Venus Transit Retro-Blog: Visiting Gemini North

2012 June 08 – My visit to the Gemini North observatory added a new dimension to my trip. For this, my fourth visit to Mauna Kea’s summit, I’d have to drive to the summit myself. (You can see the photos of the drive here.)

As I’ve mentioned before, trying to drive a regular rental car to the summit is a very bad idea. For this trip, I rented a big four-wheel drive truck from the only outfit on the Big Island that will let you drive up Mauna Kea. This rental company seems to have interesting clientele. I asked about a clause on special cleaning charges. “Oh, that,” said the counter clerk. “You don’t have to worry about that. We charge extra for things like blood on the upholstery.” My face must have looked rather odd, because she quickly added, “Sometimes hunters put stuff on the seats!”

Glad we got that one sorted out!

A colorful young woman briefed me on using the four-wheel drive selector without spewing bits of transmission over the ground. “Ooh!” said my instructor. “You’re getting my ‘boy truck!’ Good and loud!”

This scene was getting familiar!

After fastening my GoPro camera to the windshield, I headed out of Hilo in a pickup truck that seemed the approximate size of a small tank. The day before, the drive to the VIS had put a strain on my placid rental car. Not with Boy Truck. Even in two-wheel drive, it breezed up the winding road without moving the temperature gauge even fraction of a millimeter. Fortunately, the fuel gauge hadn’t moved much, either. I’d imagined I could hear air whistling into the emptying gas tank. I guess “boy trucks” get better gas mileage these days.

With plenty of time to meet my guide, I took the opportunity to explore the area around the VIS. Three previous trips had made a difference, and I had more than enough energy to go for a short hike. Here are a few photos.

I was to meet Joy Pollard, my Gemini guide, at Hale Pohaku for lunch. That’s a name with a lot of different interpretations, depending on who you ask.  The official documentation suggests that the name applies to the entire Onizuka Center for International Astronomy. Most people who’ve been on the mountain before seem to use the term to mean the staff quarters, and possibly just the main building.

It seems the term dates to long before astronomers set up shop on the summit. In the 1930s, the Civilian Conservation Corps built several cottages (huts, by some accounts) near the present location of the VIS. Hunters and hikers used the “stone houses” while traveling on Mauna Kea.

The view downhill from the dining hall’s lanai.

Whatever name you care to use, there’s a complex of modest buildings for observatory staff and visiting workers. The main building is a combination of offices, lounge, recreation room, and dining hall. It’s a simple building, with the comfortable, slightly worn feel of a university commons.

The dining hall fit in perfectly with that general impression. The food was basic, but well prepared with good ingredients. The Gemini outreach office had asked me to pay for lunch, but $11 for an excellent beef stew, very good coffee and premium ice cream was a pretty good deal.

Joy Pollard, a Gemini outreach officer, guided me through the observatory.

Over lunch, Joy went over the plan for the afternoon and gave me a thick packet of background information on the Gemini Observatories.  She led the way in her own vehicle, while I followed in Boy Truck.

Having traveled the summit road before as a passenger made it a lot easier for me to negotiate the twisting mountain road to the summit. It’s a tricky road, and a rough one. The switchbacks can leave you awfully close to some serious drops. If you weren’t careful, you could end up with a situation that would likely result in that special cleaning charge back at the rental office.

As we worked our way up the mountain, Boy Truck had to work harder. Without a supercharger, engine power drops steadily as the air gets thinner.  There were some steep sections where Boy Truck’s engine was howling away at 4500 RPM while it crept ahead at 20 to 25 mph.  The road builders did a pretty good job, though. After each steep section, there was a flat stretch where you could gear up and let the engine cool down a bit.

John A. Burns Way eats cars!

There were plenty of warnings and signs at the VIS advising visitors to use only four-wheel drive vehicles on the road to the summit. Of course, that didn’t make a damned bit of difference. We worked our way around several cars that succumbed to the altitude and the grade. There was a vague odor of scorched something-or-other around this dreary scene.

A bit before the Mile 5.0 marker, John A. Burns Way becomes a paved road. It’s still steep, but at least the drive is smoother. That’s when I noticed how tense my arms had gotten. Boy Truck didn’t have power steering, and muscling it along the rough road made for a fair upper-body workout.

The high summit ridge, with Gemini North on the right. Just ahead, the tops of Subaru, Keck I, Keck II, and NASA IRTF. The long, thin shape in the distance (just behind IRTF) is Haleakala. At 10,023 feet, it’s Maui’s highest mountain.

Not that it mattered much, because very soon, the first observatories came into view. If that sight doesn’t make your heart beat a little faster— well, why would you bother with this drive? One more spectacular switchback (this time with guardrails!), and we were on the high summit ridge. (Check out the whole drive here.)

After cautiously parking Boy Truck, I joined Joy in the Gemini North lobby. We checked in,  put on  our hardhats and went out onto the telescope floor.

This enormous blue structure is the base of the Gemini North telescope. The blue struts hold the altitude bearings; the entire structure rotates in azimuth.

