Antennas in disguise

Ask someone to describe a desert and they will tell you of sandy, ochre landscapes. Usually, that description is spot on — but not always, like in this Picture of the Week. For most of the year, the white antennas of the Atacama Large Millimetre/Submillimetre Array (ALMA), operated by ESO and its international partners, stand out against the reddish background of the Atacama Desert. Once in a while, though, the landscape transforms, and the antennas become disguised in a white snowy panorama. 

The Atacama is situated between the Andes and the Chilean Coast Range, high mountain ranges that shield the desert from humid winds, making it one of the driest places on Earth. These conditions make places like ALMA’s site ideal for astronomical observations. Even there, though, sometimes it rains — or even snows.

During the winter months of June to September, temperatures can drop to -20 °C and precipitation falls in the shape of snow. Yet ALMA does not stop working. The antennas remain operational, but may need to sunbathe for a bit, to melt the snow that accumulates on their surface. Even the dark-yellow antenna transporters —  nicknamed Otto and Lore — can keep on moving the antennas around. Snow or no snow, ALMA is always in search of new discoveries.