The summit of Mauna Kea, a dormant volcano on the island of Hawaii, has long been valued by astronomers for its pristine dark skies and high altitude. Rising to 4200 m at its peak, the mountain is the best location in the northern hemisphere to host astronomical observatories, and is currently home to 13 different telescopes. Long before the land was leased to the University of Hawaii for research purposes, though, the mountain was a sacred place for native Hawaiians.

Now, however, plans to build a new facility that will dwarf all others on the mountain are under threat, after construction of the $1.4bn Thirty Meter Telescope (TMT) was interrupted in late March when hundreds of native Hawaiians protested and prevented construction crews from entering the site. So far, 31 people have been arrested, and on 7 April Hawaii governor David Ige announced that construction would stop; it is not known when work will resume.

International collaboration

Designed to have a primary mirror 30 m across made of 492 hexagonal segments enclosed in a structure 66 m wide and 56 m tall, the observatory will allow astronomers to resolve the faintest and oldest galaxies. It is a collaboration between the California Institute of Technology (Caltech), the University of California, the National Astronomical Observatories of the Chinese Academy of Sciences, the National Institutes of Natural Sciences/National Astronomical Observatory of Japan, the Indian Institute of Astrophysics, the Association of Universities for Research in Astronomy, and the Association of Canadian Universities for Research in Astronomy.

To [the University of Hawaii], understanding one creation story is more important than the creation story of the islands they occupy
Kamahana Kealoha, Sacred Mauna Kea Hui

Members of the TMT project insist that they have the legal right to proceed after meeting all of the requirements to build the observatory, a process that took about seven years. "We followed the process slowly and carefully," says Sandra Dawson from Caltech, who is TMT Hawaii community-affairs manager. "We got all the permits. We've been through the legal system. At every step, we have been approved." Dawson adds that the TMT Corporation held some 30 public meetings open to the community to address possible concerns.

But many residents and conservationists say that laws have been circumvented, arguing that building the TMT will harm the delicate ecosystem on the mountain. A more fundamental concern, however, is their view that colonialism is impinging on the cultural and spiritual beliefs of the indigenous population. Since 1968 the University of Hawaii has leased more than 11,000 acres of land on Mauna Kea from the Hawaiian Department of Land and Natural Resources for scientific research.

"According to the Hawaiian world view, Mauna Kea's summit is a place where creation begins," says Kamahana Kealoha of Sacred Mauna Kea, one of the groups leading the protests. He adds that the University of Hawaii – which is subleasing the land on Mauna Kea to the TMT Corporation – "insist that the quest to see the origins of the universe is paramount. To them, understanding one creation story is more important than the creation story of the islands they occupy", he says.

History, religion and culture

Upon seeing the concerns raised through the protests, some astronomers have begun to ask if construction of the observatory should continue. Emily Rice of the College of Staten Island in New York says that the astronomy community needs to talk about the issues raised by the protestors. "The discussion can't just be science, funding and environmental impact. It has to be history, religion and culture," she says. "Those [aspects] are things that scientists traditionally tend to stay away from. But we really can't, in good faith, ignore these aspects of our work anymore."

Amid the protests last month, Canada announced that it would provide $243.5m over 10 years toward the TMT's construction.