The Square Kilometre Array (SKA) is an intergovernmental international radio telescope project being built in Australia (low-frequency) and South Africa (mid-frequency). The combining infrastructure, the Square Kilometre Array Observatory (SKAO), and headquarters, are located at the Jodrell Bank Observatory in the United Kingdom. The SKA cores are being built in the Southern Hemisphere, where the view of the Milky Way galaxy is the best and radio interference is at its least.
The name refers to the notional size of the telescope's collecting area, not to the extent of the entire telescope array, which is far larger. Conceived in the 1990s, and further developed and designed by the late-2010s, the intention is that when completed it will have a total collecting area of approximately one square kilometre as originally conceived. The design of the first phase of SKA, scheduled as of 2025 for science operation in 2032, consists of of collecting area of dishes. It will operate over a wide range of frequencies and its size will make it 50 times more sensitive than any other radio instrument. If built as planned, it should be able to survey the sky more than ten thousand times faster than before. With receiving stations extending out to a distance of at least from a concentrated central core, it will exploit radio astronomy's ability to provide the highest-resolution images in all astronomy.
The SKAO consortium was founded in Rome in March 2019 by seven initial member countries, with several others subsequently joining; there were 14 members of the consortium. This international organisation is tasked with building and operating the facility. The project has two phases of construction: the current SKA1, commonly just called SKA, and a possible later significantly enlarged phase sometimes called SKA2. The construction phase of the project began on 5 December 2022 in both South Africa and Australia.
History The Square Kilometre Array (SKA) was originally conceived in 1991 with an international working group set up in 1993. This led to the signing of the first Memorandum of Agreement in 2000.
In the early days of planning, China vied to host the SKA, proposing to build several large dishes in the natural limestone depressions (karst) that dimple its southwestern provinces; China called their proposal Kilometer-square Area Radio Synthesis Telescope (KARST).
Australia's first radio quiet zone was established by the Australian Communications & Media Authority on 11 April 2005 specifically to protect and maintain the current "radio-quietness" of the main Australian SKA site at the Murchison Radio-astronomy Observatory.
The project has two phases of construction: the current SKA1, commonly just called SKA, and a possible later significantly enlarged phase sometimes called SKA2. PrepSKA commenced in 2008, leading to a full SKA design in 2012. Construction of the SKA telescopes will take 8 years, beginning in July of 2021, with the first antennas for the SKA-Low array being placed in 2024 and the first SKA-Mid receiver being placed in 2025.
In April 2011, Jodrell Bank Observatory of the University of Manchester, in Cheshire, England was announced as the location for the project headquarters. In November 2011, the SKA Organisation was formed as an intergovernmental organisation and the project moved from a collaboration to an independent, not for profit, company.
In February 2012, a former Australian SKA Committee chairman raised concerns with South African media about risks at the Australian candidate site, particularly in terms of cost, mining interference and land agreements. SKA Australia stated that all points had been addressed in the site bid. In March 2012 it was reported that the SKA Site Advisory Committee had made a confidential report in February that the South African bid was stronger. However a scientific working group was set up to explore possible implementation options of the two candidate host regions, and on 25 May 2012 it was announced that it had been determined that the SKA would be split over the South African and African sites, and the Australia and New Zealand sites. While New Zealand remained a member of the SKA Organisation in 2014, it appeared that no SKA infrastructure was likely to be located in New Zealand.
In April 2015, the headquarters of the SKA project were chosen to be located at the Jodrell Bank Observatory in England,UK to be giant telescope's HQ . Jonathan Amos, BBC News. 29 April 2015. officially opened in July 2019.
Initial construction contracts began in 2018. Scientific observations with the fully completed array Technical information: the operational model (SKA, 2 August 2018)
On 12 March 2019, the Square Kilometre Array Observatory (SKAO) was founded in Rome by seven initial member countries: Australia, China, Italy, the Netherlands, Portugal, South Africa and the United Kingdom. India and Sweden are expected to follow shortly, and eight other countries have expressed interest to join in the future. This international organisation was tasked with building and operating the facility, with the first construction contracts
By mid-2019, the start of scientific observations were expected to start no earlier than 2027. In July 2019, New Zealand withdrew from the project.
, five precursor facilities were already operating: MeerKAT and the Hydrogen Epoch of Reionization Array (HERA) in South Africa, the Australian SKA Pathfinder (ASKAP) and Murchison Widefield Array (MWA) in Western Australia and the International LOFAR Telescope, spread across Europe with a core in the Netherlands.
The construction phase of the project began on 5 December 2022 in Australia and South Africa, with delegations from each of the eight countries leading the project attending ceremonies to celebrate the event. The Australian part of the project comprises 100,000 antennas built across , also in the Murchison region, in the traditional lands of the Wajarri Aboriginal people. Bulldozers The site has been named , which means in the Wajarri language.
The Department of Atomic Energy (DAE) in India and UK Research and Innovation (UKRI) are investigating the possibility of establishing supercomputing facilities to handle data from the Square Kilometre Array radio telescope. The UK and India are part of the team developing the computational processing for the SKA radio telescope. On 3 January 2024, Indian government approved joining the SKA project accompanied by a financial commitment of ₹1,250 crore which marks the initial step towards ratification as a member state.
