This year is going to be a key year in the process of transforming the international Square Kilometre Array (SKA) radio telescope programme from concept to concrete. “We’ll have a huge amount of work going on – on the design of the SKA and its systems and subsystems,” explains SKA Organisation director-general Professor Philip Diamond. “In the third quarter of the year, we’ll have the preliminary design reviews (PDRs) for all the work groups. No major decisions will be made until the PDRs have taken place. And I’m hoping that the hosting agreements will be finalised and agreed – but not signed. They will not be signed until the governance details are worked out.”

The SKA is going to be the biggest, most sensitive radio telescope ever built. The telescope will be co-located in Africa and in Australia, with the core of the African part in South Africa. Phase 1 of the instrument will be composed of a midfrequency dish array in South Africa and low-frequency aperture arrays and a dish survey instrument in Australia. These arrays will collect and focus different radio wavelengths emitted by the many different categories of stars and other cosmological phenomena, including novas, supernovas, gas clouds, pulsars, quasars, and the accretion discs and gas jets associated with black holes (more formally known as singularities). This data will then have to be conveyed from the many antennas to computer networks for processing before computer-assisted analysis by astronomers, astrophysicists and cosmologists around the world.

“Most of the research and development (R&D) for the SKA has been done,” reports Diamond. “Decisions still have to be made, but we are in the development and design phase now. Only in some areas are we still doing R&D – most notably, concerning advanced instrumentation packages. If these come good, they may be considered for Phase 1; if not, they will be part of Phase 2.”

Oversight and Funding
The SKA Organisation is the international agency set up to oversee the SKA project. A not-for-profit private company under UK law, it is based at the world-renowned Jodrell Bank Observatory, in Cheshire, England, not far from Manchester, and is coordinating all SKA activities around the world. These include the science, engineering, operations and public information programmes. The organisation’s head office building was funded by the University of Manchester, which runs Jodrell Bank. Set up in December 2011, the SKA Organisation replaced the previous, smaller, SKA Project Office (which was based on the University of Manchester campus).

“The concept of the SKA developed in the 1990s,” says Diamond. “Astronomers were pondering the next big questions in astronomy and what instruments would be needed to try to answer them.”

In 1997, this resulted in institutions from six countries – Australia, Canada, China, India, the Netherlands and the US – signing a memoradum of agreement (MoA) to cooperate in a programme to study the technologies required for a very large radio telescope. In 2000, the International Astronomical Union meeting that year (held in Manchester) saw eleven countries sign a memorandum of understanding (MoU), which created the International Square Kilometre Array Steering Committee (ISSC). Those countries were Australia, Canada, China, Germany, India, Italy, the Netherlands, Poland, Sweden, the UK and the US. The MoU was replaced by a new MoA which came into effect at the start of 2005 and which created a 21-member steering committee and the SKA Project Office.

At the beginning of 2008, a new Interna- tional Collaboration Agreement for the SKA came into force. This had been signed by the Canadian, European and US SKA consortia, South Africa’s National Research Foundation (NRF), the Australian SKA Coordination Committee, China’s National Astronomical Observatories and India’s National Centre for Radio Astrophysics (NCRA). This agreement replaced the ISSC with the SKA Science and Engineering Committee (SSEC). At the same time, another MoA setting up the SKA Programme Development Office (SPDO) came into effect. This document was signed by the Joint Institute of Very Long Baseline Interferometry in Europe, the NRF, Calgary University, in Canada, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia Telescope National Facility and Cornell University, in the US. The SPDO was created to provide the structure for the internationalisation of SKA technology design and development. The MoA provided that the signatories would fund the SPDO and its operational activities.

Today, the SKA Organisation has 11 member countries. These are Australia (represented by the Department of Industry), Canada (National Research Council – NRC), China (National Astronomical Observatories of the Chinese Academy of Sciences), Germany (Federal Ministry of Education and Research), Italy (National Institute for Astrophysics), the Netherlands (Netherlands Organisation for Scientific Research), New Zealand (Ministry of Economic Development), South Africa (NRF), Sweden (Onsala Space Observatory) and the UK (Science and Technology Facilities Council). India, through the NCRA, is an associate member. Further, work on the SKA is also being carried out in Brazil, France, Japan, Malta, Poland, Portugal, Russia, Spain, South Korea and the US. In all, some 100 agencies in about 20 countries are involved in the design and development of the SKA.

“I’m pretty sure that India will be the next country off the block and become a full member of the SKA,” reports Diamond. “We’re having conversations with several other countries. I’d expect to see a couple more join this year and a couple more in 2015. To participate in the design phase does not cost a huge amount of money. No one has committed money for the construction phase yet. We have to design it first!”

