Thales Alenia Space announced today that it has completed the delivery of 25 dishes, each 12 meters in diameter, for the antennas making up the Atacama Large Millimeter/submillimeter Array (ALMA) astronomical observatory in northern Chile. ALMA is a huge international program built in partnership by Europe, North America and East Asia. ALMA construction and operations are led on behalf of Europe by the European Southern Observatory (ESO), on behalf of North America by the National Radio Astronomy Observatory (NRAO) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ).
The 25 antennas provided by Europe (out of a total of 66) are made by a Thales Alenia Space-led consortium, including European Industrial Engineering (Italy) and MT-Mechatronics (Germany). The ALMA antennas weight approximately hundred tons, and necessitate a special 28-wheel vehicle and a reinforced road to be moved from the assembly plant to its final destination. The dishes of these antennas have been implemented under the management of Thales Alenia Space Italy. To obtain the needed accuracy, the dishes of the antennas have to be extremely light and stable. This has been achieved by the use of ultra-stable CFRP (Carbon Fiber Reinforced Plastic) for the reflector base and of rhodium-coated nickel for the reflecting panels. The surface of the 12-meter dish, must be accurate to within 25/1000 of a millimeter, and cannot change due to any operational conditions, including wind, temperature fluctuations, solar irradiation and the frequent relocations of the antennas with their special vehicle.
“Building a 12-meter dish to these exacting standards was a real challenge for Thales Alenia Space,” notes Vincenzo Giorgio, Thales Alenia Space Italy Responsible for Exploration and Science, "not to mention that these parabolas must guarantee perfect pointing for many decades to come.”
The ALMA observatory is being built in the Atacama Desert of northern Chile, at about 5,000 meters above sea level. When finished, ALMA will comprise 66 adjustable parabolic antennas (54 with a diameter of 12 meters and 12 with a diameter of 7 meters), capable of simultaneously observing the sky at millimetric and sub-millimetric wavelengths. The observatory is based on the interferometry principle: the images produced by combining the signals from each antenna offer a resolution equal to that produced by a single gigantic parabolic antenna with a diameter of up to 16 kilometers! This highly innovative facility will give astronomers an opportunity to study the birth of the Universe and to obtain highly detailed images of the formation of stars and planets in our galaxy. ALMA is also capable of capturing very weak signals from the farthest reaches of the Universe.
Source: Thales Group (Paris: HO.PA)
Date: Jan 14, 2013