Square Kilometre Array

{{Infobox telescope

| location = Meerkat National Park, South Africa and Murchison Radio-astronomy Observatory, Australia

| coords = {{Coord|30|43|16|S|21|24|40|E}} and {{Coord|26|41|49.3|S|116|37|52.6|E}}

| first_light = 2027 (projected)

| locmapin = South Africa, Australia

}}

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.

Conceived in the 1990s, and further developed and designed by the late-2010s, when completed {{update after |2029 |text=sometime in the 2020s it will have}} a total collecting area of approximately one square kilometre. 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 {{cvt|3,000|km}} 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|lc=y}} 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.{{cite web |url=https://unitedkingdom.skatelescope.org/ska-project/ska-timeline/ |title = SKA Timeline - SKA UK| work=SKA UK }}

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).{{cite web |title=Kilometer-square Area Radio Synthesis Telescope—KARST |first1=R. |last1=Nan |display-authors=etal |url=https://www.skatelescope.org/uploaded/8481_17_memo_Nan.pdf |date=16 June 2002| archive-url=https://web.archive.org/web/20161005144909/https://www.skatelescope.org/uploaded/8481_17_memo_Nan.pdf |archive-date=5 October 2016 | url-status=live }}{{cite journal | title = An Optimal Design of Array Configuration of KARST for SKA | journal = Acta Astronomica Sinica | volume = 44 | pages = 31 | first = Yan | last = Su | display-authors = etal | url = http://zmtt.bao.ac.cn/xian/proceedings/SuY/fin/SuY.pdf| date = Feb 2003| archive-url = https://web.archive.org/web/20160303234850/http://zmtt.bao.ac.cn/xian/proceedings/SuY/fin/SuY.pdf | archive-date = 3 March 2016 | url-status = live | bibcode = 2003AcASn..44S..31S }}

Australia's first radio quiet zone was established by the Australian Communications and 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.{{cite web |title=Planning for the radio astronomy service |url=http://www.acma.gov.au/WEB/STANDARD/pc=PC_100628 |archive-url=https://web.archive.org/web/20070909092701/http://www.acma.gov.au/WEB/STANDARD//pc=PC_100628 |url-status=dead |archive-date=9 September 2007 |access-date=3 June 2012 }}

The project has two phases of construction: the current SKA1, commonly just called SKA, and a possible later significantly enlarged phase sometimes called SKA2.{{cite web | title=SKA Telescope specifications | website=SKAO | date=28 June 2022 | url=https://www.skao.int/en/science-users/118/ska-telescope-specifications | access-date=13 September 2022}} PrepSKA commenced in 2008, leading to a full SKA design in 2012. Construction of Phase 1 {{update after |2020 |text=was scheduled to take place from 2018 to 2020,}} providing an operational array, with Phase 2 {{update after |2025 |text=completion in 2025.}}{{citation needed|date=March 2019}}

File:At Jodrell Bank Observatory 2018 040.jpg in the background]]

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{{Cite web|url=https://www.universal-sci.com/headlines/2019/8/20/first-country-has-approved-participation-in-constructing-the-largest-telescope-the-world-has-ever-known|title=First country has approved participation in constructing the largest telescope the world has ever known|date=20 August 2019 }} and the project moved from a collaboration to an independent, not for profit, company.{{cite news | url= http://www.skatelescope.org/the-organisation/ | title= The organisation | publisher= SKA Organisation | access-date= 21 May 2012 | archive-url= https://web.archive.org/web/20120904115214/http://www.skatelescope.org/the-organisation/ | archive-date= 4 September 2012 | url-status= dead }}

In February 2012, a former Australian SKA Committee{{clarify|how were these committees organized? under what organizational structure?|date=August 2019}} 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.{{cite news

|url=http://www.iol.co.za/the-star/oz-telescope-body-under-microscope-after-ex-chairman-raises-difficult-questions-1.1239657 |title= Oz telescope body under microscope after ex-chairman raises difficult questions|last=Carpenter |first=Avery |date=22 February 2012 |newspaper=The Star |access-date=26 March 2012 |archive-url=https://web.archive.org/web/20140329065823/http://www.iol.co.za/the-star/oz-telescope-body-under-microscope-after-ex-chairman-raises-difficult-questions-1.1239657 |archive-date=29 March 2014 |url-status=live }} 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.{{cite news|last=Flitton|first=Daniel|title=Australia on the outer for largest space telescope|url=http://www.theage.com.au/national/australia-on-the-outer-for-largest-space-telescope-20120309-1upwr.html|access-date=9 March 2012|newspaper=The Age|date=10 March 2012}} However a scientific working group was set up to explore possible implementation options of the two candidate host regions,{{cite news | title =Further delays signalled in super-telescope plan | agency =AFP | work =The Australian | date =5 April 2012 | url =http://www.theaustralian.com.au/australian-it/further-delays-signalled-in-super-telescope-plan/story-e6frgakx-1226319328674 | access-date =10 April 2012 | archive-url =https://web.archive.org/web/20120410043337/http://www.theaustralian.com.au/australian-it/further-delays-signalled-in-super-telescope-plan/story-e6frgakx-1226319328674 | archive-date =10 April 2012 | url-status =live }} 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.{{cite news |url=https://www.bbc.co.uk/news/science-environment-18194984|title=Africa and Australasia to share Square Kilometre Array|last=Amos|first=Jonathan|date=25 May 2012|publisher=BBC|access-date=20 June 2018|archive-url=https://web.archive.org/web/20180820140222/https://www.bbc.co.uk/news/science-environment-18194984|archive-date=20 August 2018|url-status=live}} 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.{{cite web|url=https://www.skatelescope.org/location/australia/|title=Australia - SKA Telescope|date=2014|publisher=SKA|access-date=22 May 2014|archive-url=https://web.archive.org/web/20140615002233/https://www.skatelescope.org/location/australia/|archive-date=15 June 2014|url-status=live}}

In April 2015, the headquarters of the SKA project were chosen to be located at the Jodrell Bank Observatory in the UK,{{cite web |url=https://www.skatelescope.org/ska-organisation/ |title=The SKA Organisation |publisher=SKA Organisation |access-date=28 October 2014 |archive-url=https://web.archive.org/web/20150223142143/https://www.skatelescope.org/ska-organisation/ |archive-date=23 February 2015 |url-status=live }}[https://www.bbc.com/news/science-environment-32523768 UK to be giant telescope's HQ] {{Webarchive|url=https://web.archive.org/web/20181002221937/https://www.bbc.com/news/science-environment-32523768 |date=2 October 2018 }}. Jonathan Amos, BBC News. 29 April 2015. officially opened in July 2019.{{citation needed|date=December 2022}}

Initial construction contracts began in 2018. Scientific observations with the fully completed array {{update after |2027 |text=are not expected any earlier than 2027.}}[https://www.skatelescope.org/wp-content/uploads/2018/08/16231-Factsheets-operational-model-v4.pdf 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 {{update after |2020 |text=expected to be awarded in late 2020.}}{{cite press release |url=https://www.skatelescope.org/news/founding-members-sign-ska-observatory-treaty/ |title=Founding Members Sign SKA Observatory Treaty |publisher=Square Kilometre Array Organisation |date=12 March 2019 |access-date=14 March 2019 |archive-url=https://web.archive.org/web/20190330054801/https://www.skatelescope.org/news/founding-members-sign-ska-observatory-treaty/ |archive-date=30 March 2019 |url-status=live }}

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.{{cite news |url=https://physicsworld.com/a/new-zealand-pulls-out-of-the-square-kilometre-array-after-benefits-questioned |title=New Zealand pulls out of the Square Kilometre Array after benefits questioned |publisher=IOP Publishing |work=Physics World |date=4 July 2019 |access-date=5 July 2019 |archive-url=https://web.archive.org/web/20190704174649/https://physicsworld.com/a/new-zealand-pulls-out-of-the-square-kilometre-array-after-benefits-questioned/ |archive-date=4 July 2019 |url-status=live }}

