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TMT illustration
Construction of the Thirty Meter Telescope, illustrated above, in Hawaii remains on hold, and the project has developed a “Plan B” should those plans fail to win approval. (credit: TMT)

Decision time for the Thirty Meter Telescope

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Two years ago, astronomers were gearing up for the beginning of construction of one of the world’s largest telescopes. The Thirty Meter Telescope (TMT)—named descriptively, if unimaginatively, after the diameter of its primary mirror—was set to start taking shape near the summit of Maunakea on the Big Island of Hawaii. With approvals from state officials and funding from various partners in place, the consortium working on the observatory for years was ready to start turning its concepts into reality.

Except the telescope didn’t start construction. Protests by native Hawaiian groups blocked access to the summit by construction crews for months, forcing the TMT to halt plans to start building the observatory (see “Thirty meter troubles”, The Space Review, July 6, 2015). The effort suffered another setback in December 2015, when the Supreme Court of Hawaii revoked the TMT’s construction permit, citing procedural errors by the state during a “contested case” hearing about the permit.

“We decided on the board that we needed to have a Plan B,” said Bolte.

More than a year later, there’s still no certainty about when, or where, the TMT will be built. A new contested case hearing for a building permit in Hawaii finally started in October, and has gone slowly. “We were hoping it would start last spring,” said Michael Bolte, an astronomer at the University of California Santa Cruz and a member of the TMT’s board of governors, during a town hall meeting about TMT Friday at the 229th Meeting of the American Astronomical Society in Texas. “And it started out very slowly.”

The pace of the hearing has picked up since that slow start, he said, when it took 12 days of hearings just to get through the first three witnesses. Bolte didn’t give an estimate of when the hearing would be completed and a ruling made about the permit, but suggested that the process would be completed, with a permit hopefully issued, in the next few months.

That’s unlikely to end the debate about building TMT atop Maunakea. “If we go through that and a permit is issued in the next few months, almost for sure it’ll be challenged in court,” he said. Such a challenge would go directly to the state supreme court under a new law, he said, expediting the process. That’s already happened with another observatory, with the court upholding in October a permit issued for the Daniel K. Inouye Solar Telescope being built atop Haleakala on Maui.

Bolte and other TMT officials said they remain optimistic that they will get a permit and win any legal challenge. They have, though, been actively developing a backup to Maunakea.

“There’s a risk the contested case won’t be ruled in our favor. There’s a risk that the land board will not issue a new permit, depending on what happens with the contested case. There’s a risk that the Hawaii Supreme Court will throw out our permit, not on procedural grounds this time, but on the substance,” he said. “So we decided on the board that we needed to have a Plan B.”

That effort included studying several alternative locations in China, Chile, India, Mexico, and Spain’s Canary Islands. For each site, Bolte said, the TMT team looked at several issues, from the scientific benefits and technical feasibility of building the TMT there to regulatory and other legal issues involved with getting approvals to build it.

In October, the TMT board reached a decision: the Observtorio del Roque de los Muchachos (ORM), on La Palma in the Canary Islands, will serve as the alternate site for the telescope, should Maunkea not be feasible for some reason.

Bolte argued that ORM would be a good fit for TMT if it can’t be built in Hawaii. While the design of the observatory would require some modifications to fit on the alternative site—the construction of the foundation, for example, would have to be changed because of the different geology of the mountain, he said—the site overall offered a similar fraction of clear nights and good seeing as Maunakea.

A big difference, he acknowledged, is the altitude: ORM is only about 2,400 meters above sea level, a kilometer and a half lower than Mauna Kea. That means a warmer atmosphere with more water vapor, which could affect infrared observations in particular. “If you’re planning to do lots of lots of work in the mid-infrared, it’s not as good a site,” he said.

“Hawaii remains our preferred site,” Bolte said. “All of us are working as hard as we can to make Hawaii work, and we hope that’s how it works out.”

ORM is also at a higher latitude: about 29 degrees north, versus 20 degrees north for Maunakea. That would keep TMT from observing some parts of the southern sky visible from Hawaii but not the Canaries. That, however, is not considered a dealbreaker, in part because two other so-called “extremely large telescopes,” the European Extremely Large Telescope and the Giant Magellan Telescope, are planned for Chile.

“Being in the north is an important aspect for the site,” said Catherine Pilachowski of Indiana University, who is working on a planning document that would define possible future options for National Science Foundation participation in the TMT. “In some sense, it makes no sense to have all of the large telescopes in the southern hemisphere.”

Not everyone at the town hall meeting, though, was convinced of the quality of ORM, with attendees exchanging anecdotes about good or bad experiences observing at other telescopes there. “I was a little dubious about the Canary Islands,” Bolte admitted. “There are many anecdotal stories. But in the end we’re scientists, and the data didn’t bear out a number of anecdotal stories.”

With ORM selected as the backup site, the TMT is starting work there to prepare construction there, including negotiating a hosting agreement with ORM and beginning the permitting process. At the same time, TMT officials say they’re still committed to building the telescope on Maunakea if it can secure a permit and survive a likely legal challenge.

“Hawaii remains our preferred site,” Bolte said. “All of us are working as hard as we can to make Hawaii work, and we hope that’s how it works out.”

Why, then, pick an alternative site and start planning for its development if Maunakea remains the preferred location? Bolte suggested that the observatory’s patience for delays building Hawaii was running out, saying that TMT needs “assured access” to a site in place by this fall so that some of the TMT’s various partners can include construction plans into their 2018 budgets.

“We’re going to build this telescope some place, either in Hawaii or at La Palma,” he said. “We want to start construction by April 2018.”

There’s a very real question, though, of whether that will be possible on Maunakea. Even if TMT gets a new construction permit, and that permit is affirmed by the state supreme court, there’s likely to be renewed protests by native Hawaiian groups who oppose construction of any new observatory on the mountain they consider sacred. The earlier protests, after all, had very little to do about claims of procedural flaws in awarding the original construction permit.

Curiously, there was little discussion at the town hall meeting about new outreach efforts to native Hawaiians and others. “I thought we had done a quite good job” in those original outreach efforts, Bolte said. “That was a little bit mistaken.”

At the end of the town hall meeting, Bolte reiterated the TMT’s preference to building the observatory on Maunakea. “But, you adjust your expectations to reality,” he said. “We’ve all spent a lot of time and somebody’s dollars on this project. And if the choice is walk away, or an alternative site, I think everyone will go for an alternative site.”