The Square Kilometre Array will be the most powerful radio telescope in the world. It will enable transformational science that will change our understanding of the Universe. Split between the remote deserts of South Africa and Australia, the telescope will consist of hundreds of antennas that will generate unprecedented data volumes.
The Netherlands is an official partner in the SKA and ASTRON leads the Dutch effort in this highly international and global project. Construction of the SKA is due to start in 2021.
The Square Kilometre Array (SKA) will be the world's largest radio telescope. The antennas and dishes and first stages of data processing will be built in the remote deserts of Western Australia and South Africa. The project is currently in the final stages of design. Construction is due to start in 2021.
The table below lists key characteristics and technical specifications for the first phase of the SKA. You can also see a comparison of the SKA with other radio telescopes or explore more SKA technical details.
Time-frame for deployment and early science
2021 – 2027
2021 – 2027
Number of stations, antennas or dishes
131,072 antennas distributed over 512, 35-m diameter stations
197 (including 64, 13.5-m diameter MeerKAT dishes)
Frequency coverage (MHz)
50 – 350
350 – 15300
Instantaneous bandwidth (MHz)
1000 – 5000
Field of view
2.3 – 113
0.007 – 12.5
Maximum baseline (km)
3.3 – 23
0.03 – 1.4
(μJy beam-1 hr-1, fractional bandwidth 0.3)
14 – 26
1.2 – 4.4
The NL-SKA Office
Twelve countries now form the core of the SKA project, while more than 100 organisations from 18 different countries participate in the development of the telescope.
NWO is the formal Dutch representative in the Square Kilometre Array organisation, while ASTRON (1) coordinates the plan for Dutch involvement in SKA on behalf of the entire astronomical community in The Netherlands, and (2) contributes major components and systems for the SKA.
ASTRON was among the founding partners of the SKA and has played a major role in advocating the science case and conceptual design of the SKA. The Research and Development group at ASTRON has made and continues to make significant contributions to the design and prototyping of key SKA subsystems and provide experts to serve on key Boards and advisory bodies.
Science with SKA
The ambitious SKA science case covers key fundamental topics in astrophysics covering over 13.6 billion years of cosmic time: from 100 million years after the Big Bang, when the first stars began to form (the 'Cosmic Dawn'), through to the present day, dark energy dominated, accelerating Universe. The SKA will bring new insights about the formation and evolution of radio galaxies, quasars, supernovae, pulsars, fast radio bursts, flare stars and many other cosmic objects. In 2015, the SKA Organisation (SKAO) published a 2000-page, 2-volume SKA science book. The unique capabilities of the SKA will also bring completely unexpected discoveries.
The Netherlands continues to play a vital leading role in SKA science. ASTRON is represented in all 13 science working groups and focus groups, and several staff astronomers have previously or currently lead specific working groups.
Astronomers at ASTRON and in the Netherlands carry out high-impact, world-class science with SKA precursors and pathfinders, such as LOFAR and WSRT-APERTIF, and develop the detailed expertise that will be required to fully exploit the scientific capabilities of the SKA. The Dutch astronomy community also holds annual SKA-NL science meetings (see SKA-NL 2017 and SKA-NL 2018).
Design and Technology
The design of the SKA is being delivered by 12 international engineering consortia with contributions from over 500 engineers and scientists from the SKA member countries and beyond. ASTRON is involved in the following consortia, focusing on various aspects of the low frequency phased array SKA-low.
Low Frequency Aperture Array (LFAA)
The Low Frequency Aperture Array consortium is developing the antennas, low noise amplifiers, analogue signal transport, A/D conversion and beamforming stages of the SKA-low signal chain.The LFAA covers the low frequency band of the SKA, between 50 and 350 MHz. Over 130,000 two metre high antennas are distributed in 512 stations spread across an area 60 km in diameter. The individual antenna signals are converted from the analogue to the digital domain and combined into beams on the sky which are subsequently fed into the Correlator and Beamformer developed by the Central Signal Processor (CSP) consortium.
ASTRON leads the consortium, focusing on project management and system engineering as well as the deployment of the Aperture Array Verification System (AAVS1) a prototype SKA low station installed at the Murchison Radio Observatory, close to the SKA-low site in Western Australia. The team has extensive experience building modern low frequency aperture array systems, such as LOFAR, the Murchison Widefield Array and Nenufar.
Central Signal Processor (CSP)
The Central Signal Processor element is the “brain” of each of the SKA telescopes. It combines the digitised astronomical signals detected by the SKA antenna stations and dishes. Its output can be used to make images of the sky or the summed data streams (known as beams) can be analysed to search for signals from time variable sources, such as pulsars. The CSP element includes the design of extremely high performance signal processing hardware as well as associated firmware/software that is required to implement the various observation modes. The CSP consortium, led by the National Research Council (Canada), is split in two teams, developing independent correlator/beamformers for the two SKA telescopes. ASTRON is involved in the design and development of Perentie, the correlator/beamformer for SKA-low, together with CSIRO (Australia, lead organisation) and Auckland University of Technology (AUT, New Zealand).
