• Nekoreguojami


2023. 05. 03 -

Prof. J. Žmuidzinas on the planned giant observatory: it will make it easier to search for distant planets

23 billion kilometres away, the Voyager 1 probe - the furthest man-made spacecraft ever to leave Earth - is bidding farewell to the Solar System as it orbits in interstellar space. The fact that it is still in operation (it was launched 45 years ago) and gathering information from uncharted territories is breathtaking. What's more, a Lithuanian-American scientist has also contributed to the Voyager mission.
When the spacecraft was being developed, Jonas Žmuidzinas, a young student at the California Institute of Technology (Caltech), calibrated the probe's electronic spectrometer. This technology will come in handy more than 30 years from now when, in August 2012, scientists will know that Voyager 1 has already entered interstellar space.
Today, Professor Žmuidzinas is a renowned physicist who has contributed to a wide range of world-class projects. Always smiling broadly, the scientist, who loves to interact with young people, was at Center for Physical Sciences and Technology (FTMC) from 18 to 21 April for the Open Readings 2023 student conference. At the conference, the Lithuanian-American gave a presentation on the achievements and plans of Caltech Optical Observatories. He is the head of this department at the university.
Žmuidzinas is also a member of FTMC International Advisory Board.
He talks about the importance of large telescopes, future breakthroughs in the search for other planets, and astronomers' complex relationship with Hawaii's inhabitants.
(Prof. Jonas Žmuidzinas. Screenshot from the Youtube channel "Lietuvos nacionalinė fizikos konferencija")
Professor, how often do you have the opportunity to visit Lithuania?
The last time was in 2018, so it's been five years. It is too long for me, I would like to visit more often. It was more difficult during the COVID-19 pandemic. But my family and I are thinking of trying to spend more time in Lithuania next year. We will have to plan.
And how long will you stay now?
Just a week. The whole family flew in, just not all at the same time. My son and my mother-in-law came from San Francisco, and my daughter and her husband first stopped in Norway to visit friends and then flew to Vilnius, so now there are six of us. It's great to be in Lithuania with the whole family. But only for a week, not enough.
At the Open Readings conference, you will be presenting on the Caltech Optical Observatories and the telescopes that have been built, are being built, or are yet to be built. How is this topic important?
I think it would be interesting to talk about observatories, because here in Lithuania, maybe not everybody knows so much about what is going on in our astronomy world. We are also celebrating the 75th anniversary of the Hale Telescope at the Palomar Observatory and 35 years since the W. M. Keck Observatory in Hawaii. I thought it would be a good opportunity to talk about that, as well as what we are doing and what the future holds. I'm sure the students will be interested, we'll see.
Looking ahead to your presentation, what will be your main focus?
When you have a large telescope, like in Palomar or later in Hawaii, you can observe more distant objects in the galaxy and understand more about the history of the Universe. I will also talk about dark matter and dark energy in the Universe and how these telescopes have contributed to the study of such things.
But I will also present how they are helping to search for exoplanets.
(Computer rendering of the Thirty Meter Telescope. Illustration: Courtesy TMT Observatory Corporation / Wikipedia.org)
One of Caltech major projects is the Thirty Meter Telescope (TMT), which will be one of the largest in the world. It will be as big as an 18-storey building and the primary mirror will be about the width of two basketball courts!
Engineers also call these mirrors M1 - Mirror 1. The telescope first catches the light coming from the sky, then the light is reflected from M1 and reflected to M2 (secondary mirror). Depending on the system, the telescope may also have M3, M4, M5 mirrors and so on (smiles).
And what is the significance of mirror size for telescopes? Why was it necessary to have such a wide set-up?
The simplest reason is to catch more light. But physicists also understand that the bigger the telescope, the better the picture of the celestial object.
However, when you have a telescope on the ground, atmospheric turbulence interferes with observations. The atmosphere moves and changes and spoils the focus: the image of the star starts to flicker.
This can be corrected with adaptive optics: thanks to various activators on the telescope, we can change the shape of the mirror in a thousandth of a second. The computer controls this: the mirror moves as needed to correct what the atmosphere has done.
It will be very important to develop adaptive optics for the TMT telescope to accurately correct the distortions in the images. If this works, TMT will be a very powerful telescope.
(A render of the completed Thirty Meter Telescope during nighttime in Hawai‘i. Illustration: NOIRLab/NSF/AURA / „Wikimedia Commons“)
How to imagine the power of the future TMT telescope?
You can see further. This is the first, simplest, thing. If you want to study the history of the Universe, how galaxies evolved, this is very important.
But it also helps to study exoplanets. The biggest problem is that exoplanets are very close to the stars they revolve around. This makes it very difficult to distinguish between the light from a planet and the light from a star.
The first thing to do is to try to reduce the light coming from the star. There are various methods to do this. For example, there is a device called a coronagraph, which tries to block out the light from a star so that we can see the planet next to it. It never works to reduce the star's light to zero, but it works up to a thousand or ten thousand times. And with good instruments, up to a million times.
So if you have a bigger telescope, it's easier to do it. You can distinguish the light of a planet from the light of a star.
Large telescopes might have the ability to make observations of planets that could even have life. We call them potentially habitable planets. And that requires them to be neither too cold nor too hot; liquid water, not ice.
Are any such planets already known?
At the moment, there are, but they revolve around stars that are quite different from our Sun. These are tiny stars, called M stars, which have certain characteristics, such as more magnetic activity.
The Sun has a magnetic field that changes, leading to solar flares. This is magnetic activity: the star emits not only light, but also different particles, etc. So living near a magnetically active star might not be so easy. It would be better if the star was a bit calmer, like our Sun.