{{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.{{cite web |title=Precursors and Pathfinders |url=https://www.skatelescope.org/precursors-pathfinders-design-studies/ |website=Square Kilometre Array |access-date=22 November 2020}}

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.{{cite web|title=SKA: Construction to begin on world's biggest telescope| first= Jonathan |last= Amos|url=https://www.bbc.com/news/science-environment-63836496| website=BBC News|date=5 December 2022|access-date=5 December 2022}} The Australian part of the project comprises 100,000 antennas built across {{cvt|74|km}}, also in the Murchison region, in the traditional lands of the Wajarri Aboriginal people. Bulldozers {{update after |2023|06 |text=were expected to start working on the site in early 2023,}} {{update after |2028 |text=with the completion date estimated as 2028.}} The site has been named {{lang|wbv|Inyarrimanha Ilgari Bundara|italics=unset}}, which means {{gloss|sharing sky and stars}} in the Wajarri language.{{cite web | last=Clifford | first=Rachael | title=Square Kilometre Array Telescope construction begins in West Australian outback |publisher = Australian Broadcasting Corporation | website=ABC News| date=5 December 2022 | url=https://www.abc.net.au/news/2022-12-05/square-kilometre-array-telescope-construction-begins-in-wa/101733396 | access-date=6 December 2022}}

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.{{Cite web |date=18 October 2023 |title=UK, India Scientists To Collaborate In Astronomy, Bio-Imaging |url=https://www.ndtv.com/india-news/uk-india-scientists-to-collaborate-in-astronomy-bio-imaging-4492943 |access-date=2024-01-03 |website=NDTV.com}} 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.{{Cite web |last=Marar |first=Anjali |date=2024-01-03 |title=Another eye in sky, on ground: India is now part of world's largest radio telescope project |url=https://indianexpress.com/article/india/another-eye-in-sky-on-ground-india-is-now-part-of-worlds-largest-radio-telescope-project-9092577/ |access-date=2024-01-03 |website=The Indian Express |language=en}}

Description

File:SKA participants map.svg

The SKA will combine the signals received from thousands of small antennas spread over a distance of several thousand kilometres to simulate a single giant radio telescope capable of extremely high sensitivity and angular resolution, using a technique called aperture synthesis.{{cite web|title=The SKA Layout|url=https://www.skatelescope.org/layout/|website=SKA Telescope|access-date=5 October 2015|archive-url=https://web.archive.org/web/20150921001143/https://www.skatelescope.org/layout/|archive-date=21 September 2015|url-status=live}} 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.{{cite web|title=The World's Largest Radio Telescope Takes A Major Step Towards Construction|url=https://www.skatelescope.org/news/worlds-largest-radio-telescope-near-construction/|website=SKA Science|date=9 March 2015|access-date=5 October 2015|archive-url=https://web.archive.org/web/20160108044154/https://www.skatelescope.org/news/worlds-largest-radio-telescope-near-construction/|archive-date=8 January 2016|url-status=live}} One innovative development is the use of focal-plane arrays using phased-array technology to provide multiple FOVs.{{cite web|title=SKA Aperture Arrays|url=https://www.skatelescope.org/aperture-arrays/|website=SKA Telescope|access-date=5 October 2015|archive-url=https://web.archive.org/web/20150921022000/https://www.skatelescope.org/aperture-arrays/|archive-date=21 September 2015|url-status=live}} 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.{{cite web|title=How will SKA1 be better than today's best radio telescopes? [image]|url=https://www.skatelescope.org/wp-content/uploads/2015/03/SKA-3-aspects-Infographic_OP-rgb.jpg|website=SKA Telescope|access-date=5 October 2015|archive-url=https://web.archive.org/web/20160304085949/https://www.skatelescope.org/wp-content/uploads/2015/03/SKA-3-aspects-Infographic_OP-rgb.jpg|archive-date=4 March 2016|url-status=live}}

The combined SKA will provide a wide range of coverage, with Australia's Murchison Widefield Array providing low-frequency coverage and South Africa's MeerKAT providing mid-frequency coverage.{{cite web |url=http://www.skatelescope.org/about/facts-figures/ |title=Facts and figures |publisher=SKA Organisation |access-date=26 May 2012 |archive-url=https://web.archive.org/web/20120728191729/http://www.skatelescope.org/about/facts-figures/ |archive-date=28 July 2012 |url-status=dead }}{{Cite journal | doi = 10.1117/2.3201407.12| title = Philip Diamond plenary: The Square Kilometre Array: A Physics Machine for the 21st Century| journal = SPIE Newsroom| year = 2014| last1 = Spie}} There will be continuous frequency coverage from 50 MHz to 14 GHz in the first two phases of its construction.

Phase 1: Providing ~10% of the total collecting area at low and mid frequencies by 2023 (SKA1).{{cite web|title=SKA1|url=http://astronomers.skatelescope.org/ska1/|website=SKA Science|date=21 February 2014 |access-date=5 October 2015|archive-url=https://web.archive.org/web/20160108044154/http://astronomers.skatelescope.org/ska1/|archive-date=8 January 2016|url-status=live}}
Phase 2: Completion of the full array (SKA2) at low and mid frequencies by 2030.{{cite web|title=SKA2|url=http://astronomers.skatelescope.org/ska2/|website=SKA Science|date=21 February 2014 |access-date=5 October 2015|archive-url=https://web.archive.org/web/20160108044154/http://astronomers.skatelescope.org/ska2/|archive-date=8 January 2016|url-status=live}}

The frequency range from 50 MHz to 14 GHz, spanning more than two decades, cannot be realised using one design of antenna and so the SKA will comprise separate sub-arrays of different types of antenna elements that will make up the SKA-low, SKA-mid and survey arrays:

File:SKA sparse array big.jpg

File:SKA dense array big.jpg

SKA-low array: a phased array of simple dipole 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.{{cite web |url=https://research.csiro.au/ska/technology/ |title=Developing technologies for SKA-Low |access-date=2022-10-22}} 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.{{cite web |url=https://www.skatelescope.org/lfaa/ |title=Low-Frequency Aperture Array |access-date=2022-10-22}}
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.{{Cite web |date=2024-01-03 |title=Square Kilometre Array Project - Rau's IAS |url=https://compass.rauias.com/current-affairs/square-kilometre-array-project/ |access-date=2024-01-04 |website=compass.rauias.com |language=en-US}}
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.{{cite web|last1=McPherson|first1=A.|title=REPORT AND OPTIONS FOR RE-BASELINING OF SKA-1|url=https://www.skatelescope.org/wp-content/uploads/2014/03/SKA-TEL-SKO-0000229_Report-and-Options-for-Re-Baselining-of-SKA-1-Word_Amm-signed.pdf|website=SKA Telescope|publisher=SKAO|access-date=5 October 2015|archive-url=https://web.archive.org/web/20151006071718/https://www.skatelescope.org/wp-content/uploads/2014/03/SKA-TEL-SKO-0000229_Report-and-Options-for-Re-Baselining-of-SKA-1-Word_Amm-signed.pdf|archive-date=6 October 2015|url-status=live}}

The area covered by the SKA – extending out to ~3000 km – will comprise three regions:{{cite web|last1=Dewdney|first1=P. E.|title=SKA Baseline Design|url=https://www.skatelescope.org/wp-content/uploads/2012/07/SKA-TEL-SKO-DD-001-1_BaselineDesign1.pdf|website=SKA Telescope|access-date=5 October 2015|archive-url=https://web.archive.org/web/20160602160221/http://www.skatelescope.org/wp-content/uploads/2012/07/SKA-TEL-SKO-DD-001-1_BaselineDesign1.pdf|archive-date=2 June 2016|url-status=live}}

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.{{cite web |url=http://www.skatelescope.org/about/project/ |title=The project timeline |publisher=SKA Organisation |access-date=28 October 2014 |url-status=dead |archive-url=https://web.archive.org/web/20120805230658/http://www.skatelescope.org/about/project/ |archive-date=5 August 2012 }}{{cite web |url=http://www.ska.ac.za/about/bid.php |title=SKA site bid outcome |publisher=SKA Africa |access-date=28 October 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140626022118/http://ska.ac.za/about/bid.php |archive-date=26 June 2014 }} There have been numerous delays and rising costs over the nearly 30-year history of the intergovernmental project.

