From Hoskote to Hawaii: The intriguing world of large telescopes

Having been around telescopes for most of his life, Proteep Mallik muses on the promises and perils of the Thirty Metre Telescope (TMT), and what it means for a country like India.

18 Proteep in optics lab

Just about 30 kilometres from the University campus, in Hoskote taluk in Karnataka, lies the India-TMT Optics Fabrication Facility (ITOFF). The typical modern office building façade hides the fact that inside, cutting-edge machines are precisely polishing and preparing about 84 mirror segments to be shipped to Hawaii, where they will be assembled into one of the world’s largest telescopes.

The Thirty Metre Telescope (TMT) is an international mega project that, once completed, could tell us about supermassive black holes, the early universe, planets outside our solar system and the possibility of life in them. Along the way, the TMT project has unwittingly revived the age-old conflict of whose science is this anyway?’ 

The earliest telescopes

The Thirty’ in TMT refers to the diameter of the primary lens or mirror inside a telescope. The bigger this number, the more light the telescope can collect and the further out in space we can see. And humans have come a long way in our engineering of telescopes.

Galileo, considered to be the first to point a telescope towards the sky, used a lens that was just a few centimetres in size. This was in 1609. Even with such a small lens size, Galileo was able to see the four largest moons of Jupiter. That was really revolutionary for the time,” pointed out Proteep Mallik, who teaches physics at Azim Premji University and specialises in telescope optics. 

Over the next few decades, the lens inside telescopes got bigger, and we could see more and more of the solar system. The trouble was, lenses get really thick as they expand in diameter, so telescopes with large lenses were too heavy to maneuver.

Newton is credited with the breakthrough of using mirrors instead of lenses, and this allowed telescopes to see better whilst staying relatively compact. By 1781, William Herschel had built a 6‑inch telescope which he used to discover Uranus, the first planet to be discovered by a telescope. 

Herschel would go on to construct a 1.2‑metre telescope that would remain the largest telescope in the world for 50 years. Despite being terribly unwieldy, it is said to have been used to discover Enceladus and Mimas, the 6th and 7th moons of Saturn.

Building a culture of astronomy using a telescope

It was a matter of great joy for Proteep and his students when the University agreed to fund the purchase of an 8‑inch telescope. Ever since, the astronomy enthusiasts on campus have gotten together for periodic stargazing nights. 

We also designed an astronomy elective course, and that’s how over the last 6 – 7 years, we’ve built up a culture of astronomy here,” said Proteep, who himself had benefited profoundly from such a culture. Both his parents were astronomers, and so dinner table conversations tended to revolve around scientific discoveries, newly published papers, the latest images from the Hubble Space Telescope, etc.

Moreover, he began accompanying his mother to the 1‑metre telescope at the Vainu Bappu Observatory in Kavalur, Tamil Nadu. This observatory would soon have a 2.3‑metre telescope as well. Proteep went on to study physics and specialised in optics. 

He worked with technologies related to telescopes and telescope building — for example, figuring out the precise shape of optical mirrors that needed to be used. A lot of those technologies are what is enabling the building of a lot of these fancy, expensive, new large, ground-based and space-based telescopes today,” he said.

A new generation of large telescopes

For decades, Proteep has enthusiastically tracked the rapid evolution of telescopes— first as a curious youngster, then as an optical engineer, researcher, and finally as a physics teacher. One of the breakthroughs that excited him the most came from Roger Angel, an astronomer at the University of Arizona who Proteep worked with during his graduate studies. 

In the 1970s and 80s people had started trying to build very large mirrors which were also light,” he explained. This wasn’t easy, because though mirrors may be more compact than lenses, a thin single massive mirror is highly prone to bending and breaking. Scientists had to come up with a more practical way to build telescopes large enough to see distant secrets of the universe.

Angel, inspired by the architecture of a beehive, came up with an innovation that would kick off a new generation of large telescopes. You have these hexagonal honeycomb structures that make the hive very sturdy and stable. So why not try and do something like that with large mirrors?” asked Proteep. Eventually, Angel would figure out that hexagonal support structures could be used to build 8.4‑metre diameter mirrors that are relatively light.

