Today in the Chilean Atacama Desert, work is in full swing to create the dome of the Extremely Large Telescope and the bed for the 200-ton 39-meter mirror. Construction equipment and cranes seem like toys against the backdrop of a colossal structure. The project started 10 years ago and is moving toward completion in four years. This will be the largest optical telescope on Earth, which will expand the horizons of our knowledge of the Universe.
Image source: ESO
Representatives from the European Southern Observatory (ESO) shared footage from the construction site taken last month. In the pictures we see, first of all, a giant dome, which will be equipped with sliding doors. During a hot day or dust storms, the telescope will hide behind them and behind the insulating lining of the dome. The entire structure will be covered with thermal insulation to maintain a more or less stable temperature inside the room until nightfall.
A special bed is created inside the dome for the world’s largest mirror. It must withstand 200 tons and will compensate for temperature changes and vibrations caused, for example, by strong winds. In addition, each segment of the mirror, made up of 798 hexagonal pieces, will be adjusted. Each segment will have its own module with an alignment system.
Also, the optics of the telescope will have adaptive laser adjustment to compensate for turbulence in the atmosphere. The system will monitor four artificial stars in the sky, and adjust one of the mirrors in the telescope’s optical system to the air turbulence in the viewing area a thousand times per second. In total, the telescope’s optical system will include six mirrors along with the main one. The observatory expects to receive first light in 2028, which will be 4 years later than original plans.