[SciShow Intro Music] The Thirty Meter Telescope, or TMT for short, might just be the most famous and infamous observatory on the planet.

Which is impressive, considering it has not yet been built. But what is it?

Well, the TMT is just one of several ambitious telescope projects in the works that promise to help astronomers probe the secrets of the universe in ways that were no more than a pipe dream a few short decades ago. But the choice of site for this project, Maunakea, on the Big Island of Hawai`i has stirred up a storm of controversy. Now, you might think, hey, you're SciShow, I know where you're going to come down on this debate!

You want telescopes! And yes, yes, we do want telescopes. But, look, our goal here isn't to come down on any side, but instead to show some of the reasons why this is complicated, and share some of the difficult questions it brings up.

But first, let's start with the telescope itself. Thanks to some 21st century improvements in technology, the race is on to design and build the world's biggest telescope. These projects are collectively called Extremely Large Telescopes, or ELTs.

The University of California and the California Institute of Technology were quick to begin making plans for an especially ambitious one: a thirty meter telescope. It's called, get this The Thirty Meter Telescope. It's also called the TMT.

So the 'Thirty Meter' in the name refers to the size of the observatory's aperture in other words, the diameter of the part of the telescope that collects light. And that is big. About three times as big as the biggest operational telescope of its kind today.

You see, the TMT is a reflecting telescope. It uses curved mirrors to reflect light onto a focal point, where the image is then obtained.

The aperture is the diameter of the primary mirror it uses to do that, which may be one single mirror in smaller telescopes, or in the case of the big ones like the TMT it's a whole lot of, like, little-er mirrors that work together.

They're als- they're pretty big. And bigger is better when it comes to seeing deep into the universe around us, because the amount of light a telescope mirror can gather is proportional to the size of its aperture. Like, this part isn't complicated; the more light-collecting area, the more light is collected. Bigger telescopes mean we might actually be able to detect the faintest of distant objects, and that thirty-metre mirror will have nine times the light-collecting area of any telescope in use today!

There are not any ELTs in operation yet, but once there are, we'll be able to use them to study some of astronomy's biggest questions. They will have the power to peer into the so-called "dark ages" of the universe, when the first heavy elements formed. They'll reveal the large-scale structure of the universe when it was young, including the formation of the first stars! They'll be able to examine black holes over time and explore exoplanets with detail and resolution we can only dream of today!

Indeed, they will be our best near-term shot at finding truly Earth-like, perhaps even inhabited, worlds! In other words, this is big stuff! ELTs have the potential to do amazing science!

But, there are downsides to being a really big telescope too, like the overall field of view becomes smaller. And more importantly here, bigger telescopes are very sensitive to, like, everything. You need the clearest, most ideal conditions to get good images.

And that's where location comes into play - you can't just stick a thirty-metre telescope anywhere. The light from big cities would totally swamp its sensors, and the nearer it is to sea level, the more atmosphere there is between the scope and the rest of the universe: atmosphere that's full of turbulent air, water vapor, dust and other stuff which interferes with the light the telescope is trying to collect.

And to minimize interference, you also want somewhere super cold, so there’s no thermal interference.

In some ways, the most ideal place for a telescope like the TMT is not on Earth at all. In space, you don’t have all that pesky atmosphere to deal with, and it’s super cold, as long as you can find a shadow to hide in.. like the shadow of the Earth, which is where the James Webb Space Telescope will be hiding. But we don’t have the engineering capability to build a thirty-meter telescope in space.

The Webb will have an aperture of 8 meters. Still hefty, but not 30!

So, once they knew they wanted to build a really big telescope on Earth, the TMT team went about deciding where would be best. They had a list of five options at one point, but the top two were Cerro Armazones in Chile's Atacama Desert Either could have worked, but two others ELTs already had their eyes on Chile— the Giant Magellan Telescope with its twenty four point five-meter mirror, and Europe's Extremely Large Telescope, which will have a mirror that’s about nine meters bigger than the TMT’s. A FORTY METER TELESCOPE ! Lord this is exciting. But! Having all of the world’s ELTs in the same hemisphere would mean that we’d be missing out on studying a big hunk of the sky.

So scientists decided the TMT should be somewhere in the northern hemisphere to balance things out. And so, in July of 2009, the TMT board announced that it wanted the telescope to be built on Maunakea.

And then the questions started popping up. So, first, in Native Hawaiian culture, Maunakea isn’t just a mountain. I’m not qualified to teach you native Hawai’ian tradition, but for a necessarily imperfect metaphor, imagine someone told a bunch of Catholics that the best place for a telescope would be on the current site of the Sistine Chapel.

Mauna Kea is a natural temple and a sacred place of worship. And it’s not just integral to their spirituality—it’s culturally important, too. Chiefs and priests were buried high up on the mountain, and it remains a key place for cultural practice.

So why is it possible for us to build a bunch of telescopes on it? Well, I mean, this is SciShow, not history show, but we’ll do our best.

