25 September 2003

South African scientists have submitted a bid to host the Square Kilometre Array (SKA), an enormous radio telescope that will enable astronomers to probe the early evolution of our galaxy, about 14 billion years after the universe began with the Big Bang.

If South Africa were to win the bid, it would bring a massive injection of expertise and economic activity to the Northern Cape, with benefits for the local aluminium, computer, communications, electronics, and steel industries.

The international project will cost about US$1-billion, and according to Arts, Culture, Science and Technology Minister Ben Ngubane, could generate as much as R500-million in foreign investment for South Africa.

South Africa's offer to host the SKA was submitted in May to an international panel of experts who will select the host country based on a comprehensive set of criteria.

The South African SKA has identified three sites in the Northern Cape, all three boasting radio interference-free zones of 150 kilometres, which far exceeds the requirement of 100 kilometre radio interference-free areas. They are in the Kalahari (north of Upington), in the Karoo (north of Carnarvon), and in Namaqualand (east of Springbok).

South Africa faces competition from Australia, China and the US to host the SKA. A final decision is expected during 2005, while construction on the SKA will probably start in 2010.

It's thought that Australia offers the stiffest competition, although South Africa's bid is likely to be the cheapest. Counting in Australia's favour is a well-established astronomy base and a larger geographical area in which to extend the SKA.

Professor Justin Jonas, a radio astronomer based at Rhodes University, and a member of the South African bid's steering committee, says the southern hemisphere nations have an advantage over their northern hemisphere competitors.

"The southern hemisphere is a winner, because we see more of the sky than the northern hemisphere. We are also in the same longitude as Europe, which means we see the same night sky, and can easily link up with facilities there", Jonas said.

Some of the most important reasons why the Northern Cape is ideal include the "radio quietness" of the area (minimum radio interference from cellphone and radio networks), low population density and suitable topography.

In addition to the location of the three identified sites, South Africa has the capabilities and track record to host, support, and contribute to the science that will be generated by this giant radio telescope.

The core element of the SKA should be in the centre of a radio interference-free region 100 kilometres in diameter. This is because radio emissions from the early universe - which the SKA will seek to capture - are in the range of a few hundred megaHertz, a frequency band now crowded on earth with TV and cellular telephone transmissions.

To pick up these radio emissions - literally, radio signals from the past - the SKA will have a receiving surface of one million square metres, which is 100 times larger than the current biggest surface.

The huge receiving surface will consist of many small antennae, divided into a core element and a periphery. The peripheral antennas could be between 1 000 and 10 000 kilometres away from the core element, making the SKA an intercontinental system.

The signals received by all these antennae will be combined to form one single, big picture. The result will be an instrument capable of probing the secrets of the very early universe, just after the Big Bang.

"The southern African region has become a premier destination for cutting-edge astronomy projects as a result of decisions taken by governments in the region," says Dr Rob Adam, director-general in the department of science and technology and chairperson of the South African project steering committee.

"South Africa clearly has the history, experience and expertise in constructing, hosting and cooperating in major astronomical and space science projects to make the SKA a success."

Comments Dr Khotso Mokhele, president of the National Research Foundation (NRF), the lead agency in the SKA project: "We already have the Southern African Large Telescope (SALT) at Sutherland in the Northern Cape that will be the largest telescope in the southern hemisphere, while in neighbouring Namibia there is the High Energy Stereoscopic System (HESS) gamma ray observatory that will be the largest of its kind in the world.

"We see the location of global astronomy infrastructure in our region as a way of promoting high-technology investment and of ensuring that local scientists are able to participate in world-class science at limited cost."

SouthAfrica.info reporter

	South Africa - ready for a new era in radio astronomy

	SALT: Africa's eye on the universe Rediscovering African starlore Research opportunities SA joins search for gamma-rays Satellite centre scores with Nasa

	Square Kilometre Array SA  SKA International  Hartebeesthoek Radio Astronomy Observatory  Southern African Large Telescope  SA Astronomical Observatory  National Research Foundation  Dept of Science & Technology

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 1 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 South Africa