In Australia and South Africa, there are a series of radio telescopes that will be soon joined by a number of newly-constructed facilities to form the Square Kilometer Array (SKA). Once established, the SKA will have a collecting area that measures a million square meters (close to 2 million square yards). It will also be 50 times more sensitive than any radio telescope currently in operation, and be able to conduct surveys ten thousand times faster.
During a historic meeting that took place on June 29th, 2021, the member states that make up the SKAO Council voted to commence construction. By the late 2020s, when it’s expected to gather its first light, the array will consist of thousands of dishes and up to a million low-frequency antennas. These will enable it to conduct all kinds of scientific operations, from scanning the earliest periods in the Universe to searching for extraterrestrial intelligence (SETI).
At its core, the SKA relies on a process known as interferometry, where light from cosmic sources is gathered by multiple telescopes and then combined to create high-resolution images. For radio telescopes, this technique has the added advantage of allowing for observations where only a subset of the full array is available. With such a large collecting area, the SKA will allow for all kinds of revolutionary science.
A Huge Effort
The SKA consists of four “precursor facilities,” which include the MeerKAT and the Hydrogen Epoch of Reionization Array (HERA) in South Africa, and the Australian SKA Pathfinder (ASKAP) and Murchison Widefield Array (MWA) in Australia. Beyond these, there are also the “pathfinder” facilities located outside of these two countries, consisting of the Allen Telescope Array in northern California and the Low-Frequency Array (LOFAR) in the Netherlands.
These facilities are divided into two networks designated SKA-Low and SKA-Mid, which describe the radio frequency range they will cover. The decision to approve construction comes on the heels of two major developmental milestones for the SKAO. First, there was the publication of two key documents last year, the Observatory’s Construction Proposal and Observatory Establishment and Delivery Plan, and an executive summary of both.
The documents are the culmination of over seven years of design and engineering work by more than 500 experts from 20 countries, the purpose of which was to test the technologies needed to build and operate the largest radio telescope array ever built. Second, there was the creation of the SKAO as an intergovernmental organization, which took place earlier this year. As SKAO Director-General Prof. Philip Diamond said in a recent SKAO press release:
“I am ecstatic. This moment has been 30 years in the making. Today, humankind is taking another giant leap by committing to build what will be the largest science facility of its kind on the planet; not just one but the two largest and most complex radio telescope networks, designed to unlock some of the most fascinating secrets of our Universe.”
“I would like to thank everyone who has contributed to making this possible over the past decades, from the early inception of the project until now, and in particular all the teams who have worked so hard over recent years and powered on through a pandemic in very difficult circumstances to meet deadlines and make this milestone possible. I would also like to thank our Member States for their vision and the trust they’re placing in us by investing in a large-scale, long-term research infrastructure at a time when public finances are under intense pressure.”
This organization now accounts for eleven international consortiums that represent more than 100 research labs, universities, and companies from all sixteen Member States who were responsible for designing the necessary hardware, software, and infrastructure. These include Australia, Canada, China, France, Germany, India, Japan, Italy, the Netherlands, Portugal, South Africa, South Korea, Spain, Sweden, Switzerland, and the United Kingdom.
Construction is expected to last until 2028 and will be followed by the first science operations in the early 2030s. The cost of the entire project, including constructing the two telescopes, associated operations, and business-enabling functions is projected at €2 billion ($2.38 billion USD) over a nine-year period (2021 – 2030). The first significant activity on site is scheduled to take place early next year, but procurement of major contracts will begin immediately.
Over the next few months, the SKAO will issue about 70 contracts to all of its Member States, which will then put them for competitive bidding locally. The SKAO anticipates that once they have started gathering light, the two arrays will remain scientifically productive for 50 years or more. Dr. Catherine Cesarsky, Chairperson of the SKAO Council, expressed her gratitude to all those who helped get the SKA to this pivotal point in its development:
“I would like to add my thanks to the members of the SKAO Council and the governments they represent. Giving the green light to start the construction of the SKA telescopes shows their confidence in the professional work that’s been done by the SKAO to get here, with a sound plan that is ready for implementation, and in the bright future of this ground-breaking research facility… Today’s commitment by Member States is a strong signal for others to get aboard and reap the benefits of participation in this one-of-a-kind research facility.”
In addition to delivering exciting and revolutionary science, the organization maintains that the SKA will provide tangible social and economic benefits for those countries involves – such as innovation, technological spin-offs, new high tech jobs, boosted industrial capacity, and others. Beyond the Member States, this will include the African Partner Countries – which include Ghana, Kenya, Zambia, Mozambique, Namibia, Botswana, and Madagascar.
Then there are the many Indigenous peoples in South Africa and Australia whose lands the telescopes will be built on. In order to foster respectful dialogue and engagement, the San Council of South Africa (SCSA) and the South African Radio Astronomy Observatory (SARAO) signed a Memorandum of Understanding. Since then, in-principle support for the project has been announced by the Wajarri Yamaji (on whose lands the SKA-Low telescope will be built).
“The SKAO will be a good neighbor and will work with local stakeholders, and in particular Indigenous communities, to ensure that they also benefit from the SKA project alongside other stakeholders nationally and internationally,” added Prof. Diamond. “We certainly intend to play our part in supporting local communities and boosting the local economy.”
In terms of science opportunities, the SKA will conduct a wide range of observations that will yield valuable scientific insight. In particular, the SKA will conduct some of the most stringent tests of General Relativity to date, where astronomers will observe how the path of electromagnetic radiation is altered by the influence of gravitational fields and the curvature of spacetime.
The sensitivity of the SKA will allow it to observe the spectral line of radiation created by a change in the energy state of neutral hydrogen atoms – aka. the 21 cm hydrogen line. This means that the SKA will be able to pierce the veil of the cosmic “Dark Ages” when the first galaxies were forming. It will also allow astronomers to see how the large-scale structure of the Universe has since evolved, providing insight into the role of Dark Matter and Dark Energy.
The SKA will also allow for some of the most rigorous surveys in the Search for Extraterrestrial Intelligence (SETI) to date. Traditionally, radio astronomy has been the preferred means of searching for signs of technological activity (i.e. technosignatures) and the SKA’s multiple telescopes will be able to monitor target star systems in different radio wave frequencies for extended periods of time.
Over the past few years, excitement about the SKA and what cosmic mysteries it will reveal has been growing, and not just in the scientific community. Among the general public, the SKA is seen as a next-generation facility that will address many enduring mysteries of the cosmos. And like the James Webb Space Telescope (JWST), the Extremely Large Telescope (ELT), and many others, we will only have to wait a few more years before the scientific returns start coming in.
Further Reading: SKOA