What you need to know about the Giant Magellan Telescope and how the University of Arizona is playing a major role in building it.

​​Scientists are building an enormous telescope called the Giant Magellan Telescope (GMT) that just might help us discover signs of life on other planets. Its tagline? “The universe awaits.”

The GMTO Corporation is an international nonprofit and consortium of 14 universities and research institutes that are working to bring this project to life. Tucson-based University of Arizona is playing a major role by constructing the telescope’s mirrors.

According to the telescope’s website, it will “have 50 million times the light gathering power of the human eye and will be up to 200 times more powerful than today’s best telescopes.” The telescope will have “4 to 10 times the resolution of today’s best space-based telescopes” and will be “largest public-private funded science project in history.” The GMT is slated to be finished in the early 2030s. 

“It’s a big deal,” says Buell T. Jannuzi, head of the Department of Astronomy at the University of Arizona and director of Steward Observatory. “One of the things that people ask is ‘Why spend money on telescopes like this?’ And the only good answer is to help satisfy humanity’s curiosity. And that means it’s very important that this kind of work is widely shared and widely available.”

Whether or not the telescope will help find signs of life is not certain, but Jannuzi tells us that it will most certainly help us find and identify new planets that have previously gone undiscovered.

Discover more about this literally massive project below. (Note: Although this project is a collaborative effort, this article will primarily focus on the U of A’s role.)

How did this project come to be?

 Jannuzi explained that every 10 years, the astronomy community in the United States comes together for the National Academy of Sciences Decadal Survey. The National Academy of Science advises the government. They gather at the request of the National Science Foundation, NASA, and the Department of Energy.

“They get together a segment of the community to survey the whole community and identify what science problems and astronomy and astrophysics are particularly ripe for major progress in the coming decade. And after they identify that science, they also recommend what new facilities or ongoing facilities or capabilities are needed in order to realize that science,” he says.

The most recent study was supposed to come out in 2020, but it was delayed by about 18 months due to the pandemic. Part of that survey included a recommendation to build two telescopes: a 30-meter telescope in Hawaii and the Giant Magellan Telescope that is going to be built in Chile. Jannuzi told us why building two telescopes is an important task.

“By building those two telescopes, you provide access to the whole sky. In order to observe something from Earth, your telescope has to be able to point at it. And if you’re at the North Pole, it’s pretty obvious you can’t point to anything in the southern hemisphere because the Earth’s in the way. If you’re at the Equator, you can see the whole sky, but a lot of it is going to be viewed through an awful lot of the Earth’s atmosphere and the Earth’s atmosphere absorbs light, and it also blurs or distorts images. So it’s easier if you can have one telescope in the northern hemisphere and one in the south,” he says. 

How the University of Arizona will play a key role

 In case you weren’t aware of this (we weren’t before writing this), southern Arizona is somewhat of an astronomical destination.

“We’re the only university to have built more than one instrument for NASA’s great observatories,” Jannuzi says. “That’s the Hubble Space Telescope, Spitzer Space Telescope, Chandra X-ray Observatory and Fermilab.”

The astronomy’s sister department, the Lunar and Planetary Lab, has been involved in almost every mission to Mars.

“The Giant Magellan Telescope comes from a history of telescopes that the University of Arizona has been part of. One called the large binocular telescope that’s on Mount Graham,” he says.

The National Observatory is headquartered in Tucson. The U of A has telescopes on Mount Lemmon, Mount Bigelow and Mount Hopkins — all in Southern Arizona. U of A also helps build and run telescopes in Chile.

One reason why so many telescopes are located in Southern Arizona? Optimal weather conditions and mountain peaks. U of A is playing a key role in building parts of the new giant telescope.

“The Giant Magellan Telescope uses mirrors that are made at the University of Arizona, like the ones we made for the large binocular telescope,” he says.

Given the number of high-quality telescopes, it can be difficult for some people to imagine why we’d need another one. But the GMT is special. These large mirrors will provide a clearer image of space.

“For small telescopes, they have a 36-inch telescope. That means the mirror is 36 inches in diameter. You can sort of think one mirror, that’s the primary focus is the light to a point that’s in front of it. It hits usually a secondary mirror or second mirror, and then it goes into an instrument,” he says.

“The primary mirror for the Hubble Space Telescope is 2.4 meters. The primary mirror for the Giant Magellan Telescope is 25.4 meters, so more than 10 times bigger. Now, the bigger the telescope, the more light it can collect in a given amount of time. You can just think of it as a bigger bucket collecting the light. And then the bigger the telescope, the finer the detail, you can see wherever you’re looking at.”

He gave us the example of how our eyes work and how telescopes, to an extent, mimic that.

“If you were interviewing me in my office, we would be close enough that if you looked at my hair, your pupil is big enough to resolve an individual hair. But if I was a mile away from you, I would just be a little dot if you were just looking at me with your eyes. But if you got a big pair of binoculars, where the lenses were maybe four inches in diameter, then maybe you could still see my face. So we use a big telescope to do this same thing. If we’re trying to study a faint planet around another star, then we need a big telescope in order to be able to just collect enough light from the planet to see it. But we also need a big telescope to separate the image of the star and the planet from each other. Otherwise, they blur together,” he says.

