When complete, the ELT dome will stand almost 262 feet (80 meters) high atop Cerro Armazones, a 1.8-mile-high (3 kilometers) mountain in the Sierra Vicuña Mackenna section of the Chilean Coast Range in the Atacama Desert, where the instrument will face rigorous winds. [The Biggest Telescopes on Earth: How They Measure Up]
"These conditions present an engineering challenge, making wind-tunnel tests vital," ESO officials explained in a new video.
During the tests, a model of the ELT faced blustery conditions in a wind tunnel at the Polytechnic University of Milan in Italy. It was plastered with sensors to measure the structural load it could face.
"The wind-tunnel test is developed to reproduce the conditions that the ELT will face when it's operational," said engineer Luca Ronchi in a blog post, "so, basically, it's about reproducing the dome and telescope on a smaller scale (made of glass-fiber-reinforced plastic), equipping it with sensors, calibrating these sensors, placing the object in the wind tunnel and — according to the established and agreed-upon test program — reproducing the conditions that the ELT will actually face on top of Cerro Armazones."
When complete, the Extremely Large Telescope will use a colossal, 128-foot (39 m) primary mirror, made up of 798 hexagonal mirror segments, to survey the universe like never before.