The international engineering consortium tasked with designing the SKA’s low-frequency telescope (SKA-Low), to be sited in Western Australia, has completed its work after six years of international collaboration.
Nine institutes in six countries contributed to the Low Frequency Aperture Array (LFAA) consortium*, co-led by the Netherlands Institute for Radio Astronomy (ASTRON) and the SKA Global Headquarters. This included major design and development contributions from the Universities of Cambridge and Oxford in the UK, the Italian National Institute for Astrophysics (INAF) and the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) in Australia.
The consortium’s work included not only the design of the SKA-Low antennas, of which there will be some 130,000 in the first phase of construction, but also the low-noise amplifiers (LNAs) which will boost the faint astronomical signals being received, optical systems to carry RF signals for long distances without attenuation and custom high performance, and digital processing for each antenna station.
SKA-Low is a true “electronic telescope” in the sense that there are no moving parts. Rather than physically moving the antennas, as occurs with traditional “dishes”, instead a technique known as beamforming will be used to combine signals from some or all of the antennas in the array, in order to focus on specific areas of the sky. This method gives the telescope a huge field of view.
“The relatively small antennas of SKA-Low may themselves look simple, but combined with state-of-the-art back-end technologies they become incredibly powerful, together forming an instrument that can ‘see’ further than we’ve ever been able to before, back to the Cosmic Dawn of the universe,” said André van Es, SKAO’s Project Manager for the Low telescope.
“The antenna design is crucial, because we need something that is cost-effective, can be reliably replicated tens of thousands of times, is quick to install, and yet still meets our extremely demanding system requirements – this is a tricky balancing act,” he added.
Over the past few years, teams from Australia, Italy, Malta, the Netherlands and the UK have built and tested variations of the design on site at the Murchison Radio-astronomy Observatory in Western Australia.
“Within the design of a complex system like the SKA, prototyping is absolutely crucial, as many SKA precursors and pathfinders have shown” added Pieter Benthem, LFAA Project Manager at ASTRON.
Now in its fourth generation, the latest prototype is currently being tested in a full station configuration of 256 antennas, alongside other antennas based on the MWA design, one of the SKA precursor telescopes. A quarter station is also being built for detailed testing at the Mullard Radio Astronomy Observatory (MRAO) near Cambridge, UK.
The completion of the SKA-Low consortium’s work follows hot on the heels of the successful overall system review last month, which endorsed the overall design, costing and planning of the SKA telescopes.
“There has been a huge amount of work done to ensure we get to the best possible result, including many demanding weeks on site. It has not always been easy, but I want to thank all the partners for their perseverance in getting us to this point,” added André van Es. “Although the consortium has now disbanded, in 2020 we are continuing to collaborate with our partners in the final testing of the various antenna prototypes on site and the preparation of the SKA construction proposal to turn this design work into reality. We’re all looking forward to really start building the telescope”
The LFAA consortium was formed in late 2013 as one of 12 international engineering consortia tasked with designing the SKA, a global effort representing 500 engineers in 20 countries. Nine consortia focused on core elements, while three developed advanced instrumentation for the telescope. Critical Design Reviews for the nine consortia began in 2018 and continued through 2019 culminating in the overall System CDR in December, which endorsed the overall design, costing and planning of the telescope.
Members of the LFAA consortium included: Australia’s International Centre for Radio Astronomy Research (ICRAR), Key Lab of Aperture Array and Space Application (KLAASA) in China, Italy’s National Institute for Astrophysics (INAF), the University of Malta, the Netherlands Institute for Radio Astronomy (ASTRON) and the Joint Institute for VLBI ERIC (JIVE), and the UK’s University of Cambridge, University of Manchester and University of Oxford.