The Atacama Large Millimeter/submillimeter Array (ALMA) is currently the largest astronomical initiative in existence. But plans exist to construct an even larger and more sensitive radio telescope, the Square Kilometre Array (SKA). There are several nations involved in the race for hosting the new international collaboration, but Australia has recently taken a huge step towards becoming that country, when the first antenna of its Australia Square Kilometre Array Pathfinder (ASKAP) telescope received its first radio signals. The observatory is an important precursor for the SKA instrument, and so the southern nation has a higher chance than other contestants of actually housing the new project.
“ASKAP's progress to date shows that our goals, although ambitious, are achievable. The journey to a thousand SKA dishes begins with a single photon,” says professor Brian Boyle, who is the SKA director at the Commonwealth Scientific and Industrial Research Organization (CSIRO), the nation's main government body for scientific research. The antenna that was recently put to the test is just the first of 36 other, 12-meter dishes that are to be built at the Murchison Radio-astronomy Observatory, in the Mid West region of Western Australia. The new antenna was constructed during the Southern Hemisphere summer.
“It's a great moment – the first time a telescope receives light or radio waves – is always very satisfying and exciting. It means the project is firmly on track. The test results show that the antenna is working beautifully, beyond specifications,” says Dr David DeBoer, who is the CSIRO ASKAP project director. The new tests were conducted so that researchers and astronomers on the ground could measure the shape of the antenna's surface. In order to achieve this, they used a process called holography, which involves comparing how a test signal is reflected from the antenna surface, as opposed to how the same signal bounced from a reference dish. If the two are different, then the new antenna does not have the “perfect shape”.
“We have arrived at this point thanks to tremendous efforts by the construction teams which erected the antenna through the heat of summer, and the team supporting the holographic testing,” DeBoer adds. All of the ASKAP antennas will have a diameter of 12 meter, and a height of 18 meters, and they too will be linked as an interferometer. The entire telescope, comprising 36 dishes, is scheduled to be opened for business in 2013, with the first batch of six antennas planned for completion by next year. The CSIRO Astronomy and Space Science division will operate the new observatory, once it is made operational.