June 24, 2021

I, Science

The science magazine of Imperial College

After 18 years of hard work, the world’s largest observatory has finally been inaugurated ...


In 13 March 2013, ALMA (Atacama Large Millimeter/submillimeter Array) was formally inaugurated. Located 5,000 metres above sea level and in the middle of one of the driest places in the world, ALMA – which in Spanish means ‘soul’ – will study the cold and distant Universe.

Multiple radio antennas – whose dishes measure either 12 or 7 metres in diameter – behave as a single telescope with a total diameter of 16 kilometres. In fact, ALMA is more powerful than the orbiting Hubble telescope, allowing it to perform delicate interferometry experiments. In such experiments several antennas work in perfect synchrony, observing the cosmos to a precision of one millionth of a millionth of a second.

The size of this project – and its £660 million price tag – required many partners to work together: Europe (the European Southern Observatory, including the UK), North America (Canada and the USA), and East Asia (Japan and Taiwan), in co-operation with the Republic of Chile. The antennas, each weighing around 100 tonnes, can ‘walk’ thanks to two custom-built transporters, Otto and Lore. These allow astronomers to arrange the antennas in different configurations, effectively changing the zoom level of the resultant image.

Although ALMA released its first images in October 2011, the official inauguration ceremony was celebrated in March 2013 at ALMA´s Operations Support Facility (located ‘only’ 2,900 metres above sea level). Here, authorities and scientists from around the world greeted this new astronomical tool.

“This is an example of the great achievements that become possible when institutions and nations pool their efforts… Applying this on a global scale by partnering up in such a great project, we are giving the astronomers the possibility of doing the unique research that is only possible with ALMA,” commented Tim de Zeeuw, ALMA’s former director.