Large section of the Giant Magellan Telescope.

About 4,500 miles south of the forty acres, on a deserted mountaintop in the heart of the world’s driest desert, is a large concrete circle. It doesn’t seem like much today, but this slab in the Atacama Desert in Chile is the basis for one of the most powerful portals to the universe ever imagined. It is the future home of the Giant Magellan Telescope (GMT), which will provide astronomers with an unprecedented window into the early universe and billions of exoplanets across the Milky Way.

Work on GMT has been going on for over a decade, and there’s still a lot more to do before it gets its first glimpse into the universe in 2029. Aside from the great engineering challenges that come with building a scientific instrument that can see into the depths of the past more than anything before it One of the biggest hurdles GMT engineers faced was ensuring that the project received enough funding to be completed on schedule. The total cost is expected to be more than $2 billion, which would make GMT one of the largest telescopes in the world and one of the most expensive.

As a founding member of the Consortium of Universities and Research Organizations Responsible for Sponsoring the Telescope from Conception to Completion (known as the GMT Organization), the University of Texas played an important role in both the scientific and financial aspects of the project. In August, Utah committed $45 million to fund the telescope as part of a $205 million funding package backed by Harvard University, the Carnegie Institution for Science, the São Paulo Research Foundation, the University of Arizona, and the University of Chicago. It brings UT’s full commitment to the telescope to just over $110 million, which will go a long way toward accelerating construction of this one-of-a-kind observatory.

Interior view of NASA’s Giant Magellan Telescope.

Since 1996, UT has operated one of the world’s largest optical telescopes—meaning it collects light in the visible part of the spectrum as opposed to X-rays, for example—at the MacDonald Observatory in the Davis Mountains in West Texas. Known as the Hobby-Eberly Telescope, it has allowed UT astronomers and their collaborators to make amazing discoveries, including the discovery of Earth-like planets around other stars and what may be the largest black hole ever found. The Hobby Eberle telescope was – and still is – an amazing scientific instrument. “To address the latest scientific problems, we need to expand even further,” says Taft Armandrov, director of the McDonald’s Observatory at the University of Utah and vice chair of the Greenwich Organization board. “Therefore, we are collaborating with some of the most ambitious and best astronomy programs as a group to build GMT.”

When it comes to optical telescope performance, it’s all about the amount of light the sensors can collect. One way to do this is to position the telescope where the sky is dark and clear, which is why GMT is built on top of a mountain in the middle of the Atacama Desert. But the most important parameter is the size of the telescope mirror. You can think of a telescope mirror as a bucket for collecting particles of light – or photons – and the larger the area of ​​the mirror, the more photons it can collect.

The GMT has seven primary mirrors, combined, equal to the equivalent of 25 meters – or 82 feet – in diameter. To put that in perspective, GMT has about five times the gathering area of ​​UT’s Hobby-Eberly Telescope and about four times the area of ​​NASA’s recently launched James Webb Space Telescope, which studies the universe from about a million miles from Earth in deep space.

Side by side accuracy comparison between JWST and GMT.

Its massive mirrors mean GMT will be able to see faint light sources such as ancient galaxies and distant exoplanets in greater detail. Given the speed with which the James Webb Space Telescope is changing our understanding of the universe, astronomers expect to see similar breakthroughs from GMT.

“GMT is a big step for changing the capabilities of the telescope,” says Steve Finkelstein, associate professor and Isabel McCutcheon Hart Centenary Chair in Astronomy at the University of Texas. “I can’t predict exactly what the huge discoveries will be, but I have no doubts they will be there.”

For Finkelstein, one of the most exciting applications of GMT is to study the formation of the first stars and galaxies during a period in the history of the early universe known as reionization. The light from these first stars and galaxies has been traveling through space for more than 12 billion years, making it extremely difficult to detect without a massive telescope. The same goes for the exoplanets in our galaxy, which are incredibly faint compared to the brightness of our host star. But with huge GMT mirrors and sophisticated equipment, astronomers should be able to get a clear enough view of these exoplanets to study their atmospheres.

Giant Magellan telescope view

Although Finkelstein and his colleagues won’t be able to use GMT before the end of the decade, UT’s investment in the telescope is already transforming the astronomy department. Like any university, UT competes with other organizations to attract the best talent. “When we ask these early-career professionals what cut the deal to get to UT, they often said it was because they were going to be part of the GMT and they preferred access to the telescope for themselves, the postdocs and their students,” says Armandrov.

Armandroff sees a great opportunity to use UT’s access to GMT to improve astronomy education for students across the university. Given the number of non-professionals who take astronomy courses at UT, the university’s involvement with the telescope is a unique opportunity for them to interact with the universe using state-of-the-art equipment.

“The GMT clock will really tell us about our origins and put our history as a species within the larger astronomical history,” says Armandrov. “There is a lot to tell us about a special place for Earth in the context of the universe and that, I think, is something worth considering for everyone.”

Credit: Courtesy of NASA


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