Elon Musk’s worldwide satellite internet service Starlink has been hailed as a lifesaver for Ukraine after Russian invaders cut off terrestrial services.
It is also a positive step for remote dwellers in many countries seeking affordable internet, and Nigeria and Mozambique are the first in Africa where regulators have approved SpaceX’s service.
But in SA, the country of Musk’s birth, Starlink and its planned 42,000 satellites pose a threat to the Square Kilometre Array (SKA), destined to be the world’s largest radio observatory.
The large groups of satellites that orbit Earth, known as mega-constellations, would interfere with SKA and are already affecting optical astronomy.
SKA head Philip Diamond, who was in SA last week for the next phase of construction and talks with science minister Blade Nzimande, said everyone at SKA “appreciates that a large fraction of the world’s population is deprived of internet” and that it’s “vital” for them to be connected.
However, he added, the interference it would cause with radio telescopes is “worrying and this is why we’re taking this matter seriously”.
The 15 countries involved in SKA, which will be co-located in Australia, want to “minimise the affect of those mega-constellations on the telescope”.
This would involve Starlink “switching off transmission as they fly over telescopes or pointing their beams away”, said Diamond.
SpaceX hopes to launch in SA next year, but did not respond to questions from Sunday Times Daily.
197: SKA dishes in the Karoo
150km: Maximum distance between dishes
8.8: Data transmission rate in terabits per second
— IN NUMBERS
Musk has made statements on Twitter saying “Starlink won’t be seen by anyone unless looking very carefully & will have ∼0 affect on advancements in astronomy”.
But in January, The Astrophysical Journal published a paper by the Zwicky Transient Facility in California which said in 2021, when only about 1,000 planned satellites were in orbit, 20% of its images had streaks on them.
Modelling by the massive Vera Rubin Observatory in Chile suggests when Starlink is fully operational, a third of its images will be marred by satellite streaks. This points to a bigger clash between two advanced forms of technology, not just between Starlink and SKA.
Diamond said the satellites use radio beams to connect to ground stations, “so in the future the sky might have all these moving radio sources beaming downwards and interfering with radio telescopes”.
In the meantime, SKA has moved ahead. “We are into the construction phase now,” Diamond said between his meeting with Nzimande and a trip to the Northern Cape, where precursor telescope MeerKAT has already made several breakthroughs.
“We are evaluating the biggest contract, which is the infrastructure like roads, power, buildings, fibre and so on. That is the next phase of work we’re engaged in, and assuming those contract negotiations are successful, we should be able to start doing that.”
Diamond said while the array had withstood some Covid-19 shocks, the pandemic had affected the project.
“At first we could continue to work and we have done so at pace, but all the pressures we read about in the paper affect us, like the cost of fuel going up, the cost of steel. But we have contingency plans to handle this. We are still evaluating what the full affect of the pandemic might be, but I am extremely pleased with what we have achieved collectively with all our partners under extremely challenging circumstances.”
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