In a little over twelve months, an international selection panel will select the host country of what I like to refer to as the last great (radio) astronomical adventure on earth: the Square Kilometre Array (SKA). I could extoll ad nauseum on the virtues and potential benefits of this R15-billion marvel of science and technology. But suffice to say, we have a very real chance of winning the bid, and when it is built, much of it will be using home-grown, cutting-edge technology. 

Hypothetically, let us assume for the time being that the Astronomy Geographic Advantage Act, which was declared in 2007 to protect astronomy (particularly the SKA) from all detrimental sources of interference through the establishment of Astronomy Advantage Areas (AAAs), did not exist.

Let us also assume that Shell could continue unhindered in its "great trek" to suck every gram of shale gas out of every nook and cranny in the Karoo - a declared AAA and the core site proposed by the Department of Science and Technology for the SKA. What impact would this have on the SKA? I doubt Shell knows, because they haven't asked me.

 
A radio telescope, such as the SKA, is an extremely sensitive radio receiver - about 15 orders of magnitude more sensitive than a cellular phone - in order to detect the extremely faint radio signals that have traversed the universe for billions of years. This means that any terrestrial source of radio frequency interference has the potential to destroy radio astronomy observations.

There are two types of sources of interference that give astronomers headaches.

Firstly, there are the strong narrowband radio signals that provide telecommunication services. These take up valuable spectrum, but they are not too bad, as long as there aren't too many signals, and they are not strong enough to interfere with the telescope receiver equipment.

Secondly, providing the bigger headache and bigger potential to destroy radio astronomy observations, there is the broadband electromagnetic interference that is generated from electrical devices.

The sensitivity of the radio telescope means that a petrol vehicle producing electromagnetic interference at the prescribed limits of South African National Standard 212: 2009 (read CISPR-12) would need to be at least 11 km away to ensure no interference.

For heavy equipment associated with mining, this distance would increase. That is, of course, assuming there isn't a great big hill in the way, which can shield the radio emissions to a certain degree. Not a lot, but enough to make the Karoo one of the best locations in the world for radio astronomy - remote, and sufficiently protected by topography from existing sources of interference.

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. My advice? Just stay away from the SKA.

Thankfully, back in the real world, the Astronomy Geographic Advantage Act exists, and the declaration of AAAs is continuing with the support of a large number of stakeholders to ensure that the SKA, and other existing radio astronomy facilities such as MeerKAT, are protected from these kinds of activities.

Our economic future lies in the development of a knowledge economy, in the harnessing of renewable energy resources and reducing dependence on resource based commodities. Let's not go after another fossil fuel - it's like something out of the Stone Age.

Dr. Adrian Tiplady

SKA South Africa, Tel 011 442-2434, atiplady@ska.ac.za

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