The achievement of building the world’s largest telescope

This story was produced by Science Friday and America Futura as part of our „Astronomy: Made in Latin America” ​​newsletter and series. It is available in Spanish here.

In the remote Atacama Desert of northern Chile, an ambitious project is underway that will revolutionize space exploration: the construction of A very large telescope (ELT). Dubbed the „world’s largest eye on the sky,” the massive instrument is part of the European Southern Observatory (ESO)—an organization that includes 16 European countries as members, Australia as a strategic partner, and Chile as its host. Explore the mysteries of the universe.

With a primary mirror 129 feet in diameter, it will be the largest visible-light and infrared telescope on Earth. Astronomer and ESO representative in Chile, Dr. Luis Chavarria says the ELT’s operations, scheduled to begin in 2028, could lead to a paradigm shift in our view of the universe. Telescope.

The telescope is expected to help solve the most complex questions in modern astronomy. This will allow researchers to study black holes and the first galaxies that formed in the universe, as well as dark energy and dark matter in greater detail, says Savaria. The ELT could help scientists find Earth-like planets, and could be the first telescope to find evidence of life outside our solar system, he says. „It will take us beyond where we have been before. And of course, its power will lead to unexpected discoveries, new areas of research and questions that we cannot ask today,” says Savaria.

It will perform better than the James Webb Space Telescope, which discovered some Long-lived galaxies, because it can take five times sharper images due to the size of its primary mirror. „The bigger the telescope, the more detail we can see in the universe,” says ESO astronomer Dr. Michael Marchett. Paranal Observatory From 2021 onwards.

A galaxy of technology

Location is key when it comes to stargazing, and the Atacama Desert has become a veritable constellation of technology thanks to its uniquely dry and clear atmosphere. It is of great interest to astronomers, and houses a network of telescopes, including ESO’s Very Large Telescope (VLT), 14 miles from the ELT building site.

So, the world’s largest eye was destined to appear in the middle of this arid desert – a place where the Milky Way lights up the night sky, and the hills seem endless. But it also seems awe-inspiring. Its unfinished metal dome catches the eye of people driving the highway 12 miles from the summit of Mount Armazon, 10,000 feet above sea level.

However, Marcet explains that the cloud-topping altitude of the ELT will not be sufficient – ​​it will require adjustable mirrors on the telescope and its instruments to compensate for image distortions caused by atmospheric turbulence.

The work is a huge feat of engineering, but inside ESO, they say, you have to think big to overcome the limits of science. Because of its size it would be impossible to build it in one piece, the telescope’s primary mirror, one-fifth and identified as M1, is made up of 798 ceramic mirror hexagons joined together like a honeycomb.

Tobias Müller, ELT’s on-site assembly, integration and verification manager, inspects the coating of M1 glass parts in a large room of a building in Paranal. He wears a cap, mask, gown and surgical gloves so that there are no airborne contaminants. „It’s like an incubator (for pieces),” he says. „Between entering and exiting the chamber, this entire process takes about 8 to 10 hours.”

Muller and his team process two sections a day. The goal is to give the pieces a highly reflective finish. Once the pieces leave the room, they are stored until they are installed. But so far, only a 2,500-ton metal dome has been erected to protect the telescope.

Extreme desert conditions can pose challenges during construction. A site supervisor, Marco Bravo, measures the wind speed to avoid endangering the dozens of workers inside the dome. „To make progress, at least on the front end, we need to take advantage of the wind dying,” he says.

In many ways, bad weather can be costly, says astronomer Marcela Espinosa, who operates Paranal telescopes and instruments that monitor weather conditions as part of her job. Although he has special tools for forecasting rain, he also uses what he calls his official machine: the human eye. That is why, in the evenings, she occasionally leaves the observatory to look at the clouds. Protecting the binoculars is always a top priority in what looks like bad weather.

The same treatment is applied to the ELT when the ELT is running. „We have high expectations—I hope I get my turn (to watch it),” says Espinosa. Construction started in June 2014, but work slowed for two years due to the Covid pandemic, and now the project is more than 50% complete.

Italian Davide Deiana, ESO’s deputy site manager, said the ELT was impressive not only for its technological progress but also for its architecture. „It’s like Chile’s own Colosseum,” he says.

This is not the first time he has been involved in an astronomy project. He already worked at the ALMA observatory in Atacama, which, among other milestones, has documented the birth and death of stars, thanks to an image of a galaxy formed 600 million years after the Big Bang.

Based on his experience, he believes they create unprecedented work: “Everything is well planned. It would be revolutionary.

This story was translated from Spanish Laura Gonzalez.