The project of the Extremely Large Telescope (ELT), currently under construction in the arid Atacama Desert in Chile, represents one of the most spectacular advances in the history of astronomy. This telescope will be the most powerful ever built, featuring a segmented mirror 39 meters in diameter that will allow it to capture images of the universe with unprecedented clarity.
The ELT will not only be fundamental for the study of galaxies and exoplanets but will also mark a turning point in the search for life outside our solar system. With the promise of uncovering the deepest secrets of the cosmos, this instrument will be capable of observing details that have so far been beyond the reach of the most advanced ground-based telescopes.
Key Features of the ELT: A Monumental Work
The Extremely Large Telescope has been designed with revolutionary features in mind. Its primary mirror, composed of 798 carefully aligned hexagonal segments, will be the largest in the world, with a diameter of 39.3 meters. This mirror is complemented by other large secondary and tertiary mirrors, which allow it to capture more light than any other similar instrument.
One of the main objectives of the ELT is to perform precise observations of both the nearby cosmos and the distant universe, thanks to its ability to capture images in the visible and infrared light spectrum. This makes it the most versatile telescope for exploring planets beyond our solar system or galaxy structures millions of light-years away.
The entire structure will have a total weight of 6,100 tons, equivalent to a moving skyscraper. The mirror will have the ability to deform as needed, which will allow it to correct distortions produced by Earth’s atmosphere through its advanced adaptive optics system.
Additionally, it will use eight laser guide star units to improve its precision. This technology is crucial for obtaining images five times sharper than those captured by the James Webb Space Telescope. In this way, the ELT will not only be large in size but also in its ability to provide unparalleled visual data.
Location and Construction: Why the Atacama Desert?
The Atacama Desert has been the logical choice for the ELT’s location due to its exceptional astronomical conditions. With a clean and stable atmosphere, low humidity year-round, and minimal interference from artificial light, Atacama offers one of the best skies in the world for astronomical observation.
Construction of the ELT on Cerro Armazones, at an altitude of 3,060 meters, officially began in 2014, following the site selection by the European Southern Observatory (ESO). This monumental work required leveling part of the mountain’s summit to make room for the telescope’s structure. The ELT is located just 20 km from the Very Large Telescope (VLT), another ESO facility.
The design and construction have involved dozens of companies and research centers worldwide, including several Spanish centers working on the development of its instruments. The current phase of construction has already reached half of the project, and the telescope is expected to be operational by 2028. This telescope will be one of the first to employ advanced seismic resistance techniques, capable of withstanding large-magnitude earthquakes.
Scientific Objectives: The Search for Life Beyond Earth
One of the primary goals of the ELT is the search for Earth-like planets that could harbor life. Thanks to its great light-gathering capacity, the ELT will be able to make direct observations of exoplanets, including the characterization of their atmospheres. Unlike current telescopes, which only detect planets indirectly, the ELT will allow for direct imaging of these celestial bodies.
This ability to observe exoplanets in detail will enable scientists to search for biomarkers—that is, signs that could indicate the presence of life in distant atmospheres. Additionally, the ELT will be capable of exploring other key areas of astronomy, such as galaxy formation, stellar evolution, and the search for the first stars that formed in the universe after the Big Bang.
It is also expected that the ELT will provide key data on dark energy, a phenomenon that remains mysterious to science but is related to the accelerated expansion of the universe. The analytical power of this telescope makes it an essential tool for answering fundamental questions about the nature of the cosmos.
Advanced Instruments: Beyond the Telescope
The ELT will be equipped with a series of next-generation instruments that will make it even more versatile and powerful. Among the most notable is the CODEX spectrograph, designed to perform extremely precise measurements of variations in spectral lines. This will be useful, for example, in studying the possible variability of the universe’s fundamental physical constants.
Another key instrument will be HARMONI, a broadband spectrograph that will allow detailed imaging of astronomical objects at various wavelengths. Along with other instruments like EPICS and MICADO, the ELT will be prepared to tackle a wide range of scientific projects, from the search for exoplanets to the exploration of galaxies located billions of light-years away.
Additionally, the telescope will use adaptive optics modules like ATLAS and MAORY, which will correct distortions caused by Earth’s atmosphere, allowing for more precise observations from the Earth’s surface. This will give the ELT an advantage over other telescopes, especially those located in space.
A Giant Leap Toward the Future of Astronomy
The Extremely Large Telescope, with a budget of 1.45 billion euros, represents a colossal investment in the future of astronomy. Its development has been made possible thanks to international collaboration, with dozens of countries and research centers involved in its construction.
This project not only aims to make revolutionary scientific discoveries but also to drive advances in engineering and technology. The construction of the ELT has involved unprecedented technical challenges, from the transportation and assembly of gigantic pieces to the creation of advanced seismic stabilization systems.
When it becomes operational, the ELT will set a new standard for ground-based telescopes and will be the first of a new generation of super telescopes. Other projects like the Giant Magellan Telescope (GMT) and the Thirty Meter Telescope (TMT) will follow its example, but the ELT will be the pioneer in breaking the barriers of what is possible to observe from Earth.
In short, this colossal project not only promises to unveil the mysteries of the universe but also ensures that humanity continues to explore the confines of the cosmos with increasingly advanced technologies. Thanks to the ELT, the limit of what we can discover now is only the beginning.