Square Kilometre Array is a project to build the world’s largest and most sensitive radio telescope. It is abbreviated SKA. The array will consist of thousands of radio wave antennas linked together. The total collecting area will be about 1 square kilometer (0.4 square mile). The array will help astronomers and physicists investigate the formation and evolution of the first stars and galaxies and the nature of gravity. It will also help them study the role of magnetism in the cosmos and possibly even search for life beyond Earth. The Square Kilometre Array will be built in remote desert regions in southern Africa, primarily South Africa, and Australia. It is scheduled for completion in 2024.
Unlike optical telescopes, which detect visible light, radio telescopes detect radio waves. Telescopes that use radio waves can reveal objects that are invisible to other types of telescopes, such as optical telescopes. The objects are often blocked by dust clouds. Such clouds can prevent other types of radiation from passing through them. SKA observations will also be combined with data from telescopes that detect different kinds of light.
The array will use three types of antenna to receive a range of radio waves. It will include 3,000 dish antennas, each about 50 feet (15 meters) in diameter. Each such dish antenna will be equipped with two different types of radio receiver. The dishes can be pointed at a particular object in the sky. The two other main antennas will be aperture arrays. Such arrays are comprised of many antennas similar to the common radio antennas used in cellular telephones, home cordless phones, and car radios. The many antennas are precisely coordinated to operate together as one antenna. The aperture arrays will be used to observe large areas of the sky simultaneously. Antennas will be spread over distances of up to 1,800 miles (3,000 kilometers) at the sites.
Scientists, engineers, and other partners from around the world are working together on the telescope’s design. The proposed building sites offer excellent observation conditions of our own galaxy, the Milky Way. The sites also have a low population, providing for a minimum of interference from radio sources on the ground.
In late 2012, the Australian Square Kilometer Array Pathfinder (ASKAP) was completed. The radio telescope consists of 36 dish antennas, each about 38 feet (12 meters) across. The ASKAP telescope is able to collect data alone, but the 36 dishes will become part of the SKA when the larger array is completed.
