- The Square Kilometer Array (SKA) will be the largest radio telescope in the world when completed in 2028.
- Split across South Africa and Australia, with a headquarters in the UK.
- The facility will address the biggest questions in astrophysics.
It will perform the most precise tests of Einstein’s theories, and even search for extraterrestrials.
Delegations from the eight countries leading the project are attending ceremonies in the remote Murchison shire in Western Australia and in the Karoo of South Africa’s Northern Cape. When the festivities are over, the bulldozers will move in.
“This is the moment it becomes real,” said Prof Phil Diamond, director general of the Square Kilometer Array Organization. “It’s been a 30-year journey. The first 10 years were about developing the concepts and ideas…” The initial architecture of the telescope will incorporate just under 200 parabolic antennas, or “dishes”, as well as 131,000 dipole antennas, which look a little like Christmas trees.
The aim is to construct an effective collecting area measuring hundreds of thousands of square metres. This will give the SKA unparalleled sensitivity and resolution as it probes targets in the sky.
Faint Radio Signals
The system will operate across a frequency range from roughly 50 megahertz to, ultimately, 25 gigahertz. In wavelength terms, this is in the centimeters to meters range. This should enable the telescope to detect very faint radio signals coming from cosmic sources billions of light-years from Earth, including those signals emitted in the first few hundred million years after the Big Bang.
The telescope should be able to detect hydrogen’s presence even before great clouds of it collapsed to form the first stars. “The SKA is going to contribute to so many areas of astronomy,” said Dr Shari Breen, the observatory’s head of science operations.
The telescope is being built in areas already used for radio astronomy on a smaller scale. To expand these sites, however, has required various land agreements, with farmers in the Karoo; and with the Wajarri Yamaji, the Aboriginal title holders in the Murchison.
Full Roll Out
The first major milestone should come in 2024, when four dishes in Australia and six antenna stations in South Africa are made to work seamlessly together as a basic telescope. This proof-of-principle moment will then trigger the array’s full roll-out.
By 2028, the SKA will have an effective collecting area of just under 500,000 square meters. But the set-up is such that it can continue growing, perhaps up to the much desired one million square meters, or one square kilometer.
The current members are: South Africa, Australia, the UK, China, Italy, Netherlands, Portugal and Switzerland. These countries have ratified the treaty. Canada, India, Sweden, South Korea and Japan have indicated their intention to join at some point.
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