An international radio telescope array project, led by the US National Science Foundation, is being built in South Africa’s radio astronomy reserve in the Karoo region of the Northern Cape province by local artisans, and has already started doing valuable science, the South African Radio Astronomy Observatory (SARAO) has reported. The project is designated Hera, an acronym for the Hydrogen Epoch of Reionisation Array (Hera was the Queen of the gods in ancient Greek mythology, the wife and sister of Zeus).
“Construction of the array is phased in such a way that, as antennas are completed, they are hooked into the telescope data correlation system,” explained original Hera project engineer Kathryn Rosie. “This enables observations and early science to be carried out while construction continues.”
Construction of Hera started in 2015. By the South African summer of 2017/18 some 50 dishes had been completed and early science started. Currently, the array contains 332 dishes and when completed, it will have 350. Completion is now only a matter of weeks away. “Commissioning and construction activities are progressing well, we are currently conducting a logistic and support analysis to ensure smooth operations for the coming seasons in order to facilitate future discoveries,” reported current Hera project engineer Ziyaad Halday.
The design and construction of the Hera array is deceptively simple for a complex instrument. It is composed of fixed dish antennas, concentrated in a hexagonal grid, 300 m across. Each dish has a diameter of 14 m, and is made from wire mesh stretched between PVC pipes, supported by wooden poles. They collect low-frequency radio waves from outer space in the 70 MHz to 200 MHz band.
At start of construction, the project employed four artisans, growing to 20 at the peak of the work. Currently, the construction team numbers ten. All the artisans hail from the local town, Carnarvon, and none had a qualification higher than matric (high school diploma). The role of SARAO in the Hera project is to be the hosting partner and to be a contributor to the broad Hera collaboration. Consequently, the systems engineering, construction management, location, and the power and fibre networks are SARAO’s responsibility.
The function of Hera is to gather data from earlier in the history of the universe than has hitherto been possible. It seeks to gather information about the development of large-scale structures in the universe during the period known as the Epoch of Reionisation, during which the first stars and galaxies emerged. This period started 400-million years after the Big Bang (the event which created our universe, which is now some 13.77-billion years old), or perhaps even much earlier.