I’m sitting shotgun on the ride up to the summit of Mauna Kea, a little carsick and feeling like someone sneaked industrial-grade intoxicants into my morning coffee. My legs are wooden and my speech stutters. Mauna Kea ranger and my guide for the day, Kelvin Andrade, is a three-year veteran of the summit. He asks how I’m feeling.
“A bit peaked,” I pun. Andrade, a former Hawai‘i County police officer, nods and tells me to breathe deeply, his sense of humor seemingly the only thing altitude-impaired. We drive past the rare Hawaiian snowplows (I count six) and smoothly navigate patches of ice. When he’s not assisting motorists, guiding road crews and keeping order on the summit, Andrade wrangles feral cattle on the lower slopes of Hawai‘i’s tallest peak. All he’s missing is the Stetson, and when he breaks his dour paniolo (cowboy) countenance, it’s to offer some sage advice on dealing with the altitude. “Just ignore it. Move slow, and if someone offers you a snack, take it.”
Mauna Kea is the pinnacle (to pun again) of terrestrial astronomy. Due to the clear skies at altitude, accessibility and lack of light pollution, it is one of the best places on Earth to view the cosmos. Starting in the 1970s, thirteen observatories have been constructed at the summit, and they have produced world-altering science. Some of these telescopes are technological marvels, unique on the planet; others are classics, the workhorses of basic astronomy. All of them require constant maintenance and upgrades to peer ever more deeply and finely into a universe we’re just beginning to explore.
Andrade is taking me into the rarefied, clear and cold air atop Mauna Kea to watch as hardy technicians give a few high-tech telescopes an even higher-tech upgrade. It’s rare for someone outside the community of researchers and support staff to be allowed access to these facilities, even rarer on days when they’re undergoing delicate maintenance and upgrade work. Though I hardly have the lungs for it, to someone like me, who loves tech and astronomy, this is Graceland.
Andrade stops not far from the 13,796-foot peak and a safe distance from the Canada-France-Hawaii Telescope. Chunks of ice and slush slide from its pure-white dome as they melt in the morning sun. It’s a big day for CFHT; inside its huge dome the staff, a mix of French, Canadian and local technicians, is uncrating parts of the new SPIRou sensor. Once assembled in the massive clean room and fiber-optically linked to the telescope, SPIRou will measure the subtle wobble of distant stars, a telltale sign that they might host a planet.
Starting observations in 1979, the pioneering 3.6-meter CFHT was one of the more sophisticated telescopes operating on Mauna Kea (and on Earth) at the time. It was designed to detect both optical and infrared light (light you can see, plus thermal imaging). CFHT data was the envy of astronomers worldwide, showcasing Mauna Kea as a premium site for astronomy. Its images were sharp from the get-go, good enough to detect evidence of mysterious dark matter (and verified by the Hubble Space Telescope).
Its old but proven equipment is mixed in among state-of-the-art electronics. The control panel still has the kind of gauges and lighted buttons you’d see in a ’70s James Bond villain’s lair, right beside the updated digital display with real-time video, weather satellite feeds and other atmospheric data essential for astronomy. On the fifth floor is the observation deck, where the enormous yellow telescope is mounted on hydrostatic bearings and a gimbal structure known as a yoke-and-horseshoe. It’s almost as cold inside as it is out. “We keep it air-conditioned to within a degree or two of the lowest temperature forecast for tonight so the optics won’t fog,” says Ivan Look, who’s spent the last thirty years as the mechanical design engineer for CFHT.
SPIRou aside, it’s business as usual at CFHT, with the workers getting the telescope ready for the next observation period slated to use the super-zoom capability of the secondary mirror. The crew has just removed a sensor called MEGAcam, which is best suited for taking high-resolution photos of large patches of sky, and installing the secondary mirror to reflect starlight into ultra-cooled sensors. Crane operator Seizen Tsuha gently maneuvers the manhole-size secondary mirror on the business end of the CFHT. “It’s eleven thousand pounds,” Look remarks casually. Tsuha moves the crane to pick up a wiry metal contraption affectionately called the “monkey cage.” Two technicians play rock-paper-scissors for the “privilege” of riding the monkey cage up to the secondary mirror to install coolant, electrical and data cables to the deceptively simple-looking mirror attachment. The winner of that rock-paper-scissors shootout is Grant Matsushige, who doesn’t mind being the monkey in the cage. “Oh, I like to do it. Make sure it’s done right.”
