The $1.6 Billion Extremely Large Telescope (ELT) In Chile

In April 2010, the European Southern Observatory, or ESO, Council announced that it would build the Extremely Large Telescope or ELT in Cerro Armazones, Chile.

Planned to be the world’s largest optical and near-infrared extremely large telescope, ELT is no less than an engineering marvel.

From its design to its planning and construction, every aspect of this Mega Build is a story of its own.

Why did the ESO Council choose Chile to build the ELT? How much is the project going to cost? And when will the Extremely Large Telescope in Chile be completed for intergalactic exploration?

Watch this video until the very end to find answers to all these questions and discover exciting details about the ELT!

But, before we begin, don’t forget to leave a like, share your thoughts about this project in the comments, and subscribe for more amazing videos like this one!

The Idea Behind ELT

The idea behind building the ELT was to have a telescope that could help humanity find extrasolar exoplanets or the planets that are orbiting other stars.

The scientists believed that ELT would not only search for Earth-like planets but also capture important details about their atmospheres.

Another goal set for the Extremely Large Telescope was exploring the most distant objects and assisting scientists study things like black holes, primordial galaxies, primordial stars, and phenomena of various processes in space. 

The ESO Council also aimed to directly measure the rate at which the universe is expanding to better understand the space we live in.

Early designs showed that the ELT would have a primary mirror that would be 39.3 meters in diameter and a secondary mirror with a diameter of 4.2 meters.

Planning Phase

When the feasibility study of the Extremely Large Telescope concluded the diameter of the ELT was proposed to be 100 meters which would cost €1.5 billion or $1.6 billion upon completion.

The current largest telescopes in the world, which include the Keck Telescopes, the Gran Telescopio Canarias, and the Southern African Large Telescope, use a composite mirror design that puts smaller mirrors together to make a large mirror having a diameter of 10 meters or 33 feet.

The ELT’s mirror design was also kept similar with a single mirror measuring nearly 8 meters or 26 feet in diameter.

A Phase B study was carried out in 2014 that included the design and making of prototypes of key parts of the ELT, such as the mechanical structure and the mirror segments.

Design of the ELT

The ELT will be using a new design that combines a total of five mirrors which are divided into two sections.

It has a three-mirror anastigmat design using the first three mirrors which are curved, and nearly flat fourth and fifth mirrors.

The first three mirrors are designed to provide sharp images of the galaxies with a field of view spanning 10 arcminutes or one-third of the width of the full Moon.

Whereas, the Extremely Large Telescope will use the fourth and fifth mirrors for tip-tilt correction for image stabilization and adaptive optics correction for atmospheric distortions.

Primary Mirror

The primary mirror of the ELT has extraordinary dimensions that make it stand out from all the telescopic mirrors used in different projects so far.

Its diameter measures a staggering 39 meters in curved form. James Web Space Telescope was launched in December 2021 and is considered a turning point in telescope technology using a mirror that’s 6.5 meters in diameter, nearly six times less in size than the ELT’s primary mirror.

The light collection ability of a telescope plays an important role in determining how far it can see in space and how sharply it can capture the images.

Due to its humongous size, the Extremely Large Telescope will collect light at an unprecedented level. 100 million times more light than a human eye captures, and 8 million times more than Galileo’s famous telescope. 

Not only this, the ELT’s light collection capacity is 10 to 15 times more than even the Very Large Telescope that is located in Antofagasta, Chile, and became operational in 1998.

In addition, the ELT’s highly advanced mirror will have 798 hexagonal segments each having a diameter of 1.5 meters. These components are currently under manufacturing by a German company, Schott AG. 

The Extremely Large Telescope will also have 4608 edge sensors that will enable it to measure the relative positions of objects to nanometre accuracy.

Secondary Mirror

The secondary mirror of the ELT is no less than an engineering marvel either.

With a total weight of 3.5 tonnes, this mirror is 4.2 meters in diameter. 

This huge mirror will function as the focal point for the light captured by the primary mirror.

Another special feature of this mirror is its height. Once operational, the secondary mirror of the ELT will stand at a staggering height of 60 meters. 

Dome of ELT

When completed, ELT’s dome will be 74 meters high with a diameter of 86 meters. This will be the largest dome for a telescope having a total mass of 6100 tonnes and a moving mass of 2800 tonnes.

Italian ACe Consortium, a joint venture of Ansaldi and Cimolao has been granted the contract to build the dome of the Extremely Large Telescope so it can protect the telescope in adverse weather conditions.

The dome will also have a pair of sliding doors with a total width of 45.3 meters. There will be a windscreen as well to protect the telescope against strong winds, considering the ELT is located in the middle of nowhere.

The construction of the ELT’s dome began in 2017 and the wind tunnel work and simulations are underway to understand the wind flow patterns in the area and modify its design accordingly.

The dome will also be equipped with a highly advanced air conditioning system that will cool the telescope by 10 degrees Celsius in 12 hours.

Comparison with Other Telescopes

The Extremely Large Telescope is not only bigger than the currently operational telescopes but also the ones planned for the future.

For example, the Giant Magellan Telescope, which is also under construction, will have a mirror of 25 meters in diameter. Similarly, the Thirty Meter Telescope will also have a mirror of 30 meters in diameter, meaning both these telescopes will be smaller than the ELT.

Although the ELT’s size has been reduced from 100 meters in diameter to 39.3 meters, it is still larger than other telescopes. This is the reason why the Extremely Large Telescope 

Outro

In 2017, the foundation stone of the ELT was laid at Cerro Armazones in Chile.

This gigantic telescope passed the halfway mark of its construction in 2023 and is planned to be completed by 2028. 

This $1.6 billion mega project will be one of its kind when it receives its first light. 

The scientists looking to explore unexplored territories in space are excited to use data that will be collected by the ELT to study planets, stars, and other celestial bodies and phenomena.

The Extremely Large Telescope will push the boundaries of space exploration adding helpful information to what humans already know about the universe.

If you liked this video, give it a thumbs up and remember to subscribe to our channel for more!