Description
Each of the two parts of the SKA (SKA-low in Australia and SKA-mid in Africa) will combine the signals received from thousands of small antennas spread over a distance of up to 150 km to simulate a single giant radio telescope capable of extremely high sensitivity and angular resolution, using a technique called aperture synthesis. In addition, each of the two parts of the SKA will link to other radio telescopes located up to thousands of km away, using the technique of Very-long-baseline interferometry, to provide extremely high resolution. Some of the sub-arrays of the SKA will also have a very large field-of-view (FOV), making it possible to survey very large areas of sky at once. This will greatly increase the survey speed of the SKA and enable several users to observe different pieces of the sky simultaneously, which is useful for (e.g.) monitoring multiple pulsars. The combination of a very large FOV with high sensitivity means that the SKA will be able to compile extremely large surveys of the sky considerably faster than any other telescope.
The two sub-arrays of the SKA are: SKA-low array: a phased array of low-frequency "Chistmas-tree" antennas to cover the frequency range from 50 to 350 MHz. These will be grouped in 40 m diameter stations each containing 256 vertically oriented dual-polarisation dipole elements. Stations will be arranged with 75% located within a 2 km diameter core and the remaining stations situated on three spiral arms, extending out to a radius of 50 km. SKA-low produced its first image using just 1,000 of the planned 131,000 antennas in March 2025, but completion is not expected until about 2030. SKA-mid array: an array of several thousand dish antennas (around 200 to be built in Phase 1) to cover the frequency range 350 MHz to 14 GHz. It is expected that the antenna design will follow that of the Allen Telescope Array using an offset Gregorian design having a height of 15 metres and a width of 12 metres. Early designs also called for an SKA-survey array: a compact array of parabolic dishes of 12–15 meters diameter each for the medium-frequency range, each equipped with a multi-beam, phased array feed with a large field of view and several receiving systems covering about 350 MHz – 4 GHz. The survey sub-array was removed from the SKA1 specification following a "rebaselining" exercise in 2015.
The area covered by the SKA – extending out to ~3000 km – will comprise three regions: A central region containing about 5 km diameter cores of SKA-mid antennas (South Africa) and SKA-low dipoles (Western Australia). These central regions will contain approximately half of the total collecting area of the SKA arrays. A mid region extending out to 180 km. This will contain dishes and pairs of SKA-mid and SKA-low stations. In each case they will be randomly placed within the area with the density of dishes and stations falling off towards the outer part of the region. An outer region from 180 km to 3000 km. This will comprise five spiral arms, along which dishes of SKA-mid, grouped into stations of 20 dishes, will be located. The separation of the stations increases towards the outer ends of the spiral arms.
Costs The SKA was estimated to cost €1.8 billion in 2014, including €650 million for Phase 1, which represented about 10% of the planned capability of the entire telescope array. There have been numerous delays and rising costs over the nearly 30-year history of the intergovernmental project.
, the whole project was reported to be worth around A$3 billion.
Members
As of June 2026, the members of the SKAO consortium were:
Founding members: Australia: Department of Industry and Science China: National Remote Sensing Centre of the Ministry of Science and Technology of the People's Republic of China (中华人民共和国科学技术部 - Zhōnghuá Rénmín Gònghéguó Kēxué Jìshùbù) Italy: National Institute for Astrophysics (Istituto Nazionale di Astrofisica) Portugal: Portugal Space Agency (Agência Espacial Portuguesa) South Africa: South African Radio Astronomy Observatory of the National Research Foundation The Netherlands: ASTRON - Netherlands Institute for Radio Astronomy ( (ASTRON - Astronomisch Onderzoek in Nederland) United Kingdom: Science and Technology Facilities Council
Joined in 2022: Switzerland: SKACH Consortium
Joined in 2023: Spain: Institute of Astrophysics of Andalusia (Instituto de Astrofísica de Andalucía)
Joined in 2024: Canada: Radio Astronomy Directorate of the National Research Council Germany: Association for Data-Intensive Radio Astronomy (Verein für datenintensive Radioastronomie e.V.) India: National Centre for Radio Astrophysics (राष्ट्रीय रेडियो खगोल भौतिकी केन्द्र - Raashtreey Rediyo Khagol Bhautikee Kendr) Joined in 2025: Sweden: Onsala Space Observatory - Chalmers University of Technology (Onsala rymdobservatorium - Chalmers tekniska högskola) Joined in 2026: France: National Centre for Scientific Research (Centre National de la Recherche Scientifique)
Observers: Japan: National Astronomical Observatory (国立天文台 - Kokuritsu Tenmondai)xhttps://www.skao.int/en/partners/prospective-members/191/japan South Korea: Korea Astronomy and Space Science Institute (한국천문연구원 - Hangugcheonmun-Yeonguwon)
African Partners, involved in coordinated action to support the future expansion of the SKA project in Africa: Botswana Ghana Kenya