Square Kilometre Array Observatory Begins Construction in South Africa and Australia

Karoo, Northern Cape, South Africa · 5 December 2022 — The Square Kilometre Array Observatory (SKAO) officially commenced construction of its radio telescopes at dual sites in South Africa and Australia, marking the transition from decades of planning and design to physical building. Ceremonies were held at both locations — in the Karoo region of South Africa's Northern Cape for the SKA-Mid array, and at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory in Western Australia, for the SKA-Low array.

The construction start followed the SKAO Council's approval of building plans in June 2021 and the subsequent awarding of major construction contracts. The SKAO is an intergovernmental organisation headquartered at Jodrell Bank Observatory in the United Kingdom, with member states including Australia, Canada, China, India, Italy, the Netherlands, Portugal, South Africa, Spain, Switzerland, and the United Kingdom.

SKA-Mid: South Africa's Karoo Array

The South African component, SKA-Mid, is being constructed in the Karoo, a semi-arid region of the Northern Cape province chosen for its exceptionally low levels of radio frequency interference. The site is adjacent to the existing MeerKAT radio telescope, a 64-dish precursor array that has been operational since 2018 and has already produced significant scientific results, including the most detailed radio image of the centre of the Milky Way.

SKA-Mid will add 133 new parabolic dishes to the existing 64 MeerKAT dishes, forming an array of 197 dishes. Each dish is 15 metres in diameter and operates across a frequency range of approximately 350 MHz to 15.4 GHz. The dishes are connected by optical fibre to a central processor that combines their signals using a technique called interferometry, effectively creating a single telescope with a collecting area equivalent to a dish far larger than any individual antenna.

The dishes will be arranged in a configuration that extends from a dense core out to spiral arms reaching up to 150 kilometres from the centre, providing both high sensitivity and high angular resolution. The configuration is designed to balance the ability to detect faint, diffuse emission with the ability to image fine structural details.

SKA-Low: Australia's Low-Frequency Array

The Australian component, SKA-Low, operates at much lower frequencies — between 50 and 350 MHz — and uses a fundamentally different antenna design. Rather than parabolic dishes, SKA-Low consists of 131,072 individual antennas arranged in 512 stations, each station containing 256 dual-polarisation log-periodic antennas mounted on stands approximately 2 metres tall.

These antennas resemble simple metal structures rather than traditional telescope dishes, but they are designed to detect low-frequency radio waves that carry information about the very early universe. The low-frequency regime is particularly important for studying the Epoch of Reionisation — the period when the first stars and galaxies formed and ionised the surrounding hydrogen gas, ending the cosmic dark ages.

The SKA-Low site is located at Inyarrimanha Ilgari Bundara, meaning "sharing sky and stars" in the Wajarri Yamaji language, on the traditional lands of the Wajarri Yamaji people. The Wajarri Yamaji Indigenous Land Use Agreement, signed in 2022, provides consent for the construction and operation of the telescope on Wajarri Yamaji country.

Scientific Objectives

The Square Kilometre Array is designed to address some of the most fundamental questions in astrophysics and cosmology:

The Epoch of Reionisation

SKA-Low will attempt to detect the faint radio signature of neutral hydrogen gas during the Epoch of Reionisation, a period roughly 400 million to 1 billion years after the Big Bang. By mapping the distribution of hydrogen during this era, astronomers hope to understand how the first stars and galaxies formed and how they transformed the universe from a neutral gas to an ionised plasma.

Dark Energy and Dark Matter

The SKA will conduct large-scale surveys of galaxies, measuring the distribution of matter across cosmic time. These surveys will test models of dark energy — the mysterious force driving the accelerated expansion of the universe — and may provide clues about the nature of dark matter.

Cosmic Magnetism

The origin of cosmic magnetic fields is one of astrophysics' enduring mysteries. The SKA will map magnetic fields across galaxies and intergalactic space using the polarisation of radio waves, helping to determine whether magnetic fields are primordial — generated in the early universe — or produced later by astrophysical processes.

The Cradle of Life

The SKA will be sensitive enough to detect radio emission from protoplanetary disks — the discs of gas and dust around young stars where planets form. This could reveal the presence of complex organic molecules, the building blocks of life, in other planetary systems.

Pulsars and General Relativity

The SKA will discover and time thousands of pulsars — rapidly rotating neutron stars that emit beams of radio waves. By monitoring the arrival times of pulses from pulsars in binary systems, astronomers can test general relativity in strong gravitational fields and potentially detect gravitational waves from supermassive black hole mergers.

South Africa's Role and Benefits

South Africa's selection as a co-host of the SKA has been a source of national pride and a catalyst for scientific development. The country's investment in the MeerKAT precursor telescope demonstrated its technical capability and commitment to the project. MeerKAT, designed and built primarily by South African engineers and scientists at the South African Radio Astronomy Observatory (SARAO), has been internationally recognised for its scientific output and engineering quality.

The construction phase is expected to create jobs and stimulate local industry. South African companies have been awarded contracts for dish manufacturing, site infrastructure, and software development. The SKAO has reported that the total construction cost is approximately €2 billion, with operations expected to begin in the late 2020s.

Data Challenges

The SKA will generate enormous volumes of data — estimated at approximately 700 terabytes per second of raw data from the antennas, which will be processed and reduced by dedicated high-performance computing facilities. The processed data will still amount to petabytes per year, requiring sophisticated data management and distribution systems.

To address this challenge, the SKAO has established regional data centres in member countries, including the SKA Regional Centre in South Africa, which will process, store, and distribute data to researchers across Africa and beyond. The data infrastructure represents a significant investment in computational capacity and is expected to drive advances in data-intensive astronomy.

Timeline and Next Steps

Following the December 2022 construction commencement, the project entered a multi-year building phase. The first dishes and antenna stations are expected to be installed during 2024–2025, with early science observations anticipated to begin as components come online. Full operations are targeted for the late 2020s, though the telescope will conduct science observations incrementally as the array is built out.

The SKAO has emphasised that the telescope will not be a single completion event but rather a phased deployment, with scientific capability growing as more dishes and antennas are added and commissioned.

Sources

• SKAO, "SKA construction starts: ceremonies in Australia and South Africa," skao.int, 5 December 2022
• South African Radio Astronomy Observatory (SARAO), press release, December 2022
• MyBroadband, "Square Kilometre Array to begin construction in South Africa," mybroadband.co.za, December 2022
• ITWeb, "SA to benefit as R55bn SKA construction projects begin," itweb.co.za, December 2022
• ASTRON, "Construction of Square Kilometre Array commences," astron.nl, December 2022
• SKAO construction journey documentation, skao.int/en/explore/construction-journey