15 August 2013
The concrete for the first MeerKAT antenna foundation was poured at South Africa’s Square Kilometre Array (SKA) site in the Northern Cape on Wednesday.
The SKA project is an international effort to build the world’s largest radio telescope, which is to be co-hosted by South Africa and Australia.
The 64-dish MeerKAT radio telescope is due to come online in 2016 both as a precursor to the SKA and as one of the most powerful telescopes in the world in its own right.
The foundation laid on Wednesday is the first of 64 similar foundations – each comprising 78 cubic metres of concrete and 9 tons of steel – that will be built for the MeerKAT over the next nine months.
“Designing a foundation for a high-tech telescope is complex and challenging since it has to meet a set of stringent requirements,” Tracy Cheetham, general manager for infrastructure and site operations at SKA South Africa, said in a statement.
“The foundations must ensure that each of the 19-metre high antennas with its 13.5 x 16 metre main reflector will be exceptionally stable and able to point accurately at distant celestial objects at wind speeds gusting to 69 kilometres an hour as well as survive wind speeds of up to 144 kilometres an hour.”
Another challenge for the design team, working with contractors Brink & Heath Civils, was to ensure that each antenna was carefully earthed and would not be damaged in the event of a lightning strike.
To meet these stability requirements, each foundation consists of eight steel-reinforced concrete piles at depths of between 5 to 10 metres, depending on the local soil conditions. A square slab of concrete (5.2 x 5.2 metres, and 1.25 metres thick) rests on top of the piles to add further stability. The 32 “holding down” bolts are pre-assembled in a circle to form a steel ring cage, or so-called “bird’s nest”, into which the concrete is cast.
“This first foundation will now be verified through a series of load tests to ensure that all specifications have been met,” Cheetham said.
“Getting this absolutely right is critically important for the science to be done with this instrument, and will also inform the construction of foundations for other SKA dishes to be built in the Karoo.”
The MeerKAT is due to be commissioned in 2014/15, and to come online for science operations in 2016. It will be the largest and most sensitive radio telescope in the southern hemisphere until the Square Kilometre Array itself is completed around 2024. Leading radio astronomy teams from around the globe having already signed up to use the instrument.
Via the MeerKAT, South Africa is playing a key role in design and technology developments for the SKA, with close to 100 young scientists and engineers working on the MeerKAT project.
“Based at the engineering office in Cape Town, and at universities and technology companies across South Africa and Africa, these researchers interact closely with SKA teams around the world,” SKA South Africa says on its website.
“In collaboration with South African industry and universities, and collaborating with global institutions, the South African team has developed technologies and systems for the MeerKAT telescope, including innovative composite telescope dishes and cutting-edge signal processing hardware and algorithms.”
According to Professor Justin Jonas, associate director for science and engineering at SKA South Africa, the MeerKAT “will make up one quarter of SKA Phase 1 mid-frequency array, and the science planned for SKA Phase 1 is very similar to the MeerKAT science case – just much more ambitious.
“Our researchers and students who participate in the MeerKAT surveys have a huge advantage. They are well placed to enter SKA Phase 1. They have the opportunity to become science leaders in future SKA projects.”
Up to 2016, South Africa will be constructing the 64 MeerKAT dishes in the Karoo, with construction on the 190 dishes of SKA Phase 1 probably starting around the time the MeerKAT is complete.
“The design of the SKA dishes is not yet final, but they should look similar to the Gregorian-offset dish design chosen for MeerKAT,” Prof Jonas expects.