Once again the day started with a brisk and cold breeze blowing across the MRO (Murchison Radio-astronomy Observatory) as we set about the arduous task of laying antenna tiles at precise locations throughout the site. With the core tiles completed our method has evolved from clearing multiple sites at once and laying mesh simultaneously to clearing and completing sites one at a time due to the distance between each away from the core.
Engineer Dave Emrich levelling out some rock under a tile site.
The shift in tack makes for slow going extenuated by driving several hundred metres through track-less bush between each tile location, being careful to disturb the natural landscape as little as possible as we navigate our way through dense scrub. Before lunch we hit our first major problem for the trip, with the lead vehicle suffering a flat tyre. On inspection of the trailing vehicle we found it too had a slow puncture. With one vehicle closely following the tracks of the other both had seemingly been the victim of some unseen bush or rock which had sought to make its presence known by piercing the same tyre on both cars.
The tyres were changed leaving one spare for each vehicle and we proceeded on through the bush, clearing land and laying mesh as we went, stopping only briefly for lunch. So as to avoid a repeat of a simultaneous blowout we decided that wherever possible the trailing vehicle, without the long trailer carrying the mesh sheets in tow, would take its own course through the scrub.
Despite the slow going and flat tyre episode we still managed to lay 26 tiles for the day bringing us to a total of 95 out of the 128 we need to complete before the end of the trip. Laying each tile involves clearing a 5m by 5m square of ground, so in 4 days with a 4 man team armed with hand tools alone we’ve cleared nearly 2,500 m2 of ground, an impressive feat to say the least.
This evening as we sat down to dinner to mull over the days highs and lows we received news that a decision on the Square Kilometre Array project had been made after months and years of deliberation. This exciting news is of great significance for us, and for ICRAR, as the MWA is one of the three official precursor projects for the SKA, with the lessons learned from building the telescope and the science it will eventually deliver feeding directly into the design process for the SKA. With the news that the biggest radio telescope ever to be built will have parts located in both Australia and Southern Africa our spirits picked up at the end of a gruelling day.
The new plan to share the SKA will see Australia’s Mid West hosting two key components of the telescope – a group of dishes equipped with Australian-designed multi-pixel radio cameras and the ‘Aperture Array’ portion, made up of innovative, non-moving, antennas designed to collect lower frequency radio waves from the whole sky.
Such a split will mean that Australia continues its long history of survey science, observing the entire radio sky and flagging potential areas of scientific interest for deeper follow-up by antennas located in Southern Africa. This decision means the project is set to benefit from the best of both sites, building on the substantial investment in infrastructure and expertise that already exists in both locations.
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I particularly like this statement given by Professor Brian Gaensler, Director of the Centre for All-sky Astrophysics, Sydney University, who was formerly the International Project Scientist for the SKA project. It summarises this historical day for the project very well.
“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.
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 into 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.
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.
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 piece of the puzzle are “phased array feeds”, the fish-eye lens technology being developed by CSIRO for their Australian SKA Pathfinder (ASKAP) in Western Australia. These will be further developed and expanded in Australia and NZ, and then possibly later installed on dishes in Africa. Aus/NZ technology on an African telescope is truly a win-win scenario.
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 Aus/NZ 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.
Few people will appreciate the small teams at the heart of the two site bids who have sunk years of their lives into this project. For Australia and NZ, special mention must go to the extraordinary CSIRO team lead by Brian Boyle, Michelle Storey, Phil Diamond and Lisa Harvey-Smith, who made a superb case for Aus/NZ to host the SKA. Africa, led by Justin Jonas and Bernie Fanaroff, must also be congratulated, for creating a thriving African radio astronomy community and a stellar SKA site bid from scratch in barely 10 years. The governments involved have also all been extremely supportive: a positive sign that amidst all the other pressures and challenges, basic research and cosmic discovery still have a place in our nations’ priorities.
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!”
An artists impression of SKA “dish” antennas. Credit: SPDO / Swinburne Astronomy Productions