{{as of|2022|12}}, the whole project was reported to be worth around A$3 billion.

File:Square Kilometre Array Organisation members.svg

=Members=

As per march 2025, the members of the SKAO consortium were:https://www.skao.int/en/about-us/governance/100/skao-councilhttps://www.skao.int/en/partners/skao-members

Founding members:
Australia: Department of Industry and Sciencehttps://www.skao.int/en/partners/skao-members/133/australia
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)https://www.skao.int/en/partners/skao-members/372/china
Italy: National Institute for Astrophysics (Istituto Nazionale di Astrofisica)https://www.skao.int/en/partners/skao-members/292/italy
Portugal: Portugal Space Agency (Agência Espacial Portuguesa)https://www.skao.int/en/partners/skao-members/389/portugal
South Africa: South African Radio Astronomy Observatory of the National Research Foundationhttps://www.skao.int/en/partners/skao-members/397/south-africa
The Netherlands: ASTRON - Netherlands Institute for Radio Astronomy ( (ASTRON - Astronomisch Onderzoek in Nederland)https://www.skao.int/en/partners/skao-members/163/netherlands
United Kingdom: Science and Technology Facilities Councilhttps://www.skao.int/en/partners/skao-members/396/united-kingdom

Joined in 2022:
Switzerland: SKACH Consortiumhttps://www.skao.int/en/partners/skao-members/302/switzerland

Joined in 2023:
Spain: Institute of Astrophysics of Andalusia (Instituto de Astrofísica de Andalucía){{cite web |title=Spain joins the SKA Organisation - SKA Telescope |url=https://www.skatelescope.org/news/spain-joins-skao/ |website=SKA Telescope |access-date=19 June 2018 |date=19 June 2018 |archive-url=https://web.archive.org/web/20180619213907/https://www.skatelescope.org/news/spain-joins-skao/ |archive-date=19 June 2018 |url-status=live }}https://www.skao.int/en/partners/skao-members/398/spain

Joined in 2024:
Canada: Radio Astronomy Directorate of the National Research Councilhttps://www.skao.int/en/partners/skao-members/388/canada
Germany: Association for Data-Intensive Radio Astronomy (Verein für datenintensive Radioastronomie e.V.)https://www.skao.int/en/partners/skao-members/399/germany
India: National Centre for Radio Astrophysics (राष्ट्रीय रेडियो खगोल भौतिकी केन्द्र - Raashtreey Rediyo Khagol Bhautikee Kendr){{cite web |url=https://www.skatelescope.org/news/indias-ncra-becomes-11th-full-skao-member/ |title=India's National Centre for Radio Astrophysics becomes the 11th full SKA Organisation member |date=11 August 2014 |publisher=SKA Organisation |access-date=11 August 2014 |archive-url=https://web.archive.org/web/20160108044154/https://www.skatelescope.org/news/indias-ncra-becomes-11th-full-skao-member/ |archive-date=8 January 2016 |url-status=live }}{{Cite web |title=Explained {{!}} Square Kilometre Array project, world's largest radio telescope, and India's role in it |url=https://www.deccanherald.com/science/space/explained-square-kilometre-array-project-worlds-largest-radio-telescope-and-indias-role-in-it-2833808 |access-date=2024-01-04 |website=Deccan Herald |language=en}}https://www.skao.int/en/partners/skao-members/393/india

Observers:
France: National Centre for Scientific Research (Centre National de la Recherche Scientifique)https://www.skao.int/en/partners/prospective-members/188/france
Japan: National Astronomical Observatory (国立天文台 - Kokuritsu Tenmondai) xhttps://www.skao.int/en/partners/prospective-members/191/japan
Korea: Korea Astronomy and Space Science Institute (한국천문연구원 - Hangugcheonmun-Yeonguwon)https://www.skao.int/en/partners/prospective-members/193/south-korea
Sweden: Onsala Space Observatory - Chalmers University of Technology (Onsala rymdobservatorium - Chalmers tekniska högskola)https://www.skao.int/en/partners/prospective-members/186/sweden

African Patners, involved in coordinated action to support the future expansion of the SKA project in Africa:
Botswana
Ghana
Kenya
Madagascar
Mauritius
Mozambique
Namibia
Zambia

SKA locations

File:SKA-scanner.jpgThe headquarters of the SKA are located at the University of Manchester's Jodrell Bank Observatory in Cheshire, England,{{cite web |date=18 April 2012 |title=Construction starts on SKA Organisation headquarters |url=http://www.skatelescope.org/news/construction-starts-ska-organisation-headquarters/ |url-status=live |archive-url=https://web.archive.org/web/20120519072853/http://www.skatelescope.org/news/construction-starts-ska-organisation-headquarters/ |archive-date=19 May 2012 |access-date=26 May 2012 |publisher=SKA Organisation}} while the telescopes will be installed in Australia and South Africa.[http://www.ska.gov.au/About/Pages/CohostingTheSKA.aspx Co-hosting the SKA] {{Webarchive|url=https://web.archive.org/web/20180411031202/http://www.ska.gov.au/About/Pages/CohostingTheSKA.aspx|date=11 April 2018}}. SKA

Suitable sites for the SKA telescope must be in unpopulated areas with guaranteed very low levels of man-made radio interference. Four sites were initially proposed in South Africa, Australia, Argentina and China.{{cite journal|last=Koenig|first=Robert|date=18 August 2006|title=RADIO ASTRONOMY: Candidate Sites for World's Largest Telescope Face First Big Hurdle|journal=Science|publisher=AAAS|volume=313|issue=5789|pages=910–912|doi=10.1126/science.313.5789.910|pmid=16917038|s2cid=42969567}} After considerable site evaluation surveys, Argentina and China were dropped and the other two sites were shortlisted (with New Zealand joining the Australian bid, and 8 other African countries joining the South African bid):{{Cite web |title=SA's bid to host Square Kilometre Array (SKA) Radio Telescope: briefing by Department & SKA Project Team {{!}} PMG |url=https://pmg.org.za/committee-meeting/11284/ |access-date=2024-01-04 |website=pmg.org.za |language=en}}

=Australia=

The core site is located at the Murchison Radio-astronomy Observatory (MRO) at Mileura Station near Boolardy in the state of Western Australia, {{cvt|315|km}} north-east of GeraldtonAmos, J. [http://news.bbc.co.uk/2/hi/science/nature/5388690.stm Nations vie for giant telescope] {{Webarchive|url=https://web.archive.org/web/20060929070255/http://news.bbc.co.uk/2/hi/science/nature/5388690.stm |date=29 September 2006 }}, BBC News, 28 September 2006.[http://www.sciencewa.net.au/index.php?option=com_content&task=view&id=635&Itemid=587, Science Network WA], 16 February 2007 {{webarchive |url=https://web.archive.org/web/20140427010540/http://www.sciencewa.net.au/index.php?option=com_content&task=view&id=635&Itemid=587 |date=27 April 2014 }}

=South Africa=

The core site is located at the Meerkat National Park, at an elevation of about 1000 metres, in the Karoo area of the arid Northern Cape Province. There are also distant stations in Botswana, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Namibia and Zambia.{{Cite journal |title=The Square Kilometre Array (SKA) |url=https://journals.co.za/doi/pdf/10.10520/EJC127429 |journal=Quest |volume=8 |issue=3 |pages=3 |via=Sabinet}}

Precursors, pathfinders and design studies

Many groups are working globally to develop the technology and techniques required for the SKA. Their contributions to the international SKA project are classified as either: Precursors, Pathfinders or Design Studies.

