The go-ahead has been given to build what will be the world’s largest radio telescope network. Last week the council of the Square Kilometre Array Observatory (SKAO) gave the green light to construct the €2bn Square Kilometre Array (SKA) in Australia and southern Africa. To be complete by 2028, it is anticipated that the SKA will operate for the next 50 years.
This moment has been 30 years in the making
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. 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 dropping out, such as Germany, and increases in the baseline cost of the project to €900m, that timeline was delayed. Yet a big boost for the project came 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 in the process.
An “ecstatic” moment
More than 500 engineers from 100 institutions worldwide have been involved with the design of the SKA telescopes with over 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 SKA 1 — includes 197 radio dishes in South Africa, including 64 dishes belonging to the existing MeerKAT array, as well as 131 072 individual antennas in Australia. The cost of constructing the two telescope arrays and operations for the coming decade will be about €2bn – €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.
SKA will be built in stages with eight dishes and an 18-station array of antennas – each station featuring 512 antennas — ready by 2025. By the start of the following year 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 the following year marking the end of construction.
SKA is going to be a key piece of global science infrastructure for astrophysics and will do fantastic science
Philip Diamond, director-general of SKAO, says he is “ecstatic” by 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.”
“Lack of candour”
Richard Easther, a cosmologist at the University of Auckland says that it is “great news” to see a construction schedule and budget for SKA. “[It] is going to be a key piece of global science infrastructure for astrophysics and will do fantastic science,” he adds.
Yet one open question is whether the original intention of SKA that features 2500 radio dishes and a million radio antennas – later dubbed SKA 2 – will ever be constructed. Indeed, in 2013 SKA 2 was budgeted at over €1.5bn, which is now near to the cost for SKA 1.
Easther says that there has been a “lack of candour” about this timeline from the SKA leadership. “There was no formal downsizing so that SKA 2 – 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.”
Timeline: The Square Kilometre Array
2006 Southern Africa and Australia are shortlisted to host the Square Kilometre Array (SKA) beating off competition from Brazil and China. Due to be completed in 2020 and cost €1.5bn, the facility would comprise about 4000 dishes, each 10 m wide, spread over an area 3000 km across
2012 The SKA Organisation fails to pick a single site for the telescope and decides to split the project between Southern Africa and Australia. Philip Diamond is appointed SKA’s first permanent director-general replacing the Dutch astronomer Michiel van Haarlem, who had been interim SKA boss
2013 Germany becomes the 10th member of SKA, joining Australia, Canada, China, Italy, the Netherlands, New Zealand, South Africa, Sweden, the UK. SKA’s temporary headquarters at Jodrell Bank in the UK opens. SKA members propose a slimmed-down version of SKA known as SKA1. With a cost cap of €674m, it would consist of 250 dishes in Africa and about 250 000 antennas in Australia
2014 Germany announces it will pull out of SKA the following year
2015 Jodrell Bank beats off a bid by Padua in Italy to host SKA’s headquarters. India joins SKA
2017 Members scale back SKA again following a price hike of €150m, which involves reducing the number of African dishes to 130 and spreading them out over 120 km
2018 The first prototype dish for SKA is unveiled in China. Spain joins SKA
2019 Convention signed in Rome to create an intergovernmental body known as the SKA Observatory. The Max Planck Society in Germany joins SKA. New Zealand announce it will pull out of SKA in 2020
2021 SKA Observatory comes into force. Start of construction annouced.