All alone in the desert

Take a look at this aerial photo of the Atacama Pathfinder Experiment, or APEX for short, sat stoically atop the Chajnator plateau in Chile’s Atacama Desert. This remote, dry location, some 5100 metres above sea level, is the perfect location to uncover the secrets of the so-called “cold universe”, the regions in space only a few tens of degrees above absolute zero. 

APEX is a 12-metre telescope hosted and operated by ESO on behalf of the Max Planck Institute for Radio Astronomy (MPIfR). It observes at millimetre and submillimetre wavelengths — between infrared and radio waves — where vast cold clouds of interstellar dust and gas glow. These clouds act as the birthplace for new stars and would be obscured in the visible light range. 

Light collected by APEX is then recorded by different instruments. One of these, known as the Large APEX Bolometer Camera (LABOCA), has an array of 295 “pixels” known as bolometers (highly sensitive thermometers) which are used to detect tiny fluctuations in the faint radiation coming from astronomical objects. To do this, each bolometer must be cooled to less than 0.3 degrees above absolute zero — that’s a very chilly -272.85 degrees Celsius! With this advanced equipment, APEX peers into remote clouds of cold gas from the chilly solitude of the Atacama Desert.