SciFi Movie Set? No- It’s the Atacama Desert Space Array, the World’s Largest Astronomical Center



The Atacama Large Millimeter/submillimeter Array (ALMA) is an international partnership between Europe, North America, East Asia and the Republic of Chile to build the largest astronomical project in existence. It is an astronomical interferometer, comprising an array of 66 12-meter and 7-meter diameter radio telescopes observing at millimeter and submillimeter wavelengths. It is being built on the Chajnantor plateau at 5000 meters altitude in the Atacama desert of northern Chile.

ALMA is expected to provide insight on star birth during the early universe and detailed imaging of local star and planet formation. Costing more than a billion dollars, it is the most ambitious ground-based telescope currently under construction. ALMA will begin scientific observations in the second half of 2011 and is scheduled to be fully operational by the end of 2012.

ALMA will be a single telescope of revolutionary design, composed initially of 66 high precision antennas, and operating at wavelengths of 0.3 to 9.6 mm. The array will have much higher sensitivity and higher resolution than existing sub-millimeter telescopes such as the single-dish James Clerk Maxwell Telescope or existing interferometer networks such as the Submillimeter Array or the IRAM Plateau de Bure facility.The antennas can be moved across the desert plateau over distances from 150 m to 16 km, which will give ALMA a powerful variable "zoom", similar in its concept to that employed at the VLA site in New Mexico, US.The high sensitivity is mainly achieved through the large numbers of telescopes that will make up the array.The telescopes are provided by the European, North American and East Asian partners of ALMA. The American and European partners have each placed orders for twenty-five 12-meter diameter antennas, that will compose the main array. East Asia is contributing 16 antennas (four 12-meter diameter and twelve 7-meter diameter antennas) in the form of the Atacama Compact Array (ACA) which is also part of the enhanced ALMA.By using smaller antennas than ALMA, larger fields of view can be imaged at a given frequency using ACA. The ability to move them closer together also results in the possibility to image sources of larger angular extent. The ACA will work together with the main array in order to enhance the latter's wide-field imaging capability.


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