SKA’s double site splits opinion

Published in Physics World, 1 Jul 2012

The decision to build the world’s biggest radio telescope – the Square Kilometre Array – on two separate sites in Africa and Australasia has been praised by many. Jon Cartwright examines whether dual sites will hamper science prospects

Two sites are better than one: that is the consensus among the five voting members of the SKA Organisation on the location of the world’s biggest radio telescope. Before the votes were cast on 25 May, the widespread expectation had been that the Square Kilometre Array (SKA) would be hosted in either Africa or in Australasia. As it turned out, the voters plumped for both.

Double the site, double the prides left intact. After an escalating bidding war that has lasted almost a decade, neither Africa nor Australasia will be able to boast a lion’s share of the 71.5bn telescope. Come 2024, when the telescope is slated for completion, Africa will host most of the mid-frequency dishes, which provide high sensitivity, while Australasia will host the equally important low-frequency antennas, which provide a broad field of view. But some observers have been left wondering if it will be possible to have a dual site without subtracting from SKA’s design goals.

“I am troubled by this decision to split the bid,” says Dale Frail, an astronomer at the US’s National Radio Astronomy Observatory (NRAO) in Socorro. Frail, who is not associated with the SKA Organisation, refers to the “first photon” problem, namely that a big chunk of any observatory’s construction budget must be spent on site-specific infrastructure and personnel before the first data can be collected. “So the issue for me is that SKA will now split this infrastructure cost among two sites,” he says. “As there is a finite amount of money, I fear that the remaining dollars will just build less scientific capability.” […]

For the rest of this article, please contact Jon Cartwright for a pdf.