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Rhodes > Physics and Electronics > Latest News

Once upon a starry night: The story (so far) of the Square Kilometre Array

Date Released: Thu, 7 February 2013 18:22 +0200

The Square Kilometre Array (SKA) will eventually become the most sensitive radio telescope ever built, able to survey the heavens more than 10 000 times faster than current technologies.

Operating across a range of frequencies, this world's largest radio telescope will also be 50 times more sensitive than any other radio instrument. The point of all this fine-tuned complexity is to allow astronomers the opportunity to peep into the past, to study the formation of the first stars and galaxies after the Big Bang. The SKA also intends to confirm the veracity of Einstein's general theory of relativity, explore the interplays of cosmic gravity and search for signatures of life elsewhere in the universe.

Receiving stations will be built at a minimum of 3 000km from a central core, which will ensure focused, high-resolution images from deep space. The best sites on earth for radio telescopes are in the quiet skies of the southern hemisphere, with core sites in South Africa and Australia. The Karoo, an area in SA that was once the floor of an inland sea, is one of the best places in the world to listen to the twinkle of the stars; ideal for its near absolute lack of radio interference. Members of the SKA Organisation agreed in May 2012 on a dual site for the SKA at the candidate sites in SA and Australia.

The decision was based on maximising investments already made. According to the SKA, both sites offer "exceptionally radio quiet environments for detecting very faint radio waves from the early universe, and many thousands of SKA receptors will soon be constructed across these two desert regions". In September 2012, Prof Philip Diamond was appointed as the first permanent Director General of the SKA Organisation.

By November, staff had moved into SKA headquarters at Jodrell Bank Observatory near Manchester in the UK. In December, the SKA Board of Directors approved Germany as the tenth member of the organisation, along with Australia, Canada, China, Italy, the Netherlands, New Zealand, SA, Sweden and the United Kingdom. India is an associate member.

The physical array itself will be split into three main SKA receivers: two in SA and a third in Australia. The first phase of the project will set up around a tenth of the entire SKA project using the MeerKAT telescope under construction in the Karoo and a similar, twin telescope project in Australia. Phase two involves around 4 000 dishes erected in Southern Africa, 50% in the Karoo and 40% spread across eight partner countries in Africa (Botswana, Namibia, Mozambique, Madagascar, Mauritius, Ghana, Kenya and Zambia).

But how and why did SA come to play such a prominent role on such a prestigious global project? An early visionary, Prof Justin Jonas, Associate Director of Science and Engineering at the SKA South Africa Project, was at least one scientist who saw the potential of the Karoo early on. Speaking recently at the SKA South Africa's Johannesburg office, Jonas revealed that his interest in science and radio astronomy was first piqued by David Bowie.

He admits that he wanted to build a hi-fi large enough to do justice to Bowie's music. Jonas describes the process of building the SKA SA team as "a networking kind of thing, identifying early on in the programme the kind of people who, I knew, could help us with what we needed to do". When the process started, George Nicolson, now one of Jonas's colleagues, was the director at Hartbeesthoek at the time.

The Hartebeesthoek antenna (also known as "The Big Dish") has been operational since 1961 when NASA required assistance to commmunicate with spacecraft on deep space missions within our solar system. The Americans officially named Hartbeesthoek their Deep Space Instrumentation Facility 51. Locally it was simply "The Johannesburg Tracking Station".

The 26m-diameter antenna was built at a cost of around $1m. One of its first functions was to monitor the Ranger 1 mission, which was tasked with photographing the moon. Ranger 1 was the first of many missions that paved the way for the Apollo moon landings, but the tracking station also monitored Pioneer spacecraft through interplanetary space, tracked Mariner's missions to Mars and Venus and received the first pictures of Mars via Mariner IV in mid-1965.

Nine years later, NASA decommissioned the station, after which the CSIR took over operations on NASA's behalf. An engineer, George Nicolson, who had been using the antenna for limited radio astronomy research, was appointed director of the Hartebeesthoek Radio Astronomy Observatory (HartRAO) for South Africa's National Research Foundation.

The key step achieved at Hartebeesthoek was developing very long baseline interferometry, which is the  capability to merge signals from radio telescopes on different continents. Intercontinental distances facilitate images with ultra-fine detail from radio signals in space. Before the SKA, the Hartebeesthoek antenna was the only operational radio telescope with this capability in Africa. Since the Eighties, great advances have been achieved in radio astronomy, the momentum of which is still being felt today.

Now, a steady stream of young astronomers are emerging via collaborations with local universities, along with the development of new instrumentation. If local scientists wanted to expand on the operational capabilities of radio telescopes like the one at Hartebeesthoek (about 50km outside Johannesburg), a first step for Jonas and his crew was to identify areas in South Africa that were radio quiet, and that meant going out to these sites and taking measurements.

Jonas and a student protégé "jumped into a car and joined the guys from ICASA, in their kombi, and we sort of drove off into the Karoo, and Namaqualand, and the Kalahari. We camped in the bush, set up our antennas and took measurements manually, 24/7." ProfJonas says that two of his former students went on to study at Oxford and Caltech, but they are "coming back into the project".

According to Jonas, a who's who of today's SKA SA team did "sorties" back then, a group that included "Bernie, George, Adrian and Anita". Dr Bernie Fanaroff is SKA South Africa's project director, Nicolson (who with fellow astronomer Jonas was instrumental in securing the SKA bid for SA), KAT Project Manager Anita Loots and some of Jonas's students did the grassroots work that led to the SKA.

"Those were the exciting days," Jonas chuckles, "out in the Wild West. Not even putting up a tent in some cases and doing measurements." One of those students Jonas mentions was none other than Dr Adrian Tiplady. Tiplady studied his doctorate at Rhodes University and under Jonas's professorship has since become an integral part of the SKA SA project. Tiplady, in turn, credits his own contributions to personal one-on-one attention received at Rhodes, South Africa.

Source: FINWEEK (English)

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