7 November 2006
South Africa has been shortlisted to host what will be one of the biggest and most sophisticated scientific instruments in the world, the Square Kilometre Array (SKA) - a future generation international radio telescope that will enable astronomers to probe the early evolution of our galaxy.
The International SKA steering committee in the Netherlands announced in September that South Africa and Australia had been shortlisted as sites for the SKA, a set of thousands of antennae that, put together, would cover a square kilometre.
The network of dishes will be at least 50 times more powerful than any telescope yet built.
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 SKA project will cost in the region of 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 and Australia beat bids from Argentina and China to make the SKA shortlist. A final decision is expected by 2008, while construction on the SKA will probably start in about 2013 and be completed by about 2019.
Global design programme
Earlier this year, European funding was agreed for a €38-million (US$46-million) global programme to design the Square Kilometre Array.
The four-year Square Kilometre Array Design Studies programme will see astronomers in Australia, South Africa, Canada, India, China and the US collaborating closely with their colleagues in Europe to formulate the most effective design and develop the technology required for the SKA.
"Designing and then building such an enormous technologically advanced instrument is beyond the scope of individual nations," said Professor Richard Schilizzi, the International SKA Project director. "Only by harnessing the ideas and resources of countries around the world is such a project possible".
South Africa's 'mini-SKA'
In the meantime, South Africa has begun work on a SKA prototype known as the Karoo Array Telescope (KAT), with technology that will parallel that of the SKA.
Construction on this smaller version of the SKA is expected to be complete in 2008/9, and will entail cooperation with some of the other countries involved in the SKA project to ensure efficient technology transfer.
While the KAT will have about 1% of the SKA's receiving capacity, it will still be a powerful radio telescope in its own right. It will also prove that South Africa is committed and ready to host the SKA.
Radio 'quietness'
A radio telescope has to be as far away as possible from man-made sources of radio waves, such as cellphone and radio networks.
Working with the Independent Communications Authority of SA (Icasa) to measure radio frequency interference levels in some of the most remote parts of SA, the South African SKA team has identified three sites in the Karoo in the Northern Cape, all three boasting radio interference-free zones of 150 kilometres, far exceeding the SKA requirement of 100km radio interference-free areas.
The Northern Cape sites also have a low topography suited to the SKA, with mountains providing extra shielding against radio waves from remote metropolitan areas.
Professor Justin Jonas, a radio astronomer based at Rhodes University, and a member of the South African bid steering committee, said before the latest announcement that the southern hemisphere bidders had a natural advantage.
"The southern hemisphere is a winner, because we see more of the sky than the northern hemisphere", says Jonas. "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."
In addition to the "radio quietness" of its sites, South Africa has the capabilities and track record to host, support and contribute to the science that will be generated by largest radio telescope ever built.
Cutting-edge astronomy projects
"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."
Dr Khotso Mokhele, president of the National Research Foundation, the lead agency in the South African SKA project, notes: "We already have the Southern African Large Telescope (SALT) at Sutherland in the Northern Cape that is 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."
Radio signals from the past
The core element of the SKA should be in the centre of a radio interference-free region at least 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, 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.
"If you imagine one million DSTV dishes all linked together and feeding into one computer, you start to get the picture," explains Bernie Fanaroff, South Africa's bid project manager.
The result will be an instrument capable of probing the secrets of the very early universe, just after it began about 14 billion years ago - so science tells us - with the "Big Bang".
SouthAfrica.info reporter
|
Published for Brand South Africa by Big Media Publishers