Australasian Science: Australia's authority on science since 1938

Our Last-Gasp Share of Giant Telescope

Artist's impression of SKA static, low frequency aperture arrays

Artist's impression of SKA static, low frequency aperture arrays to be built in Phase 1 at the Murchison site in WA. Credit: SKA Organisation/TDP/DRAO/Swinburne Astronomy Productions

By Peter Pockley

What was the back story behind the decision to split the Square Kilometre Array between southern Africa and Australia?

The scientific goals for the SKA are truly grand. “The SKA will transform our view of the universe,” according to the Interim Director General of the SKA Organisation, Dr Michiel van Haarlem, when announcing the decision on 25 May. “With it we shall see back to the moments after the Big Bang and discover previously unexplored parts of the cosmos. The SKA will enable astronomers to glimpse the formation and evolution of the very first stars and galaxies after the Big Bang, investigate the nature of gravity, and possibly even discover life beyond Earth.”

These questions had been the goal of Australian Dr Ron Ekers, who as director of world-leading arrays in the USA and Australia is widely credited as the “father of the SKA”. In 1990 he and a few colleagues first proposed that if radioastronomers were to address these questions they would need a telescope with a receiving area equivalent to one square kilometre.

Ekers doggedly pursued the project through the Inter­national Astronomical Union, and encouraged his successors and colleagues to bring it to fruition. Speaking from a conference in Moscow, Ekers (now a CSIRO Fellow) acknowledged: “I was certainly the one who triggered interest in the project in Australia and proposed Australia as a possible site”.

A subsequent two-decade-long battle over the planning of these megafacilities came down to the wire as the international consortium promoting the establishment of what will be the world’s largest telescope had to decide in mid-May between the two national blocs short-listed to host the array – South Africa leading a southern African consortium of eight other African nations, and Australia/New Zealand.

At an estimated total cost of $2 billion spread over many years and with 3000 steerable dish antennas to be built and coordinated in simultaneous observations of cosmic objects at hitherto unreachable sensitivity and precision, the prize was expected to be a case of winner-takes-all. The pressure was intense.

In February word leaked out (but with no attributable sources for verification) from the site assessment committee of the SKA Organisation – a consortium of nine nations – that the southern African site had been judged narrowly superior to the Western Australian site proposed for the core of an Australian array.

The South African bid has been driven by an energetic Dr Bernie Fanaroff. Their straight-shooting Science Minister, Mrs Naledi Pandor, publicly inferred that the Aussie/Kiwi team had planted the rumour, breaking a confidential embargo.

Meanwhile, the South Africans were running a parallel, non-scientific story through the European Parliament that the SKA would provide a great platform for educational and social renewal in the continent. Pandor upped the ante by “refusing to engage in a debate with the Australian Minister”. Since the dual decision was announced Pandor has toned down the rhetoric to: “We accept the compromise in the interest of science”.

For Australia Dr Brian Boyle, seconded from CSIRO to be SKA Director, and Science Minister, Senator Chris Evans, had played cool in public, not wanting to be seen to be breaking the embargo on the assessment and decision process. They continued publicly to promote superior experience in radio­astronomy research, building and operating world-class radio­telescopes and brilliance in design of the highly versatile and sensitive radio receivers needed at the heart of SKA telescopes.

But Boyle and Evans were working strenuously to press the ANZAC case behind the scenes at scientific and political levels. Evans had picked up the SKA baton after its long-term champion in Senator Kim Carr had personally lodged Australia’s bid at an SKA meeting in Canada last year but had then been demoted out of the Science and Innovation portfolio after backing the failed challenge in February by former Prime Minister Kevin Rudd to current PM Julia Gillard.

From it first airing in February, the unsubstantiated rumour spread that the South African site had won the race to host the SKA. This was not denied, lending weight to the assumption that this committee’s preference was not unanimous and was only by a fine margin. This turned out to be correct.

The SKA Organisation could not decide the major prize on the basis of the siting committee alone, and convened another committee charged with searching for an “inclusive solution”. This opened the door again for the Australia/NZ team to prosecute a dual deal rather than one outright winner.

Privately, Australian radioastronomers had been incredulous that the international scientific community with whom they have worked at high levels for decades would overlook Australia’s track record and potential for innovative instruments and research. Scientists involved would tell me that they were very wary of the incursion of a political dimension but acknowledged that it could not be avoided in the next hurdle of raising large funds to build and operate the SKA.

In May, a close solution emerged – pointedly admitted as “a majority decision” – with the South African-led group being given the greater receiving area with some 3000 steerable antennas working on the higher frequencies of celestial observation. Meanwhile, in Phase 1 – to commence in 2016 – the Australia/NZ team will work at the lower end of the frequency spectrum with 60 static dipole receivers built alongside the 36-dish Australian SKA Pathfinder radiotelescope (ASKAP) that began installation in 2010 at Murchison in Western Australia.

Boyle and company might have lost the original sole-siting question, but they are quietly delighted that they have rescued a substantial portion of their original bid and are keen to promote what they can now plan on providing for their international colleagues.

Speaking from Amsterdam immediately after the decision, Boyle said: “Phase 1 of the dual site option makes sound scientific sense by maximum use of existing infrastructure, and represents a very good outcome for A/NZ technology. A simple count of antennas is meaningless as that’s only one bit of the telescopes; there are all the receivers and computer hardware behind it. Overall, South Africa will get 190 antennas to complement their (planned) steerable 64-dish MeerKAT pilot array.”

From Sydney the Director of CSIRO’s Astronomy and Space Science Division, Dr Philip Diamond, added: “Steerable antennas may look pretty but it’s the receiver systems – the fibre infrastructure and the digital processing – that is the real innovation in the SKA. With 4000 [static] dipole antennas in Australia in Phase 1 alone, the signal processing system will be a major development.

At first sight it seemed that NZ had been written out of the story, as the key advantage they had brought to the Australian bid seemed to be the potential linkage of steerable dishes in both of its islands across the Tasman Sea to the Australian array, which was to span the continent from west to east, thereby adding a valuable extra 2000 km to the “baseline” (the larger this is, the finer the resolution of radio “pictures” it synthesises).

Dr Melanie Johnston-Hollitt, NZ’s SKA head, acknowledged that a few dishes would not be sited in NZ during Phase 1 but said this was never planned in this phase. “The move to host SKA low frequency infrastructure in Australia and NZ is a natural path forward for us. Our scientific interests are in low frequency astronomy and survey science, [so] the dual plan allows NZ to continue to make an important contribution into the SKA project.”

The Australian 2011 Nobel Laureate in Physics, Prof Brian Schmidt, is both enthusiastic and cautious: “The split decision provides the opportunity to more fully understand the challenges of building the full SKA (Phase 2) in both sites. If we were to then have flexibility for SKA-Phase 2, the split site then really mitigates a lot of risk associated with building the full $2 billion array.

“I am concerned that from what I have read there is not a lot of flexibility described in the arrangements right now for Phase 2. I hope we can ensure that we eventually build the full SKA, making sure it is both scientifically capable and as cheap as possible. I would be surprised if this is best done with a split site in Phase 2. We will know a lot more once Phase 1 commences.”

Ekers is reassuring that discoveries with Australia’s allocation of frequencies will be significant: “The full low frequency array in Australia will almost certainly be needed to understand, and probably to detect, the universe’s ‘epoch of re-ionisation’ after the Big Bang, one of the key scientific objectives of the SKA”.

Peter Pockley has been reporting the SKA saga for Australasian Science since the project was first conceived. © Peter Pockley (scicomm@bigpond.net.au)