South Africa has already built prototype dishes that will form part of the Square Kilometre Array, which will be the world’s largest radio telescope. Credit: Mujahid Safodien/AFP/Getty

A map showing how mobile-phone use might be restricted because of a giant radio telescope in South Africa has angered people who will live near the instrument — deepening a rift between the local farming community and those backing the project.

The row has arisen over the South African portion of the Square Kilometre Array (SKA), which will eventually consist of thousands of radio dishes in Africa and up to a million antennas in Australia. The array, which begins construction in 2019 for completion in the 2030s, will have a total signal-collecting area of more than 1 square kilometre, making it the world’s largest radio telescope. The telescope’s first phase in South Africa involves 194 radio dishes, to be laid out like a galaxy with three arms spiralling out from a core cluster.

Local residents in the Northern Cape province, where the government has acquired nearly 1,400 square kilometres of land for the initial phase, have already expressed concerns about the telescope. Some are angry that the SKA won’t boost the region’s economy as much as they had expected; others fear the land acquisition will damage local agricultural activity — in particular, sheep farming.

But the map of projected mobile-phone coverage around the project, uploaded to Facebook on 2 November, has brought to light another problem facing the local community. It shows the area around the SKA’s radio dishes where the use of electronic devices will eventually be restricted, because their signals would interfere with the relatively weak radio signals that the dishes will try to pick up from the distant Universe.

Communications problem

Nearby residents had been aware that mobile-reception ‘dead zones’ could be a side effect of the SKA. But Eric Torr, a light-aircraft-business owner who uploaded the map, says it shows the area affected is “larger than we were led to believe”. The map suggests that six towns fall into the dead zone, he says, and that this could have serious implications for their farming economies.

The map was produced by the South African Radio Astronomy Observatory (SARAO), which is leading the SKA project in South Africa. Lorenzo Raynard, head of communications at the SARAO, says it shows areas where mobile-phone coverage could be reduced by 20% or more (see ‘Telescope side effect’). The chart was part of a presentation calling on businesses to submit alternative communications solutions for affected areas, he says.

Credit: Adapted from SARAO map

An informal collection of farming organizations has already been working with the observatory to find alternative communications technologies, such as satellite phones, that can be used around the antennas, according to Henning Myburgh, a farmer in the area. “Adequate electronic communications, especially for children, are a basic human right,” he says. Myburgh says that the cooperative’s search has now moved to finding cell-phone technologies that can co-exist with the SKA and replicate the phone facilities the farmers currently have. “This is a major shift and if possible will be a huge step forward,” he says.

Still, says Myburgh, there are farmers who are unhappy. “I don't think that anybody will ever be happy with the situation, taking into account the massively intrusive nature of the project in the region,” he says.

Nicol Jacobs, who farms in the spiral arms, says the SKA was originally going to affect only two farms. He says he found out about the full extent of the telescope when the government began buying more farms. “We’re going to be eaten piece by piece,” he says. Jacobs says he would like the government to return the bought farms to the agricultural community: “I will fight as long as I can,” he adds.

Despite residents’ annoyance, South African law says that the country’s science and technology minister can preserve the area of the SKA’s land for astronomy. The department of science and technology, which oversees astronomy in the country, is responsible for finalizing regulations about areas that will lose mobile-phone coverage, and to define radio-wave frequencies that will be protected for astronomy. Asked when they would be finalized, the department’s astronomy-management authority declined to give a firm date.

Environmental assessment

Although resident’s complaints may not affect the SKA’s layout, an environmental assessment — due to be finalized next year — could change matters.

Earlier this month, the SARAO tasked the South African Environmental Observation Network to implement an environmental assessment of the telescope site, and made 3 million rand (US$209,000) available for the work.

“The relative position of the dishes determines the quality of the telescope beam,” says Robert Braun, science director at SKA Organisation, which is designing the telescope.

The organization has drawn up an ideal map of dish positions, says Braun. But it might have to shift them if the environmental assessment finds that local habitats or biomes are affected, says Casper Crous, an ecologist who is part of the assessment collaboration.

The overarching plan is to turn South Africa’s SKA site into a nature reserve and a site for long-term environmental research once the telescope is operational, says Crous. So a no-go zone for dishes, for example, “would be kokerboom [quiver tree] populations or ephemeral wetlands — areas that if impacted are unlikely to ever recover,” he says.