Look is proud of the updated cooling system that supports the SPIRou sensor (which is kept at -203.15 degrees centigrade, plus or minus .001 degree). It requires less maintenance while using some creative plumbing that looks like a giant car radiator. Cooling is critical to a telescope that captures visible and infrared light, some-thing that CFHT pioneered. If the sensors and mirrors get even as warm as the frigid summit temperatures, the signals become “noisy.” Clean signals are essential, especially if you’re observing a very cold, faint object that suddenly comes shooting through our solar system.
Of course I’m talking about ‘Oumuamua (Hawaiian for messenger or scout), the mysterious, two-hundred-meter, cigar-shaped asteroid that streaked through our neighborhood in 2017. It was moving too fast to have originated in our solar system, so CFHT and other telescopes seized upon the opportunity to observe the first large extrasolar object known to have passed by.“There was an air of quiet excitement here when we were observing ‘Oumuamua and we couldn’t tell anyone,” Mary Beth Laychak, the outreach program manager for CFHT, recalls. “Claiming an asteroid is from outside our solar system is an extraordinary finding, and astronomers like to be sure before telling the world.”
Teaching the CFHT new tricks paid off almost immediately, I’d later find out. With the SPIRou plugged into the CFHT, test observations of well-studied stars were exactly as crisp as expected—a bit like hitting the bull’s-eye the first time you throw a dart. SPIRou can now compete with the orbital planet-hunters by measuring the tiny wobble in a star’s position that indicates the presence of extrasolar worlds. The prize, though, is the ability to study the weather patterns of distant stars like brown dwarfs or giant gaseous orbs that are not quite stars. That’s a big if: It’s a bit like trying to forecast the weather on Jupiter through a pair of binoculars. But it’s a start.
Andrade drives across the stretch of frozen mountaintop from CFHT to Subaru. From half a mile away, the Subaru Observatory looks like an art-deco condo in downtown Honolulu, only it houses one of the largest single-mirror telescopes in the world. It too is getting an upgrade; some-thing called a MOIRCS (Multi-Object Infrared Camera and Spectrograph), which can read the unique optical “fingerprint” of multiple stars during a single observation, is being attached to its massive mirror.
It takes three elevator rides to get to the top of Subaru: one to the break room, alive with chatter in accents from around the world; another to the observatory floor, filled with machinery; the last to the upper reaches of the observatory. Each one has emergency supplies stacked in a corner: an inflatable mattress, a radio and a bucket marked “Emergency Restroom.” Turns out people get trapped during power outages.
We leave the elevator and walk out on the level four mezzanine. I grip the hand-rail to steady myself against vertigo because I am looking down on the seventy-two-foot-tall telescope. Subaru is a beautiful giant, gleaming in blue aluminum thermal cladding. It is one of many telescopes in the 8.3-meter class, with mirrors bigger than most swimming pools. Above me is an eighty-ton-capacity crane and the structure supporting the retractable roof. Down below, technicians are preparing to attach cables to the MOIRCS, an instrument about the size of a beer keg and weighing 2,160 kg (according to its placard). Like the SPIRou on CFHT, it requires a lot of cabling and a complicated cooling system.
Subaru’s primary mirror takes up more floor space than my apartment, though it’s only about eight inches thick, and like CFHT, it can detect both optical and infrared light. Small temperature changes can fog the mirror and, because it’s so big, can even warp it (thus the blue thermal insulation). Moving the telescope to aim it can also result in warping, so Subaru’s mirror is kept perfectly reflective by “adaptive optics”: A twenty-watt laser (a half-watt laser could blind you) detects atmospheric distortions, then 261 robotically controlled arms gently massage the mirror to compensate, making it a sort of living membrane. To keep the mirror sharp, its surface is blasted once a month with dry-ice crystals, which gently scour away accumulated dust. But this doesn’t keep the mirror clean forever, so every four years it’s lifted off by crane and lowered through retractable doors in the floor to a huge sublevel where the thin aluminum reflective coat is removed and reapplied.
Subaru is Japan’s largest telescope. Some believed building a telescope of its size would be impossible, so it’s no surprise that its success is a point of national pride. Such a Herculean effort was undertaken for an equally epic endeavor: to answer questions about the origin of the universe. Subaru’s huge mirror can collect incredibly faint light and feed it into specialized instruments like the MOIRCS, which can observe the gravitational behavior of distant galaxies in order to refine the Hubble Constant, or the speed at which the universe is expanding. Having a precise measure of such a thing is essential for “big picture” astronomy.
