A proposed solution to the impasse over construction of the mammoth new Thirty Meter Telescope (TMT) on Hawaii’s Mauna Kea volcano is less bold than it seems—and potentially more difficult. The proposal, to dismantle one-quarter of Mauna Kea’s 13 existing telescopes in return for allowing construction to proceed, would only accelerate vague existing plans to shutter some of the telescopes. Yet it promises no end of political pain, forcing researchers from different institutions and countries to compete over which telescopes to keep alive. And it may not defuse the protests that have blocked the TMT project.
"It's going to be complicated," predicts Sunil Golwala, a physicist at the California Institute of Technology (Caltech) in Pasadena, who uses one of the existing telescopes. "There are legal issues and leases that can't necessarily be broken right away." The shutdowns could also cost millions of dollars per telescope. "In many cases it is actually cheaper to keep [telescopes] running than to pay for the deconstruction and site restoration," says Lynne Hillenbrand, an optical astronomer at Caltech.
The proposed culling is one of 10 new conditions on the mountain’s use that Hawaii Governor David Ige (D) announced during a 26 May press conference. The measures aim to address the concerns of Native Hawaiian protesters who claim the mountain as sacred ground and have blocked access to the TMT construction site. "We have not done right by a very special place and we must act immediately to change that," Ige said.
Ige affirmed that the TMT team has a right to proceed with construction. But he called for removal of 25% of Mauna Kea’s existing telescopes by the time the TMT is finished, perhaps by 2022. He also asked the University of Hawaii (UH), which leases the summit from the state, to agree that the TMT will be the last new observatory site on Mauna Kea, to return 4000 hectares of unused land, and to shorten a proposed 65-year renewal of its lease, which expires in 2033.
Protesters weren't swayed and vow to continue blocking access to the construction site. “It’s contradictory to say, ‘We’re going to do a better job, but we’re going to start after the TMT,’ ” says Kahookahi Kanuha, a protest organizer.
Astronomers have already thought about closing some of Mauna Kea’s existing telescopes. In 2010, a UH contractor wrote a decommissioning report as part of a broader management plan, ordered in 2006 by a state judge who blocked a NASA-funded project to add four to six small "outrigger" telescopes around the twin 10-meter Keck I and Keck II telescopes. Although the report mostly describes the process for decommissioning an observatory, it also estimates that by 2033 there should be just 10 telescopes on Mauna Kea—including TMT—and even provides a rough list of facilities that might come down.
That list shouldn't be taken as definite, cautions Günther Hasinger, director of the Institute for Astronomy at UH Manoa. Still, it points to a trend that's likely to sway deliberations, others say.
Mauna Kea’s telescopes come in two types. Nine are optical and infrared (IR) telescopes housed in swiveling domes, with mirrors ranging from 0.9 to 10 meters in diameter. Four are dishes or arrays of dishes that collect radio waves and microwaves. The decommissioning report suggests that only one of the four radio and microwave facilities would remain by 2033, whereas eight of the nine optical and IR telescopes would stay.
The move away from the radio facilities reflects the fact that they have been surpassed by the 66-dish Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, astronomers say. "It's clear that Atacama is a better submillimeter site than Mauna Kea," says Dariusz Lis, an astronomer at the Paris Observatory. Still, researchers say that at least one of instruments—the James Clerk Maxwell Telescope, a 15-meter dish built in 1987—is a better survey instrument than ALMA, as it has a wider field of view.
Among the optical and infrared telescopes, the four newest and biggest—Keck I and Keck II, Japan's 8.3-meter Subaru Telescope, and the international 8.1-meter Gemini North Telescope—are vital, says Paul Schechter, an astronomer at the Massachusetts Institute of Technology in Cambridge. He served on a recent National Research Council panel that examined how to optimize the U.S. optical and infrared science program and says that the four instruments “are things that the people on our committee would be horrified to see shut down."
In principle, some of the smaller optical telescopes could go without damaging scientific capabilities, says Robert Lupton, an astronomer at Princeton University. "They could get down to below 10 [telescopes] with no loss to U.S. astronomy," he says. But shuttering the smaller observatories may prove difficult for political reasons.
Canadian researchers, for example, hope to replace the 3.6-meter Canada-France-Hawaii Telescope, built in 1979, with a 10-meter telescope in the same dome. UH is already upgrading its 2.2-meter telescope, built in 1970, with state-of-the-art robotic optics. Even the 3.8-meter United Kingdom Infrared Telescope, which the decommissioning report suggested closing, has advocates. It's a better survey telescope than some of the bigger instruments, Caltech's Hillenbrand says.
How researchers will decide which telescopes to kill remains to be determined—as does how those decisions will be enforced on various funding agencies and foreign partners. But removing the instruments will be expensive. Currently only the Caltech Submillimeter Observatory, a 10.4-meter dish built in 1987, is slated for decommissioning—at a cost that's not yet known. "You can guess that it's bigger than a million dollars and smaller than 10 million," Caltech's Golwala says. Decommissioning costs fall to a telescope’s owner.