 Artist's impression | |
| Alternative names | SKA |
|---|---|
| Location(s) | Meerkat National Park, South Africa andMurchison Radio-astronomy Observatory, Australia |
| Coordinates | 30°43′16″S21°24′40″E / 30.72111°S 21.41111°E /-30.72111; 21.41111 and26°41′49″S116°37′52″E / 26.69694°S 116.63111°E /-26.69694; 116.63111 |
| Built | 2018– |
| First light | 2027 (projected) |
| Collecting area | 1 km2 (11,000,000 sq ft) |
| Website | www |
 Related media on Commons | |
TheSquare Kilometre Array (SKA) is anintergovernmental internationalradio 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 theJodrell Bank Observatory in the United Kingdom. The SKA cores are being built in theSouthern Hemisphere, where the view of theMilky Way galaxy is the best andradio interference is at its least.
Conceived in the 1990s, and further developed and designed by the late-2010s, when completed it would have a total collecting area of approximately onesquare 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.[1] 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 tosurvey 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 exploitradio astronomy's ability to provide the highest-resolution images in all astronomy.
The SKAO consortium was founded inRome in March 2019 by seven initial member countries, with several others subsequently joining; as of 2021[update] 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.
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.[2]
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 proposalKilometer-square Area Radio Synthesis Telescope (KARST).[3][4]
Australia's firstradio quiet zone was established by theAustralian Communications and Media Authority on 11 April 2005 specifically to protect and maintain the current "radio-quietness" of the main Australian SKA site at theMurchison Radio-astronomy Observatory.[5]
The project has two phases of construction: the current SKA1, commonly just called SKA, and a possible later significantly enlarged phase sometimes called SKA2.[6] PrepSKA commenced in 2008, leading to a full SKA design in 2012. Construction of Phase 1was scheduled to take place from 2018 to 2020,[needs update] providing an operational array, with Phase 2 completion in 2025.[citation needed]
In April 2011,Jodrell Bank Observatory of theUniversity of Manchester, inCheshire, England was announced as the location for the project headquarters.[7] In November 2011, the SKA Organisation was formed as anintergovernmental organisation[8] and the project moved from a collaboration to an independent, not for profit, company.[9]
In February 2012, a former Australian SKA Committee[clarification needed] 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.[10] 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.[11] However a scientific working group was set up to explore possible implementation options of the two candidate host regions,[12] 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.[13] 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.[14]
In April 2015, the headquarters of the SKA project were chosen to be located at theJodrell Bank Observatory in the UK,[15][16] officially opened in July 2019.[citation needed]
Initial construction contracts began in 2018. Scientific observations with the fully completed array are not expected any earlier than 2027.[17][18]
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 contractsexpected to be awarded in late 2020.[needs update][19]
By mid-2019, the start of scientific observations were expected to start no earlier than 2027.[17] In July 2019, New Zealand withdrew from the project.[17]
As of November 2020[update], five precursor facilities were already operating:MeerKAT and theHydrogen Epoch of Reionization Array (HERA) in South Africa, theAustralian SKA Pathfinder (ASKAP) andMurchison Widefield Array (MWA) inWestern Australia and the International LOFAR Telescope, spread across Europe with a core in the Netherlands.[20]
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.[21] The Australian part of the project comprises 100,000 antennas built across 74 km (46 mi), also in theMurchison region, in thetraditional lands of theWajarri Aboriginal people.Bulldozerswere expected to start working on the site in early 2023,[needs update] with the completion date estimated as 2028. The site has been namedInyarrimanha Ilgari Bundara, which means'sharing sky and stars' in theWajarri language.[22]
TheDepartment of Atomic Energy (DAE) in India andUK Research and Innovation (UKRI) are investigating the possibility of establishingsupercomputing 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.[23] 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.[24]
The SKA will combine the signals received from thousands of smallantennas 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 calledaperture synthesis.[26] Some of the sub-arrays of the SKA will also have a very largefield-of-view (FOV), making it possible to survey very large areas of sky at once.[27] One innovative development is the use offocal-plane arrays usingphased-array technology to provide multiple FOVs.[28] 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.[29]
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.[30][31][6] There will be continuous frequency coverage from 50 MHz to 14 GHz in the first two phases of its construction.
The frequency range from 50 MHz to 14 GHz, spanning more than twodecades, 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:
The area covered by the SKA – extending out to ~3000 km – will comprise three regions:[26][38]
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.[39][40] There have been numerous delays and rising costs over the nearly 30-year history of the intergovernmental project.[17]
As of December 2022[update], the whole project was reported to be worth around A$3 billion.[22]
As per March 2025, the members of the SKAO consortium were:[9][41][42]
The headquarters of the SKA are located at theUniversity of Manchester'sJodrell Bank Observatory inCheshire, England,[62] while the telescopes will be installed in Australia and South Africa.[63]
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.[64] 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):[65]
The core site is located at theMurchison Radio-astronomy Observatory (MRO) atMileura Station nearBoolardy in the state ofWestern Australia, 315 km (196 mi) north-east ofGeraldton[66][67]
The core site is located at theMeerkat National Park, at an elevation of about 1000 metres, in theKaroo area of the aridNorthern Cape Province. There are also distant stations inBotswana,Ghana,Kenya,Madagascar,Mauritius,Mozambique,Namibia andZambia.[68]
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.
