Designing infrastructure for radio astronomy on an epic scale

The preparations for the Square Kilometre Array are advancing: construction is due to begin in 2020. An EU-funded project team working on infrastructure was one of several groups involved in the detailed design of this instrument, which will be co-located on two continents. In Australia, 133.000 antennas are to be deployed - and that's just for starters.

The In-SKA project focused on infrastructure - buildings, roads and power distribution, for example - at key locations for the many thousands of receivers that will jointly compose the new Square Kilometre Array (SKA). More specifically, it looked into the requirements at the chosen sites for the first phase of the instrument's deployment, which are situated in Australia and South Africa.

The SKA will be the world's largest radio telescope - and, in fact, the world's largest scientific instrument. It will involve hundreds of thousands of receivers, according to project coordinator Simon Berry of the SKA Global Headquarters in the United Kingdom. "You need something this big to tackle a number of fundamental questions about the universe", he explained.

The new instrument will widen the scope to work out how the first stars and galaxies formed, for example, and what the universe looked like in its initial stages shortly after the Big Bang, Simon Berry explained. It will also boost scientists' chances of picking up markers of any biological life that might exist elsewhere in the galaxy or beyond, he added.

SKA1 corresponds to some 10% of the full array, which is referred to as SKA2. The In-SKA team was one of several groups handling aspects of the detailed design for this initial version of the planned instrument. Other efforts addressed different pieces of the puzzle, such as the receivers that will be used, and signal and data transport between the individual components of the SKA.

Following in-depth review, these complementary contributions will combine to form the tender material for the construction of SKA1, said Simon Berry. The array does not have to be complete to carry out observations, he explained. Its first receivers are expected to start producing initial science as soon as 2024/25.

One of the main challenges in terms of the site infrastructure is the need to ensure that the electronics required on site don't interfere with the receivers. "You have to design a building that is effectively invisible in terms of its radio emissions, even though you've got a lot of kit inside it", said Simon Berry.

The same requirement applies to all other aspects of the infrastructure, from the power and fibre distribution to weather stations and the cameras used for site monitoring, added Antony Schinckel, who led the In-SKA work in Australia on behalf of national science agency CSIRO, the Commonwealth Scientific and Industrial Research Organisation. "All of these things have to be modified or designed from scratch so they don't generate any radiofrequency interference that would affect the SKA observations", he explained.

The use of radio quiet techniques is therefore a defining feature of the design proposed by In-SKA: while the sub-arrays planned in Australia and South Africa differ in some respects, the underlying challenges are the same. Antony Schinckel emphasised the close collaboration between the teams in both locations, which is representative of the wider international cooperation that is driving this massive undertaking.

The SKA Organisation itself has 10 member countries, and many other entities are participating in various forms. The European Union, for example, has made substantial contributions to the endeavour at several stages, said Simon Berry.

"From the Australian perspective, it's been great to have that much broader engagement with this large consortium, in terms of all the different countries, institutions and companies that are involved", said Antony Schinckel.

"Many of the steps on the way to the construction of the SKA are very exciting and important in their own right, with potential uses in other industries", Antony Schinckel noted. "But the real end point is that there will be this fantastic telescope able to do all this science, this unprecedented capability available to the astronomers of the world."