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SKA South Africa
  New Karoo Radio Telescope to
Put SA Science On The World Stage- Marina Joubert Together with Australia, China and Argentina, South Africa is on the shortlist to host the world’s largest radio telescope, the Square Kilometre Array, or SKA. “Competition in this bid is tough, as the winning country will attract a billion euro investment and one of the most ambitious science projects ever,” says Dr Bernie Fanaroff, South Africa’s SKA Project Manager. “The winner in the SKA bid will only be known by 2008, but in the mean time we are planning to build the Karoo Array Telescope, or KAT, in the same region where we hope to site the core of the SKA.” Read more... What is SKA? The Square Kilometre Array is a $1 billion international project to create a receiving surface of a million square metres, one hundred times larger than the biggest receiving surface now in existence. This huge surface will be composed of many small antennas, divided into a dense inner core array which becomes more diffuse with increasing radius. Many details still have to be worked out, and the peripheral antennas could be 1 000 km from the core, or 5 000 km, or even 10 000 km, making the SKA an intercontinental system. Whatever the final form and scale of the instrument, the signals received by every one of these antennas will be combined to form a single, big, picture. This will require complex computing and information processing systems. The result will be an instrument capable of probing the secrets of the very early universe. The science of the SKA Astronomers explore the universe by passively detecting electro-magnetic 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 atmosphere with little impediment or distortion. These radio signals have frequencies between about 30 megahertz and 40 gigahertz, or equivalently, wavelengths from 10 metres down to 7 millimetres. History has shown that for any scientific discipline to remain active and productive, the power of its instrumentation must grow exponentially with time. Without this growth the discipline tends to stagnate and new discoveries are not made. Most of the telescopes being used currently, 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 Square Kilometre Array (SKA) was conceived as a new international project to meet the future needs of radio astronomers. One of the prime objectives of the SKA is to 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. Because electromagnetic radiation travels at a fixed speed of about 1.08 billion kilometres per hour, 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. For example, the recent results from the WMAP Cosmic Microwave Background Radiation satellite observatory provide us with a view of the universe 300 000 years after the Big Bang, at the time when radiation and matter became separated. The Hubble Deep Field (HDF) image produced by the Hubble Space Telescope (HST) shows us what the early galaxies looked like some billion or more years later. We need to know how the 'lumpy' galaxies seen in the HDF were born during the 'Dark Ages' out of the 'smooth' early universe observed by WMAP. Radiation reaching us from the 'Dark Ages' has travelled a long way 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. The SKA will provide data for a whole range of astronomical investigations and it will complement other planned instruments in the optical, infrared and millimetre wavebands. It will provide sharp radio images of all categories of astronomical objects, investigate the nature of the enigmatic gamma-ray burst sources, detect the gravitational waves predicted by Einstein's theory of General Relativity by using radio pulsars as cosmic clocks, detect extra-solar planets, and may even detect signals transmitted by intelligent extraterrestrial civilisations (SETIs). There is no doubt that the SKA will also make new discoveries not predicted by the astronomers and engineers involved in its design. The history of astronomy, particularly radio astronomy, is full of accounts of serendipitous discoveries that have changed the course of science. Some of these discoveries have resulted in the award of a Nobel Prize, and the SKA is expected to produce more such awards. Link to Square Kilometre Array's own website, www.ska.ac.za. |
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