The Square Kilometre Array (SKA) is a time machine under development – but not the pop-culture kind you may be thinking. This one runs on radio waves.
“With the SKA you can look back millions of years to the origins of the Universe,” Theunis Kotze, In-House Legal Counsel at SKA, told ITU News. “It is probing what we call the dark ages; trying to find out how galaxies formed; how planets formed… and also looking for signs of life elsewhere in the Universe.”
Using satellite dishes and antennas tuned to radio frequencies, the SKA hopes to answer some of humankind’s biggest scientific questions: What is dark matter? How does magnetism work throughout the universe? What did the universe look like when the first galaxies were formed?
“The SKA is one of the biggest global scientific infrastructure projects of the next 50 years,” Mr Kotze said.
As opposed to optical astronomy (the observation of space in visible light), radio astronomy is about observing space using radio frequencies.
Just as X-rays and infrared can tell us different things about our environment, looking at the Universe at different wavelengths can reveal different phenomena otherwise invisible to optical telescopes.
Radio telescopes are uniquely suited to peer through the clouds of dust and gas that absorb visible light, detecting signals from the very early stages of the Universe, at a time when the first stars and galaxies formed.
“Elements of the periodic table can emit radiation at specific (but different) frequencies. Atomic Hydrogen, the most abundant element in the Universe by far, emits a distinct signal with a wavelength of 21cm or frequency 1420 MHz. Radio telescopes are thus perfect to study it, revealing a wealth of information about our Universe. So in a way, you can really determine what is out there just by ‘listening’ to radio waves. Can you believe it, every little thing in the world – including us – is generating a radio signal!” says Mr Kotze.
Since mobile phones, radios, digital cameras and any electronic equipment generate powerful radio signals that drown the weak signals that astronomers are trying to detect, radio quiet environments are critical to conducting the SKA’s observations.
“We’ve got hundreds of antennas, listening all the time, collecting a massive amount of data … That’s why you’ve got to build supercomputers, and to write the innovative software to churn that and extract the scientific gold nuggets – it’s an immense task!” – Theunis Kotze, In-House Legal Counsel at SKA
“You cannot do this science without radio quietness. Many years ago, within the ITU-R [ITU’s radiocommunications arm], some radio frequency bands were given a protected status to ensure that harmful interference to radio astronomy observations was significantly reduced; but observational techniques have moved on since, and some bands we use today don’t have that status. That is why we participate in ITU-R, to raise awareness about this, working with other bodies and industry to find innovative solutions, and to emphasize the need for continuing protection of the bands that have been allocated for radio astronomy.”
There are two sites that have been identified as quiet enough to conduct the observations the SKA plans to do: the first in Western Australia, roughly 800km North East of Perth, and the second in the Karoo region in South Africa, roughly 800km North of Cape Town.
“After many years of studies, they are the two single most radio quiet places we found with easy access. They are now protected from radio frequency interference by legislation, but that legislation only applies to ground-based systems, not aircraft or satellites. Hence our work at the ITU.”
Australia will host over 130,000 low frequency aperture array antennas, each about 2 metres in height, covering low frequency radio waves from 50 MHz to 350 MHz, to be expanded to up to five hundred thousand antennas at a later date.
Currently being commissioned on the Australian site, the Australian Square Kilometre Array Pathfinder (ASKAP) is an important precursor for the SKA; the telescope is conducting groundbreaking research into new promising technologies for the SKA, able to survey large areas of the sky in great detail.
Similarly, the 64-dish MeerKAT telescope array in South Africa – a precursor to the 130 SKA dishes to be built there to observe between 350 MHz and 15 GHz – is under construction and is already generating some important findings. “The science they have produced is amazing. It’s already way, way beyond what we expected. It’s not the full 64 dishes yet, but the science is incredible,” Kotze said.
In addition to the telescopes, listening to the radio waves and analysing the data will require “the world’s two biggest supercomputers by today’s standard,” Kotze said.
“We’ve got hundreds of antennas, listening all the time, collecting a massive amount of data … more data to be collected per day than the entire global Internet traffic currently per year,” he said. “That’s why you’ve got to build supercomputers, and to write the innovative software to churn that and extract the scientific gold nuggets – it’s an immense task!”
Engineering-wise, the project is in the final design stage. Construction can then start once the observatory convention – which is currently being negotiated between 10 participating nations – comes into force, expected to be in 2019.
“There is still a lot of work to do in terms of international law before we get to build the SKA,” Kotze said.
Once the telescope becomes operational, there are many questions the SKA aims to answer but one really captures the imagination: Will they find compelling evidence of life elsewhere in our universe? And if so, what happens then?
By Lucy Spencer (@inquisitivelucy), ITU News