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Location of radio telescope array (SKA) announced

For years, New Zealand has awaited a decision on where the world’s largest and most sensitive radio telescope array is to be built. The choices were down to two rival bids: a joint Australia/New Zealand bid and a South African bid. On 25 May 2012, the Square Kilometre Array (SKA) Organisation finally announced that the massive telescope array will be built in both Australasia and South Africa – both sites will get a SKA, but each SKA will handle different tasks. Both SKAs will have a total collecting area of approximately 1 square kilometre, giving 50 times the sensitivity and 10 000 times the survey speed of the best current-day radio telescope arrays.

Division of SKA dishes between South Africa and Australasia

In a statement issued by the SKA Organisation following a meeting in Amsterdam, the group wrote that both sites were well suited to hosting the SKA and that all countries had already made considerable investment to support their bids, such as the MeerKAT array of dishes already under construction at the SKA core site in the Karoo desert region of South Africa and the Australian SKA Pathfinder (ASKAP) array in Western Australia.

The statement says the majority of SKA dishes in Phase I will be built in South Africa, combined with MeerKAT. Further SKA dishes will be added to the ASKAP array in Australia. All the dishes and the mid-frequency aperture arrays for Phase II of the SKA will be built in South Africa, while the low frequency aperture array antennas for Phases I and II will be built in Australia and New Zealand.

SKA will transform our view of the Universe

“This hugely important step for the project allows us to progress the design and prepare for the construction phase of the telescope. The SKA will transform our view of the Universe; with it, we will see back to the moments after the Big Bang and discover previously unexplored parts of the cosmos,” Dr Michiel van Haarlem, Interim Director General of the SKA Organisation, said in the SKA statement.

Professor Bryan Gaensler, Director of the Centre for All-sky Astrophysics, Sydney University, and formerly the International Project Scientist for the Square Kilometre Array, was interviewed by the Science Media Centre in Australia and further clarifies the SKA Organisation’s statement.

“The Square Kilometre Array is a concept that’s been slowly growing and evolving since 1991. But today, this ambitious project took a sudden giant leap towards reality with the announcement of the SKA site decision. The decision is a complex one, which recognises the enormous amount of international investment that will be needed to make the SKA happen: the array will be split between Africa and Australia/New Zealand.”

Full square km of collecting area at each site

“What this does not mean is that half the telescope will be built in each continent. Each site gets a full square kilometre of collecting area, with the full scientific functionality originally envisaged. However, the SKA’s science goals require a facility that can tune in to radio waves ranging from 70 MHz up to above 10 000 MHz. It’s impossible for any single technology to cover this vast range, so the plan has always been to build two or even three different types of antennas, which together can span the full range needed.

“What the SKA project has decided is to put different technologies in different places, playing to the strengths of each site.”

Lowest frequency component in Australasia

“The lowest frequency component, consisting of antennas that do not move or steer and that can collect signals from the whole sky at once, will be built in Australia and New Zealand. This capitalises on the superb radio quietness of the SKA core planned for Murchison in outback Western Australia – one of the few places on the planet that isn’t polluted by FM radio and other artificial signals in this low-frequency band.”

Higher frequency technology in South Africa

“The higher frequency technology, consisting of more traditional steerable dishes like the one at Parkes, will be built in Africa. This naturally extends on the MeerKAT array of dishes already under construction at the SKA core site in the Karoo desert region of South Africa.

“The remaining pieces of the puzzle are ‘phased array feeds’, the fish-eye lens technology being developed by CSIRO for their Australian SKA Pathfinder in Western Australia. These will be further developed and expanded in Australia and New Zealand and then possibly later installed on dishes in Africa. Australian/New Zealand technology on an African telescope is truly a win-win scenario.”

Collaboration instead of competition from now on

“Going forward, what this all means is that the money committed to construction by all the SKA’s international partners can now begin to flow. The hard-working engineers and scientists in Australia and New Zealand and in Africa can go back to collaborating rather than competing. And the SKA will attract brilliant young researchers from around the world to help solve the daunting technological challenges ahead of us.

“I am excited that the SKA now looks like it’s really going to happen. I can’t wait to point it at my favourite stars and galaxies, and to get the data in my hands!”

The SKA will enable astronomers to glimpse the formation and evolution of the very first stars and galaxies after the Big Bang, investigate how dark energy is accelerating the expansion of the Universe, understand the role of magnetism in the cosmos, investigate the nature of gravity and possibly even discover life beyond Earth.

The target construction cost is €1500 million, and construction of Phase I of the SKA is scheduled to start in 2016.

Useful links

Read more details about the SKA announcement.
www.skatelescope.org/news/dual-site-agreed-square-kilometre-array-telescopeexternal link

Activity idea

Your students may like to view this video clip in which Dr Melanie Johnston-Hollitt explains how the SKA will help explore the far reaches of the Universe.
Radio telescopes of the future

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