South Africa’s proposed site for the Square Kilometre Array (SKA) has been confirmed as one of the quietest places on earth. Recent measurements of radio frequency interference, conducted by the international SKA consortium, confirmed the site’s extremely low occurrence of radio frequency interference (RFI).
South Africa’s SKA site will be as close to perfect as the community needs it to be when the SKA begins construction, says Dr. Adrian Tiplady, RFI and site characterisation manager at the SKA South Africa Project.
South Africa was shortlisted in 2006 as a SKA host because the Karoo site had already met the science, technology and infrastructure requirements determined by the international astronomy community.
The low level of radio frequency interference was a key factor in 2006, and we’ve made significant improvements since then, says Dr. Adrian Tiplady, SKA South Africa RFI and site characterisation manager.
Initial measurements showed the presence of some RFI from broadcasting and mobile phone infrastructure. These have been addressed through a combination of political and legislative support for the SKA, cooperation with South African industry, and innovative technology and engineering.
The integrity of the South African SKA site is protected by the world’s most progressive science-based legislation – the Astronomy Geographic Advantage Act – which ensures protection of the radio frequency environment for the future and regulates all future development in the area.
In a lead editorial in the April 2011edition of EngineerIT Dr. Tiplady wrote that the introduction of new mining and exploration activity by Shell would not be able to comply with the protection requirements of radio astronomy without very careful and detailed analysis. And even after this analysis, the chances don’t look good for compliance to the act. His advice to Shell was to just stay away from the SKA.
SKA South Africa has engaged with the broadcasting sector to develop plans that will establish an optimal radio frequency-free environment for the SKA, following the imminent migration to digital broadcasting in the Karoo region, thereby significantly increasing access to valuable spectrum for radio astronomy observations.
New technology developed to support the African SKA site bid by telecommunications operator Vodacom, to be shared with other operators, will see a significant reduction in potential interference from GSM signals.
The central astronomy advantage area in the Karoo region of South Africa’s Northern Cape Province is protected by legislation.
The availability of grid power on the SKA site is a key advantage for South Africa’s bid. Detailed studies and design processes were carefully undertaken to design a transmission system that offered cheap and available power without compromising the site’s RFI silence.
Power cables have been routed through valleys, support and strain structures adapted, and key equipment buried underground. The lack of economically viable mineral deposits within 180 km of the SKA core site ensures that there is a very low risk of future mining developments, and hence sources of RFI.
Naturally occurring disturbances are virtually eliminated on the high and dry SKA site in the Karoo, where the stable and benign climate means radio astronomy is not disturbed by severe weather, atmospheric turbulence, hurricanes or floods.