Warkworth ruled out of telescope project

21:46, Feb 22 2012
STAR CLUSTER: Delegates who visited the Warkworth Observatory included, from left, legendary Australian astronomer Dr Ron Ekers who helped demote Pluto from planet status, WiFi inventor Dr John O'Sullivan, and observatory director professor Sergei Gulyaev.

North Auckland will miss out on a radio telescope dish site if Australia and New Zealand win the right to host the $2.5 billion international Square Kilometre Array, a mega-science radio astronomy project.

The two groups vying for hosting rights will know soon which site has been recommended by an independent committee. Then there will likely be a negotiation period of about six weeks before the site is officially announced.

The project could see 3000 dishes spread across 5500km from a core site in Murchison, Western Australia, to a possible two sites of around 30 dishes in New Zealand.

One site was expected to be set up north of Auckland – possibly at Warkworth – and another likely near Invercargill.

The African proposal would see an array centred in South Africa with sites in Namibia, Botswana, Mozambique, Zambia, Kenya and Ghana, along with the islands of Madagascar and Mauritius, giving a spread of 3000km.

The extra distance to New Zealand will add about 60 percent resolution to the quality of any images.


But it became clear the northern option had been ruled out during the SKANZ conference in Auckland last week that was attended by stars of the astronomy world.

Victoria University astronomer Dr Melanie Johnston-Hollit confirms that a South Island site only is part of the Australian and New Zealand proposal.

She's not willing to be drawn on the exact location and says another site may be considered at a later date, but is firm it wouldn't be north of Auckland.

The higher the population density the higher the levels of radio interference from the likes of mobile phones and power pylons in the range the dishes will be gathering information, she says.

Although the proposed Auckland long term district plan will largely constrain growth to current urban limits with the city going up rather than out, Auckland's population looks set to double to three million in 30 years.

The only radio telescope site in New Zealand, the Warkworth Observatory, is about five kilometres south of Warkworth and 55 kilometres north of downtown Auckland.

Auckland University of Technology Institute for Radio Astronomy and Space Research director Sergei Gulyaev is in charge of the observatory.

He's disappointed at the decision and says radio levels are similar to the core site in Australia and he believes the site would still be suitable.

The narrow valley is mostly owned by Telecom and is purposely kept radio-quiet.

The core site in Western Australia is the size of the Netherlands and has only 110 permanent residents.

With the SKA expected to operate for 50 years, choosing a sparsely populated site in New Zealand is the best option, Dr Johnston-Hollit says.

Dr Gulyaev says that even if we miss out on the bid, the case is strong for at least one other radio telescope in the South Island to be involved with geodesic work, particularly in light of the Christchurch earthquakes.

New Zealand sits on the edge of the Australian and Pacific tectonic plates and 150 GPS stations up and down the country track land movements as these plates slowly grind past, over and under each other.

They are accurate to millimetres horizontally and centimetres vertically between stations. But using stable radio stars called quasars as reference points can see an accuracy of millimetres across thousands of kilometres.

This technique is now part of the toolkit available for tracking plate movement, along with GPS systems, geology and seismology around the world.Its real-time viewing can help detect where plates have stopped moving. This jamming of the plates sees tensions building.

The sudden release of these plates can result in not just big earthquakes but also destructive tsunamis, as happened with the magnitude 9 earthquake off northern Japan last year which killed 16,000 people, and the Boxing Day tsunami in 2004 which killed 230,000 around the Indian Ocean rim after a massive 9.3 quake off Indonesia.

The radio telescope at Warkworth on the Australian plate combined with just one other on the Pacific plate in southern New Zealand would be very useful, Dr Gulyaev says.

Rodney Times