The current phase – the design phase – is fully funded. “We have €120-million,” he states. “The €120-million is secure. About €25-million is coming to the SKA office in cash to fund our operations, and €95-million is being provided for the consortia to fund the design work. About 65% of that €95- million is new, while 35% is existing funding for staff and institutions. Many institutions are also putting heir own resources into the project, but we have no firm figures.”

Strikingly, the global economic recession that started in 2008 has had little impact on the SKA. “It is surprising that the impact on the SKA has been relatively minimal, with one outstanding case – the US,” says Diamond. “We have eleven countries signed up. They have provided all the money needed so far. But the US has a problem, namely sequestration.” (Sequestration refers to automatic US government spending cuts that came into effect on March 1.) “That is part of the reason that the US is not part of the SKA at the moment. They’re in a tougher situation than some of their international counterparts at the moment. Our partner nations have provided full commitments for the next three years.”

For the actual construction of Phase 1 of the SKA, the board of the SKA Organisation has set a cap of €650-million. This figure is the capital expenditure for the construction of the instrument, and excludes the design costs and the operating costs. “Phase 2 will cost considerably more,” he points out. “But I can’t put a number on it yet.” The building of Phase 1 is scheduled to start in 2018 with scientific commissioning and start of operations in 2020. Phase 2 will add midfrequency aperture antennas to the array. By the time Phase 2 is completed, the SKA will comprise thousands of dishes and millions of other antennas spread across Africa (not just South Africa) and Australia.

Work Packages

In early November last year, the SKA Organisation announced the different work packages that would be used to develop the technologies for the SKA, and the consortia that would carry them out. At that time, SKA board chairperson Professor John Womersley stated: “Each element of the SKA is critical to the overall success of the project and we certainly look forward to seeing the fruits of each consortium’s hard work shape up over the coming years. Now, this multidisciplinary team of experts has three full years to come up with the best technological solutions for the final design of the telescope, so we can start tendering for construction of the first phase in 2017 as planned. The directors of the SKA board feel that the consortia selected represent some of the world’s very finest scientists and engineers.” In all, the consortia encompass more than 350 scientists and engineers from 18 countries.

There are ten work packages, although one of these is split into two, meaning that there are eleven consortia involved. These are the dish work package (known as DSH for short), which includes the phased array feeds – this is the responsibility of a consortium led by Dr Mark McKinnon of Australia’s CSIRO; the Low Frequency Aperture Array (or LFAA) package, led by Jan Geralt Bij de Vaate of the Netherlands Institute for Radio Astronomy; the Mid-Frequency Aperture Array (MFAA), also led by Bij de Vaate; the Telescope Manager (TM), headed by Professor Yashwant Gupta of India’s NCRA; the Science Data Processor (SDP), led by the University of Cambridge’s Professor Paul Alexander; the Central Signal Processor (CSP), headed by David Loop of Canada’s NRC; Signal and Data Transport (SaDT), which includes synchronisation, led by Dr Keith Grainge of the University of Manchester (UK); Assembly, Integration and Verification (AIV), headed by SKA South Africa’s (SKA SA’s) Dr Richard Lord; Infrastructure, which is divided into Infrastructure South Africa (INFRA-SA), led by Tracy Cheetham of SKA SA, and Infrastructure Australia (INFRA-AUS), headed by Dr Michelle Storey of the CSIRO; and the Wideband Single Pixel Feeds (WBSPF), led by Professor John Conway of Sweden’s Chalmers University.

The DSH package incorporates everything required for the acquisition and operation of the dishes for the SKA. This includes all the associated electronics, feeds, local control (pointing the dish) and monitoring, local infrastructure, as well as planning for their manufacture, transport, erection, fitting out and testing. A final design for the SKA dishes has not yet been selected – three options are under consideration. One is a Canadian design, in a programme headed by that country’s NRC, the second is a Chinese design, being developed by China Electronics Technology Corporation No 54, while the third is South Africa’s MeerKAT dish which is being developed by SKA SA with US company General Dynamics Satcom (most of the key intellectual property is South African). Prototypes of all three dishes will be completed during this year, with the Canadian starting testing first, followed by the MeerKAT dish and then the Chinese one.

The LFAA consortium covers the antennas, antenna-mounted amplifiers and the local processing for this component of the SKA. It includes the hardware needed to link the antennas and to convey their data to the local processing station, as well as the design of the local station signal processing system. Again, local control and monitoring are incorporated, as is the aperture array software development.

The MFAA team forms part of the advanced instrumentation programme. This package essentially replicates the work of the LFAA, but for mid-range frequencies.

The TM group has the responsibility for developing the system that will monitor the entire SKA. This will include monitoring the engineering and operational condition of all the telescope’s components.

The SDP package will be concerned with computing the algorithm, software and hardware design for the processing of the data from the correlator (which is the non- imaging data processor for the SKA) to produce usable science data products.

