The SKA Project
The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, with eventually over a square kilometre (one million square metres) of collecting area. The scale of the SKA represents a huge leap forward in both engineering and research & development towards building and delivering a unique instrument, with the detailed design and preparation now well under way. As one of the largest scientific endeavours in history, the SKA will bring together a wealth of the world’s finest scientists, engineers and policy makers to bring the project to fruition.
The SKA will eventually use thousands of dishes and up to a million low-frequency antennas that will enable astronomers to monitor the sky in unprecedented detail and survey the entire sky much faster than any system currently in existence.
Its unique configuration will give the SKA unrivalled scope in observations, largely exceeding the image resolution quality of the Hubble Space Telescope.
It will also have the ability to image huge areas of sky in parallel a feat which no survey telescope has ever achieved on this scale with this level of sensitivity. With a range of other large telescopes in the optical and infra-red being built and launched into space over the coming decades, the SKA will perfectly augment, complement and lead the way in scientific discovery.
Both South Africa’s Karoo region and Western Australia’s Murchison Shire were chosen as co-hosting locations for many scientific and technical reasons, from the atmospherics above the sites, through to the radio quietness, which comes from being some of the most remote locations on Earth.
South Africa’s Karoo will host the core of the high and mid frequency dishes, ultimately extending over the African continent. Australia’s Murchison Shire will host the low-frequency antennas.
A global effort
Whilst 10 member countries are the cornerstone of the SKA, around 100 organisations across about 20 countries are participating in the design and development of the SKA. World leading scientists and engineers designing and developing a system which will require supercomputers faster than any in existence in 2015, and network technology that will generate more data traffic than the entire Internet.
The SKA will be developed over a phased timeline. Pre-construction development started in 2012 and will last until the latter half of this decade, involving the detailed design, implementation, R&D work, and contract preparation needed to bring the SKA’s first phase to construction readiness. This first phase will involve testing the full system in a “proof of concept” manner.
In Australia, the SKA low-frequency telescope will comprise 512 stations in a large core and three spiral arms creating a maximum baseline of 65km. Each of the stations will contain around 250 individual antennas, meaning almost 130,000 will be installed on site in total.
Initially, 476 of these stations will be constructed with a maximum baseline of 40km. The further away antennas are from the core of the telescope, the more expensive they become, so slightly reducing the number in the early stages of construction will allow the SKA to stay within the budget available at the time construction begins. The remainder will be added when funding allows.
Unlike telescopes that take the form of one huge dish, the scalable nature of interferometers like the SKA means that more stations can simply be added to the array further down the line.
A similar situation will apply with the mid-frequency telescope in South Africa, where 133 antennas will be added to the existing the 64-dish MeerKAT precursor telescope, forming an array of nearly 200 dishes. Some of them will be arranged in three spiral arms with a maximum baseline of 150km.
Initially, 130 of these dishes will be constructed with a maximum baseline of 120km; the remaining three will be added later.
The ultimate goal is to expand the SKA further, to 10 times this size, with a million low-frequency antennas in Australia and some 2000 high and mid frequency dishes and aperture arrays extending into African partner countries across the continent.
The SKA will start conducting science observations in the mid-2020s with a partial array.
The cost of the SKA
In July 2013, the SKA Board passed the following resolution:
‘Following the recommendation of the Director-General of the SKA Organisation, the SKA Board has instructed the SKA Office to proceed with the design phase for SKA Phase 1 assuming a capital expenditure cost ceiling for construction of €650M. The evolution of the SKA Phase 1 project to fit within this cost ceiling will be guided both during the design phase and construction by scientific and engineering assessments of the baseline design undertaken by the SKA Office in collaboration with the community and SKA’s advisory bodies including the Science and Engineering Advisory Committee (SEAC). This decision is consistent with the primary objective of building an exciting, next-generation telescope capable of transformational science.’
Following a successful rebaselining process, the design of SKA1 is now broadly established and is within the cost-cap that was set. Teams can now work on refining the design towards construction.
The cost of constructing and operating the full SKA (Phases 1 and 2) is, as yet, not established. Any estimate must be based on costs supported by engineering.
Some planned components of SKA Phase 2 are still in the early stages of a multi-year design process and the final costs of manufacture, installation and operation are unknown at this time. The construction costs of the full SKA will, therefore, be presented to the Board once credible estimates have been developed based on detailed engineering and design work. These may require refinement as the SKA Phase 2 science drivers are further developed.
Precursors and pathfinders
Even before the SKA comes online, a series of demonstrator telescopes and systems known as pathfinders and precursors, are already operational or under development across the world, paving the way for the kinds of technology which the SKA will need to pioneer to make the huge data available to scientists.
The key science goals
The SKA will be able to conduct transformational science, breaking new ground in astronomical observations. SKA scientists have focussed on various key science goals for the telescope, each of which will re-define our understanding of space as we know it.
From challenging Einstein’s seminal theory of relativity to the limits, looking at how the very first stars and galaxies formed just after the big bang, in a way never before observed in any detail, helping scientists understand the nature of a mysterious force known as dark energy, the discovery of which gained the Nobel Prize for physics, through to understanding the vast magnetic fields which permeate the cosmos, and, one of the greatest mysteries known to humankind…are we alone in the Universe, the SKA will truly be at the forefront of scientific research.
Early science observations are expected to start in 2020 with a partial array.
Organisations from ten countries are members of the SKA Organisation – Australia, Canada, China, India, Italy, New Zealand, South Africa, Sweden, The Netherlands and the United Kingdom. This global organisation is managed by the not-for-profit SKA Organisation, who have their headquarters at the Jodrell Bank Observatory, near Manchester in the United Kingdom. The participating countries page details more on the countries involved in the SKA.