A artist's impression of low-frequency stations forming the Square Kilometre Array (SKA) radio telescope, to be built in Western Australia. Photo: AFP / Australian Department of Industry, Science and Resources
One of the grand scientific projects of the 21st Century has started construction.
The Square Kilometre Array (SKA) will be the largest radio telescope in the world when completed in 2028.
Split across South Africa and Australia, with a headquarters in the UK, the facility will address the biggest questions in astrophysics.
It will perform the most precise tests of Einstein's theories, and even search for extra-terrestrials.
Delegations from the eight countries leading the project attended ceremonies in the remote Murchison shire in Western Australia and in the Karoo of South Africa's Northern Cape.
"This is the moment it becomes real," Square Kilometre Array Organisation professor Phil Diamond said.
"It's been a 30-year journey. The first 10 years were about developing the concepts and ideas. The second 10 was spent doing the technology development. And then the last decade was about detailed design, securing the sites, getting governments to agree to set up a treaty organisation (SKAO) and provide the funds to start," he told BBC News.
The initial architecture of the telescope will incorporate just under 200 parabolic antennas, or "dishes", as well as 131,000 dipole antennas, which look a little like Christmas trees.
The aim was to construct an effective collecting area measuring hundreds of thousands of square metres.
This will give the SKA unparalleled sensitivity and resolution as it probes targets on the sky.
The system will operate across a frequency range from roughly 50 megahertz to, ultimately, 25 gigahertz. In wavelength terms, this is in the centimetres to metres range.
This should enable the telescope to detect very faint radio signals coming from cosmic sources billions of light-years from Earth, including those signals emitted in the first few hundred million years after the Big Bang.
Square Kilometre Array Observatory radio astronomer Tyler Bourke told Morning Report they would be looking back to the time when the first stars were formed, not long after the Big Bang, and up to the present day.
"We're going to look at how the universe has evolved from those early times, right through now."
Computing technology would produce an image of the sky from the signals collected, Bourke said.
"In 2024, we'll be taking real data form the sky and from then once we think that the design is ready to go, we'll be pumping out the dishes and antennas," he said.
"Hopefully, we expect we'll be having a good telescope running well before the end of the decade."
Tracing the full history of hydrogen
One of the SKA's great quests will be to trace the full history of hydrogen, the most abundant element in the Universe.
The telescope should be able to detect hydrogen's presence even before great clouds of it collapsed to form the first stars.
"The SKA is going to contribute to so many areas of astronomy," the observatory's head of science operations Dr Shari Breen said.
"One would be these 'fast radio bursts' that have been detected. These things output the equivalent of an entire year's worth of energy from our Sun in just a fraction of a second. And we have no idea what they are. How is that possible? Hopefully the SKA will have an answer."
The telescope was being built in areas already used for radio astronomy on a smaller scale.
To expand these sites, however, has required various land agreements, with farmers in the Karoo; and with the Wajarri Yamaji, the Aboriginal title holders in the Murchison.
The Wajarri community organised a celebration on Monday to inaugurate the SKA.
Various procurement contracts will be announced around the ceremonies.
These will take the total financial outlay to date to just under €500 million (NZ$830.7m) - out of an expected final construction budget of €2 billion.
The first major milestone should come in 2024, when four dishes in Australia and six antenna stations in South Africa were made to work seamlessly together as a basic telescope. This proof-of-principle moment will then trigger the array's full roll-out.
By 2028, the SKA will have an effective collecting area of just under 500,000 square metres. But the set-up was such that it can continue growing, perhaps up to the much desired one million square metres, or one square kilometre.
One way this could happen was if more and more countries join the organisation and provide the necessary funds.
The current members were: South Africa, Australia, the UK, China, Italy, Netherlands, Portugal and Switzerland. These countries have ratified the treaty.
In 2018, the New Zealand government pulled back from becoming a full member of the project after pouring NZ$2.3m into its construction and failing to secure a bid to have on the telescope sites in the country.
France, Spain, and most recently Germany, have got themselves on to the accession path.
Canada, India, Sweden, South Korea and Japan have indicated their intention to join at some point.
"And we're actually in the process of talking to other countries as well, to see what interest they might have in joining the observatory," professor Diamond said.
-BBC, with additional reporting by RNZ
