Engineering News

The construction of a radio telescope that will look for the first stars in the universe is making headway near Carnarvon, in the Northern Cape.

It is also making waves for the way it has involved the local community and boosted the local economy.

A construction team of 24 people on site and another three in Cape Town are working on the Hydrogen Epoch of Reionisation Array (Hera) project.

About one-third of the 350 14-m-diameter dishes for the radio telescope have been built so far, Hera project engineer Kathryn Rosie says.

Hera forms part of the wider Square Kilometre Array (SKA) and will look at the first period after the Big Bang.

It

will be instrumental in detecting the distinctive signature that will enable astronomers to understand the formation and evolution of the first luminous sources – the first stars and galaxies in the universe. Scientists call this period the Epoch of Reionisation.

T

he low-frequency instrument needs only a simple construction, as it has only one goal in mind.

“The instrument itself needs to do only one thing – to look at the period in our history when the first stars in our galaxy lit up. They think they know where to look. Because it doesn’t have to do a range of things and low frequencies can get away with lower tolerances, we are able to have a low-cost, efficient construction,”

says Rosie.

Hera comprises a closely packed array of fixed parabolic reflector elements or dishes. The instrument is largely constructed from surprisingly simple materials. The materials and labour are sourced in South Africa, mostly in the Karoo.

“We’ve been able to source material locally and hire people from the community, many of whom don’t have a tertiary education. They’ve been able to learn on the job and be part of this very exciting project,” says SKA South Africa head of communication and stakeholder relations Lorenzo Raynard.

SKA South Africa senior astronomer working on Hera Dr Gianni Bernardi explains that the centre piece of each dish is determined by the placement of a concrete hub. These hubs constrain radial PVC spars, tensioned into approximate parabolas against a rim, which is supported by telephone poles. Welded mesh panels are installed on the spars to form the reflector surface.

Lorenzo sees the US’s investment in Hera as a strong indication of confidence in the overall SKA project.

“While the US is not yet part of the SKA, it’s been rewarding to see how our infrastructure projects in South Africa are attracting interest indirectly from the US.”

Last year, the project was awarded a $5.8-million grant by the Gordon and Betty Moore Foundation in the US, supplementing an earlier $9.5-million investment by the US-based National Science Foundation.

The funding by the Gordon and Betty Foundation enabled 110 dishes to be added to the project, increasing the sensitivity of Hera.

The Hera collaboration includes Arizona State University, Brown University, Cambridge University, the Massachusetts Institute of Technology, the National Radio Astronomy Observatory, Scuola Normale Superiore, Square Kilometre Array South Africa, the University of California at Berkeley, the University of California at Los Angeles, the University of Pennsylvania and the University of Washington.

The universities of Rhodes, KwaZulu-Natal, the Western Cape and the Witwatersrand are also participating in the project.