A young Proteep in front of the Carl Zeiss 1‑metre telescope at the Vainu Bappu Observatory in Kavalur, in the late 1980s; Proteep (right) with his mother and brother, during one of their trips to Kavalur. Source: Proteep Mallik

If you’re wondering how a telescope can look back in time, it’s because light, though very fast travelling, takes time to reach us — especially if we are looking at something that’s very far away. So, the further away we can see, the deeper into the past we are looking at.

Looking far and back in time

According to Proteep, there are two major motivations for larger telescopes. One is to look into the very distant universe and see if we can get close to the time of the origin of the universe and see what the universe looked like, then,” he said. 

If you’re wondering how a telescope can look back in time, it’s because light, though very fast travelling, takes time to reach us — especially if we are looking at something that’s very far away. So, the further away we can see, the deeper into the past we are looking at. 

Secondly, said Proteep, there are also questions about the current universe — is there life on other planets, other than in our own solar system?” Space telescopes can answer these questions too, and they have the giant advantage of being outside the Earth’s messy atmosphere. It’s a boon to all living life on the Earth, but for astronomers, it’s a terrible thing… astronomers would love the Earth’s atmosphere to just go away,” joked Proteep. 

However, space telescopes suffer the limitation of being far more expensive than ground telescopes. The 6.5‑metre James Webb Space Telescope cost over 5 times as much as the 30-metre TMT is estimated to cost.

Currently, the largest functional telescopes are about 10 metres in size; the 10-metre Keck telescope is what astrophysicist Andrea Ghez used to prove the existence of a supermassive black hole at the centre of the Milky Way. Thanks to the lightweight mirror technology, there are more and much larger telescopes underway. One of them is the Giant Magellan Telescope (GMT), which at 25 metres is slated to be the largest optical telescope on Earth when it becomes operational in 2029. With a diameter of 30 metres, the TMT will be larger, but it has a long way to go. 

The TMT is proposed to be built on the historical Mauna Kea mountain in Hawaii. Close to 14,000 feet tall, yet relatively accessible, this mountain is a dream destination for astronomers. It’s surrounded by the Pacific Ocean, which is this lovely thermal sink,” said Proteep. 

The temperature over the Pacific Ocean creates a kind of equilibrium, such that you don’t have a lot of atmospheric turbulence which would have caused blurry images of stars and galaxies. It’s really one of the best sites on the planet to do astronomy. You’re far away from the sloppiness of the atmosphere, that you can even imagine doing infrared astronomy, other kinds of astronomy that you couldn’t possibly do at lower elevations. It’s almost like space astronomy!” 

Some of the telescopes on Mauna Kea. Source: Frank Ravizza/​Wikimedia Commons 

But way before Western astronomers got attached to this mountain, it was already being revered by the native people of Hawaii who believe that many of their spirits and deities reside on the mountain. For years, Hawaiians have resisted the loss of their rights over this land.

Scarred by science?

As of now, 11 countries have already built 13 astronomical observatories on Mauna Kea since 1964. If you look at a picture of this mountain, it’s not smooth as other mountains are,” pointed out Proteep. You see these buildings and domes. So I can imagine, a native person looking at that mountain would find it completely scarred… scarred by science.”

Conflicts such as these are not new to science, and neither is it to Proteep. Even as a kid visiting the Kavalur observatory with my mother, I remember thinking about the fact that here is this internationally-trained group of scientists from the city of Bengaluru, coming to this tiny village and essentially taking over 100 acres of forest to do their science. We need to think very carefully about how an institution situates itself within the local community. We need the support of the local community to do this kind of work.”

Years later, Proteep would find himself at the Kitt Peak Observatory on a mountain in Arizona, that is part of the Native American Tohono O’odham Nation. The observatory has done a reasonably good job of astronomy outreach with the Tohono O’odham people. They also train and hire a lot of Native American people,” he added.