Precursor facility: A telescope on one of the two SKA candidate sites, carrying out SKA-related activity.
Pathfinder: A telescope or programme carrying out SKA-related technology, science and operations activity.
Design Study: A study of one or more major sub-systems of the SKA design, including the construction of prototypes

=Precursor facilities=

File:CSIRO ASKAP 2010.jpg's ASKAP antennas at the MRO in Western Australia]]

==Australian SKA Pathfinder (ASKAP)==

The Australian SKA Pathfinder, or ASKAP, is an A$100 million project which built a telescope array of thirty-six twelve-metre dishes. It employs advanced, innovative technologies such as phased array feeds to give a wide field of view (30 square degrees). ASKAP was built by CSIRO at the Murchison Radio-astronomy Observatory site, located near Boolardy in the mid-west region of Western Australia. All 36 antennas and their technical systems were officially opened in October 2012.{{cite news |last=Osborne |first=Darren |url=http://www.abc.net.au/news/2012-10-05/outback-observatory-open-for-business/4298094 |title=Outback observatory open for business - ABC News (Australian Broadcasting Corporation) |newspaper=ABC News |date=5 October 2012 |publisher=Abc.net.au |access-date=7 October 2012 |archive-url=https://web.archive.org/web/20121007084631/http://www.abc.net.au/news/2012-10-05/outback-observatory-open-for-business/4298094 |archive-date=7 October 2012 |url-status=live }}

== MeerKAT ==

File:2017 meerkat 01.png in the Karoo]]

MeerKAT is a South African project consisting of an array of sixty-four 13.5-metre diameter dishes as a world class science instrument, and was also built to help develop technology for the SKA.

KAT-7, a seven-dish engineering and science testbed instrument for MeerKAT, in the Meerkat National Park near Carnarvon in the Northern Cape Province of South Africa was commissioned in 2012 and was up and running by May 2018 when all sixty-four 13.5-metre diameter (44.3 feet) dish antennae were completed, with verification tests then underway to ensure the instruments are functioning correctly.{{cite news|last1=Tshangela|first1=Lebo|title=MeerKAT telescope is complete|url=http://www.sabcnews.com/sabcnews/meerkat-telescope-is-complete/|access-date=25 May 2018|work=SABC News|date=16 May 2018|archive-url=https://web.archive.org/web/20180519064052/http://www.sabcnews.com/sabcnews/meerkat-telescope-is-complete/|archive-date=19 May 2018|url-status=live}}{{update after|2018}} The dishes are equipped with a number of high performance single pixel feeds to cover frequencies from 580 MHz up to 14 GHz.{{cite web|url=http://www.ska.ac.za|title=SKA SA – Square Kilometre Array radio telescope (SKA) South Africa|access-date=1 February 2017|archive-url=https://web.archive.org/web/20170114122619/http://www.ska.ac.za/|archive-date=14 January 2017|url-status=live}}

==Murchison Widefield Array (MWA)==

The Murchison Widefield Array{{cite web|url=http://www.mwatelescope.org/|title=MWA - Home|website=www.mwatelescope.org|access-date=1 February 2017|archive-url=https://web.archive.org/web/20170131053124/http://www.mwatelescope.org/|archive-date=31 January 2017|url-status=live}} is a low-frequency radio array operating in the frequency range 80–300 MHz that began upgraded operation in 2018 at the Murchison Radio-astronomy Observatory site in Western Australia.

==Hydrogen Epoch of Reionization Array (HERA)==

The HERA array is located in South Africa's Meerkat National Park. It is designed to study highly redshifted atomic hydrogen emission emitted prior to, and during the epoch of reionization.

=Pathfinders=

APERture Tile in Focus (Apertif){{cite conference | author=Tom Osterloo | author2=Marc Verheijen | author3=Wim van Cappellen | name-list-style=amp | title=The latest on Apertif | date=10–14 June 2010 | conference=ISKAF2010 Science Meeting | arxiv=1007.5141 | url=http://pos.sissa.it/archive/conferences/112/043/ISKAF2010_043.pdf | bibcode=2010iska.meetE..43O | access-date=15 April 2013 | archive-url=https://web.archive.org/web/20141206045454/http://pos.sissa.it/archive/conferences/112/043/ISKAF2010_043.pdf | archive-date=6 December 2014 | url-status=live }}
Very Long Baseline Interferometry[http://www.aerospace-technology.com/features/featuresquare-kilometre-array-africa-australia-astronomy-telescope/ Aerospace-Technology.com] {{Webarchive|url=https://web.archive.org/web/20120615215656/http://www.aerospace-technology.com/features/featuresquare-kilometre-array-africa-australia-astronomy-telescope |date=15 June 2012 }}{{Unreliable source?|reason=domain on WP:BLACKLIST|date=July 2016}}
Electronic MultiBeam Radio Astronomy ConcEpt{{cite web|url=http://www.skads-eu.org/p/embraceConcept.php|title=Electronic Multi Beam Radio Astronomy ConcEpt|access-date=1 February 2017|archive-url=https://web.archive.org/web/20160512195218/http://www.skads-eu.org/p/embraceConcept.php|archive-date=12 May 2016|url-status=live}}
e-MERLIN{{cite web|url=http://www.e-merlin.ac.uk/|title=e-MERLIN / VLBI National Radio Astronomy Facility - e-MERLIN|first=Rob|last=Beswick|access-date=1 February 2017|archive-url=https://web.archive.org/web/20170101203916/http://www.e-merlin.ac.uk/|archive-date=1 January 2017|url-status=live}}
Expanded Very Large Array{{cite web|url=http://www.aoc.nrao.edu/evla|title=Expanded VLA|access-date=1 February 2017|archive-url=https://web.archive.org/web/20161022143316/http://www.aoc.nrao.edu/evla/|archive-date=22 October 2016|url-status=live}}
Long Wavelength Array{{cite web|url=http://lwa.phys.unm.edu/|title=Long Wavelength Array|access-date=1 February 2017|archive-url=https://web.archive.org/web/20161117123028/http://lwa.phys.unm.edu//|archive-date=17 November 2016|url-status=live}}
SKA Molonglo Prototype (SKAMP){{cite web|url=http://www.physics.usyd.edu.au/sifa/Main/SKAMP|title=Sydney Institute for Astronomy - The University of Sydney|first=Bryan|last=Gaensler|access-date=1 February 2017|archive-url=https://web.archive.org/web/20170218230743/http://www.physics.usyd.edu.au/sifa/Main/SKAMP|archive-date=18 February 2017|url-status=dead}}
NenuFAR{{cite web|url=http://nenufar.obs-nancay.fr|title=NENUFAR website|access-date=1 February 2017|archive-url=https://web.archive.org/web/20160527195520/http://nenufar.obs-nancay.fr/|archive-date=27 May 2016|url-status=live}}{{cite web|url=https://www.skatelescope.org/news/french-nenufar-telescope-granted-ska-pathfinder-status/|title=French NenuFAR telescope granted SKA Pathfinder status - SKA Telescope|date=5 September 2014|access-date=1 February 2017|archive-url=https://web.archive.org/web/20160108044154/https://www.skatelescope.org/news/french-nenufar-telescope-granted-ska-pathfinder-status/|archive-date=8 January 2016|url-status=live}}
Giant Metrewave Radio Telescope{{cite web |title=India's GMRT telescope granted SKA pathfinder status |url=https://www.skatelescope.org/news/indias-gmrt-telescope-becomes-ska-pathfinder/ |website=SKA Telescope Public Website |access-date=3 January 2020 |language=en |date=6 February 2015}}

