Go ahead for the SKA radio telescope
Costing €2bn, the Square Kilometre Array will be complete by 2029 and feature hundreds of radio dishes and more than 130,000 radio antennas to observe the universe, as Michael Banks reports
Construction of the Square Kilometre Array (SKA) – the world’s largest radio telescope network – has finally been approved three decades after it was first dreamed up. In late June the council of the Square Kilometre Array Observatory (SKAO) gave the go ahead to build the €2bn facility, which will be spread across Australia and southern Africa. To be complete by 2029, it is anticipated that the SKA will operate for the next 50 years.
As its name suggests, the SKA is a facility that intends to have a total collecting area of 1 km2, achieved by spreading out thousands of individual dishes in southern Africa as well as a million wire antennas in Australia. The SKA is designed to provide astronomers with unprecedented views of the first stars in the universe and observations of gravitational waves via the radio emissions from pulsars, among other things.
That initial design, however, proved too ambitious and in 2013 officials concentrated on building a much smaller preliminary facility known as SKA1, which was to be complete by 2018. It would feature 250 mid-frequency radio dishes and 250,000 low-frequency dipole antenna to keep costs below a cap of €674m. Despite further woes with members, such as Germany, dropping out and increases in the baseline cost of the project to €900m, that timeline was delayed.
A big boost for the project occurred in March 2019 when Australia, China, Italy, the Netherlands, Portugal, South Africa and the UK signed the SKA convention treaty in Rome. That came into effect earlier this year after five countries – including Australia, South Africa and the UK – ratified the convention, creating the SKAO.
An “ecstatic” moment
More than 500 engineers from 100 institutions worldwide have been involved with the design of the SKA telescopes, with more than 1000 scientists from 40 countries working on the science case of the project. The final SKA design to be built – similar to that proposed for SKA1 – features 197 radio dishes in South Africa, including 64 dishes belonging to the existing MeerKAT array, as well as 131,072 antennas in Australia. The cost of constructing the two telescope arrays and operations for the coming decade will be about €2bn – roughly €1.3bn to build the instrument and €700m for operations. The UK, which hosts the headquarters of the observatory at the Jodrell Bank site in Cheshire, will contribute £270m.
The SKA will be built in stages, with eight dishes and an 18-station array of antennas – each featuring 512 antennas – ready by 2025. By the start of the following year the SKA will include a 64-dish array and 64 antenna stations, while in 2027 it will have a 133-dish array and 256 antenna stations. In 2028 there will be an “operation readiness review”, with construction ending in 2029.
Humankind is committing to build the largest science facility of its kind on the planet
Philip Diamond, director-general of the SKAO, says he is “ecstatic” about the latest development. “This moment has been 30 years in the making,” he says. “Today, humankind is taking another giant leap by committing to build what will be the largest science facility of its kind on the planet; not just one but the two largest and most complex radio telescope networks, designed to unlock some of the most fascinating secrets of our universe.” That view is backed up by Catherine Cesarsky, who is chair of the SKAO Council. “Giving the green light to start the construction of the SKA telescopes shows…the professional work that’s been done by the SKAO to get here, with a sound plan that is ready for implementation, and in the bright future of this ground-breaking research facility.”
Richard Easther, a cosmologist at the University of Auckland, says it is “great news” to see a construction schedule and budget for the SKA. “[It] is going to be a key piece of global science infrastructure for astrophysics and will do fantastic science,” he adds. But one open question is whether the original intention of the SKA to feature 2500 radio dishes and a million radio antennas – later dubbed SKA2 – will ever be constructed. Indeed, in 2013 SKA2 was budgeted at over €1.5bn, which is now near to the cost for SKA1.
Easther says that there has been a “lack of candour” about this timeline from the SKA leadership. “There was no formal downsizing so that SKA2 – representing 90% of the actual project – has effectively been airbrushed away, even though its capabilities were key to the hype that got the project rolling in the first place,” adds Easther, who supported a decision by New Zealand in 2019 to pull out of the project. “This certainly undercut the value of the project for New Zealand – it became harder to claim that the investment stacked up scientifically or economically.”