The construction of the ELT giant telescope in Chile’s Atacama Desert is now halfway complete, according to the European Southern Observatory (ESO). The construction work is progressing rapidly, and it is expected that the remaining 50% will be completed much faster than the first half. The preparatory work at the site began in 2014, and the earthwork on the foundation started four years later. The telescope is scheduled to start its scientific work in 2028.
The ESO has announced that the progress on the components is going well. The gigantic dome is currently being manufactured and its progress can be tracked online. The ESO states that the giant telescope will soon take on the typical form of such instruments. Additionally, 70% of the hexagonal segments of the main mirror have been completed, and two more mirrors are finished and being polished. The individual parts of the adaptive fourth mirror are also finished and being assembled.
The first half of the construction work took nine years, almost twice as long as planned for the second half. The delay was not only due to the COVID-19 pandemic, but also because of the lengthy process of finalizing the design of most components and the need for prototyping and testing. After the production processes were resumed following the pandemic-related break, the construction is now expected to be completed in five years.
When completed in 2028, the Extremely Large Telescope will be the largest optical and infrared telescope on Earth. It is being built on the Cerro Armazones, at an altitude of approximately 3000 m. The foundations of the telescope were completed in early 2022, using almost 9000 m³ of concrete. The steel frame of the dome has been erected, with each individual block weighing 70 tons. The ESO attributes the 50% completion of the observatory to the earned value analysis, a project controlling tool.