==Allen Telescope Array==

The Allen Telescope Array in California uses innovative 6.1m offset Gregorian dishes equipped with wide band single feeds covering frequencies from 500 MHz to 11 GHz. The 42-element array in operation by 2017 is to be extended to 350 elements.{{when|date=August 2019}} The dish design has explored methods of low-cost manufacture.{{cite web|url=http://www.seti.org/ata|title=The Allen Telescope Array - SETI Institute|access-date=1 February 2017|archive-url=https://web.archive.org/web/20110704063659/http://www.seti.org/ata|archive-date=4 July 2011|url-status=live}}

==LOFAR==

The International LOFAR Telescope —a €150 million Dutch-led project— a novel low-frequency phased aperture array spread over northern Europe. An all-electronic telescope covering low frequencies from 10 to 240 MHz, it came online from 2009 to 2011. LOFAR was in 2017 developing crucial processing techniques for the SKA.{{cite web|url=http://www.lofar.org/|title=LOFAR - LOFAR|access-date=1 February 2017|archive-url=https://web.archive.org/web/20170131053112/http://www.lofar.org/|archive-date=31 January 2017|url-status=live}}{{update after|2017}}. Because of its baselines of up to 2000 km, it can make images with sub-arcsecond angular resolution over a wide field of view. Such high-resolution imaging at low frequencies is unique and will be a factor of more than an order of magnitude better than SKA1-LOW.

=Design studies=

class="mw-collapsible mw-collapsed wikitable" align="right"

bgcolor=#FFFFFF

!colspan=5 bgcolor=#EFEFEF align=center| Data challenges of SKA pathfinders

bgcolor=#FFFFFF

|align=center|Challenge

|align=center|Specifications{{cite book

|author = Ray P. Norris

|title = 2010 Sixth IEEE International Conference on e-Science Workshops: Data Challenges for Next-generation Radio Telescopes

|pages = 21

|date = 7 January 2011

|doi = 10.1109/eScienceW.2010.13

|arxiv = 1101.1355

|isbn = 978-1-4244-8988-6

|s2cid = 34645164

}}
budgeted for ASKAP
Requirements for the SKA itself are about 100 times greater.

bgcolor=#FFFFFF

|align=center|Large bandwidth from
telescope to processor

|align=center|~10 Tbit/s from antennas to correlator (< 6 km)
40 Gbit/s from correlator to processor (~ 600 km)

bgcolor=#FFFFFF

|align=center|Large processing power

|align=center|750 Tflop/s expected/budgeted
1 Pflop desired

bgcolor=#FFFFFF

|align=center|Power consumption
of processors

|align=center|1 MW at site
10 MW for processor

bgcolor=#FFFFFF

|align=center|Pipeline processing
essential

|align=center|including data validation, source extraction,
cross-identification, etc.

bgcolor=#FFFFFF

|align=center|Storage and duration
of data

|align=center|70 PB/yr if all products are kept
5 PB/yr with current funding
8 h to write 12 h of data to disk at 10 GB/s

bgcolor=#FFFFFF

|align=center|Retrieval of data
by users

|align=center|all data in public domain
accessed using VO tools & services

bgcolor=#FFFFFF

|align=center|Data-intensive research

|align=center|data mining, stacking,
cross-correlation, etc.

Aperture Array Verification Programme{{cite web|url=http://www.ska-aavp.eu/|title=The Square Kilometre Array - SKA-AAVP|access-date=1 February 2017|archive-url=https://web.archive.org/web/20170202145456/http://www.ska-aavp.eu/|archive-date=2 February 2017|url-status=live}}
Canadian SKA Program{{cite web|url=http://www.skatelescope.ca/|title=Home - SKA|access-date=1 February 2017|archive-url=https://web.archive.org/web/20170223134627/http://skatelescope.ca/|archive-date=23 February 2017|url-status=live}}
Preparatory Study for the SKA{{cite web|url=http://www.jb.man.ac.uk/prepska|title=PrepSKA|access-date=1 February 2017|archive-url=https://web.archive.org/web/20160428172155/http://www.jb.man.ac.uk/prepska/|archive-date=28 April 2016|url-status=live}}
Square Kilometre Array Design Studies (SKADS){{cite web| url=http://www.skads-eu.org/p/technology.php| title=SKADS Technology| publisher=SKADS| access-date=2015-05-23| archive-url=https://web.archive.org/web/20160303222507/http://www.skads-eu.org/p/technology.php| archive-date=3 March 2016| url-status=live}}
Electronic MultiBeam Radio Astronomy ConcEpt (EMBRACE){{cite web| url=http://www.astron.nl/r-d-laboratory/ska/embrace/embrace| title=EMBRACE| publisher=ASTRON| access-date=2015-05-21| archive-url=https://web.archive.org/web/20171226020648/http://www.astron.nl/r-d-laboratory/ska/embrace/embrace| archive-date=26 December 2017| url-status=dead}}
BEST