The CSP consortium will be responsible for the telescope’s brain. The CSP itself will convert the data gathered by the dishes and other antennas into the information needed by the SDP system to produce detailed images of the phenomena being observed by the SKA. Further, this team will design a non-image processor to allow an unprecedentedly large-scale search for undiscovered pulsars and to precisely time already known pulsars.

The SaDT team are responsible for designing the SKA’s backbone. The telescope will have three data transport networks – the digital data backhaul (taking signals from the antennas to the CSP), the network carrying the converted data from the CSP to the SDP and the network linking the SDP to regional SKA Data Centres.

The AIV package incorporates the planning of all remote site activities needed to connect the SKA elements, including SKA precursor telescopes, with existing infrastructures.

The INFRA-SA and INFRA-AUS groups are in charge of their respective local facilities. Each will have to take care of all the SKA infrastructure, across huge distances, in their respective countries and regions. Their responsibilities include the construction and maintenance of buildings, roads, power generation and distribution facilities and water reticulation systems, as well as the deployment and use of vehicles, cranes and other specialist maintenance equipment. These teams will not be responsible for land access rights, protecting against external interference, environmental monitoring or protection.

The WBSPF consortium is also part of the advanced instrumentation programme. This group is seeking to develop a broad spectrum band single-pixel feed for the SKA.

“The hardest bit is data transport and processing: the computing,” affirms Diamond. “That’s where we’re pushing the state of the art. On Phase 1, we’ll have to handle huge data rates – ten times the current global internet traffic.”

“SKA SA, South African industries and academics are involved in all of the SKA design consortia that are relevant to the SKA midfrequency dish array, the component of the SKA to be deployed in South Africa,” highlights SKA SA associate director: science and engineering Professor Justin Jonas. “There is also some academic involvement in SKA-low, to be deployed in Australia. South Africa has concentrated its efforts in the systems engineering aspects of the various consortia, so we will have a significant influence on the design of the various subsystems and of the instrument as a whole. Assembly, integration and verification form an essential part of systems engineering – hence, our leadership of this work package. South Africa is also significantly involved in specialist technical domains such as single- pixel receivers, digital signal processing, computing and dish design.”

Precursors

The SKA is being preceded by a number of pathfinders – a set of ten existing, refurbished or new telescopes and arrays that are undertaking SKA-related technology and science projects – and precursors. The precursors are new design radio telescope arrays situated in the future locations of the SKA, which will help develop and test the technologies needed by the SKA, as well as carrying out scientific research. There are three precursors – one in South Africa and two in Australia.

The South African precursor is the 64-dish MeerKAT, which is now under construction. This has been preceded by a prototype array, the seven-dish KAT-7 (for Karoo Array Telescope). It has proven much more successful than expected. “KAT-7 has evolved from its originally intended role as an engineering prototype into a fully fledged science instrument that has most of its operating time allocated to scientific observations,” reports Jonas. “International science teams are making use of niche characteristics of KAT-7 to perform experiments that cannot be done on larger and more established telescopes.

“The development and delivery of MeerKAT is well under way, with nearly all the infrastructure contracts being completed in the next few months,” he elucidates. “This infrastructure includes dish construction buildings, the buried data processing and electrical power facility, and the 64 antenna foundations. The first two MeerKAT antennas are being fabricated in specialist steel fabrication factories in Gauteng, and the first prototype receiver is undergoing field tests at the Karoo site. Digital electronics and computing systems are also in prototype and early development phases. The first antenna will be on site early this year and all the subsystems are on schedule for the delivery of the completed MeerKAT at the end of 2016.”

In Australia, there are the Murchison Widefield Array (MWA) and the Australian SKA Pathfinder (ASKAP). The MWA is a joint Australia, India, New Zealand and US programme and is a low-frequency antenna array operating between 80 MHz and 300 MHz. Already operational, it is composed of 2 048 dual-polarisation dipole antennas deployed in 128 ‘tiles’, each of 16 antennas arranged in a 4 × 4 pattern. These are organised into a core (112 tiles in a 1.5 km2 area) and 16 outstations, each about 1.5 km from the core.

ASKAP is a 36 dish array. It will be able to survey the sky much more rapidly than any existing telescope or array. “It’s at a more advanced stage than MeerKAT, which is still under construction,” points out Diamond. “It’s built and in the commissioning phase. It should start early science within six months. The recent change of government in Australia has had no effect. There is bipartisan support for the SKA and that continues with the new government. The Australian government has put A$19-million into the pot for the SKA design phase. And some of their institutions have added funds from their own resources. Things are gong very well there; they’re very active and supportive.”

Both the ASKAP and MeerKAT precursors will, in due course, be integrated into SKA Phase 1. “All technology and infrastructure work is coordinated through the SKA Organisation,” notes Jonas. “The consortia are operating very well, despite being dis- tributed across the globe.”