SA’s gigantic window on the cosmos finally begins to open
It is ready, set, go for the Square Kilometre Array (SKA), the world’s largest telescope. Construction officially began on Monday in South Africa and Australia and will continue until 2027.
This comes 10 years after both countries won the bid to co-host the telescope. Years ago, the experts knew what they wanted to build, but had to invent most of the technology to do it.
The construction will cost €1.3-billion (R23.6-billion), and €700-million has been earmarked for operational costs over the next 10 years, which includes staff in South Africa and Australia and at the headquarters at Jodrell Bank near Manchester.
Professor Phil Diamond, director-general of the SKA Observatory (SKAO), the intergovernmental organisation established to bring all 16 participating countries under one umbrella, says it was a long process to secure the money, ensure each country’s parliamentary approval of the treaty and complete the design.
The SKA-Mid (which refers to the mid-frequency radio waves it can detect from the universe) will be built in South Africa, 90km outside Carnarvon in the Karoo. The MeerKAT precursor telescope, which has already produced quality science, is on this site along with high-end infrastructure, which will be expanded. MeerKAT will form part of the core of the SKA-Mid.
Dr Lindsay Magnus, telescope director of the SKAO in South Africa, says the SKAMid will consist of 197 dishes, including MeerKAT’s 64.
The area is huge: “The SKA-Mid will also have three spiral arms which will extend far out [from the core]. The greatest distance between two dishes will be 150km. MeerKAT will be in the core along with 80 more dishes, and then 53 more will complete the three spiral arms.”
MeerKAT is kept going during load shedding by huge diesel tanks – less than a second after loss of power, a generator kicks in, burning 300 litres an hour.
The first four SKA dishes have already been manufactured in China and will arrive in South Africa early next year. It was confirmed on Monday that the Chinese company CETC54 had been selected to manufacture the SKA-Mid’s dishes.
Magnus says the first four dishes will be used for testing before mass-production begins: “We want to make sure everything
is correct before we build.”
The dishes will be shipped in containers to South Africa and assembled on site.
Even though a lot of the infrastructure is already in place – including a massive underground signal processing centre, dish and pedestal assembly sheds, roads and an electrical substation – a lot more infrastructure is needed.
Heading site construction in South Africa is Tracy Cheetham, who did the same for MeerKAT.
“We are the boots on the ground,” she said during a recent visit to the site, when all the council members of participating countries were present.
Contending with extremes in the weather, poisonous snakes, scorpions and even swarms of bees is part of Cheetham and the team’s day.
The two SKA telescopes differ in design and are complementary. Both are interferometers: arrays of antennas, which, when linked, act as one enormous telescope. The Australian SKA-Low (low frequency) is being built at Murchison in the western outback. It consists of 131,071 smaller dipole antennas at 517 stations.
The SKA telescopes’ exceptional sensitivity will allow them to see far deeper into the universe than current telescopes, revealing far fainter details than have previously been observed. They will also see more of the sky at once, vastly improving survey speeds, according to the SKAO.
The SKAO is also looking to the future, as a second, larger phase has been planned. If built, SKA2 would be the largest scientific facility in the world, says Diamond.
“I am often asked if this will happen,” he says. “But let’s build SKA1 first and demonstrate the science as we promised. Then there will be a good chance that it will happen.
“MeerKAT is just a taste of the SKA’s ability. Our understanding of the universe will greatly improve with the SKA … and there is so much we still do not know,” said Diamond.
The SKA has many scientific aims but here are some highlights. It will have the ability to observe the cosmic dawn and the early epoch of re-ionisation, using the faint radio light coming from the hydrogen itself. The resulting “movie” of the universe’s first 700 million years will answer a multitude of questions about this vital chapter.
There is evidence that star formation was fundamentally different in the early universe, often occurring within intense concentrations of super star clusters that have few, if any, counterparts today.
Cosmic magnetism has been an elusive question. How, when and where did magnetism originate? The SKA will enable the creation of the first three-dimensional magnetic map of the universe.
The telescopes will also make it possible, for the first time, to detect emissions from planets orbiting nearby stars that are comparable to those generated by human activity on Earth. This will open the possibility of detecting technological alien civilisations.
Radio frequency interference at the site is taken very seriously. Everything is shielded, from the thick steel doors in the underground Karoo Array Processor Building where the first data arrives via optical fibre, to the vehicles that are allowed. No unmodified computers, cellphones or cameras may enter the site.
Even the scientists themselves are not on the site, but in Cape Town, from where MeerKAT is remotely operated. A new Science Operations Centre will be built outside Cape Town. It will also house the Science Processing Centre, containing a powerful supercomputer.
The data transfer rate from the SKA to the processing facility in Cape Town is about 20 terabits per second – 100,000 times faster than the global average home broadband speed.
To accommodate tourists and the curious, a new visitor centre will be built in Carnarvon and will offer a science tour to a lookout point from where people will be able to view the SKA’s core.