment area," De Boer explains.

The preparation of the astronomy site at Losberg, the support base at Klerefontein and the infrastructure has created business and job opportunities in the area for local people, and there is huge enthusiasm for the project in these communities.

SKA collaboration

The MeerKAT scientists are fully embedded in the international SKA project, participating in technical committees and working groups set up by the SKA project development office.

Bilateral agreements have been established with key institutions involved in the international SKA consortium, including the Universities of Oxford and Cambridge, the University of California at Berkeley and Caltech, the National Radio Astronomy Observatory (NRAO) of the USA, the national radio astronomy centre in India, and thee radio astronomy institutes in Italy.

In South Africa, the Hartebeesthoek Radio Astronomy Observatory and the South African Astronomical Observatory are participating in the MeerKAT project, while researchers and students at many universities in South Africa and the rest of Africa are also actively participating.

The local SKA project's head office is in Rosebank, Johannesburg, while the MeerKAT engineering office is in Pinelands, Cape Town. The Department of Science and Technology is funding the SKA project via the National Research Foundation.

Skills development and training

The SKA South Africa project, including the MeerKAT telescope, is one of the biggest science and engineering projects in South Africa. It thus represents an unrivalled opportunity for the development of very high-level science and technology expertise – paving the way for Africa to contribute significantly to the global knowledge economy and global technology trade.

These technologies include very fast grid computing, very fast data transport, data storage, wireless engineering, digital electronics, image processing and software development.

In 2005, the South African SKA project initiated a targeted "Youth into Science and Engineering Programme" to develop highly skilled young scientists and engineers.

"The young people supported by this programme will serve South Africa, and our African partner countries, in the future in key areas of economic development in addition to their participation in 'blue skies' scientific research," De Boer says.

The programme offers comprehensive bursaries to students in engineering, mathematics, physics and astronomy at undergraduate and postgraduate level. Bursary holders also benefit from regular workshops and conferences where they interact with the world's leading astronomers.

"To date, more than 80 postgraduate students and about 40 undergraduate students are studying or have studied with SKA bursaries, and are on their way to being a part of South Africa's exciting future in radio astronomy," De Boer says.

Article last updated: July 2009

SAinfo reporter



	Artist's impression of the core of the Square Kilometre Array (Image © Xilostudios / SKA)



	Two supersized cranes are used to lift the first composite dish of the KAT-7 prototype telescope onto its pedestal outside Carnavon in the Northern Cape province (Photo: SKA South Africa)



	The 15-metre MeerKAT prototype antenna at the Hartebeesthoek Radio Astronomy Observatory in Gauteng province (Photo: SKA South Africa)



	The Sutherland Observatory in the Northern Cape province is home to one of the world's largest telescopes, the Southern African Large Telescope, or SALT (Photo: Graeme Williams, MediaClubSouthAfrica.com)

Listening to the early Universe

Astronomers explore the universe by passively detecting electromagnetic radiation and cosmic rays emitted by celestial objects. The earth's atmosphere shields us from much of this radiation, so modern astronomy is done from large optical telescopes on high mountains, or from orbiting satellite observatories.

Radio astronomers, on the other hand, concentrate on the relatively long wavelength (or low frequency) radio waves that penetrate the earth's atmosphere with little impediment or distortion.

Because electromagnetic radiation travels at a fixed speed of about 1.08 billion km/h, very distant objects are observed as they were in the distant past. Astronomers are therefore able to "look back in time" to observe the early stages of the evolution of the universe.

Most existing radio telescopes were built 10 to 30 years ago. For radio astronomy to progress, a new telescope with 100 times the collecting surface of existing telescopes will be needed in about 10 years' time.

The SKA will probe the so-called "Dark Ages", when the early universe was in a gaseous form before the formation of stars and galaxies. At present, astronomers do not have the necessary tools to observe radiation from this period of the universe, which extends from about 300 000 years till one billion years after the Big Bang.

Radiation reaching us from the "Dark Ages" has travelled a huge journey through space, and is in the form of radio signals emitted by the neutral hydrogen gas that dominated the universe during this period. The signals are, however, extremely faint, and require a telescope with the planned sensitivity of the SKA to be detected.

The SKA will map the time evolution of this cosmic web of primordial gas as it condenses to form the first objects in the universe. It will also chart the development of these adolescent stars and galaxies, which will provide us with information about our own origin. The atoms in our bodies, our planet and our star were formed by the nuclear reactions that powered these early stars.

Source: Square Kilometre Array SA