Giant radio telescope reaches milestone en route to construction start

The Square Kilometre Array Observatory aims to build 130,000 wire antennas in Australia. The image shows a cluster of existing prototypes (left) next to an artist’s impression of the finished array (right).

SKAO/ICRAR

The Square Kilometre Array has been a dream of radio astronomers for nearly 3 decades. Today, the project officially becomes the Square Kilometre Array Observatory (SKAO). Last month, a treaty ratified by six of the project’s member governments came into force. The project’s governing council—with delegates from the six ratifying nations and 10 others as observers—meets (virtually) for the first time and conjures the SKAO into existence.

The aim is to build the world’s biggest radio observatory, originally envisioned as having 1 square kilometer of collecting area. With such a photon-gathering potential, the telescope could see the universe’s very first stars and galaxies, study the effects of cosmic magnetism and gravity, and listen for the signs of alien civilizations.

The €2 billion project is split across two sites: 130,000 wire antennas in the Western Australian desert to collect low-frequency signals, and 130 dishes in South Africa for higher frequencies, which will be added to that country’s existing 64-dish MeerKAT array. In both cases, the receivers are arranged in dense cores with arms extending out hundreds of kilometers. By digitally combining the signals picked up by many widely spaced receivers, the array gains both sharp resolution and exquisite sensitivity.

With the design vetted and approved, and other governments preparing to join, the SKAO can now get on with inviting bids from companies to build the observatory, with a view to starting construction later this year.

Yesterday, astronomer Philip Diamond was head of the U.K. not-for-profit company managing the project; today he becomes the new SKAO director-general, whose members so far include the United Kingdom, South Africa, Australia, Italy, the Netherlands, and Portugal. Science spoke with him by Zoom from SKAO headquarters at Jodrell Bank near Manchester, U.K., in the shadow of the historic 76-meter Lovell Telescope. His replies have been edited for clarity and brevity.

Q: So what is happening today?

A: It’s the first meeting of the council of the Square Kilometre Array Observatory, an intergovernmental organization governed by treaty which will build and operate the SKA.

It’s been a journey. The idea of developing a treaty dates back to 2009 and negotiations started in 2015. It was signed in a ceremony in Rome in March 2019 and we achieved the minimum set of ratifications before Christmas [2020].

Q: What happens next?

A: Right now, the observatory is an empty vessel. It doesn’t even have a bank account yet. The council will give the observatory the authority to approve things … [such as] opening a bank account, the ability to pay people, and make purchases. At the beginning of May, we will transfer the assets of the company to SKAO and it will no longer be an empty vessel but a ship ready for a journey.

After that, the council will approve the beginning of the construction activity. That’s a few months off yet, but we’re optimistic that it will be by midyear.

Q: Has COVID-19 delayed the project from your original plan to start construction in 2020?

A: We won’t be turning over a spade by midyear, it’ll be bids and contracts. If all goes smoothly, we could break ground by the end of 2021. Lockdown travel constraints do delay us, so we’re watching very carefully. We ensured that planning was as flexible as possible, so I hope we won’t have to slow down.

Q: Last year we reported that South Africa cut SKAO funding to support measures for COVID-19. Is that going to be a problem?

A: Because we’re starting 6 months or more later than planned, [the South African arm of the project] handed back unused money to the treasury on the understanding that it would be available when needed. It was sensible.

Q: How are you dividing up the cost of the project among the members?

A: Other international collaborations, such as CERN and the European Southern Observatory, follow gross domestic product [GDP]. But that doesn’t work for SKA. With members including China and India it was not appropriate [because their GDP is much larger than their astronomical communities]. We searched hard for other mechanisms and found one that is surprisingly robust: research capacity, which is related to the number of astronomers. It correlates fairly well with GDP with some slight oddities, such as China and India. South Africa and Australia are different, as hosts. This provided some guidance, and then we negotiated with each member.

Q: Although the United States is not intending to join, there was talk a couple of years ago about collaborating with the proposed Next Generation Very Large Array. Has that come to anything?

A: We had a meeting in Reykjavik, Iceland, in 2019 and we stayed in touch. But they’re waiting to hear the outcome of the decadal survey [of astrophysics]. That will determine if it’s a reality and on what timescale. Then I expect we will work out a more formal relationship.

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