With MOIRCS working with Subaru’s other impressive instruments, like the Hyper SuprimeCam (a digital still camera that’s taller than a human being), Subaru has recorded the telltale spectral signals of stars in galactic formations eleven billion light-years away—regarded as the current limit of how far we can see into the past of the cosmos. To top that off, twenty-four separate galaxies were precisely examined in just two hundred hours of observation, much less time than many other telescopes would require. Subaru plus MOIRCS found that these distant and ancient stars were not spring chickens. They were mature, with a similar chemical composition to “nearby” mature galaxies. Because the MOIRCS-enabled Subaru can collect so much data, astronomers have refined their estimates about the age of the universe and concluded that it is billions of years older than previously thought.
To me such discoveries are mind-blowing, but for the Subaru crew it’s just one of many interesting reads on the cork-board in the break room. Jimmy Ferreira is used to this; he has been at Subaru from the beginning, when he worked as a welder during its construction. After twenty years at the observatory, Ferreira has done everything from shovel snow off the roof to help resurface the mirror. “How many locals can say they’ve missed a Super Bowl and a Christmas because they had to shovel snow?”
Just up the hill from Subaru, the twin domes of the W.M. Keck Observatory house telescopes even more astonishing than the Subaru, whose mirror is the maximum size a single mirror can be. But Keck’s mirrors aren’t single: Thirty-six“small” mirrors are fitted together, forming ten meters of perfectly reflective surface. Even its designers called Keck 1 “the impossible telescope.” But after Keck 1 was completed in 1990, proving its moniker wrong, Keck 2 was constructed. Combining the two images from each telescope gives single clear images of things otherwise impossible to see from Earth, including faint planets orbiting distant stars.
Keeping Keck’s seventy-two mirrors functional requires daily maintenance. As soon as we enter the low building connecting the observatory’s twin domes, we’re met with the urgent cry, “Mirror in the hallway! Mirror in the hallway!” I sneak a cautious peek; getting too close to a mirror segment could contaminate it. The eight-foot-tall hexagonal mirror segment nestles in a wheeled cart, flanked by technicians in clean-room suits. As soon as the mirror is secured in the clean room, we’re allowed to move on.
John Baldwin, Keck’s summit superintendent, has the job of choreographing the complex ballet of maintenance tasks. At a meeting with some fifteen technicians in the break room, he lays out the day’s schedule. Keck 2 needs its tertiary mirror swung out of the way, and one of its lasers needs maintenance (Keck has two twenty-watt lasers, of course). But the big job is the “SegEx,” or segment exchange, of three delicate and irreplaceable mirrors. These orphan, refurbished segments need to go from clean storage to a segment reunion in eight hours. And they need to be perfect and unblemished during the journey. “It’s like replacing spark plugs on an engine while it’s still running,” Baldwin says, and it all has to be completed by nightfall so observations can run on schedule.
After a firm and explicit briefing, I am allowed to enter the Keck 1 dome. CFHT is big, Subaru is huge, but I can’t even fit the entirety of Keck’s cold, gray and clean telescope in my field of view. It’s awe-inspiring; I am standing next to a pinnacle of astronomical technology. “Does this ever get old, John?” He cracks a smile. “Never,” he says. “But I do look forward to long weekends.”
I’m allowed to climb into the telescope itself. Even some veteran Keck employees haven’t had this privilege. I don’t dare breathe as I pass feet from its precious mirrors, then make my way through the complex structure to a small maintenance platform. Two technicians start the SegEx while John narrates. “The segment has been pushed up by a jack so that this crane can hook to it.” A padded, claw-like crane attachment slowly descends from the dome ceiling. “At this point,” John says breathlessly, “the technician has to make sure the mirror isn’t warping too much.” Mirror segments are exquisitely fragile, delicately linking together on laser-cut seams. No one dares mention the possibility of one breaking. We watch as the segment ascends toward the distant dome.
Just as with the Subaru, robotic actuators (called “whiffletrees” here) deftly massage the mirror to optical perfection, but the attachment points between the actuators and mirror had begun to fail. The Keck Observatory crew invented a highly experimental method to refurbish the attachment points in the lab, down the mountain in Waimea. It had never before been attempted, but it worked. Keck 2 recently had all thirty-six segments removed, fixed and replaced; what we’re witnessing today is the beginning of the whiffletree attachment point repair of the Keck 1 segments.
Once the wayward segment is safe on its cradle in the clean room, I spot Mike Aina, one of the technicians who had been hands-on with the mirror during the SegEx. Mike is a former UFC fighter and a bit of a local star. Was he nervous during the delicate operation? “Nah,” he says like a true Mauna Kea veteran, “I just do it the right way every time. Simple.” HH