South Africa has signed the international treaty establishing the Square Kilometre Array Observatory (SKAO) – an intergovernmental organisation tasked with building and operating the world's most powerful radio astronomy telescope.

Science and Technology Minister Mmamoloko Kubayi-Ngubane signed the Convention Establishing the SKAO on behalf of the South African government in Italy, on Tuesday.  The signing ceremony was presided over by Italy's Education Minister Marco Bussetti and witnessed by Ministers, ambassadors and other high-level representatives of countries participating in the Square Kilometre Array (SKA) project.

Seven countries – South Africa, Australia, China, Italy, the Netherlands, Portugal and the UK – signed the treaty, concluding four years of negotiations by government representatives and international lawyers, and kicking off the legislative process in each of the seven countries.

India and Sweden, who also took part in the multilateral negotiations, have one year to sign the treaty. These nine countries will then form the founding members of the new intergovernmental organisation.

The treaty establishes the SKAO as only the second intergovernmental organisation dedicated to astronomy in the world, after the European Southern Observatory, and will ensure strong governance of the SKA project.

"South Africa's signature on the establishment of the SKAO as an intergovernmental legal entity to oversee the construction and operational phases of the SKA project is a crucial milestone and one which should be celebrated.

"What makes this particularly unique is the fact that, for the first time, Africa, Asia, Australasia and Europe have committed at intergovernmental level to collaborate on a large-scale science project as equal partners. This represents the start of a new era for global science governance," Kubayi-Ngubane said.

The treaty has been named the Rome Convention in recognition of Italy's role in the negotiation process. It will come into force once it has been ratified by the legislatures of five signatory countries, including all three SKA hosts – South Africa, Australia and the UK. 

The SKA is a collection of radio telescopes spread over long distances that will be built in South Africa and Australia, with later expansion planned for both countries, as well into other African States. 

The project will help to close fundamental gaps in the world's understanding of the universe, enabling astronomers from participating countries to study gravitational waves and test Einstein's theory of relativity in extreme environments, to investigate the nature of the mysterious fast radio bursts, to map hundreds of millions of galaxies, and to search for signs of life elsewhere in the universe.

Over 1 000 engineers and scientists in 20 countries have been involved in designing the SKA over the past five years, with new research programmes and educational initiatives and collaborations being created in various countries to train the next generation of space scientists and engineers.

Construction of the first phase of the SKA is expected to start in 2021. Three prototype dishes are being built as part of the SKA critical design review – the final stage of design work before construction begins. 

One of these prototypes is currently being assembled at South Africa's SKA site in the Northern Cape, which is also home to the 64-dish MeerKAT telescope.