During the last decade, albeit quietly, there has begun a three-way race to build the next generation of optical telescopes. Three teams are competing to be the first to build a new ground-based observatory that will be much, much larger than any optical telescope built before. The competitors are: The Giant Magellan Telescope, the Thirty Meter Telescope and the European Extremely Large Telescope.
The world’s largest optical telescopes today are 10 meters. This new generation will have an effective mirror of at least 25 meters across. That’s a huge difference. Whichever group gets finished first will discover a lot of new territory in physics and astronomy.
From the Texas standpoint, we’re most interested in the Giant Magellan Telescope, because the University of Texas and Texas A&M have a combined 20 percent interest in it, which means that researchers there will get to use the telescope for 20 percent of its observing time.
To that end I recently caught up with the GMT’s leader, astronomer Wendy Freedman, who visited Houston to meet with donors. Here’s a transcript of our conversation.
How goes the telescope project?
It’s coming along extremely well. We are just in the final stages of completing the first of the primary mirrors. The telescope is a 25-meter, or 83-foot diameter optical telescope that will be located in the Andes Mountains at an altitude of about 8,500 feet. There are seven individual mirrors each of which is 8.4 meters in diameter. Completing the first mirror is a huge milestone for us. Its surface is smoothed to 20 nanometers. So it’s really a huge technical challenge. That was our biggest risk, and we’ve accomplished it. So we’ll start casting the second mirror in January at the University of Arizona, and we’ve just bought the glass for the third mirror. We’re going to build eight mirrors so there is one spare. We’re in the midst of the detailed design phase of the project, all of the engineering for the telescope mount, and the facilities that will house it. We’ve just completed four years of site testing, and in about six months we will dynamite the side of the mountain in Chile.
This region of Chile is literally the best site in the world for optical telescopes. There are about 300 clear nights a year. It’s dry. It’s very dark, there are no city lights nearby. And it turns out with this property astronomers call astronomical seeing, it’s one of the best sites in the world. There’s very little turbulence in the atmosphere that blurs out light from stars.
How do you stand from a fundraising perspective?
In terms of funding, that’s also coming together. The total cost of the telescope is $700 million. We’ve got about 40 percent raised at this point. A couple of years ago we only had 2 percent, so it’s really coming along. In terms of a declining economy, it’s really going very well. We have an international consortium of which Texas, with A&M and the University of Texas at Austin, comprises 20 percent of the overall total. Government funding has decreased so we have to do it ourselves.
You’ve gotten a lot of help from Texas, in particular, from George Mitchell haven’t you?
We just got a very generous gift from the Mitchell Foundation, a $25 million gift toward the construction of the telescope. In total he’s given $35 million. It’s been an extraordinary contribution. In fact the telescope would not be where it is today without his early involvement. He’s been a catalyst at every level, from the first mirror where he contributed to building that, to now as we’re in the detailed design phase. He expressed that he reads all the time science discovery headlines in the newspaper from professors at other universities, and he asks, “Why can’t Texas be a part of these things?” He wants that for Texas. He understands that you have to take a risk to succeed, so he took a risk early on in the project. We’re now looking for other people in Texas that would like to help.
When do you intend to complete the telescope?
On the current timeline the telescope would be operational by 2020. We would probably be doing regular operations by 2021.
Could you accelerate the process if a donor stepped forward to give you $400 million tomorrow?
Honestly, because there are big pieces to put together, it would be hard to do it that much faster. If we had the $400 million it would guarantee it would be done on time.
You’re in a race. How far along is your U.S. competition, the Thirty Meter Telescope?
We’ve concentrated on different kinds of things. They’ve worked on their detailed design, but they haven’t done any construction yet. We started with our first mirror. Our partnership is now almost complete, and our international partners are now already contributing. They’re waiting and hoping for their partners to eventually contribute funding but it hasn’t happened yet.
Are they targeting 2020 as well?
We roughly have the same time scale. But we intend to be first.
Are there groups outside the United States?
There are three next generation optical telescopes being built. One is in Europe. It was originally 100 meters, then it was scaled back to 42 meters, and I believe they have now scaled back to 39 meters. All three projects are now trying to put together their collaborations and raise the funding needed. It would also be built in Chile. The southern skies are the place where astronomy will be for the next half century.
What are the largest optical telescopes currently in operation?
There are about 17 telescopes, distributed across the world, in the 6- to 10-meter range. The Keck telescopes in Hawaii and the Hobby-Eberly telescope here in Texas are 10-meter telescopes. For optical telescopes, the space-based Hubble telescope has been the benchmark for resolving power, but the GMT will have 10 times the resolution of Hubble. It’s a huge jump.
What’s there to be found with a large new optical telescope?
We’re going to have a very wide field on the sky so we can point to a region and get thousands of objects simultaneously and study them in detail. Because it’s such a big telescope we can take images of very faint objects, further than we’ve seen before. We will actually be able to see the first objects to form in the universe. The first stars and galaxies. We know they’re there, but we’ve never seen how. Another thing is we’re really on the verge of learning there are planets like the Earth, and whether or not there is life on those planets. That’s going to take a combination of telescopes from space and land. There are a limited number of these planets nearby, and the first of these telescopes to get on the air is going to learn what we can about them.
What specifically can you see in terms of planets?
What these big telescopes let you do, because they can collect so much light, is spread out the light into a rainbow or spectrum, and by studying these spectra it gives you very detailed information about how far away the object is, how fast it is moving, and this kind of information allows you to get the mass and orbit of a planet, and what its atmosphere is like. Do we see water? Oxygen? Carbon dioxide? The things we know are indicators are life.
How far back toward the beginning of the universe can we expect to see with these large telescopes?
The period between 400 million years and 1 billion years after the Big Bang, we don’t know anything about it right now. It’s what astronomers refer to as the Dark Ages. We literally just don’t have telescopes powerful enough to see there. And we’ll be able to see directly what is going on in those epochs.
Can these telescopes provide any answers on the mystery of dark energy?
The Nobel Prize just given for the discovery of dark energy was based on observations of these objects called supernovae, large explosions near the end of certain stars’ lives. To really understand dark energy we want to follow the evolution of the universe over time, and so again we’ll be able to chart out to even more distant and earlier supernovae with bigger telescopes. We really don’t understand what’s causing this acceleration, but by seeing what these objects are telling us we can put constraints of the acceleration. This ability to pick out fine detail, to find these distant, faint supernovae, will be very helpful.
What’s the benefit for the Texas institutions participating in your project?
The universities that are involved will have this unique access to the telescope. The faculty at UT and A&M will be in a position to things that no one else can. It’s a tremendous tool for bringing talented young scientists into the state and then retaining them. There going to go where they can do the best science.
What’s the first thing you will observe when you turn the telescope toward the heavens?
The first thing will be a very deep field image, and surely planets, the best targets for Earth-like planets, will be very high on our list.