Construction on what will be humanity's largest-ever telescope has finally started in South Africa and Western Australia after a 30-year wait and seven years of planning and engineering work. However, it's facing threats from satellite constellations.

The Square Kilometre Array Observatory (SKAO) will cost $2.2 billion. It will consist of two massive and sophisticated radio telescope networks: 197 radio dishes in South Africa's Northern Cape and 131,072 antennas in Western Australia's Murchison.

Artists impression of ASKAP antennas at the Murchison Radioastronomy Observatory
(Photo: CSIRO via Wikimedia Commons)
ASKAP is open to projects from astronomers from all over the world, with projects determined according to their scientific merit and operational feasibility. During the telescope's first five years, at least 75 percent of its time will be used for large Survey Science Projects, each needing more than 1500 hours to complete and designed to take advantage of ASKAP's unique capabilities.

They will form a one-kilometer-wide collecting area spanning two continents, allowing for the detection of very faint radio signals.

"I am ecstatic-this moment has been 30 years in the making," Professor Philip Diamond, Director-General of SKAO, said in a statement released by the European Astronomical Society. "Humankind is taking another giant leap by committing to build what will be the largest science facility of its kind on the planet," he added.

SKAO To Reveal Secrets Of Cosmos

SKAO is a radio astronomy project that aims to reveal some of the secrets of the cosmos. Radio astronomy is the study of the night sky in radio frequencies. Radio telescopes detect and amplify radio waves from space, such as those generated by stars, galaxies, and other celestial bodies.

The SKAO is based on interferometry, which uses a network of tiny antennas connected by optical fiber to form a virtual telescope known as an array. It will have significantly more sensitivity and resolution than a single massive radio dish.

SKA-Mid (South Africa) and SKA-Low (Western Australia) are the names of the two sites, which describe the radio frequency ranges they cover.

 SKA-Mid will host around 197 parabolic radio dishes every 50 feet/15 meters in diameter. Around a third of them have already been built by the South African Radio Astronomy Observatory (SARAO).

Meanwhile, the SKA-Low project will erect 131,072 low-frequency aperture array telescopes, measuring 6.5 feet/2 meters in height. The Wajarri Yamaji, the traditional indigenous owners of the site on which the SKA-Low telescope will be built, are helping to build them.

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"The SKAO will be a good neighbor and will work with local stakeholders, and in particular Indigenous communities, to ensure that they also benefit from the SKA project," said Diamond per HPC Wire. "We certainly intend to play our part in supporting local communities and boosting the local economy."

When fully operational, the two locations are expected to generate a total of 710 petabytes of science data. This is projected to happen in 2029, after which astronomers can expect 50 years or more of transformative science.

Radio Telescope Faces Threat from Satellite Constellations

The SKA Observatory's spectrum manager, Federico Di Vruno, claimed per SpaceNews that the observatory had developed "flagging and excision" methods to identify and remove radio-frequency interference from data. According to him, constellation interference by OneWeb and SpaceX would account for less than 4% of observations.

He did warn, though, that even if the problem can be solved with those constellations, future systems will only make it worse. This includes OneWeb and SpaceX's Starlink projects and the Chinese Guowang constellation, which might eventually include 13,000 satellites.

He believes that the prospect of tens of thousands of satellite constellations is particularly alarming for radio astronomy. He proposed that operators may help by agreeing not to transmit when their satellites pass through quiet radio zones around the antennas.

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