“Big scientific step forward”: the construction of the largest radio observatory in the world is finally underway

“Big scientific step forward”: the construction of the largest radio observatory in the world is finally underway

Artist's impression of a peripheral group of SKA-Low antenna stations next to a runway.

An artist’s impression of SKA-Low antenna arrays.Credit: DISR

After 30 years of planning and negotiations, construction begins this week on the Square Kilometer Array (SKA), the largest radio astronomy observatory in the world. The giant instrument – which will be built at sprawling sites in Australia and Africa – will collect radio signals from celestial objects and hopefully shed light on some of astronomy’s most puzzling issues, such as the nature of dark matter and galaxy formation. .

On Monday, astronomers and local communities will travel to remote sites in the Northern Cape and Western Australia in South Africa to celebrate the milestone with officials from the SKA Observatory (SKAO), the intergovernmental organization in charge. telescopes.

“We are laying the groundwork for this instrument for the next 50 years,” says Lindsay Magnus, director of the telescope being built in South Africa, based in Cape Town, South Africa. “That’s the exciting part – it’s a long-term legacy.”

years of preparation

In 2012 it was decided that what had originally been designed as a single giant telescope would consist of two instruments, one in South Africa and one in Australia. The large distances between the antennas and their number mean that the telescopes – called SKA-Mid and SKA-Low respectively – will pick up radio signals with unprecedented sensitivity. SKA-Low will detect frequencies between 50 megahertz and 350 megahertz and SKA-Mid will pick up frequencies between 350 megahertz and 15.4 gigahertz. Both are interferometers, in which many dish-shaped antennae act together as a single telescope.

The SKA will be built in stages, with the first 1.3 billion euro ($1.4 billion) phase expected to be completed in 2028. A further 700 million euros have been earmarked for operating costs of the telescopes during of the next decade. The ultimate goal is to have thousands of dishes in South Africa and African partner countries, and one million antennas in Australia, with a total collection area of ​​one square kilometer. The first phase represents about one tenth of the total planned project.


The SKA-Low Telescope in Australia will consist of around 131,000 antennae, each resembling a two-meter-tall wire Christmas tree. More than 500 arrays of 256 antennas will dot the red sands of the site, which has been renamed Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio Astronomy Observatory. “Inyarrimanha Ilgari Bundara”, a name chosen by the traditional owners of the land, the Wajarri Yamaji, means “Sharing the sky and the stars”.

Earlier this month, the Wajarri Yamaji and the Australian government registered a land use agreement that would allow the telescope to be built on Wajarri Yamaji land. Local people will act as heritage checkers and accompany SKAO officials before any ground disturbance during construction, says Des Mongoo, a member of the Wajarri Yamatji community who is eagerly awaiting the start of construction. “Once they begin construction, people in Wajarri have the opportunity to participate in employment and business opportunities.”

Scientists are also eagerly waiting for the antennas to start collecting data. “[SKA-Low’s] Sensitivity will allow us to observe the distant Universe in much greater detail than anything we have done so far,” says Douglas Bock, director of space and astronomy at the Scientific Research Organization and Industrial Association (CSIRO) in Sydney, Australia. “It’s especially exciting because we know so little about the first billion years of the Universe.”

But the most exciting science will be phenomena that “we didn’t even know existed” when telescopes were designed, predicts Sarah Pearce, director of the Perth-based SKA-Low Telescope. The first four tables will collect data by 2024, and all tables will be completed by 2028.

South African dishes

On Monday, preparations will also begin for the construction of the first giant SKA-Mid dishes. These will form a set of 197 antennas, stretching for about 150 kilometers in the dry Karoo region of South Africa. Four will be completed in 2024, and many more will be added by 2028.

The 64-antenna MeerKAT South African telescope already exists on the site and will be integrated into SKA-Mid. In early 2022, using data from MeerKAT, an international team released the most detailed image yet of the center of our galaxy.1, the Milky Way, as well as images of mysterious radio wires emanating from the galaxy’s black hole. The South African government and the German Max Planck Society are adding 20 more satellite dishes to the telescope, as part of an extension project. MeerKAT will only be integrated into SKA-Mid towards the end of its construction in 2027.

“SKA will be a big scientific step forward,” says Erwin de Blok, an astronomer at the Netherlands Institute for Radio Astronomy in Dwingeloo and principal investigator of MeetKAT’s MHONGOOSE large survey program on galaxy formation. SKA-Mid “will help us study nearby galaxies in detail and directly detect the gas flux in galaxies and the processes that lead to star formation.”

However, the construction of SKA-Mid will interfere with MeerKAT observations, said Pontsho Maruping, director of the South African Radio Astronomy Observatory in Cape Town. Radio telescopes are particularly sensitive to radio waves emitted by vehicles and communication devices. “We will do everything to ensure that the observations are not unduly interrupted,” she said. MeerKAT will continue to observe until its integration into SKA-Mid in 2027.

By the end of the year, the UK-based SKAO awarded €500 million in construction tenders. About 70% of the contracts must go to industry in the member countries. There are currently eight full members in the organization – namely Australia, China, Italy, the Netherlands, Portugal, South Africa, Switzerland and the UK – and France plans to join.

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