The GMT should provide astronomers with clear images so they can see things they haven’t previously been able to.

“You’ve got a star that is a billion times brighter than the planet orbiting it. If you want to just look at the planet, maybe you want to see if there’s signs of life on the planet, then you need to have a telescope as big as the GMT. And that’s what’s motivating us is the science that requires high spatial resolution in the images and the ability to put a spectrograph targeting the light from the planet,” he says. 

Building mirrors for the telescope

The U of A will be constructing the mirrors for this massive telescope in its mirror lab.

“We’re the only place in the world that can make mirrors this large,” he says. 

Jannuzi explained to us that a large amount of glass will be heated up to create a large mirror. 

“If the glass of the mirror is hollow, then you can control the temperature better and get very sharp images and if you cast the mirror, in an oven that’s spinning, you can get a curved surface,” he says. “Now, the problem is the GMT needs seven of these mirrors or one gigantic 25.4-meter mirror. We don’t know how to make a mirror that big. So we’re making it out of eight separate ones. But each of them needs to be symmetric, as if around the center of a 25- meter mirror, not around its own center. So that makes it much harder to polish.” 

Obviously, a mirror that’s that massive will take time to build. Jannuzi told us it takes roughly a year to make the mold for the glass, heat the glass and then let the glass cool. The glass has to cool for three months. Then, it takes two to three years to polish the glass.

“When those mirrors then go into the telescope, they’re coated with aluminum, aluminum that reflects the light and brings it all together at the instrument,” he says.

All in all, it takes about four years total to make one mirror. U of A started in early 2010 and aims to finish all eight mirrors before the decade’s end.

 “It’s a little bit like modern cathedral building where those of us that are building the facility won’t be the ones using it,” he says.

Once the mirrors are completed, they’ll be placed in a metal transport box that will be carried by large flatbed trucks. They will then leave a port and be taken by boat or ship to Chile. Next, they’ll be taken up the mountain top by another truck. Most of the work for the GMT is being done in the United States, some in Australia and by other partners. It will all be assembled in Chile.

Searching for signs of life

There are actually three telescopes currently being built that will aim to be the world’s biggest — the GMT is just one of them. All of these telescopes may find signs of life that are not on Earth.

“These telescopes are the first that have a realistic shot at finding signs of life one planets or on any of the stars. So that’s why I think that these particular projects are particularly timely and important … It’s guaranteed that we’ll be able to image and otherwise observed planets that aren’t yet known. But we’ll also be able to study a lot of the planets that have been detected, but have been too hard to really study,” he says.

“And then there’s no guarantee that we’ll see any signs of life. It really depends entirely on how common life is. If life is incredibly common, then I’m pretty confident we’ll be able to find signs of it. If it’s really rare, then it might unfortunately, turn out that we aren’t able to survey a big enough fraction of our galaxy to find signs of life. And even these great, giant tools we’re building now are not big enough to study planets and other galaxies yet. Those galaxies are so incredibly far away that we still can’t see something as small as a planet.”

Astronomers will be looking for oxygen and ozone and methane and other signs that may indicate life. 

“The whole debate is going to be how much of what of oxygen versus carbon monoxide is there in the atmosphere? And is it something that could occur without life? Or needs life to be present? So humans breathe in oxygen, destroy it and produce carbon dioxide. Plants produce oxygen. So the fact that we have plants and algae and humans on Earth affect what we see on Earth. But if there’s a way that could happen that doesn’t involve life, then how do you know for sure that you’ve seen life? If we get lucky, and radio telescopes get a signal from intelligent life or we see evidence of intelligent life directly. That’s great. But what’s much more likely is that we’re not going to know whether there’s intelligent life, we’re just gonna see something in the atmosphere that’s the result of life,” he says.

If signs of life are found, the scientific community will then debate the findings.

“The first 10 or 12 times somebody analyzes that they’ve found signs of life. It’ll probably be challenged and argued about and then somebody’s going to have an observation that just has 10 different things that point to life, and that’ll be the one that convinces everybody,” he says. “And then you can go back and the ones that are less convincing, you’ll be able to assess whether they’re real or not.”

Because of how incredibly massive space is, it will take a very long for us to communicate with life on other planets, assuming it exists. 

“So if I take a picture of the puppy that my wife and I got during the start of the pandemic, and I send it to the planets we know are orbiting the nearest stars, Proxima Centauri, so that’s four light years away. That means that takes the signal four years to get there,” he says. “Let’s pretend that there is intelligent life living on those planets. We don’t know if there is or not. If they liked an image and sent it back to me, by the time I know that they liked it, it’s been eight years, and the dog is eight years old. So we’re not going to have a rapid communication with intelligent life anytime soon.”

Our desire to discover the world is so deeply ingrained in us, and projects like this can help us do just that.

“One other thing about the importance of astronomy, I think to the world is, at some level, I like to say we’re one of the gateway drugs to science. Dinosaurs and astronomy, or paleontology, these kinds of sciences, you’re trying to understand humanity’s place in the universe, you’re trying to understand what our future might be, what our past has been. And it’s satisfying,” he says. “Something that’s just very common to all humans is trying to understand the world around us.”