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 asphased array feeds to give a wide field of view (30 square degrees). ASKAP was built byCSIRO at the Murchison Radio-astronomy Observatory site, located nearBoolardy in the mid-west region of Western Australia. All 36 antennas and their technical systems were officially opened in October 2012.[69]
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 theMeerkat National Park nearCarnarvon 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.[70][needs update] The dishes are equipped with a number of high performance single pixel feeds to cover frequencies from 580 MHz up to 14 GHz.[71]
The Murchison Widefield Array[72] is a low-frequencyradio 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.
The HERA array is located in South Africa's Meerkat National Park. It is designed to study highly redshiftedatomic hydrogen emission emitted prior to, and during the epoch of reionization.
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?] The dish design has explored methods of low-cost manufacture.[83]
The International LOFAR Telescope—a €150 million Dutch-led project—is 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.[84][needs update]. 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.
| Data challenges of SKA pathfinders | ||||
|---|---|---|---|---|
| Challenge | Specifications[85] budgeted for ASKAP Requirements for the SKA itself are about 100 times greater. | |||
| Large bandwidth from telescope to processor | ~10 Tbit/s from antennas to correlator (< 6 km) 40 Gbit/s from correlator to processor (~ 600 km) | |||
| Large processing power | 750 Tflop/s expected/budgeted 1 Pflop desired | |||
| Power consumption of processors | 1 MW at site 10 MW for processor | |||
| Pipeline processing essential | including data validation, source extraction, cross-identification, etc. | |||
| Storage and duration of data | 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 | |||
| Retrieval of data by users | all data in public domain accessed using VO tools & services | |||
| Data-intensive research | data mining, stacking, cross-correlation, etc. | |||
The amount of sensory data collected poses a huge storage problem, and will require real-timesignal processing to reduce the raw data to relevant derived information. In mid 2011 it was estimated the array could generate anexabyte a day of raw data, which could be compressed to around 10petabytes.[91] 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 theShanghai Astronomical Observatory, stated, "It will generate data streams far beyond the total Internet traffic worldwide." TheTianhe-2 supercomputer was used in 2016 to train the software. The processing of the project will be performed on Chinese-designed and -manufactured[92][93] Virtex-7 processors byXilinx, integrated into platforms by theCSIRO.[94] China has pushed for a unifiedbeamforming design that has led other major countries to drop out of the project.[95] Canada continues to use Altera Stratix-10 processors (byIntel).[96] It is illegal for any US company to export high end IntelFPGAs or any related CSP design details or firmware to China[97] amid the US-embargo[98][99][100][101] which will severely limit cooperation.[citation needed]
The Technology Development Project, or TDP, is aUS$12 million project to specifically develop dish and feed technology for the SKA. It is operated by a consortium of universities[clarification needed] and was completed in 2012.[102]
Potential risks for priority astronomical sites in South Africa are protected by the Astronomy Geographic Advantage Act of 2007.[103] 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 whenRoyal Dutch Shell applied to explore theKaroo forshale gas usinghydraulic fracturing, an activity that would have the potential to increaseradio interference at the site.[104]
An identified remote station location for the southern African array inMozambique was subject to flooding and excluded from the project,[105] despite the SKA Site Selection Committee technical analysis reporting that all African remote stations could implement flood mitigation solutions.[106]
During 2014, South Africa experienced a month-long strike action by theNational Union of Metalworkers (NUMSA), which added to the delays of the installation of dishes.[107]
The largest risk to the overall project is probably its budget, which up until 2014 had not been committed.[108]
There has been opposition to the project from farmers, businesses, and individuals in South Africa since the project's inception.[109] 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%.[110] Farmers had stated that the agriculture-based economy in the Karoo would collapse if they were forced to sell their land.[111][112]
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The capabilities of the SKA will be designed to address a wide range of questions inastrophysics,fundamental physics,cosmology andparticle astrophysics as well as extending the range of theobservable universe. A number of key science projects that have been selected for implementation via the SKA are listed below.
For almost one hundred years,Albert Einstein'sgeneral 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 usingpulsars as cosmicgravitational wave detectors, or timing pulsars found orbitingblack holes, astronomers will be able to examine the limits of general relativity such as the behaviour ofspacetime in regions of extremely curved space. The goal is to reveal whether Einstein was correct in his description of space, time and gravity, or whetheralternatives to general relativity are needed to account for these phenomena.
The sensitivity of the SKA in the21 cm hydrogen line will map a billion galaxies out to the edge of the observable Universe. Thelarge-scale structure of the cosmos thus revealed will give constraints to determine the processes resulting ingalaxy formation and evolution. Imaginghydrogen throughout the Universe will provide athree-dimensional picture of the first ripples of structure that formed individual galaxies and clusters. This may also allow the measurement of effectshypothetically caused bydark energy and causing the increasingrate of expansion of the universe.[113]
The cosmological measurements enabled by SKA galaxy surveys include testing models of dark energy,[114] gravity,[115] the primordial universe,[116] and fundamental cosmology,[117] and they are summarised in a series of papers available online.[118][119][120][121]
The SKA is intended to provide observational data from the so-calledDark Ages (between 300,000 years after theBig Bang when the universe became cool enough for hydrogen to become neutral and decouple from radiation) and the time ofFirst 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.[122]
It is still not possible to answer basic questions about the origin and evolution ofcosmic 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.
This key science program, called "Cradle of Life", will focus on three objectives: observingprotoplanetary discs inhabitable zones, searching for prebiotic chemistry, and contributing to the search for extraterrestrial intelligence (SETI).[123]
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.
Huawei has chosen high performance Virtex® UltraScale+™ FPGAs to power their first FP1 instance as part of a new accelerated cloud service.
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
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.
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