SKA sets out on its cosmic mission
DRIVING up to the first completed MeerKAT antenna is a little surreal: a giant dish standing on a 20m-high pillar in the vast nothingness of the Karoo veld.
It has the feeling of a science fiction movie set, a feeling compounded when one hears what the MeerKAT radio telescope will be doing once all 64 antennas are up and running: looking at the first stars and galaxies that formed just after the Big Bang, as well has understanding the nature of the mysterious force known as “dark energy”.
MeerKAT is a precursor to the international Square Kilometre Array (SKA) telescope, the largest and most sensitive in the world, an international project that will be located in Africa and Australia.
To date there is just one MeerKAT antenna completed, but when the project is finished there will be 64 spread out on the semi-desert plain about 90km from Carnarvon in the Northern Cape.
The telescope was originally known as the Karoo Array Telescope (KAT) and would have had 20 receptors. When the government agreed to increase the budget to allow 64, the team renamed it “MeerKAT” – more of KAT.
The antenna inaugurated by Science and Technology Minister Derek Hanekom last week is the first of 3 000 antennas that will make up the larger SKA project.
MeerKAT programme manager Glen Collins explained that objects in the heavens emitted energy on all sorts of radio frequencies. Radio telescopes were able to pick up these and translate them into images. “So they can be turned to look into the sky and even when black to the eye, the radio telescope reveals what is there.”
Electromagnetic waves bounced off the main reflector on to the receiver, which converted this to digital data that was transmitted via underground fibre-optic cables to the correlator in a building, the Karoo Array Processor Building, on the site.
All the signals from all the receptors were combined to form an image of the area of the sky to which the antennas were pointing.
Each antenna was built on a foundation of steel-reinforced concrete piling 10m deep, was 19.5m high and the dish was 13.5m in diameter. They were designed to survive three-second gusts of wind up to 144km/h. “It is designed to retain its sharpness in temperatures that vary from -10°C to 50°C. So it can expand and contract and still keep its optical shape. There are only about 20 companies in the world that can do that,” Collins said.
The antennas are made by Stratosat Datacom, which leads a consortium of German and US companies.
About 75 percent of the components that make up the MeerKAT dish will be made in South Africa by subcontractors.
Some of the science projects that MeerKAT will undertake include testing Einstein’s theory of gravity by investigating the physics of neutron stars, investigating different types of galaxies, dark matter and the cosmic web, uncovering galaxy formation and evolution and searching for extraterrestrial intelligence.