==Data challenges==

The amount of sensory data collected poses a huge storage problem, and will require real-time signal processing to reduce the raw data to relevant derived information. In mid 2011 it was estimated the array could generate an exabyte a day of raw data, which could be compressed to around 10 petabytes.{{cite web |url=http://www.computerworld.com.au/article/392735/ska_telescope_generate_more_data_than_entire_internet_2020/ |title=SKA telescope to generate more data than entire Internet in 2020 |date=7 July 2011 |work=Computerworld |publisher=IDG Communications |access-date=2 April 2015 |archive-url=https://web.archive.org/web/20150402091345/http://www.computerworld.com.au/article/392735/ska_telescope_generate_more_data_than_entire_internet_2020/ |archive-date=2 April 2015 |url-status=live }} China, a founding member of the project, has designed and constructed the first prototype of the regional data processing centre. An Tao, head of the SKA group of the Shanghai Astronomical Observatory, stated, "It will generate data streams far beyond the total Internet traffic worldwide." The Tianhe-2 supercomputer was used in 2016 to train the software. The processing of the project will be performed on Chinese-designed and -manufactured{{cite news| url=https://www.reuters.com/article/us-huawei-tech-usa-tsmc/taiwans-tsmc-says-chip-shipments-to-huawei-not-affected-by-u-s-ban-idUSKCN1ST08O|date= 23 May 2019| title=Taiwan's TSMC says chip shipments to Huawei not affected by U.S. ban| publisher=Reuters| quote=China’s Huawei Technologies Co Ltd are not affected by U.S. action aimed at curbing the telecom equipment maker’s access to American technology.}}{{cite news| url=https://www.xilinx.com/news/press/2017/xilinx-powers-huawei-fpga-accelerated-cloud-server.html| title=Xilinx Powers Huawei FPGA Accelerated Cloud Server| date=6 September 2017| quote=Huawei has chosen high performance Virtex® UltraScale+™ FPGAs to power their first FP1 instance as part of a new accelerated cloud service.}} Virtex-7 processors by Xilinx, integrated into platforms by the CSIRO.{{cite book| chapter=Gemini FPGA Hardware Platform for the SKA Low Correlator and Beamformer|chapter-url=https://www.researchgate.net/publication/316324649| doi=10.23919/URSIGASS.2017.8104976|title=2017 XXXIInd General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS)|pages=1–4|year=2017|last1=Kooistra|first1=E.|last2=Hampson|first2=G. A.|last3=Gunst|first3=A. W.|last4=Bunton|first4=J. D.|last5=Schoonderbeek|first5=G. W.|last6=Brown|first6=A.|isbn=978-90-825987-0-4|s2cid=35235341}} China has pushed for a unified beamforming design that has led other major countries to drop out of the project.{{cite web| url=https://irasr.aut.ac.nz/__data/assets/pdf_file/0009/68085/John-Bunton-C4SKA_LowAimsHighpptx.pdf| page=30| title=The SKA LOW correlator design challenge| author=John Bunton| date=10 February 2017| publisher=CSIRO| access-date=20 August 2019| archive-url=https://web.archive.org/web/20190122025720/https://irasr.aut.ac.nz/__data/assets/pdf_file/0009/68085/John-Bunton-C4SKA_LowAimsHighpptx.pdf| archive-date=22 January 2019| url-status=live}} Canada continues to use Altera Stratix-10 processors (by Intel).{{cite web| first1=Dan |last1=McNamara |title=Intel FPGAs: Accelerating the Future| publisher=Intel|date=15 May 2018|url=https://newsroom.intel.com/editorials/intel-fpgas-accelerating-future/#gs.yv2lyq| quote=Canada’s NRC is helping to build the next-generation Square Kilometre Array (SKA) radio telescope...NRC’s design embeds Intel® Stratix® 10 SX FPGAs}} It is illegal for any US company to export high end Intel FPGAs or any related CSP design details or firmware to China{{cite web| title=Electronic Code of Federal Regulations: PART 121—THE UNITED STATES MUNITIONS LIST| date=22 August 2019| url=https://www.ecfr.gov/cgi-bin/text-idx?SID=86008bdffd1fb2e79cc5df41a180750a&node=22:1.0.1.13.58&rgn=div5|quote="16) Hybrid (combined analogue/digital) computers specially designed for modeling, simulation, or design integration of systems enumerated in paragraphs (a)(1), (d)(1), (d)(2), (h)(1), (h)(2), (h)(4), (h)(8), and (h)(9) of USML Category IV or paragraphs (a)(5), (a)(6), or (a)(13) of USML Category VIII (MT if for rockets, SLVs, missiles, drones, or UAVs capable of delivering a payload of at least 500 kg to a range of at least 300 km or their subsystems. See note 2 to paragraph (a)(3)(xxix) of this category);""Analog-to-digital converters, usable in the system in Item 1, having either of the following characteristics: (1) Analog-to-digital converter "microcircuits", which are "radiation hardened" or have all of the following characteristics: (i) Having a resolution of 8 bits or more;" "Item 1—Category I Complete rocket systems (including ballistic missile systems, space launch vehicles, and sounding rockets (see §121.1, Cat. IV(a) and (b))) and unmanned air vehicle systems (including cruise missile systems, see §121.1, Cat. VIII (a), target drones and reconnaissance drones (see §121.1, Cat. VIII (a))) capable of delivering at least a 500 kg payload to a range of at least 300 km."}} amid the US-embargo{{cite web| url=http://www.defence.gov.au/ExportControls/Cryptography.asp| publisher=Department of Defense(Australia)| access-date=26 August 2019| title=Overview of Cryptography and the Defence Trade Controls Act 2012}}{{cite web| url=http://www.defence.gov.au/ExportControls/ICT.asp| title=Australian Export Controls and ICT|publisher=Department of Defense(Australia)| access-date=26 August 2019}}{{cite web| url=https://www.computerworld.com/article/2492071/politics--not-security--behind-huawei--zte-allegations--say-analysts.html| title=Politics, not security, behind Huawei, ZTE allegations, say analysts| date=8 October 2012}}{{cite web| url=https://www.computerworld.com/article/2908371/us-stops-intel-from-selling-xeon-chips-to-chinese-supercomputer-projects.html| title=U.S. stops Intel from selling Xeon chips to Chinese supercomputer projects| date=9 April 2015 |first=Michael |last=Kan |work=Computerworld}} which will severely limit cooperation.{{citation needed|date=August 2019}}

==Technology Development Project (TDP)==

The Technology Development Project, or TDP, is a {{USD|12 million}} project to specifically develop dish and feed technology for the SKA. It is operated by a consortium of universities{{clarify|which countries are involved? all US? or many in the TDP?|date=August 2019}} and was completed in 2012.{{cite web|url=http://skatdp.astro.cornell.edu/|title=Welcome to the SKA TDP Website|first=Shami|last=Chatterjee|access-date=1 February 2017|archive-url=https://web.archive.org/web/20161002002934/http://skatdp.astro.cornell.edu/|archive-date=2 October 2016|url-status=live}}

Project risks and opposition

Potential risks for priority astronomical sites in South Africa are protected by the Astronomy Geographic Advantage Act of 2007.{{Cite web |title=Astronomy Geographic Advantage Act |url=https://www.sarao.ac.za/about/astronomy-geographic-advantage-act/ |access-date=2024-01-04 |website=South African Radio Astronomy Observatory - SARAO |language=en-US}} Put in place to specifically support the South African SKA bid, it outlaws all activities that could endanger scientific operation of core astronomical instruments. In 2010, concerns were raised over the will to enforce this law when Royal Dutch Shell applied to explore the Karoo for shale gas using hydraulic fracturing, an activity that would have the potential to increase radio interference at the site.{{cite news|last=Nordling|first=Linda|title=Mining plans pose threat to South African astronomy site|url=http://www.nature.com/news/2011/110322/full/news.2011.174.html?s=news_rss|access-date=27 June 2011|newspaper=Nature|date=22 March 2011|archive-url=https://web.archive.org/web/20121105100331/http://www.nature.com/news/2011/110322/full/news.2011.174.html?s=news_rss|archive-date=5 November 2012|url-status=live}}

An identified remote station location for the southern African array in Mozambique was subject to flooding and excluded from the project,{{cite news|url=http://allafrica.com/stories/201206270018.html

|title=Mozambique: Exact Location of SKA Telescope Sought|date=26 June 2012|newspaper=AllAfrica|access-date=12 July 2012|archive-url=https://web.archive.org/web/20120823115512/http://allafrica.com/stories/201206270018.html |archive-date=23 August 2012|url-status=live}} despite the SKA Site Selection Committee technical analysis reporting that all African remote stations could implement flood mitigation solutions.{{cite web|url=http://www.skatelescope.org/uploaded/34228_120216_SSAC.Report_web.pdf|title=Report and Recommendation of the SKA Site Advisory Committee (SSAC)|access-date=12 July 2012|archive-url=https://web.archive.org/web/20160108044154/http://www.skatelescope.org/uploaded/34228_120216_SSAC.Report_web.pdf|archive-date=8 January 2016|url-status=live}}

During 2014, South Africa experienced a month-long strike action by the National Union of Metalworkers (NUMSA), which added to the delays of the installation of dishes.{{cite news

|url=http://mg.co.za/article/2014-10-30-strike-delays-ska-dish-installations

|title=October 2014 - Strike delays SKA Dish Installations

|last=Butoi

|first=Mario

|date=7 November 2014

|newspaper=Mail & Guardian

|access-date=1 November 2014

|archive-url=https://web.archive.org/web/20141101062028/http://mg.co.za/article/2014-10-30-strike-delays-ska-dish-installations

|archive-date=1 November 2014

|url-status=live

}}

The largest risk to the overall project is probably its budget, which up until 2014 had not been committed.{{cite web |url=https://www.skatelescope.org/project/ |title=SKA Project |publisher=SKA Organisation |access-date=28 October 2014 |archive-url=https://web.archive.org/web/20140701120111/https://www.skatelescope.org/project/ |archive-date=1 July 2014 |url-status=live }}

