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Square Kilometre Array

International radio telescope project

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Composite image of the SKA telescopes, blending real hardware already on site with artist's impressions. From left: An artist's impression of the future SKA-Mid dishes blend into the existing precurso
SKAO · CC BY 3.0

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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 21,000 square metres (0.021 km2) 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 3,000 km (1,900 mi) 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; as of 2021 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, officially opened in July 2019.

Initial construction contracts began in 2018. Scientific observations with the fully completed array are not expected any earlier than 2027.

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 expected to be awarded in late 2020.

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.

As of November 2020, 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 74 km (46 mi), also in the Murchison region, in the traditional lands of the Wajarri Aboriginal people. Bulldozers were expected to start working on the site in early 2023, with the completion date estimated as 2028. The site has been named Inyarrimanha Ilgari Bundara, which means 'sharing sky and stars' 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.

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