10 mins read 07 Jul 2021

Square Kilometre Array Cleared for Construction

Australia’s mega-science project, the Square Kilometre Array, has now officially been cleared for construction. We had a chat with Dr Sarah Pearce who has recently been appointed as the SKA-Low Telescope Director about some of the exciting science that will now start to flow from this revolutionary instrument.

Night-time artist impression of both the SKA-Mid (South Africa, left) and SKA-Low (Australia, right). Credit: SKAO, ICRAR, SARAO.

Australia’s first mega-science project, the Square Kilometre Array (SKA) is now one key step closer to being developed, after a historic meeting of the international SKA Observatory Council approved the start of the construction of the telescopes in Australia and South Africa.

The approval indicates that the commencement of the construction phase of developing the SKA-Low telescope in Australia and the SKA-Mid telescope in South Africa will now trigger the procurement and activation of contractors and vendors to start to build each of the telescopes.

The two established telescope locations – Australia and South Africa – will house different components of the enormous observatory, based on the radio frequencies they will tune into. In South Africa, SKA-Mid will tune into 350 MHz – 15.4 GHz signals, whereas in Australia, SKA-Low will zone in on the much lower frequency range of 50 MHz – 350 MHz.

For this reason, the two sites will feature different antenna designs, though they will complement each other, ensuring that the ambitious science goals are achieved collaboratively. For SKA-Mid, 133 dishes (of 15-metre diameter each) will be built and added to the existing 64-metre MeerKAT dishes and spread across a region where the largest baseline (distance between furthest antennas) is 150 km.

In Australia, the more unusual Christmas-tree-looking antennas will be developed (over 131,000 of them), which will be placed in small groups called stations, spread across the longest baseline of 65 km. The Australian site is located at the Government-designated radio-quiet zone, in the Mid West region of Western Australia – far away from most human transmissions and interference.

We had a chat with Dr Sarah Pearce, who has recently been appointed the SKA-Low Telescope Director. Prior to this role commencing, Dr Pearce was Acting Chief Scientist of Australia’s national science agency, CSIRO, as well as Deputy Director of the agency’s Space and Astronomy business unit.

A chat with Dr Sarah Pearce

Dr Sarah Pearce. Credit: CSIRO.

Firstly, a big congratulations on the new role as the SKA-Low Telescope Director, on a scale of one to 10, how excited are you that the construction wheels of motion are now starting to roll?

Thanks - it’s a really great time to be part of the SKA Observatory. The astronomy community has been working towards SKA for decades, so it’s incredibly exciting to now be at the start of the construction phase, getting ready to let contracts and start building on site. So it’s about a 9 out of 10 - I think I’ll reserve 10 out of 10 for when we finish building the telescopes!

SKA-Low is a very unique looking telescope, made up of over 131,000 Christmas-tree-looking antennas, grouped together in 512 stations, with the greatest baseline of about 65km. What makes SKA-Low special, and how does this differ from SKA-Mid in South Africa?

SKA-Low will be far the most capable telescope of its kind in the world, able to map the sky faster, with higher resolution and more sensitivity.  So we’ll be able to explore really exciting new science, such as the Epoch of Reionisation - the time, only a few hundred million years after the Big Bang, when the first stars and galaxies formed. SKA-Low will complement SKA-Mid - between them, they’ll look to address many of the most challenging questions in astronomy, such as understanding dark matter and dark energy.

In the last few years, we’ve seen the emergence of gravitational wave astronomy with giant interferometers across the globe. The associated events, such as binary neutron stars, or black holes, are often studied in radio astronomy as well. How will the SKA complement these gravitational wave discoveries? 

It’s amazing to see the field of gravitational wave astronomy open up, giving us a whole new window into the Universe. The SKA telescopes will be great at precisely timing pulsars - fast-spinning neutron stars. But as gravitational waves pass through the Galaxy, they’ll cause small changes in the distance to those pulsars - and therefore differences in the arrival time of the pulses. Using this method, we should be able to detect gravitational waves from huge events such as the merger of supermassive black holes. So the SKA project will give us a different perspective on this rapidly evolving area, complementing the discoveries from gravitational wave detectors like LIGO or VIRGO.

With the construction being approved for SKA-Low, and the roll-out looking like it will be phased over the decade, do we expect to start seeing some science as each phase of the telescope rolls out, and if so, what type of science and technology goals do you think that will be?

Like most interferometers, SKA will be rolled out in phases. In Australia, we’ll start with a small number of ‘stations’ - groups of 256 antennas - making sure that these operate as we expect and ironing out any bugs. Over time, we’ll build more stations: even with only half the antennas deployed, which we expect to happen in 2027, SKA-Low will be the largest telescope of its type.

