A technician works on the ALMA correlator at 5000 metres elevation

The ALMA correlator, one of the most powerful supercomputers in the world, has now been fully installed and tested at its remote, high altitude site in the Andes of northern Chile. Enrique Garcia, a correlator technician, examines the system while breathing oxygen from a backpack. ALMA’s Array Operations Site, at an elevation of 5000 metres on the Chajnantor Plateau in the Chilean Andes, is so high that only half as much oxygen is available as at sea level.