With the Indian government recently approving INR 2,600 crore gravitational wave detection facility to come up on 174 acres of land in Hingoli, Maharashtra, Indian scientists too will have to grapple with similar issues.

Just like the native communities around Mauna Kea and Kitt Peak, the people of Hingoli district too may question if outreach, training and job opportunities will make up for what they stand to lose to make way for the LIGO-India project.

An outreach workshop takes place at Hingoli, Maharashtra, by the LIGO-India team. Source: LIGO-India

A precedent for future big science projects

What do these conflicts mean for TMT? When can we expect it to achieve first light’? Proteep recalls discussing the project with his colleagues way back in 2014, when it was expected that the telescope would become operational in 2022. That was eight years ago,” he shrugged. 

If you go to their website now, the timeline says 2027 is when TMT will achieve first light. But given how complex the whole instrument is, and the number of people involved, the pandemic, and so on, I doubt the 2027 deadline will be met. My guess is that we could see it operational over the next eight or 10 years.” 

Proteep’s estimation definitely seems more realistic, considering that we are still not cent percent certain that Mauna Kea will be the site of the TMT. The island of La Palma in Spain’s Canary Islands was declared as an alternative destination for the telescope in light of the fierce protests in Hawaii. However, in March of 2023, there was a development indicating that a compromise may work out at Mauna Kea after all. 

Several existing telescopes may be decommissioned to reduce the burden on the mountain. It was announced that from 2028, a new oversight board would take over the management of the site from the University of Hawaii. This board would include both astronomers as well as representatives from Native Hawaiian communities. Many see this as a new and inclusive approach that could set a precedent for future big science projects.

Last year, as part of the University’s Understanding India course, Proteep took his students to the ITOFF facility. I wanted my students to grapple with the ideas of what it means for India to spend USD 200 million of taxpayer money on this extremely large and complex project,” he said. 

Students of the University are shown around the TMT optics fabrication facility in Hoskote. In the large wooden crate is a TMT mirror blank. Source: Proteep Mallik

What it means for India to contribute to the TMT project

The immediate advantage for India to be involved in the TMT project is the access to the telescope it offers our astronomers. It’s very hard to get telescope time. There are thousands of astronomers sending proposals, fighting over the limited telescope time available. Most astronomers come away disappointed,” Proteep informed. Being a 10 percent partner in TMT, India will get about 36 nights of access every year. That’s a lot of telescope time.

As they marvelled at the sight of the mirror segments waiting to be polished to perfection, Proteep pointed out to the students that telescope time wasn’t the only thing India gains by contributing to this project. While the mirror segments will eventually go to Hawaii, the expensive polishing machines made from proprietary technology will stay behind. We will, hopefully, be able to use these machines to make our own 8 or 10-metre telescope. And Indian scientists will have all 365 days of the year to use that one.”

So were his students sufficiently convinced about TMT? I think many students were impressed that scientists and engineers are doing something as complex, right here in our backyard! These capabilities will go into building many other things besides the telescope eventually,” he said. 

However, neither students nor professors are fooling themselves about the issues that do exist in spite of all the positives. Our students are very critical, you know,” he laughed. I don’t think anyone, myself included, would be fully convinced of any one of these projects. But ultimately, many of us justify these projects saying it is for the greater good of scientific discovery, and this indomitable spirit that humans have…”

I think many students were impressed that scientists and engineers are doing something as complex, right here in our backyard! These capabilities will go into building many other things besides the telescope eventually.” 

More reading

Listen to Episode 2 of What About Science? on Radio Azim Premji University

Thirty Shades of TMT

Proteep Mallik is passionate about staring into space — with purpose. In this engaging episode, he talks about the 30-metre telescope that is being built in Karnataka to be shipped to Hawaii, and the fascinating science behind gazing at the stars.

About Proteep

Proteep Mallik is a faculty member at Azim Premji University.

About the author

Nandita Jayaraj is a science writer and communications consultant at Azim Premji University. She may be contacted at nandita.​jayaraj@​apu.​edu.​in

Published on 27 April 2023