The contrast to the Canada-France-Hawaii Telescope floor was remarkable. Even though the Gemini telescope has more than twice the aperture, the size difference wasn’t immediately obvious. For one thing, the Gemini dome is enormous, even in proportion to the telescope. What struck me was the difference in design philosophy.

CFHT seems like a slender version of the Hale Telescope: a truss-work tube holding a big prime-focus assembly, all nestled inside a massive yoke.  The Gemini telescope is somewhat reminiscent of a big Dobsonian: there’s a big rocker box on a rotating azimuth plate. With its stolid bulk, telescope’s base makes the lattice-work superstructure seem delicate. The secondary mirror holder, suspended high over the primary, seems tiny.

When you pause for a moment and consider the size of the seemingly tiny secondary, the Gemini telescope’s scale hits you. The secondary mirror is a meter across — the same as the aperture of the world’s biggest refractor at Yerkes Observatory. In any case, the secondary mirror isn’t precisely visible. The almost perfectly reflective surface plays tricks with your eyes.

Just looking up from the telescope floor, the secondary mirror assembly fascinates. As you move around, the reflections shift. The image of the pitch black baffle tube makes the hyperboloid surface look like a shiny doughnut.

The secondary mirror’s surreal image of the covered primary.

When I zoomed my camera in for a close-up shot of the secondary, what appeared in my viewfinder looked like a Salvador Dali painting. This photograph doesn’t quite do justice to the viewfinder image. With the secondary mirror almost filling the field of view, it seemed as though abstract geometric shapes where hanging in mid-air, shifting as the camera moved. The pitch black circle in the center looked like a hole passing right through the secondary assembly. That’s an illusion that actually does come across in this photo.

We left the telescope floor for the mirror coating facility. Unlike many modern observatories, the Gemini Observatories coat their mirrors with silver instead of aluminum. It’s a technically complex process. A layer of nickel acts as a primer coat for the silver, and a surface layer of silica protects the silver from oxidization.  Silver is considerably more reflective than aluminum, particularly for infrared wavelengths.  An article I read recently suggests that the silver coated 8.1 meter mirror has the effective light grasp of an aluminum coated 11 meter mirror. I don’t know how valid those numbers are, but they don’t seem unreasonable.

An elaborate cable routing system prevents snarls as the telescope rotates.

Over lunch, I’d told Joy I’d been an engineer in my bushy-haired youth. I was Joy’s only guest that afternoon, so she led me into obscure spots that she didn’t always visit. I called it the “geek-peek” special tour.

I don’t imagine that many people would have shared my enthusiasm for the cable wrapping room below the telescope. But think about it! How do you route dozens of cables to a rotating telescope without snarling them?  Optics and image sensors get the attention, but none of that is worth a damn if you can’t keep the telescope from wrapping itself into a Gordian Knot of tangled cables.

Exploring obscure places means climbing the odd ladder. I wasn’t having much trouble with the altitude, but at 13,700 feet, even climbing a short ladder leaves you puffing at the top. I can’t imagine what it must have been like to do construction work at the summit.

Here’s a panoramic view of the Gemini North control room.

Our last stop on the tour was the Gemini North control room. It’s a modern facility, arrayed with digital monitors. There isn’t an analog instrument in sight. Gemini North is operated from the summit, and observers often work right along side. Apparently, there’s some remote observing done, but not remote operation.

Eventually, the tour was over. (You can find several photo sets on my Flickr photostream.) I thanked Joy for a splendid tour, climbed back into Boy Truck and made my way down to the VIS.

One of many switchbacks on John A. Burns Way

The drive down was every bit as demanding as the drive up. For one thing, you’d burn out the brakes if you tried to use them to any extent. I’ve been told the thin air doesn’t cool the brakes properly. That sounds reasonable, but even at sea level, riding your brakes for 8 miles would ruin them, too. It’s the engine that keeps the speed down. Boy Truck did that job well, but with considerable noise. Driving back down John A. Burns Way, brakes aren’t useful for much more than making small adjustments to your speed. For example, a light tap keeps a downshift from throwing you onto the steering wheel.

During compression braking, Boy Truck tended to over-steer.  That can get tiring after a while. But the scenery was spectacular, and since I’d made the trip before as a passenger, it wasn’t too hard to catch a few peeks between tough spots on the road. In retrospect, I could have stopped off at pull-off areas. At the time, it just didn’t seem to be worth the trouble, particularly since my windshield-mounted camera was recording wide-angle video. Of course, it meant I didn’t get well-framed stills from good angles. Ah, well. At least I have some pretty good video captures.

After a short break at the VIS, I had an easy drive down to the foot of the access road. On this less demanding road, it was a lot easier to enjoy the scenery.

This is the view as you reach Saddle Road. To the right, there’s Mauna Loa in the distance.

This scrubby cinder cone marks the trailhead for the the Mauna Kea access road. As I turned onto Saddle Road and headed back to Hilo, I felt oddly unsettled. Perhaps I was feeling wistful to be leaving Mauna Kea for the last time.

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About Tim Cole

Astronomy enthusiast and educator, all-around fancier of dark skies and starry nights
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