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African Astronomers Find New Use for Discarded Satellite Dishes

A radio astronomer's global map of instruments that work together to survey the heavens would show a big gap over Africa. Astronomers in South Africa hope to fill in that gap by converting old telecommunications dishes into radiotelescopes to produce a low-cost array that would span the continent.

"It will require a bit of work, but within a year we could be making the first observations," says Justin Jonas, an associate director in the Africa Project Office for the proposed Square Kilometre Array (SKA) radiotelescope. Last week a team from South Africa visited a satellite receiving site in Ghana and found one dish that may be suitable.

Across Africa, the 30-meter satellite dishes that were once the backbone of the continent's communications are being replaced by fiber-optic cables. The astronomers are hoping to bag a few of the roughly 20 dishes that are suitable before they are dismantled and their infrastructure ripped up. "If we can get a half or a third of those, it would make a substantial and important array," Jonas says. The dishes will need new detectors and the motors for steering the dishes would probably need to be adapted, he adds, but "it all looks possible."

South African astronomers have already developed political links with other African nations because they are competing with Australia to host the SKA, an array of hundreds of dishes spread over thousands of kilometers. If South Africa were picked to host the SKA, it would need to site dishes in neighboring countries. So Jonas says he and others figured, "Why wait for SKA? Why not see what we can do now?"

The South African government supports astronomy generously, in part because of the prospect of hosting SKA. Funding for the South African part of the new low-cost array would be covered by that support. The team hopes that setting up a couple of prototypes—perhaps in Ghana and South Africa itself—would encourage other governments to fund conversion of dishes within their boundaries.