Jacinta Bowler
Jacinta Bowler is a science journalist at Cosmos.
They were published in the Best Australian Science Writing 2023.
After 31 years of planning, radio telescopes called the Square Kilometre Array (SKA) have finally begun construction. Ceremonies will occur today on both Australian and South African sites to ‘break ground’.
The Australian site in the Murchison region of WA – known as SKA-Low – will eventually comprise of over 130,000 Christmas tree-like antennas.
“The Square Kilometre Array is a game-changer, not just for radio astronomy but for our collective understanding of the Universe,” says Professor Tara Murphy, Head of the School of Physics at the University of Sydney.
“After many years of planning and designing it is incredibly exciting that construction has begun.”
SKA-Low will be housed at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory.
This is already home to the ASKAP telescope, as well as other smaller radio telescope projects. The site is on Wajarri Country in Western Australia, four hours drive away from Geraldton. ASKAP is the Australian Square Kilometre Array Pathfinder, the precursor to SKA-mid in South Africa.
When SKA-Low is complete it will comprise of 131,072 antennas spread between 512 stations. The furthest antennas will be 65 kilometres away from each other throughout the desert. However, because of the way the telescope works, research will be able to be done after the first few stations are built.
“Unlike an optical telescope, where you can’t do anything until you have the mirror and the dome and all of the pieces, with a radio interferometer we can start doing science when we only have a subset of the full array,” Professor Cathryn Trott, astronomer and Chief Operations Scientist at SKA-Low told Cosmos.
“We expect to be doing commissioning and some science verification within the next couple of years … By the end of the decade, we’ll have a full array ready, scientifically verified, and ready to go.”
The venture is international. Along with both Australia and South Africa hosting one of the telescopes, the headquarters is based in the UK. The cost to construct the two telescopes will be about AU$3 billion to build and AU$1.1 billion for operations over the coming decade. Australia will contribute AU$400 million.
Once completed, the SKA-Low will be significantly more powerful than any other radio telescopes of this type – potentially up to eight times as sensitive and 135 times faster than comparable current telescopes.
SKA-Low will focus on the very early universe, where it can peer into primordial hydrogen, which was present when the first stars were forming. This will hopefully answer questions about this ‘Cosmic Dawn’.
Potentially more excitingly for alien enthusiasts, it will also be sensitive enough to be able to discover any stray alien communication signals – called technosignatures – that could be out there.
“If there are intelligent societies on nearby stars with technology similar to ours, the SKA could detect the aggregate ‘leakage’ radiation from their radio and telecommunication networks – the first telescope sensitive enough to achieve this feat,” says Dr Danny Price, Australian Project Scientist for Breakthrough Listen and Curtin University astronomer.
“To put the sensitivity of the SKA into perspective, the SKA could detect a mobile phone in the pocket of an astronaut on Mars, 225 million kilometres away.”
The SKA-Mid, which is the South African section of the project, is also a radio telescope, but looks more like a series of ‘normal’ dish telescopes. SKA-Mid will observe a higher frequency of the radio spectrum, but being relatively close together in the same hemisphere, they will regularly see the same sky and can be used together in certain situations.
“There will be some science cases where there’ll be joint observations between the two telescopes and they’ll be quite coordinated,” Trott told Cosmos.
“It will be interesting to see how much the use of the two telescopes together evolves as people become a bit more creative about how to use both.”