I don't know if even with such a Thirty Meter Telescope it will be possible to observe planets like our Earth close to stars like our Sun. Perhaps only a telescope that NASA sends into space, so that it does not have to contend with the atmosphere, will be able to do that.
In any case, will the TMT telescope still be a huge step forward?
It certainly will.
(The protesters block the access road to Mauna Kea in October 2014, demonstrating against the building of the Thirty Meter Telescope. Photo: Occupy Hilo / Wikipedia.org)
As far as I have been able to find out, since 2014, when the construction of the telescope started, there have been many protests about the fact that the TMT is planned to be located on the island's Mauna Kea volcano. Construction was halted in 2015. What is the situation today? How are things going with the locals?
I would say it has been a very difficult situation. It took many years. Astronomers have been doing research on Mauna Kea for a long time - but I don't think they've paid enough attention to the opinions of the people, especially the Native Hawaiians (whose ancestors have been here for a long time), about whether scientists are taking good care of the mountain. Because Mauna Kea is very important to the Hawaiians, it is sacred.
That understanding has been lacking, and it has been getting worse and worse for years. And when the astronomers decided to build an even bigger observatory, the Hawaiians began to protest.
But now, I think, things are slowly improving. The head of the TMT telescope project [Fengchuan Liu] no longer lives in California but in Hawaii. He spends a lot of energy meeting people to talk to them and understand what they think - and trying to explain the project to them. I think this step helps a lot.
He does other things too, like going into schools and helping children to prepare their homework. He does it himself.
As a volunteer?
As a volunteer. He's not the only one - but for a project manager to do it... He feels that this is a good use of his time, that it is important. And gradually the relationship improves.
There has also been a big change in the management of Mauna Kea. A new law has been passed that the University of Hawaii will now manage the mountain. There is a separate committee, the Mauna Kea Stewardship and Oversight Authority, with only one astronomer on it, and other members from business and the university. There are also three Native Hawaiians. This group will take over the management of Mauna Kea so that the needs of all people, not just astronomers, can be considered.
I just think it will take time. Those who protested, those who opposed the telescope project, will want to see how this committee works: whether they really hear the people, whether they can be trusted. That will not happen quickly. But it still seems to me that things are slowly starting to look up, but we will just have to wait for the protesters to feel that everything will be all right if the telescope is built. We will see how things work out.
When exactly is this telescope planned to be built?
The telescope will take at least ten years to build. It is still not clear when construction will be able to start. First we need to raise all the money. It is particularly important that the federal government - the National Science Foundation - joins the project and puts up a lot of money. That will probably take several years. Only then will we know better whether we will be able to build the telescope at all.
(Observatories from different countries, located on the dormant Mauna Kea volcano in Hawaii. Photo: Frank Ravizza / Wikipedia.org)
There are already a dozen telescopes on that volcano?
There are many. But some of them are no longer in use, and one will be taken down. The telescope I have been working on a lot is called the Caltech Submillimeter Observatory. It took a few years to plan and get all the permits to take that telescope down, to get the land back to the way it looked before. But that dismantling of the telescope will start very soon.
I understand that Mauna Kea, four kilometres above sea level in the middle of the Pacific Ocean, is a great place to watch the sky. And that this volcano is dormant. But still, it is a volcano! Isn't it scary that one day there will be a disaster and all the millions spent will go up in smoke?
Island of Hawai'i (or the Big Island) actually has another volcano that is already active. It is located in the Hawaiʻi Volcanoes National Park and you can visit it as a tourist. But there are no telescopes there. That volcano is Mauna Loa, which is also four kilometres high. It has recently started to rumble [the world's largest active volcano erupted at the end of November 2022 - S.B.].
So far, I have not heard any concerns about Mauna Kea. But nature has its own programme (laughs).
(Simonas Bendžius and Prof. Jonas Žmuidzinas. Photo: FTMC)
How do you live now? What do you normally do on a day-to-day basis as Director of the Caltech Optical Observatories?
My job, you could almost say, is administrative. When more than five years ago a professor tried to persuade me to accept the director's position, he explained how another professor, the eminent astronomer (who was one of the pioneers of infrared astronomy), Gerry Neugebauer, told him: "This job is 90% staff and 10% dealing with people" (smiles).
It's quite a big group, we have a total of 30 people who work at the university, 25 people who work at the Palomar Observatory. I don't manage the W.M. Keck Observatory myself, but I have to supervise the 120 people who work there, and to monitor what happens there. I am also a board member of the TMT telescope project.
I have to think about everything: finances, how everybody is working, new projects and instruments, what's happening in Hawaii... All sorts of concerns and things. And, of course, you have to work with our faculty and try to understand what they want, what's going well and what's not going so well.
I would say it's interesting work. I won't be a director any more soon. I promised to do that job for five years, and soon someone else will come to rescue me (laughs).
And what do you think you will do next?
I don't have that many years left when I'm 70 and it's time to retire. So I would like to have a bit more peace and quiet, less worries. And more work with students: I love teaching, mentoring PhD students. I would love that.
Written by Simonas Bendžius
(Top right: Prof. Jonas Žmuidzinas. Photo: FTMC)
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2024. 04. 23 - International conference for young scientists and students Open Readings 2024 The conference will welcome more than 350 participants from various countries worldwide.
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2023. 11. 08 - You can now register for the "Open Readings 2024" scientific conference! Its participants actively exchange innovative ideas and the results of their latest carried out research.