There has been opposition to the project from farmers, businesses, and individuals in South Africa since the project's inception.{{cite news|title=Astronomers and sheep farmers butt heads over the Square Kilometer Array|url=https://www.economist.com/news/middle-east-and-africa/21713855-radio-telescope-project-encounters-nimbyism-remote-part-south|newspaper=The Economist|date=5 January 2017|access-date=30 March 2017|archive-url=https://web.archive.org/web/20170331114212/http://www.economist.com/news/middle-east-and-africa/21713855-radio-telescope-project-encounters-nimbyism-remote-part-south|archive-date=31 March 2017|url-status=live}} The advocacy group called Save the Karoo has stated that the radio quiet zone would create further unemployment in the South African region where unemployment is already above 32%.{{cite web|title=Save the Karoo|url=http://savethekaroo.com/|website=savethekaroo.com/|access-date=30 March 2017|archive-url=https://web.archive.org/web/20170331032940/http://savethekaroo.com/|archive-date=31 March 2017|url-status=live}} Farmers had stated that the agriculture-based economy in the Karoo would collapse if they were forced to sell their land.{{cite web|last1=Sarah|first1=Wild|title=In South Africa, Opposition Flares against Giant SKA Radio Telescope|date=22 June 2016|url=https://www.scientificamerican.com/article/in-south-africa-opposition-flares-against-giant-ska-radio-telescope/|website=Scientific American|access-date=19 September 2017|archive-url=https://web.archive.org/web/20171204224443/https://www.scientificamerican.com/article/in-south-africa-opposition-flares-against-giant-ska-radio-telescope/|archive-date=4 December 2017|url-status=live}}{{cite journal|last1=Wild|first1=Sarah|title=Giant SKA telescope rattles South African community|journal=Nature|volume=534|issue=7608|pages=444–446|language=en|doi=10.1038/534444a|pmid=27337317|date=23 June 2016|bibcode=2016Natur.534..444W|s2cid=4451534|doi-access=free}}

Key projects

File:SKA dishes big.jpg

File:SKA cores big.jpg

The capabilities of the SKA will be designed to address a wide range of questions in astrophysics, fundamental physics, cosmology and particle astrophysics as well as extending the range of the observable universe. A number of key science projects that have been selected for implementation via the SKA are listed below.

=Extreme tests of general relativity=

For almost one hundred years, Albert Einstein's general theory of relativity has precisely predicted the outcome of every experiment made to test it. Most of these tests, including the most stringent ones, have been carried out using radio astronomical measurements. By using pulsars as cosmic gravitational wave detectors, or timing pulsars found orbiting black holes, astronomers will be able to examine the limits of general relativity such as the behaviour of spacetime in regions of extremely curved space. The goal is to reveal whether Einstein was correct in his description of space, time and gravity, or whether alternatives to general relativity are needed to account for these phenomena.

=Galaxies, cosmology, dark matter and dark energy=

The sensitivity of the SKA in the 21 cm hydrogen line will map a billion galaxies out to the edge of the observable Universe. The large-scale structure of the cosmos thus revealed will give constraints to determine the processes resulting in galaxy formation and evolution. Imaging hydrogen throughout the Universe will provide a three-dimensional picture of the first ripples of structure that formed individual galaxies and clusters. This may also allow the measurement of effects hypothetically caused by dark energy and causing the increasing rate of expansion of the universe.{{cite web|title=Galaxy Evolution, Cosmology And Dark Energy – Further Information|url=http://www.skatelescope.org/the-science/ska-key-science-projects/ska-key-science-projects/galaxy-evolution/|archive-url=https://archive.today/20120909192128/http://www.skatelescope.org/the-science/ska-key-science-projects/ska-key-science-projects/galaxy-evolution/|url-status=dead|archive-date=9 September 2012|publisher=Skatelescope.org|date=25 May 2012}}

The cosmological measurements enabled by SKA galaxy surveys include testing models of dark energy,{{Cite book |arxiv=1501.04088 |year=2015 |doi=10.22323/1.215.0024 |bibcode = 2015aska.confE..24B |s2cid=55195638 |last1=Bull |first1=Phil |last2=Camera |first2=Stefano |last3=Raccanelli |first3=Alvise |last4=Blake |first4=Chris |last5=Ferreira |first5=Pedro |last6=Santos |first6=Mario |last7=Schwarz |first7=Dominik J. |title=Proceedings of Advancing Astrophysics with the Square Kilometre Array — PoS(AASKA14) |chapter=Measuring baryon acoustic oscillations with future SKA surveys |page=024 |doi-access=free }} gravity,{{Cite book|arxiv=1501.03821 |pages=31 |year=2015 |doi=10.22323/1.215.0031 |bibcode=2015aska.confE..31R |hdl=2318/1790152 |s2cid=54072202 |last1=Raccanelli |first1=Alvise |last2=Bull |first2=Phil |last3=Camera |first3=Stefano |last4=Blake |first4=Chris |last5=Ferreira |first5=Pedro |last6=Maartens |first6=Roy |last7=Santos |first7=Mario |last8=Bull |first8=Philip |last9=Bacon |first9=D. J. |last10=Doré |first10=Olivier |last11=Ferreira |first11=Pedro |last12=Santos |first12=Mario G. |last13=Viel |first13=Matteo |last14=Zhao |first14=Gong-Bo |title=Proceedings of Advancing Astrophysics with the Square Kilometre Array — PoS(AASKA14) |chapter=Measuring redshift-space distortion with future SKA surveys |doi-access=free }} the primordial universe,{{Cite book|arxiv=1501.03851 |pages=025 |year=2015 |doi=10.22323/1.215.0025 |s2cid=59136297 |last1=Camera |first1=Stefano |last2=Raccanelli |first2=Alvise |last3=Bull |first3=Phil |last4=Bertacca |first4=Daniele |last5=Chen |first5=Xuelei |last6=Ferreira |first6=Pedro |last7=Kunz |first7=Martin |last8=Maartens |first8=Roy |last9=Mao |first9=Yi |last10=Santos |first10=Mario |last11=Shapiro |first11=Paul R. |last12=Viel |first12=Matteo |last13=Xu |first13=Yidong |title=Proceedings of Advancing Astrophysics with the Square Kilometre Array — PoS(AASKA14) |chapter=Cosmology on the Largest Scales with the SKA |doi-access=free }} and fundamental cosmology,{{Cite book |arxiv=1501.03820 |pages=32 |year=2015 |doi=10.22323/1.215.0032 |bibcode=2015aska.confE..32S |s2cid=17895596 |last1=Schwarz |first1=Dominik J. |last2=Bacon |first2=D. J. |last3=Chen |first3=Song |last4=Clarkson |first4=Chris |last5=Huterer |first5=Dragan |last6=Kunz |first6=Martin |last7=Maartens |first7=Roy |last8=Raccanelli |first8=Alvise |last9=Rubart |first9=Matthias |last10=Starck |first10=Jean-Luc |title=Proceedings of Advancing Astrophysics with the Square Kilometre Array — PoS(AASKA14) |chapter=Testing foundations of modern cosmology with SKA all-sky surveys |doi-access=free }} and they are summarised in a series of papers available online.{{Cite arXiv|eprint=1501.04076 |class=astro-ph.CO |year=2015 |last1=Maartens |first1=Roy |last2=Abdalla |first2=Filipe B. |last3=Jarvis |first3=Matt |last4=Santos |first4=Mario G. |title=Cosmology with the SKA -- overview }}{{Cite book|arxiv=1501.03989 |volume=14 |issue=2015 |year=2015 |pages=19 |doi=10.22323/1.215.0019 |bibcode = 2015aska.confE..19S |s2cid=55246221 |last1=Santos |first1=Mario |last2=Bull |first2=Phil |last3=Alonso |first3=David |last4=Camera |first4=Stefano |last5=Ferreira |first5=Pedro |last6=Bernardi |first6=Gianni |last7=Maartens |first7=Roy |last8=Viel |first8=Matteo |last9=Villaescusa-Navarro |first9=Francisco |last10=Abdalla |first10=Filipe Batoni |last11=Jarvis |first11=Matt |last12=Metcalf |first12=R. Benton |last13=Pourtsidou |first13=Alkistis |last14=Wolz |first14=Laura |title=Proceedings of Advancing Astrophysics with the Square Kilometre Array — PoS(AASKA14) |chapter=Cosmology from a SKA HI intensity mapping survey |doi-access=free }}{{Cite book |arxiv=1501.04035 |pages=17 |year=2015 |doi=10.22323/1.215.0017 |bibcode=2015aska.confE..17A |s2cid=29623186 |last1=Abdalla |first1=Filipe Batoni |last2=Bull |first2=Philip |last3=Camera |first3=Stefano |last4=Benoit Levy |first4=Aurelien |last5=Joachimi |first5=Benjamin |last6=Kirk |first6=Donnacha |last7=Kloeckner |first7=Hans Rainer |last8=Maartens |first8=Roy |last9=Raccanelli |first9=Alvise |last10=Santos |first10=Mario G. |last11=Zhao |first11=Gong-Bo |title=Proceedings of Advancing Astrophysics with the Square Kilometre Array — PoS(AASKA14) |chapter=Cosmology from HI galaxy surveys with the SKA |doi-access=free }}{{Cite book |arxiv=1501.03825 |pages=18 |year=2015 |doi=10.22323/1.215.0018 |bibcode=2015aska.confE..18J |s2cid=55630081 |last1=Jarvis |first1=Matt |last2=Bacon |first2=D. J. |last3=Blake |first3=Chris |last4=Brown |first4=Michael L. |last5=Lindsay |first5=Sam |last6=Raccanelli |first6=Alvise |last7=Santos |first7=Mario |last8=Schwarz |first8=Dominik J. |title=Proceedings of Advancing Astrophysics with the Square Kilometre Array — PoS(AASKA14) |chapter=Cosmology with SKA Radio Continuum Surveys |doi-access=free }}

