Avery Carpenter

SOUTH Africa and Australia are going head to head in a battle to host the build site for the SKA, the world’s largest radio telescope – and it’s a close fight.

Bernie Fanaroff, the director of SKA SA, said that SA had strong advantages.

“From a technical standpoint, our site is excellent, which is the first priority,” he said. “The next two largest points are the relatively low costs and proximity to existing infrastructure.”

The criteria that could drive the decision, according to the SKA site selection group, include:

Radio Frequency Interference Levels:

A big draw for Australia is the remoteness of the site – its location in the western Outback is about 500km north-east of Perth and is virtually free of human activity. The region, called Murchison, has an area of roughly 50 000km², larger than many European countries, and an estimated population of less than 150 people.

SA’s site is closer to human activity, but backed by legislation that bars radio activity from the area – the Astronomy Geographic Advantage Act allows SA’s minister of science and technology to regulate all radio transmissions and any other activities that could interfere with radio astronomy in the area.

“A radio-quiet environment does not necessarily imply a very remote location that is expensive to provide infrastructure to, and difficult to access and operate,” said Justin Jonas, the associate director of science and engineering for SKA SS.

Physical Characteristics and Climate:

SA’s physical site is located at 1 000m altitude, which Fanaroff said is ideal for observing the universe at high frequencies.

“There is more water vapour closer to sea level, which makes viewing more difficult,” he said. “Our site is also dry, with little cloud cover.”

While Australia has a stable climate, their team has repeatedly cited their larger baseline as an advantageous physical characteristic. The baseline is the geographic distance across which the telescope’s connected antennas will be distributed.

With New Zealand on board, Australia can situate antenna stations 5 500km away from its core site, a feature that may enable sharper images of the universe.

In an interview in Cosmos science magazine, Sergei Gulyaev, an astronomer at Auckland University of Technology, New Zealand, said: “For South Africa to reach the minimum SKA baseline requirements they will have to go all the way to the Congo, and many other countries have to be involved. Here you have just one country, plus New Zealand, ideally placed.”

Cost and Infrastructure:

The SA team is confident that their site is cheaper.

Simon Ratcliffe, a leading astronomer working on SA’s SKA bid, said: “Our proximity to Europe and similar time zones, coupled with value- for-money labour and good existing infrastructure can greatly reduce the major costs of the SKA.”

The SA site is closer to existing roads and infrastructure than the isolated Australian site. The Karoo site has connections to the national electricity grid, national optical-fibre backbone and road network.

“Our site has struck an ideal compromise between remoteness and proximity to infrastructure to keep costs low,” said Fanaroff.

lA technical evaluation of both sites will be released tomorrow.