Sat. Feb 4th, 2023
Two large white domes on a barren reddish landscape.
Enlarge / Keck 1 and Keck 2, near the top of Mauna Kea.

AT THE TOP OF MAUNA KEA, Hawaii — Bill Healy stares into the main mirror of the world’s largest telescope and pauses. Even now, after nearly two decades of caring for this giant mountaintop instrument, the immensity of the mirror continues to fascinate him. “It sure is a great view,” Healy marvels. “A great view.”

It is. We just climbed the tallest mountain in the Hawaiian Islands, Mauna Kea, to see the 10-meter pair of Keck telescopes, the largest and most powerful optical telescopes in the world. Hawaii is 4,000 km away from the nearest continent, North America, making it the most remote archipelago on Earth. With clear skies, Mauna Kea may therefore have the best “seeing” of any telescope in the world.

The combination of large mirrors and dark skies has proven to be nothing short of revealing. Since the first of the two Keck telescopes began observing the sky in 1993, astronomers have used the instruments to discover dark energy, find extrasolar objects that led to Pluto’s degradation, and more. On any given night, an astronomer may aim a telescope at volcanic eruptions on the Jovian moon Io or study faint galaxies at the edge of the visible universe.

But increasingly, the mountain’s beautiful sky is clouded by controversy. Native Hawaiians are challenging the right of outsiders to build large telescopes on their sacred mountain, and a proposal to build a much larger instrument, the Thirty Meter Telescope (TMT), on Mauna Kea has thrilled activists like never before.

Healy speaks with a Northeastern accent. An unlikely path led him from a career in the US Marines to “retirement,” to becoming a high school teacher in Hawaii, and finally landing a job two decades ago as a janitor for the telescopes. He struggles to reconcile his love for this facility, the mountain and the cutting-edge science they make possible with the animosity bubbling up from the valley below.

Our affable guide, Bill Healy, stands next to a spare segment mirror of the Keck telescope.
Enlarge / Our affable guide, Bill Healy, stands next to a spare segment mirror of the Keck telescope.

Eric Berger

“Until a few years ago, all the telescopes here worked pretty much under the radar,” he explained during a tour of the facility. “People either didn’t care or they really didn’t know what was going on. But because of all the attention from the TMT, it has tarnished us all with the same brush. Where you normally like to wear your Keck crew t-shirt while shopping at Costco, today you may not.”

To some natives, the majestic domes that house huge telescopes on the top of the mountain look more like pimples, best popped. As tolerance has turned to tension, legal action has begun through the Hawaiian legal system. It is no longer inconceivable that the magnificent telescope that Healy and I admire, which has in no small measure redesigned almost the entire field of astronomy, could one day be gone.

The website

Gerard Kuiper, who counted Carl Sagan among his students, is probably the greatest modern planetary scientist. He correctly predicted the composition of Saturn’s rings (ice) and that planets in our solar system formed when a large cloud of gas condensed. He also proposed the existence of a now eponymous belt of minor planets beyond Neptune’s orbit, and he “discovered” Mauna Kea for astronomers.

After the University of Hawaii dedicated the Haleakala Observatory on Maui in 1964 to study the sun, Kuiper—then at the University of Arizona’s Lunar and Planetary Laboratory—came to visit. He wanted to determine whether Maui Mountain, which tops out at 3,000 feet, might also be suitable for planetary observations. It turned out not to be high enough to stay consistently above the regional inversion layer, making many nights too cloudy for observations.

However, when Kuiper looked across the Maui Channel to the Big Island, he could see Mauna Kea looming 4,000 feet above the clouds. Soon, Kuiper had persuaded Hawaii Governor John Burns to provide funds to flatten a road and build a small telescope for testing. The website was great. In 1970, the University of Hawaii had built a 2.2-meter telescope on Mauna Kea. More would soon follow.

Easterly trade winds blow over the islands and because there are no other mountains downwind, there is little turbulence. At the top, water vapor levels are very low compared to most observatories. Also the inversion layer is a boon at 14,000 feet. During the nighttime hours, the clouds settle as the air temperature cools. While lights from cities along Hawaii’s coast aren’t much of a problem, any light pollution from Hilo, Kona, and Waikoloa is often shrouded by these clouds.

By akfire1

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