=Epoch of re-ionization=

The SKA is intended to provide observational data from the so-called Dark Ages (between 300,000 years after the Big Bang when the universe became cool enough for hydrogen to become neutral and decouple from radiation) and the time of First Light (a billion years later when young galaxies are seen to form for the first time and hydrogen becomes ionized again). By observing the primordial distribution of gas, the SKA should be able to see how the Universe gradually lit up as its stars and galaxies formed and then evolved. This period of the Dark Ages, culminating in First Light, is considered the first chapter in the cosmic story of creation, and the resolving power required to see this event is the reason for the Square Kilometre Array's design. To see back to First Light requires a telescope 100 times more powerful than the biggest radio telescopes currently in the world, taking up 1 million square metres of collecting area, or one square kilometre.{{cite web | author=RiAus | date=2011 | title=Radio Astronomy: Something Kinda Awesome, (SKA)" | accessdate=1 October 2014 | url=http://vimeo.com/23460933/ | archiveurl=https://web.archive.org/web/20141211074804/http://vimeo.com/23460933 |archivedate=11 December 2014 }}

=Cosmic magnetism=

It is still not possible to answer basic questions about the origin and evolution of cosmic magnetic fields, but it is clear that they are an important component of interstellar and intergalactic space. By mapping the effects of magnetism on the radiation from very distant galaxies, the SKA will investigate the form of cosmic magnetism and the role it has played in the evolving Universe.

=Search for extraterrestrial life=

This key science program, called "Cradle of Life", will focus on three objectives: observing protoplanetary discs in habitable zones, searching for prebiotic chemistry, and contributing to the search for extraterrestrial intelligence (SETI).[https://science.nrao.edu/science/Decadal%20Survey/rfi/SKA.pdf The Square Kilometre Array Project Description for Astro 2010] {{Webarchive|url=https://web.archive.org/web/20180724224543/https://science.nrao.edu/science/Decadal%20Survey/rfi/SKA.pdf |date=24 July 2018 }} -Response to Program Prioritization Panels. James Cordes. 1 April 2009.

The SKA will be able to probe the habitable zone of Sun-like protostars, where Earth-like planets or moons are most likely to have environments favourable for the development of life.[https://www.skatelescope.org/cradle-life/ SKA - Cradle Of Life] {{Webarchive|url=https://web.archive.org/web/20150315002407/https://www.skatelescope.org/cradle-life/ |date=15 March 2015 }}. T.J.W. Lazio, J.C. Tarter, D.J. Wilner. 2004. The signatures of forming Earth-like planets imprinted on circumstellar dust may be the most conspicuous evidence of their presence and evolution, and may even detect planets capable of supporting life.[http://astronomy.curtin.edu.au/research/ska.cfm Curtin Institute of Radio Astronomy] {{Webarchive|url=https://web.archive.org/web/20150226205518/http://astronomy.curtin.edu.au/research/ska.cfm |date=26 February 2015 }} - Cradle of Life. April 2015.
Astrobiologists will also use the SKA to search for complex organic compounds (carbon-containing chemicals) in outer space, including amino acids, by identifying spectral lines at specific frequencies.
The SKA will be capable of detecting extremely weak radio emission "leakage" from nearby extraterrestrial civilizations, if they exist.

References

{{Reflist|refs=

{{Cite news

| title = Jodrell Bank chosen as base for largest radio telescope

| work = BBC News

| date = 2 April 2011

| url = https://www.bbc.co.uk/news/science-environment-12947435

| access-date = 2 April 2011

| archive-url = https://web.archive.org/web/20110403035639/http://www.bbc.co.uk/news/science-environment-12947435

| archive-date = 3 April 2011

| url-status = live

}}

External links

International

[http://www.skatelescope.org/ SKA website]
[http://www.scholarpedia.org/w/index.php?title=Square_kilometre_array&editsenior=1/ SKA on Scholarpedia]

Australia/NZ

[http://www.ska.gov.au SKA Australia web site]
[https://web.archive.org/web/20120404100722/http://www.cosmosmagazine.com/node/5201 "Inside the Square Kilometre Array"], Cosmos magazine online, January 2012
[http://theconversation.edu.au/pages/square-kilometre-array "The Square Kilometre Array Category"], The Conversation, 2011/12
{{cite web|url=http://www.atnf.csiro.au/news/aspo-newsletter/ASPO_newsletter_10.pdf|title=Australian SKA Planning Office Newsletter|work=CSIRO|date=10 April 2007|access-date=19 March 2007|url-status=dead|archive-url=https://web.archive.org/web/20120512034007/http://www.ska.gov.au/Pages/default.aspx|archive-date=12 May 2012}}
[http://www.astro.uwa.edu.au/ska/mro Boolardy Station and the Murchison Radio-Astronomy Observatory (MRO)] – University of Western Australia
[https://web.archive.org/web/20100918221820/http://local.wasp.uwa.edu.au/data/Boolardy/ Photographs from the Boolardy site, June 2010]
[http://www.ska-at-carnarvon.com A Trojan Affair] {{Webarchive|url=https://web.archive.org/web/20181123161221/http://www.ska-at-carnarvon.com/ |date=23 November 2018 }} - Novel about the SKA

Canada

[https://web.archive.org/web/20140506012419/http://www.skatelescope.ca/ Canadian SKA Consortium web site]

Europe

[http://www.skads-eu.org/ SKA Design Studies web site] {{Webarchive|url=https://web.archive.org/web/20111230231313/http://www.skads-eu.org/ |date=30 December 2011 }}

South Africa

[http://www.ska.ac.za SKA South Africa web site]

Other

{{cite web|last=Merrifield|first=Michael|title=Where to Build The Square Kilometre Array?|url=http://www.deepskyvideos.com/videos/other/SKA_decision.html|work=Deep Space Videos|publisher=Brady Haran|author2=Crowther, Paul }}
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