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Worth its SALT: The Southern African Large Telescope in the Great Karoo 

The Great Karoo, the semi-desert region which accounts for 400,000 square kilometres (or about one third) of South Africa, is a dry, empty and beautiful place, recalling Buzz Aldrin's description of the moon — "a magnificent desolation". For many millions of years it was an inland sea or swamp and the fossils reveal that strange creatures roamed there at least ten million years before the dinosaurs, such as the Pareiasaurus, a weird cross between a hippo and a crocodile. Its rocks, dating from the Permian and Triassic periods, contain fabulous coal deposits as well as an estimated 800 billion fossils. The world's oldest people, the San, lived here and gave the area its name — Land of Great Thirst. Its few small towns — Calvinia, Carnarvon, Hopetown, Hanover — harbour a mainly coloured population and both they and the few hardy whites speak only Afrikaans: virtually no blacks live there. The trekkers had to make it through the Karoo and something of it has been burnt into the South African soul. People love coming here for its uncompromising landscapes, its quiet emptiness, a land that time forgot.

Now, however, the Karoo is alive with controversy. In 2005 the Southern African Large Telescope (SALT), the biggest in the southern hemisphere, was opened near Sutherland. Backed by an international consortium, SALT has become a tourist attraction as well as a major astronomical resource. Immediately there were proposals to build safari lodges and golf estates nearby, which were batted down because the whole point was that the Karoo has clear skies and no industrial or light pollution. Now it seems possible that the world's biggest radio telescope, SKA (Square Kilometre Array) will be sited near Carnarvon for similar reasons. SKA, which will cost an international consortium 1.5 billion euros and be run by Jodrell Bank, will see 3,000 dishes each 15 metres wide at the centre of five spiral arms extending at least 3,000 kilometres, with further linked antennae all over southern Africa and as far afield as Kenya and Ghana. The result, a telescope more than 50 times as powerful as anything now extant, will see back almost to the Big Bang and thus study the formation of the earliest stars and galaxies. Surveying the skies 10,000 times faster than anything now possible, it will map a billion galaxies out to the edge of the universe and should be able to solve such riddles as dark energy, dark matter and even the existence of gravity waves. 

In effect what this will mean is the final experimental tracking down of all the theories and possibilities suggested by Einstein. By mapping the evolution of galaxies and studying their outward expansion SKA should be able to make definitive new findings about the dark energy driving them apart and the dark matter between them. Similarly, by using pulsars as monitoring devices SKA will be able to study the operation of gravity in areas on the edge of black holes where the curvature of space reaches extreme proportions. Thus far, all Einstein's theoretical postulates have been borne out, but SKA could see us not only completing the process but pushing our knowledge further into a post-Einstein direction.

Already South Africa is building a precursor facility to SKA, MeerKAT, with 64 linked dishes, for the government is keen to have projects which put the country at the technological cutting edge. The only other possible SKA site (in Western Australia) lacks many of the Karoo's advantages and linked antennae could be placed only in New Zealand. The final decision on SKA has to be made next year. It should start work in 2019 and be in full operation by 2024, with MeerKAT ready by 2012. SKA will have to have enormous computer and internet capacity, for the way modern astronomy works is by teams of scientists anywhere in the world sending immense amounts of data, observations and questions by email to those operating the telescope, who then feed these demands into the telescope and send the equally complex results back by email for analysis elsewhere.

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