On Monday, the construction of the largest radio astronomy facility in the world began in Australia and South Africa. The Square Kilometre Array will consist of 131,072 low-frequency antennae in Australia (SKA-Low), combined with a sister facility (SKA Mid) in South Africa with 133 dish antennae.
“Astronomers like myself will use the telescopes to trace hydrogen over cosmic time and make precise measurements of gravity in extreme environments. What’s more, we hope to uncover the existence of complex molecules in planet-forming clouds around distant stars, which could be the early signs of life elsewhere in the Universe,” wrote SKA scientist Cathryn Trott in The Conversation.
The SKA project is an international effort to build the world’s largest telescope. As the name suggests, the telescope will eventually have a collecting area of over a square kilometre. The pre-construction development for the project initially began in 2013. Even though construction for the project has already begun, it is only expected to begin science observations in the late 2020s.
In Australia, SKA-Low will initially consist of 512 stations that are arranged in the shape of a large core with three spiral arms spread over a distance of 65 kilometres. Each of these stations will contain around 256 individual antennae.
Sarah Pearce, SKA-Low’s director, told The Guardian that the observatory would “define the next fifty years for radio astronomy, charting the birth and death of galaxies, searching for new types of gravitational waves and expanding the boundaries of what we know about the universe”.
Meanwhile, in South Africa, the 133 dish antennae will be added to the existing 64-dish MeerKAT telescope. There, most of the dishes will be concentrated in a core, with three spiral arms that will extend over 150 kilometres. Reuters reports that the precursor MeerKAT telescope was built in the Carnarvon region in South Africa due to its remoteness and the fact that the hills surrounding the area will shield it against radio interference.
Unlike single-dish telescopes, interferometers like SKA are scalable, meaning that more antennae can be added over time to improve its capabilities. According to the SKA, its ultimate vision is to expand the facility across both sites and into more African countries.
Scientists will focus on a variety of different science goals for the immensely powerful telescope, from challenging the limits of Einstein’s theory of relativity to understanding the mysterious force known as dark energy. According to Trott, SKA will allow scientists to observe the “cosmic dawn,” or the beginning of the Universe when the first stars and galaxies formed. This period marks the end of the “cosmic dark ages,” which was a period after the Big Bang when the Universe cooled down through expansion.
This dark universe was transformed by the light from the first stars, which tore apart electrons and protons in neutral hydrogen atoms, transforming the universe from dark and neutral to bright and ionised. SKA will map this fog of hydrogen, allowing scientists to explore the births and deaths of the earliest stars and galaxies. Pearce told The Guardian that the SKA will be “sensitive enough to detect an airport radar on a planet circling a star tens of light years away,” saying that it could be used to look for signs of extraterrestrial life.