LOOKING UP: South Africa and Australia are each developing precursors to the Square Kilometer Array of radio telescopes. Above, an Australian dish built in 2010. Image: John Matson/Scientific American
MURCHISON SHIRE, Western Australia—The pilot of the eight-passenger Cessna turboprop lines up the nose of his plane with a red-dirt landing strip ahead, a band of cleared Earth not all that different from the flat, sparsely vegetated terrain below.
He eases the plane down to an altitude of 90 meters, then levels off, buzzing the airstrip for a visual inspection. At the remote Boolardy pastoral station here in Western Australia, about 600 kilometers north of Perth, any manner of debris might have blown onto the landing strip since it was last used. Or perhaps a stray cow or goat has wandered into harm's way. But no—the airstrip is clear. The pilot circles back for a gentle landing and taxis the Cessna to a halt near a collection of farm equipment belonging to a nearby homestead. Heat mirages shimmer on the smooth red dirt of the airstrip as a dust devil looms over the airplane's right wing.
This is hard country, a place where the barren wilderness stretches to the horizon in every direction, where termite mounds and the droppings of feral goats are about the only signs of life. But the Boolardy homestead in Murchison is plenty lively, occupied by a rotating cast of engineers, construction workers, scientists and, now, four North American reporters on a government-sponsored visit. Federal and state agencies plunked down about $5 million to purchase some 3,500 square kilometers of this rangeland in 2009, then signed a land-use agreement with the indigenous Wajarri Yamatji people worth more than $18 million to allow for construction on a core region of almost 130 square kilometers. Since that time the site has seen numerous upgrades in power generation, water storage and high-speed communication infrastructure. The dirt roads leading from the homestead to the core of the site have been graded to a flatness and smoothness that rivals most highways.
Nine thousand kilometers to the west, across the Indian Ocean, a similar scene is unfolding. Near the town of Carnarvon in the Karoo region of South Africa, a government-backed project has acquired 140 square kilometers of farmland about 450 kilometers northeast of Cape Town. Surrounding the remote plot is a newly designated 125,000-square-kilometer protected reserve. Like Murchison, the Karoo site has undergone a progressive makeover since its 2008 purchase—better roads, new fiber-optic cables, new power lines—to become ever more incongruous with its rugged surroundings.
The multibillion-dollar reason for all this parallel activity in Australia and South Africa has recently become clearer. At each of the far-flung sites, a handful of radio telescopes has sprung up like clusters of white mushrooms blooming from the red earth. Radio telescopes, which look like oversize satellite dishes, receive emissions from space at the longest wavelengths on the electromagnetic spectrum. Those emissions may come from natural radio sources in the galaxy, such as the spinning stellar remnants known as pulsars, or may originate as shorter-wavelength signals, such was microwaves, that have been stretched into the radio band as they travel from distant sources, across an expanding universe, to reach Earth.
Australia has six dishes, with designs on 30 more; South Africa has built seven of a planned 64. When the two projects, the Australian Square Kilometer Array Pathfinder (ASKAP) and the Karoo Array Telescope (MeerKAT), are finished, each will be among the most powerful radio observatories in the world. But both countries have set their sights on a bigger prize. South Africa is building MeerKAT, and Australia is building ASKAP, in the hopes of landing the $2-billion Square Kilometer Array, one of the most ambitious telescope projects in history.
In 2012 an international consortium will choose Murchison or Karoo as the home of the Square Kilometer Array, or SKA, a vast network of 15-meter radio telescopes that, as proposed, would comprise 3,000 steerable dishes that pivot on multiple axes to aim at celestial targets. (The project's name is a bit of a misnomer; the dishes would together provide about a half a square kilometer of collecting area.) With an array of interconnected dishes, astronomers can yoke all the telescopes together, essentially combining the collective observing power of the group into one super telescope. Adding more collecting area—that is, building more dishes—boosts the array's sensitivity, whereas spacing the dishes out across great distances gives the array better resolution.
A complementary array of stationary antennas—more like old-fashioned rooftop TV antennas than satellite dishes—would collect lower-wavelength radio waves and would bring the project closer to its nominal square kilometer of coverage. At full build-out, slated for the mid-2020s, the digital output from the SKA could exceed the current volume of Internet traffic worldwide. The project's cost would be split among a number of partner countries. But just how many of those 3,000 planned dishes will ever be built, and just who will foot the bill for them, remain unsettled.
Regardless, both South Africa and Australia are eager to reap the economic benefits and scientific glory that would come from hosting such a world-beating project. And representatives of each nation are quick to point out the advantages of their respective site.
"I think Australia is the site for the SKA, undoubtedly," says Phil Diamond, the chief of astronomy and space science for the Commonwealth Scientific and Industrial Research Organization (CSIRO), the Australian national science agency that is leading the country's bid for the project. Diamond points to the extreme remoteness of the Murchison site and the sparsely populated region surrounding it, which means a quieter background of radio waves generated by Earthlings—key for sensitive radio astronomy. "There are no people, no mobile phones, no microwave ovens, no garage-door openers," Diamond says. His CSIRO colleague Brian Boyle, director of the Australian SKA project, is fond of tossing off population density figures for Murchison Shire—in "nanopeople" per square meter. "It has no towns," Boyle says of the shire. "It prides itself on having no towns."
The South African contingent contends that remoteness is not everything and that the Karoo site offers important cost savings. "It's a lot cheaper to build infrastructure in South Africa, and it's a lot cheaper to carry out maintenance and upkeep in South Africa," says Bernie Fanaroff, project director for that country's SKA program. Plus, the MeerKAT site now has grid power, which the ASKAP site does not. Powering thousands of telescopes, their receivers and all the associated computer equipment would be costly off the grid. Justin Jonas, the South African SKA associate director for science and engineering, sums up his nation's rationale for choosing a proposed home for the SKA as, "Let's find a site that is remote enough to satisfy the science goals, but is not so remote that it's going to cost an arm and a leg to establish anything there."
Diamond says that the core of the SKA, where about half of the telescopes would be clustered, would require about 40 megawatts of electricity. The other half of the telescopes would fan out in long arms that would stretch to New Zealand to maximize the array's resolution; in Africa the arms would spread across several nations.
Although Murchison shire is an ideal site for solar power—it has both abundant land and abundant sunshine—a 40-megawatt solar plant would be a huge undertaking on its own. "Energy is a big problem for us," Diamond acknowledges.
An international committee short-listed the two sites in 2006 from four proposals, which also included a pitch from China and one from Argentina and Brazil. "The SKA science board said that these two sites were acceptable" from a science standpoint, says Cornell University astronomer Yervant Terzian, a member of the SKA siting group. "I think that's pretty good. The rest is refining."