|Phase 1||Phase 2|
|Name||Square Kilometre Array|
|Sites||Australia (low-frequency) and South Africa (mid-frequency)|
|Organisation members||Australia, Canada, China, France, Germany, India, Italy, the Netherlands, New Zealand, South Africa, Spain, Sweden, United Kingdom|
|Estimated completion date||2023||2030|
|Frequency/Wavelength||Radio: 6m to 20cm (SKA-low: 50 MHz to 350 MHz; SKA-mid: 350 MHz to 15.3 GHz)|
|Number of dishes||SKA-mid: 197 15-m wide dishes (complemented by 131,000 antennas for SKA-low)||SKA-mid: ~3000 15-m wide dishes (complemented by up to a million antennas for SKA-low)|
|Total collecting area||0.1 square kilometre||1 square kilometre|
During the International Union of Radio Science (URSI) in 1993, the global astronomical community began a worldwide effort to develop the scientific goals and technical specifications for a next generation radio observatory. The proposed project began to take form with the creation of the International Square Kilometre Array Steering Committee in 2000 which included eleven signatory countries, including Canada.
The Long Range Plan (LRP) prepared in 2000 for the Canadian Astronomical Society (CASCA) identified the study of a Canadian Large Adaptive Reflector (LAR) concept that could be used in the Square Kilometre Array (SKA) as a highest priority for moderate-sized projects. The 2010 LRP confirmed this priority and emphasized the synergy between the SKA and upcoming ground- and space-based missions such as the Thirty Meter Telescope (TMT) and the James Webb Space Telescope (JWST), Hubble’s successor.
The SKA project brings together astronomers, engineers and scientists from 13 membre countries (including Canada) to build the world’s largest radio telescope, which will eventually have a collecting area of over one square kilometre (or one million square metres). The unprecedented scale of this project, including thousands of radio dishes and up to a million low-frequency antennas, will enable astronomers to probe the radio sky with much higher resolution than the Hubble Space Telescope and at a much faster pace than currently possible for a survey telescope.
The SKA will follow a phased timeline and will utilise a number of already existing radio astronomy facilities in its network. These “precursor” and “pathfinder » telescopes such as the 64-dish MeerKAT telescope in South-Africa and the 36-dish Australian Square Kilometre Array Pathfinder (ASKAP) telescope in Australia are paving the way for the kinds of technology that will be needed to handle the huge amounts of data produced by the SKA.
Phase 1 of the SKA should be completed by 2023 and will provide approximately 10% of the total collecting area at low and mid-radio frequencies. Phase 2 will enable the use of the entire proposed collecting area by 2030. A Phase 3 may be added to probe even longer radio wavelengths. The SKA’s truly innovative approach to varied instruments, receiver configuration and telescope sites will allow for truly transformational science and will help redefine our understanding of the Universe as we know it. Additionally, we expect a number of spinoff technologies to emerge from such a feat of technical engineering. Wi-fi is one such invention used in our daily lives that was developed by radio astronomers.
The SKA will be studying the Universe at radio wavelengths. Radio telescopes are designed quite differently from optical and infrared telescopes that use mirrors. While some radio telescopes are a single dish, like the 305-m Arecibo telescope in Puerto Rico, many are made up of an array of multiple radio dishes that can act as one single massive telescope. One well known example is the Very Large Array (VLA) in Socorro, New Mexico which is comprised of 27 25-m radio dishes. These arrays act like single-dish telescopes with a diametre the length of the distance between the two farthest dishes. This distance is called the baseline, and this technique is called interferometry. In SKA’s case, the largest baseline during Phase 1 will be a staggering 150 km. The dishes will be arranged in multiple spiral arm configurations which was determined to be the best layout design to optimise the SKA’s versatility and high-resolution imaging capability.
In addition to the thousands of steerable radio dishes deployed over several countries, low-frequency aperture array dipole antennas and mid-frequency aperture array antennas will also be used as SKA receivers. In 2012, the SKA Organisation agreed to disperse the SKA over two different sites: Australia and South Africa. The SKA Organisation Headquarters is located in the United Kingdom. As with optical telescopes, site selection was essential in best utilising the SKA’s innovative design. Selection criteria such as radio frequency interference, climate, temperature and characteristics of the Earth’s ionosphere and troposphere were all considered.
As the largest and one of the most sensitive radio telescopes in the world, the SKA will allow astronomers to solve some of the biggest questions we still have about the Universe. The key science drivers for the SKA include the following:
- Galaxy Evolution, Cosmology and Dark Energy
- Tests of Gravity using Pulsars and Black Holes
- Origin and Evolution of Cosmic Magnetism
- Probing the Cosmic Dawn when the First Black Holes and Stars Formed
- The Cradle of Life, Exoplanets and Searching for Extraterrestrial Life
In addition to these themes, SKA’s versatile and flexible design means that the telescope will be able to adapt to answer completely new and unexplored questions, leading to completely unexpected discoveries.
- September 1993: The Large Telescope Working Group is established following the International Union of Radio Science to develop a next generation radio observatory.
- 1997: Eight institutions from six countries (Australia, Canada, China, India, the Netherlands and the USA) sign a Memorandum of Agreement to cooperate on a study programme leading to a future very large radio telescope.
- August 2000: The International Square Kilometre Array Steering Committee is established between eleven countries (Australia, Canada, China, Germany, India, Italy, the Netherlands, Poland, Sweden, the United Kingdom and the United States) via a Memorandum of Understanding.
- October 2007: The University of Manchester in the United Kingdom is chosen as the host organisation for the SKA Project Office.
- 2008-2012: The SKA telescope system design is developed.
- December 2011: The SKA Organisation, a not-for-profit company, is established to lead the SKA project.
- 2012: Pre-construction development for the SKA begins. Members of the SKA Organisation agree on a dual site location for the project: Australia and South Africa.
- 2013: The cost ceiling for the SKA project is established and the design consortia for the different aspects of the project begin their work.
- 2016: Construction for SKA’s Phase 1 is approved and the prototype systems are deployed.
- 2018: Construction of SKA’s Phase 1 begins (to be completed around 2023). A detailed design study of SKA’s Phase 2 begins.
- March 2019: The Square Kilometre Array Observatory (SKAO) is founded in Rome by seven initial member countries: Australia, China, Italy, the Netherlands, Portugal, South Africa and the United Kingdom.
The following timeline is an estimate and is subject to change:
- 2020: Early science with SKA’s Phase 1 begins.
- 2023: Construction of SKA’s Phase 2 begins (to be completed around 2030).