The wonderful CSIRO Parkes radio telescope has now been in operation for 60 years - and in that time, has made some remarkable discoveries. The SKA’s projected lifetime is expected to run for the next 50+ years. What’s your educated guess as to what discoveries SKA might make over its lifetime?

The SKA telescopes have enormously interesting science goals, from testing the limits of relativity to understanding how magnetic fields shape our Universe. But I can’t predict what its major discoveries will be! One of Parkes’ greatest scientific achievements has been detecting more than half of all known pulsars. But pulsars weren’t discovered at all until 1967 - 6 years after Parkes was opened. So the most exciting thing about a telescope like the SKA is all the new science it will do, that we can’t predict. And a critical challenge is to make a telescope that gives you the best possible view of the Universe, so you’re able to take advantage of new science as it arises.

One of the most mind-boggling outputs of the SKA-Low (and SKA in general) is the amount of data the telescope will produce and the speed at which it will produce it. How much of this data is used, and how does this data get pushed out to scientists all over the world who are working with the telescope? 

The SKA telescopes are both really big data telescopes. In the case of SKA-Low, it will produce about 7 Terabits of data each second: that’s equivalent to around 100,000 simultaneous home broadband connections. It’s too much raw data to store, so we’ll have to deal with it in real-time. The data from the telescope will be processed first by very specialised high-speed digital systems, and then sent on to the Pawsey Supercomputing Centre in Perth. There it will be analysed on the SKA’s supercomputer, before being sent out to SKA Regional Centres, a network of supercomputing facilities around the world for scientists to access.

There’s already a couple of existing telescopes at the CSIRO Murchison Radio-astronomy Observatory (MRO), like ASKAP. Does this existing infrastructure continue to work with the SKA-Low once it commences operations?

One of the great benefits of the SKA project for Australia has been the establishment of CSIRO’s Murchison Radio-astronomy Observatory (MRO) in WA, as one of the best sites in the world for radio astronomy. So telescopes such as CSIRO’s ASKAP will continue to operate on the MRO through construction and operations of SKA-Low. The MRO is also the site of the Murchison Widefield Array, another precursor to the SKA telescope which, as well as being a great low-frequency telescope in its own right, has taught us an enormous amount technically and scientifically in preparation for SKA-Low. 

We’ve started to notice that engagement with young people in our region when it comes to space has started to increase. Many are really interested, and fascinated, by all the amazing work we do here in Australia. What advice would you give to young people who are reading this and want to one day work at the SKA? What steps should they take now to end up with a career at the SKA?

I agree - when I go out to talk to young people in schools, they’re fascinated by astronomy and inspired by the opportunities of the SKA. And they ask really difficult questions! Of course, a lot of the jobs on SKA will be in science and engineering, so doing these subjects at school and university or TAFE will really help. But we also need people in a whole range of other areas, from lawyers negotiating contracts to writers helping us communicate science to the public. So whatever you’re interested in, you could be involved with SKA. 

The Square Kilometre Array Observatory

Fast facts about both the SKA-Low (Australia) and SKA-Mid (South Africa). SKA-Low will cover the lower end of the frequency range, whilst SKA-Mid will go higher. Credit: SKAO telescope brochure.

The SKAO will be the world’s largest radio observatory, consisting of two telescopes located in South Africa and Australia, headquartered in the UK. It will probe the Universe, searching across radio frequencies (50 MHz - 15.4 GHz bandwidth) to provide data and context to questions such as why the Universe’s expansion accelerating, can we test Einstein’s theory of gravity to a higher degree, and even search for other civilisations that might exist amongst the stars. 

The project has been in the works for a number of decades (as expected for the scale) and has involved many scientists, and industry partners from around the world working on science, technology and engineering challenges that have required resolution to make such a powerful instrument operationally possible. 

Additionally appointed to the SKAO as the Site Construction Director for the Australian arm of the project - and working alongside Dr Sarah Pearce - is Mr Antony (Ant) Schinckel, who was Head of the CSIRO’s SKA program. Earlier this year, Ant spoke with about the road ahead for the SKA here in Australia. 

Such is the size and enormity of the SKA, it has required governments to come together, and dedicate their science objectives and resources towards the build, with Australia, making a large funding and science commitment through agencies like CSIRO (who is the operating partner for SKA in Australia), ICRAR, Pawsey Supercomputer Centre and several universities. The SKA will be developed and located at CSIRO’s Murchison Radio-astronomy Observatory, located in Western Australia. 


We acknowledge the Wajarri Yamatji as the traditional owners of the Murchison Radio-astronomy Observatory site.