First 7-metre ALMA Antenna Arrives at Chajnantor
{"Image ImageDescription": "The  first of twelve 7-metre diameter ALMA antennas has just been  transported on 24 August 2011 to the 5000-metre-high Chajnantor plateau, where the Atacama  Large Millimeter/submillimeter Array (ALMA) is under construction. ALMA  is a giant radio telescope composed of an array of fifty 12-metre  antennas, as well as a smaller array known as the Atacama Compact Array  (ACA). This will have a total of four 12-metre antennas and the twelve  7-metre dishes. The  four 12-metre ACA antennas have already been moved up to the high  plateau, but this is the first of the smaller 7-metre dishes \u2014 which put  the \u201ccompact\u201d into Atacama Compact Array \u2014 to reach Chajnantor. It is seen in the centre of this photograph, surrounded by some of the other ALMA antennas. Penitentes ice formations are seen in the foreground.The  larger 12-metre antennas of the main array cannot be placed closer than  15 metres apart as they would otherwise bump into each other. This  minimum separation between antennas governs the maximum scale of the  features that they can detect in the sky. This means that the main array  cannot observe the broadest features of extended objects such as giant  clouds of molecular gas in the Milky Way, or nearby galaxies. The ACA is  specifically designed to help ALMA make better observations of these  extended objects. Its smaller 7-metre antennas can be placed closer  together, making them better able to measure the broader structures that  the main array misses.ALMA,  an international astronomy facility, is a partnership of Europe, North  America and East Asia in cooperation with the Republic of Chile. ALMA  construction and operations are led on behalf of Europe by 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 Joint ALMA Observatory (JAO) provides  the unified leadership and management of the construction, commissioning  and operation of ALMA.All  of the ACA antennas are being provided by Japan through a contract with  MELCO (Mitsubishi Electric Corporation). ALMA will also have 25  12-metre antennas provided by ESO, and 25 by NRAO. Links  For more information about ALMA at ESO The Joint ALMA Observatory website"}