The team have developed the Gemini high performance signal processing board which forms the heart of the correlator. Each board has a state-of-the-art Xilinx Field Programmable Gate Array (FPGA). 288 Gemini boards will process 5.8 Terabits of data per second from the 512 SKA-low antenna stations. The board is water-cooled with an ASTRON designed mono-cool block which dissipates the considerable amount of heat that the electronic components on the board generate. The prototype boards were produced by a Dutch company from the EMS sector.
Science Data Processor (SDP)
The SKA Science Data Processor (SDP) is the final stage of the SKA processing chain, before handing over the data to the astronomers. The purpose of the SDP is to take the data streams from the SKA Central Signal Processor (CSP) and turn them into science-ready data products. In order to handle the vast amounts of incoming data (currently several Tbit / sec per instrument), the SDP will be based on a scalable, data-driven architecture that heavily exploits data parallelism.
There will be two instantiations of the SDP: one in Cape Town, South Africa, for the SKA-MID and one in Perth, Australia, for the SKA-LOW. Data may be accessed through the Archive Facilities on these sites or through Regional Science Centers which are to be located all over the globe. The ASTRON contribution has been to lead the design of the compute hardware.
The Electronic Multi Beam Radio Astronomy ConcEpt (EMBRACE) demonstrates the design readiness of the phased array technology for the Square Kilometre Array (SKA). There are two stations, one in Nançay, France, and the other one at the Westerbork Synthesis Radio Telescope (WSRT) in the Netherlands.
The front-end consists of the antenna array including a radio frequency transparent radôme and supporting mechanics for the array. The array is organised in tiles of approximately a square meter containing 144 antenna elements in dual polarisation. Each tile is independently controlled by means of a local control unit (LCU), which is located in the back-end. All tiles will only listen and act as slave. The back-end contains all remaining electronics required for processing the signals from the tiles including the control subsystem. The back-end part is hosted in a small shelter near the array. For more details click here.
Mid Frequency Aperture Array
The "Mid-Frequency Aperture Array" (MFAA) element of the SKA, part of the SKA Advanced Instrumentation Programme, includes the activities necessary for the development of a set of antennas, on board amplifiers and local processing required for the Aperture Array telescope of the SKA. MFAA includes the development of local station signal processing and hardware required to combine the antennas and the transport of antenna data to the station processing.
The overriding objectives of the MFAA Consortium are to prove the technological maturity of the Mid-Frequency Aperture Array technology, and to evaluate different concepts of front-end technology that can serve to assist in the preliminary design of the MFAA. When a concept is selected, it will then taken further in Stage 2 towards the preliminary design.
The two EMBRACE (Electronic Multibeam Radio Astronomy Concept ) stations built as part of the SKA Design Study project, located near the Westerbork in the Netherlands and at Nançay Observatory in France, are platforms that will function as test-bed for new developments and further validation of the key-technologies.
The SKA Mid frequency aperture array is scheduled to be deployed in the second phase of the construction of the SKA. It will cover a wide-range of radio frequencies from 400 MHz upwards. One of the key science goals for these telescopes will be their planned mission to measure the effects of dark energy on the Universe, as well as doing high speed surveys for pulsars and other radio transient events. This requires very high sensitivities, with the ability to detect very small variations in the observed signal.
Business Opportunities with the SKA
The ambitious objectives of the Square Kilometre Array (SKA) make some critical demands, requiring game-changing technologies: these are innovations that shift the boundaries of what it possible. For example: energy efficient calculations, processing of unimaginably vast amounts of data and the need to develop smart algorithms that will allow us to make the deepest and sharpest images of the sky.The developments for SKA are also relevant beyond the field of science. They fit well with current themes in society, such as the need for communication technology, fast networks and industrial automation.
The Dutch participation in SKA will be an important driver for innovation in information technology, for example because knowledge developed for processing large amounts of data can be applied in retail analytics, industry 4.0 and energy-efficient use of computers. The advance in sensor technology, combined with real-time monitoring is relevant for traffic flows, intelligence services and healthcare (healthy ageing).
Within the SKA project the members have agreed that each participating country receives a share in construction contracts that is proportional to their contribution. Dutch companies and institutes are already well-positioned to acquire contracts in many areas, for example the supply of parts for the telescope and advanced software.
ASTRON Science Data Center
The SKA will generate more data than we have processed and analysed ever before. To make this possible, innovation in hardware, software and expertise is crucial. This drives the need for a Science Data Centre (SDC) in (the north of) the Netherlands, facilitated by a public-private partnership of science, government and industry.
Investing in the Science Data Centre is an investment in far more than radio astronomy: there is a growing number of other disciplines facing big data challenges. Cooperation between these disciplines and with the Dutch academic service providers will yield tremendous added value.
The Science Data Centre demands high-end hardware and innovative software, coupled with the development of expertise in data science. While SKA data volumes will be immense, the data produced by ASTRON’s current telescopes, LOFAR and WSRT-APERTIF, are already challenging and will be used in the coming years to prepare for SKA.
Michiel van Haarlem
Head of NL-SKA Office