The Atacama Large Millimeter/submillimeter Array (ALMA) is an international collaboration to develop an astronomical interferometer formed from an array of radio telescopes, located at Llano de Chajnantor Observatory in the Atacama desert in northern Chile. The telescope array will consist of 50 to 64 antennas of 12 meter diameter and the antennas will be movable. An additional, compact array of 7-m and 12-m antennas is also foreseen. Its receivers will cover the range from 30 to 950 GHz. ALMA will be an instrument for studying the physics of the cold universe and provide an insight on star formation in the early universe. It will also imaging local star and planet formation in great detail. Construction of ALMA started in 2003 and will be completed in 2012; it will become incrementally operational from 2010 on.

GARDs contribution in the project is to build band 5 (163-211 GHz) receivers. We will produce a prototype SIS system for 1.8 mm and then produce eight 1.8 mm receiver cartridges which can be inserted in the ALMA cryocoolers. 

This band has a strong absorption line of water vapor and provides lines that are important tracers of temperature and density in regions of star formation and probably in comets as well; H2O is a crucial part of the cooling processes which allow collapsing clouds to form stars and planets, and the abundance of water vapor is a critical part of the chemistry of the interstellar medium.