Qualla: Atacama Large Millimeter Array

Atacama Large Millimeter Array: Introduction

Mon, 23 Mar 2026 00:00:00 GMT

Photo credit Chile_location_map.svg: NordNordWest derivative work: Виктор В (talk), CC BY-SA 3.0. The drivers who deliver ALMA's antennas to work carry supplemental oxygen. They have to -- the Chajnantor plateau sits at 5,000 meters above sea level, where the air holds roughly half the oxygen found at the coast. Custom-built 28-wheel transporters, each weighing 130 tonnes, haul 115-tonne radio dishes from the assembly facility at 2,900 meters up to the array site, placing them on concrete pads with centimeter precision. The thin, desiccated air that makes the job punishing is precisely why the telescopes are here. At this altitude, water vapor -- the enemy of millimeter-wave astronomy -- is nearly absent. ALMA, the Atacama Large Millimeter/submillimeter Array, is the most expensive ground-based telescope ever built, a US$1.4 billion collaboration between Europe, North America, East Asia, and Chile that has been fully operational since March 2013.

Image: Chile_location_map.svg: NordNordWest derivative work: Виктор В (talk) | CC BY-SA 3.0

Atacama Large Millimeter Array: Sixty-Six Dishes Acting as One

Mon, 23 Mar 2026 00:00:00 GMT

Photo credit Science and Technology Facilities Council, CC BY-SA 2.0. ALMA is not a single telescope but an interferometer: 66 individual antennas whose signals are combined by a supercomputer to simulate a single dish as wide as the distance between them. The main array consists of fifty 12-meter antennas -- 25 built by American contractors, 25 by...

Image: Science and Technology Facilities Council | CC BY-SA 2.0

Atacama Large Millimeter Array: The Image of a Black Hole

Mon, 23 Mar 2026 00:00:00 GMT

Photo credit Ajay Suresh from New York, NY, USA, CC BY 2.0. ALMA's most famous contribution may be one it shared with seven other observatories around the world. As part of the Event Horizon Telescope project, ALMA provided critical data that led to the first direct image of a black hole, published in April 2019. The image showed the shad...

Image: Ajay Suresh from New York, NY, USA | CC BY 2.0

Atacama Large Millimeter Array: Three Projects Became One

Mon, 23 Mar 2026 00:00:00 GMT

Photo credit Ajay Suresh from New York, NY, USA, CC BY 2.0. ALMA grew from the merger of three independent dreams. The United States had proposed the Millimeter Array, Europe the Large Southern Array, and Japan the Large Millimeter Array. In 1997, the National Radio Astronomy Observatory and the European Southern Observatory agreed to com...

Image: Ajay Suresh from New York, NY, USA | CC BY 2.0

Atacama Large Millimeter Array: Working Where the Air Runs Out

Mon, 23 Mar 2026 00:00:00 GMT

Photo credit Ajay Suresh from New York, NY, USA, CC BY 2.0. Life at 5,000 meters demands adaptation. The Operations Support Facility at 2,900 meters serves as base camp, where staff acclimatize before ascending to the array. Even so, the altitude takes a toll. In August 2013, workers went on strike for 17 days demanding better pay and wor...

Image: Ajay Suresh from New York, NY, USA | CC BY 2.0

Atacama Large Millimeter Array: Listening for the Universe's Coldest Secrets

Mon, 23 Mar 2026 00:00:00 GMT

Photo credit Catherine from Australia, CC BY 2.0. What ALMA hears is invisible and cold. Millimeter and submillimeter radiation comes from the coolest objects in the cosmos: molecular clouds where stars are forming, dusty envelopes around dying stars, and the faint glow of galaxies at the edge of the observable universe. ALMA ca...

Image: Catherine from Australia | CC BY 2.0