SKA at Night

Construction begins on the largest radio observatory in Earth’s history – could discover the first signs of life in the universe

SKA at night

SKA sites in Australia and South Africa at night. 1 credit

Construction of the world’s largest radio astronomy facility, the Square Kilometer Array Observatory (SKAO), began on December 4. The observatory is a global project that has been going on for 30 years.

With two enormous telescopes, one (low frequency) in Australia and the other (medium frequency) in South Africa, the project will look further into the history of the Universe than ever before.

Astronomers like me will use SKA (Square Kilometer Array) telescopes to trace hydrogen through cosmic time and make precise measurements of gravity in extreme environments. Additionally, we hope to discover the existence of complex molecules in planet-forming clouds around distant stars, which could be the first signs of life elsewhere in the Universe.

I have been involved with the SKA and its precursor telescopes for the past ten years, and as Chief Scientist of Australian Telescope Operations since July. I help build the team of scientists, engineers, and technicians who will build and operate the telescope, while undertaking scientific research to map primordial hydrogen in the nascent universe.

Construction of the Australian component of the world’s largest radio telescope observatory, the SKA-Low Telescope, is beginning in the country of Wajarri Yamaji in remote western Australia. The SKA telescopes will consist of more than 131,000 antennas in Australia and nearly 200 dishes in South Africa, will provide an unparalleled view of the Universe and will be one of the largest scientific facilities on Earth.

What is the SKA Observatory?

The SKA Observatory is an intergovernmental organization with dozens of countries involved. The observatory is much more than the two physical telescopes, with headquarters in the UK and collaborators around the world using advanced computers and software to tailor telescope signals to the precise science undertaken.

The South African telescope (called SKA-Mid) will use 197 radio dishes to observe mid-frequency radio waves from 350 MHz to over 15 GHz. It will study the extreme environments of neutron stars, organic molecules around newly formed planets, and the structure of the Universe at the largest scales.

The Australian Telescope (SKA-Low) in Western Australia will observe lower frequencies with 512 radio antenna stations spread over a 74 kilometer (46 mile) stretch of outback.

The site is located at Inyarrimanha Ilgari Bundara, the radio astronomy observatory of CSIRO Murchison. This name, which means “sharing the sky and the stars”, was given to the observatory by the Wajarri Yamaji, the traditional owners and holders of the aboriginal title of the site of the observatory.

SKA Low Antenna Stations

Artist’s impression of some of the SKA-Low antenna stations. Credit: DISR

Listening to the universe

After decades of planning, pioneering telescope development and testing, a ceremony marking the start of on-site construction was held on December 4. We expect both telescopes to be fully operational by the end of this decade.

Each of SKA-Low’s 512 stations is made up of 256 broadband dipole antennas, spread over a diameter of 35 meters (115 feet). The signals from these Christmas tree-shaped antennas at each station are electronically combined to point to different parts of the sky, forming a single view.

These antennas are designed to tune to low radio frequencies from 50 to 350 MHz. At these frequencies, radio waves are very long – comparable to the size of a person – meaning more familiar-looking dishes are an inefficient way to catch them. Instead, dipole antennas work much like television antennas, with radio waves from the Universe exciting the electrons in their metal arms.

Collectively, the 131,072 dipoles in the full array will provide the deepest and widest view of the Universe yet.

Combined SKA

SKA locations in Australia and South Africa. 1 credit

Watching the cosmic dawn

They will allow us to see and go back to the very beginning of the Universe, when the first stars and galaxies were formed.

This key period, more than 13 billion years in our past, is called the “cosmic dawn”: when stars and galaxies began to form, illuminating the cosmos for the first time.

The Cosmic Dawn marks the end of the Cosmic Dark Ages, a period after the

big Bang
The Big Bang is the main cosmological model explaining how the universe as we know it began about 13.8 billion years ago.

” data-gt-translate-attributes=”[{” attribute=””>Big Bang when the Universe had cooled down through expansion. All that remained was the ubiquitous background glow of the early Universe light, and a cosmos filled with dark matter and neutral atoms of hydrogen and helium.

The light from the first stars transformed the Universe, tearing apart the electrons and protons in neutral hydrogen atoms. The Universe went from dark and neutral to bright and ionized.

The SKA Observatory will map this fog of neutral hydrogen at low radio frequencies, which will allow scientists to explore the births and deaths of the earliest stars and galaxies. Exploration of this key period is the final missing piece in our understanding of the life story of the Universe.

SKA Station of Radio Antennas

An artist’s impression of a station of radio antennas. Each station has 256 antennas, and the SKA-Low telescope will have 512 stations. Credit: DISR

Unimagined mysteries

Closer to home, the low-frequency telescope will time the revolutions of pulsars. These rapidly spinning neutron stars, which fire out sweeping beams of radiation like lighthouses, are the Universe’s ultra-precise clocks.

Changes to the ticking of these clocks can indicate the passage of

Written by Cathryn Trott, Research Fellow in Radio Astronomy, SKA-Low Chief Operations Scientist, Curtin University.

This article was first published in The Conversation.The Conversation

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