South Africa and Australia have been shortlisted as possible sites for the Square Kilometre Array (SKA) radio telescope.
The telescope is being developed by scientists across 17 countries, and the recommendation was made by a group of seven scientists representing five nations.
The telescope, once built, will consist of thousands of antennae spread over an area of 3,000 square kilometres. Half of the dishes will be installed in a so-called core site, an area of 5km by 5km. The remainder will be more widely distributed.
It will be the largest telescope ever built and will be used to probe some of the most important questions in astronomy and cosmology. It will be used to investigate so-called dark energy, the origin of magnetism, and could be deployed in the search for extra terrestrial life, according to South Africa's minister for science and technology Mosibudi Mangena.
The Australian bid proposes the core site be located at Mileura Station, 100km west of Meekatharra in Western Australia (nearish to Perth). The antenna might be spread so widely that some end up in New Zealand, the CSIRO office says.
South Africa's proposal would see the core site being placed in the Karoo in the Northern Cape.
The other two bids were from China and Argentina. The SKA steering committee said the proposals were excellent, but each failed at least one of the exacting requirements.
Whichever site is chosen, it must have very low levels of man-made radio signals to avoid interfering with the cosmic radio waves the 'scope is designed to detect.
The Australian team thinks it has the edge on South Africa in this regard: "The West Australian site is better in this respect than any site in the world currently used for radio astronomy," said Commonwealth Scientific and Industrial Research Organisation's Dr Michelle Storey, leader of the Australian SKA Planning Office.
Other important conditions include a good view of the Southern Hemisphere's sky, where the centre of the Milky Way goes overhead, and stable ionospheric conditions, particularly important for low frequency observations.
As you would expect with such a large bunch of boffins, argumentative by nature, there is disagreement even on when the final decision will be made. The South Africans expect it in 2008, but the Australians have their money on 2010. ®