Construction of the world’s largest radio observatory is finally underway

After 30 years of planning and negotiations, construction of the Square Kilometer Array (SKA), the world’s largest radio astronomical observatory, begins this week. The giant instrument, to be built at widespread sites in Australia and Africa, will collect the radio signals emitted by celestial objects and hopefully shed light on some of astronomy’s most puzzling problems, such as the nature of dark matter and how galaxies form.

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

“We’re basically laying the groundwork for this instrument for the next 50 years,” says Lindsay Magnus, the director of the telescope, which is being built in South Africa and is based in Cape Town, South Africa. “That’s the exciting part — that’s a long-term legacy.”

years in the making

In 2012 it was decided that the telescope, originally conceived 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 sheer number mean that the telescopes – dubbed SKA-Mid and SKA-Low respectively – will pick up radio signals with unprecedented sensitivity. SKA-Low detects frequencies between 50 megahertz and 350 megahertz and SKA-Mid records frequencies between 350 megahertz and 15.4 gigahertz. Both are interferometers, where many dish-shaped antennas work together like a single telescope.

The SKA will be built in stages, and the €1.3 billion ($1.4 billion) first phase is expected to be completed in 2028. A further 700 million euros are earmarked for the operating costs of the telescopes over the next ten years. The ultimate goal is thousands of antennas in South Africa and the African partner countries and one million antennas in Australia with a total collection area of ​​one square kilometer. Phase one accounts for about a tenth of the entire planned project.

SKA low

The SKA-Low telescope in Australia will contain about 131,000 antennas, each resembling a two-meter-tall wire Christmas tree. More than 500 arrays with 256 antennas will dot the red sands of the site, which has been renamed the Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radioastronomy Observatory. “Inyarrimanha Ilgari Bundara”, a name chosen by the land’s traditional owners, the Wajarri Yamaji, means “to share the sky and stars”.

Earlier this month, the Wajarri Yamaji and the Australian government signed a land use agreement that would allow the telescope to be built on Wajarri Yamaji land. Local people will act as heritage observers and escort SKAO officials from ground disturbances during construction, says Des Mongoo, a member of the Wajarri Yamatji community who is excited for the work to begin. “Once they start construction, there are opportunities for Wajarri people to engage in employment and business opportunities.”

Scientists are also excited for the antennas to start collecting data. “[SKA-Low’s] Sensitivity will allow us to observe the distant universe in much more detail than anything we have done before,” says Douglas Bock, director of space and astronomy at the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Sydney, Australia. “This is particularly 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 the telescopes were designed, predicts Sarah Pearce, director of the SKA-Low telescope, based in Perth. The first four arrays will collect data by 2024, with all arrays completed by 2028.

South African dishes

Preparations for the construction of the first giant SKA-Mid bowls will also begin on Monday. These will form a cluster of 197 antennas stretching some 150 kilometers in the arid Karoo region of South Africa. Four will be ready in 2024 and many more will be added by 2028.

South Africa’s 64 dish MeerKAT telescope already exists on site and will be integrated into SKA-Mid. In early 2022, an international team released the most detailed image yet of our galaxy’s center, the Milky Way, using MeerKAT data, as well as images of mysterious radio filaments emanating from the galaxy’s black hole. The South African government and the German Max Planck Society are expanding the telescope by a further 20 dishes as part of an expansion project. MeerKAT will only be integrated into SKA-Mid towards the end of construction in 2027.

“SKA will be a major scientific step forward,” says Erwin de Blok, astronomer at the Netherlands Institute for Radio Astronomy in Dwingeloo and principal investigator of MeetKAT’s major survey program MHANGOOSE, which studies the formation of galaxies. SKA-Mid “will help us study nearby galaxies in great detail and provide direct evidence of gas flow in galaxies and the processes leading to star formation.”

However, the construction of SKA-Mid will disrupt MeerKAT observations, says Pontsho Maruping, director of the South African Radio Astronomy Observatory in Cape Town. Radio telescopes are particularly sensitive to the radio waves emitted by vehicles and communications equipment. “We will do everything we can to ensure that the observations are not unduly interrupted,” she says. MeerKAT will continue to monitor until it is integrated into SKA-Mid in 2027.

By the end of the year, UK-based SKAO had awarded construction contracts worth €500 million. About 70% of the orders have to go to the 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.

This article is reproduced with permission and was first published on December 4, 2022.