MeerKAT's astounding hearing is already eavesdropping on the universe
A focal point of South Africa’s scientific ambition, the Square Kilometre Array (SKA), reaches a milestone this weekend with the inauguration of the first 16 dishes of its precursor telescope, MeerKAT.
The country has invested more than R2-billion in the design, development and construction of the 64-dish MeerKAT telescope. Although 16 dishes represent only a quarter of the full telescope, it shows South Africa is on track to have it completed by next year.
Science and technology minister, Naledi Pandor, said the connection of the 16 antennas is “proof that the SKA team and our partners are capable of executing excellent engineering and scientific projects.” She added: “The ministry is thrilled with the progress that has been made by the SKA project.”
This telescope will ultimately be included in the SKA, which will be the largest radio telescope in the world. With large arrays in Australia and South Africa, the telescope will also eventually have dishes in eight African partner countries.
The SKA seeks to answer some of humanity’s most enigmatic questions: Are we alone in the universe? What is dark matter? What happened after the Big Bang?
Radio antennas have to be in areas where there are few interfering radio emissions, such as the Northern Cape. Celestial objects, such as stars and galaxies, emit radio waves. Radio telescopes pick up these weak signals from space and use them to create images and maps of what the universe looks like.
The visible wave spectrum is small in comparison with the radio spectrum.
Radio astronomy has been identified as an area in which South Africa, with its relatively small science budget, has a comparative advantage because of its clear skies and large sparsely populated areas.
It is also a benign area of science – compared with the apartheid government’s focus on defence technologies, munitions and uranium enrichment – that provides a vehicle for skills development and technological advancement.
Preliminary data on MeerKAT’s performance shows that, in some ways, it “will be far, far better than what was originally promised and what the specifications were”, said Fernando Camilo, SKA South Africa’s chief scientist. Camilo, formerly of Columbia University in the United States, joined the SKA South Africa project office in April.
“MeerKAT is going to be a fantastic telescope. It’s what attracted me at first to South Africa,” Camilo said.
In the L-band, a segment of the radio wave spectrum, MeerKAT is expected to be twice as sensitive as was originally anticipated. This means an experiment in this band could take a quarter of the time it was originally allocated.
Although the first five years of observing time on MeerKAT have been allocated, SKA South Africa has put out a renewed call for scientific proposals because not only is the telescope more sensitive than expected but science has also moved on. Some questions, such as whether gravi- tational waves exist, have been answered since the initial call for MeerKAT scientific proposals went out in 2010.
“We’re about a year away from having real, amazing science done on MeerKAT,” Camilo said. “So it was high time to focus those [science] plans.”
But scientists will not have to wait until next year to start.
MeerKAT, and ultimately the SKA, will be an interferometer – that is, many small telescopes making up one large telescope. The SKA, for example, will have a “receiving area” – the total area that can detect the radio emissions from objects in the sky – of one square kilometre, but it is difficult and expensive to engineer one telescope with a dish that large. Instead, the SKA will comprise thousands of antenna that act in unison as one giant telescope.
What this means for MeerKAT is that it can undertake science before all 64 dishes come online. In May, MeerKAT produced its first image with just four dishes. The image depicted never-before-seen radio galaxies.
“This wonderful result has enormous significance,” Professor Justin Jonas, the associate director for science and engineering at SKA South Africa, said at the time. “This image and all that lies behind it adds to our confidence that this very complex project will be the success that we have been planning for over the past decade.”
In 2018, construction on another 133 dishes will begin. These dishes, added to MeerKAT, will become phase one of the SKA. The cost of this phase has been capped at €650-million.
On the other side of the ocean, Australia is preparing for its SKA build. Unlike South Africa, though, Australia’s precursors – the 36-dish Australian SKA Precursor and the Murchison Widefield Array – will not form part of SKA phase one.
Instead, Australia will host about 130 000 dipole antennas – these look like 2m-high Christmas trees built out of thick wire. This was a blow for a country acknowledged to be a world leader in astronomy and one that has deep pockets. But Australian officials maintain that they have a “no regrets” policy with regard to their astronomy builds.
For some context, Peter Klinken, the chief scientist for the state of Western Australia, which is where their SKA site is, said the state and the commonwealth government invested about Aus$850-million (R9.35-billion) in radio astronomy.
“Big science is expensive,” he said. Comparatively, the amounts required for the SKA were “not that stunning” when compared with Australia’s science and research budget, which was Aus$33.5-billion in 2013-2014.
For South Africa, it is difficult to quantify how much the country has spent on radio astronomy, because it also funds university research chairs and established the Inter-University Institute for Data Intensive Astronomy, among other initiatives. But it is considerably less than Australia’s investment and represents a larger proportion of its total science spend, which in 2013-2014 was more than 10 times less than Australia’s at R25.7-billion.
Sarah Wild is the author of Searching African Skies: The Square Kilometre Array and South Africa’s Quest to Hear the Songs of the Stars (Jacana Media, 2012)