Protestors in Hawaii have blocked access to the mountain of Mauna Kea, to prevent the construction there of the Thirty Meter Telescope.Credit: Ronit Fahl/ZUMA

A stand-off over plans to build a mega-telescope on Hawaii’s tallest mountain has entered its fourth week and shows no sign of stopping. Hundreds of protestors are blocking access to Mauna Kea, the mountain on Hawaii’s Big Island where construction of the Thirty Meter Telescope (TMT) was set to begin on 15 July.

The US$1.4-billion telescope’s enormous light-gathering mirror — nine times the area of today's biggest telescopes — will let it peer at stars and galaxies with unprecedented sharpness. That will allow scientists to explore fundamental questions such as how galaxies arose in the early Universe and what planets around distant stars look like.

Here, Nature examines how the fight over the telescope could evolve.

Who are the protestors and what do they want?

The activists who oppose the TMT encompass a broad swathe of the Hawaiian community, including university professors, local leaders and students. Most are Native Hawaiians. Their protests have garnered wide support from people in and beyond Hawaii, including celebrities of Asian–Pacific ancestry such as actor Jason Momoa, who visited the encampment on 31 July.

The protestors do not want the TMT to be built on Mauna Kea, a site that is sacred to Native Hawaiians. The telescope’s opponents say that they want to protect the mountain, and that it already houses too many observatories. (There are 13, five of which are supposed to be dismantled before the TMT begins operations.)

The mountain-top battle over the Thirty Meter Telescope

“We have always been here and we will always be here,” said Kealoha Pisciotta, a protest leader, during a press conference on 18 July. “The TMT will never be built.”

Many other Native Hawaiians do support the project. And a poll of 1,367 state residents, released on 7 August by the Honolulu Civil Beat newspaper, found that 64% supported the project while 31% opposed it.

Hasn’t this been going on for a while?

Months-long protests in 2015 scuttled the TMT project’s first attempt to build on Mauna Kea. In 2018, after further legal challenges to the TMT’s right to proceed, Hawaii’s supreme court ruled that the telescope’s construction permit was valid. That move set the stage for the attempt last month to start construction.

The current stand-off is more intense than the 2015 protests in two important ways: it has drawn more activists to the mountain, and it shut down activity at the telescopes already on Mauna Kea for more than three weeks.

How have scientists reacted?

Many scientists have spoken out against building the TMT in Hawaii, citing the need to listen to indigenous voices. They include a number of students and researchers affiliated with institutions working on the TMT. The president of the University of British Columbia in Vancouver, which is participating in the TMT project as a member of the Association of Canadian Universities for Research in Astronomy, has called for a 60-day moratorium on the project.

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Other researchers, including two officials with the Canadian Astronomical Society, say that the TMT project should work towards building in Hawaii. The project should pursue a site on Mauna Kea “for as long as there remains a realistic possibility to peacefully negotiate a route for this to happen, and to do so in a way that means the project is broadly welcomed and viable in Hawaii”, astronomers Michael Balogh at the University of Waterloo in Ontario and Rob Thacker at Saint Mary’s University in Halifax, both in Canada, wrote to society members on 1 August.

TMT officials say they are hopeful that the project can move forwards. “We’ve been through a ten-year process, and it’s urgent for us to get started,” says Gordon Squires, vice-president of external affairs for the Thirty Meter Telescope International Observatory, the formal name for the telescope project. “We have a lot of respect for everybody — those who oppose us and those who support us — and are looking forward to a safe resolution to this.”

What about the telescopes that are already on Mauna Kea?

They were shuttered on 16 July, the second day of protests, when it became clear that workers would not be able to regularly go up and down the mountain. On 9 August, observatory leaders announced that they had reached an agreement with the activitists to allow limited operations to resume. The telescopes are slowly coming back online, and it could be weeks before they are back to observing as normal.

Opponents of the Thirty Meter Telescope fight the process, not science

The shutdown was the longest interruption to scientific activity on Mauna Kea in the five-decade history of astronomy on the mountain. Technicians were able to make limited visits to the summit, where the telescopes are located; each was negotiated by the activists and the office that manages scientific activities on Mauna Kea.

On 29 July, for example, technicians made an emergency delivery of liquid nitrogen to the twin 10-metre telescopes of the Keck Observatory. The nitrogen helps to keep a spectrograph cold enough to operate. If the instrument had warmed to near room temperature, it might not have functioned the same way again, even if it were chilled to the recommended working temperature, says John O’Meara, Keck’s chief scientist.

How have officials in Hawaii handled the protests?

David Ige, Hawaii’s governor, issued an emergency proclamation on 17 July that gave police greater power to restrict access to Mauna Kea and deploy additional officers, among other things. On that day, law enforcement officials arrested and released 38 protestors, most of them Native Hawaiian elders.

Hawaii telescope protest shuts down 13 observatories on Mauna Kea

On 30 July, Ige rescinded the proclamation, saying that conditions had changed on the mountain and it was no longer necessary. At the same time, he extended the window in which TMT could start construction by two years, to September 2021. That gives the project more time to negotiate a solution to the impasse.

Ige has put Harry Kim, the mayor of Hawaii County, in charge of figuring out what to do next. Kim has been meeting with a broad swathe of community leaders to discuss possible future steps.

Can the TMT be built somewhere else?

The project does have a backup site: the Roque de los Muchachos Observatory on La Palma, one of Spain’s Canary Islands. The community in La Palma has been mostly supportive, and Spain’s minister of science, the former astronaut Pedro Duque, said last week that the TMT is welcome there. But the environmental group Ecologists in Action has been speaking out this week against the idea of building the telescope on La Palma, saying it would harm a natural area of great value.

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There are some drawbacks to the La Palma site. Because it is lower in elevation than Mauna Kea — 2,250 metres as opposed to 4,050 metres — the TMT would need to peer through more of Earth’s atmosphere. Having more water vapour between the TMT and the stars would make the quality of the telescope’s observations worse than they would be at higher elevation.

And the TMT project has not yet finalized all the agreements with the local government that would allow construction of the telescope there. On 5 August, TMT executive director Ed Stone confirmed that the project has applied for a building permit at La Palma, to help keep that option open.

What would need to happen for the project to relocate there?

The TMT board, which includes representatives from two California universities and the governments of Canada, China, India and Japan, would need to approve the move.

One complicating factor is that the TMT project will likely need hundreds of millions of dollars from the US National Science Foundation to finish its construction. US legislators might be less willing to fund a project that is not on US soil. For Japan, China and India, the Canary Islands site is farther away and less desirable than Hawaii.