In 1893, the US Minister to the Kingdom of Hawai`i conspired with US citizens and a bunch of other non-native people to overthrow the Native Hawaiians’ sovereign government, which, yes, was a direct violation of international treaties.

Then, when Hawai`i became a state in 1959, more than seven thousand two hundred [7,200] square kilometers of land were “ceded” to the US. That included Maunakea.

In 1968, the state, in turn, gave management of about forty-five square kilometers of the mountain’s summit to the University of Hawai`i and its Institute for Astronomy, under the oversight of the State Board of Land and Natural Resources or BLNR.

Since then, the University has been granting subleases to various observatories for telescopes. The university has faced opposition all the way along— though in the past, much of the focus was on the environmental impacts of the construction projects.

Maunakea is the highest peak in the Hawaiian islands and home to numerous endemic species ...species found nowhere else on Earth. Even on the summit—a dry, volcanic landscape— you can find life unique to the mountain, like the hardy w?kiu bug.

And there are also non-living natural resources to consider. The mountain plays a key role in replenishing the island’s fresh water, for example. All of that is why the summit is designated the Maunakea Science Reserve— state-owned conservation lands. Not helping matters is that, initially, the University did build telescopes without conducting proper surveys to understand how those projects would impact the mountain’s ecology, geology, and hydrology, let alone anything to do with culture or history.

They built five telescopes in less than a decade before any kind of management plan for the mountain top was drawn up. The first proper environmental impact statement and comprehensive management plan didn’t happen until the 1980s, after starting construction on a sixth telescope.

As 14 more telescopes were added, environmental organizations and Hawaiian cultural communities banded together.

And in 1998 a state audit determined that the university and BLNR hadn’t held up their end of the bargain, and had neglected the summit’s cultural, historical, and natural resources to build telescopes.

So, in 2000, the university responded with the Maunakea Science Reserve Master Plan. It sought to make reforms, including ensuring that any new projects properly assess how they would impact the summit.

Except, then, in 2006, a judge revoked the Outrigger Telescopes Project’s permit because the university hadn’t properly assessed the damage that would be caused by construction, which probably didn’t help in building trust.

And that brings us to 2009, when the TMT board announced that it wanted to put their telescope on Maunakea. So, the university filed yet another comprehensive management plan, and the TMT board filed an environmental impact statement. The board said that they’ve worked hard to ensure the telescope won’t have any substantial negative impacts while groups like The Hawaiian-Environmental Alliance KAHEA, disputed those claims in court. And then court battles continued for about nine years.

Native Hawaiian elders and others who say the mountain needs protection blocked roads to prevent construction, and in 2015 Hawai’ian governor David Ige pledged that this would be the last telescope built on the summit.

Legal battles continued until finally, in October 2018, the Hawai`i Supreme Court allowed the permit and sublease to stand— and construction was scheduled to restart in July 2019. For clarity, we’re glossing over a LOT of details here. But the point is, it’s complicated, there are a lot of good reasons to want this telescope built, and a lot of good reasons to not want it built.

Or… to have it built somewhere else. Yes, Maunakea is the preferred site of the TMT board, but it’s not the only one. They have a backup location on La Palma in Spain’s Canary Islands all lined up. Much like Maunakea, La Palma already boasts several world-class telescopes.

Why not go there from the start? Well, the site is about 1800 meters lower in elevation, which could impact the telescope’s resolution a little. Some scientists have said switching to La Palma wouldn’t really impact the science the TMT could conduct, while others disagree.

The TMT’s own assessment of the site says it would be an “excellent” location that has the “full capacity” to carry out the telescope’s core scientific objectives. Spain and the government of the Canary Islands have made it clear they’d welcome the state-of-the-art scope and help ensure it’s fully funded— plus, the site already has a lot of the infrastructure in place to build it.

In fact, the process of obtaining a building permit has already begun. But, though the mountain on La Palma is not a site of current religious practice or considered sacred by indigenous groups, there is some local opposition from an environmental group, which claims the site contains archeological artifacts and construction would harm native species.

And there's even a back-up to this back-up— there's a site in Baja California that TMT scientists have said would also work, and it doesn't have the same historical or archaeological problems of the other two sites. Then there are also non-scientific reasons to build the telescope in Hawai`i.

Many residents of the islands, including some locals and Native Hawaiians, would welcome the prestige the TMT would bring the state’s astronomy program and the hundreds of millions of dollars that will be spent on the telescope won’t hurt the local economy either. But clearly, the ongoing encampment and demonstrations show that some remain unconvinced. They say the university has been mismanaging Maunakea for decades, and they don’t trust the institution to just suddenly start doing better. And yes, multiple audits and court cases have found that the university has failed its charge to take care of the mountain.

Sometimes we like to think that science is clear. Gather data, find the truth...but science has to exist in the world, and the world is complicated.

These Extremely Large Telescopes are going to be amazing scientific tools, wherever they end up.

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