The Mauna Kea Experience
The door of the plane opens and the first hint of the tropical night wafts inside. In spite of nearly twenty-four hours of traveling, the fresh air and perfumed humidity wake me up. That, and the knowledge that I’ve arrived.
I’ve flown from London to Hilo on the Big Island of Hawaii to use one of the telescopes at the famous Mauna Kea Observatory. British astronomers have been doing this since 1979 when UKIRT, the UK Infrared Telescope, opened. The high volcanic peak now hosts the Kecks, the largest and most famous ground-based telescopes, and many others. I’m here to use the James Clarke Maxwell telescope, the JCMT, a fifteen meter submillimeter dish, to study dusty galaxies near the edge of the observable universe.
But now all I want to do is get my bags, get to the hotel and go to sleep.
I hurry to the outdoor baggage hall—much of Hilo airport is outside or open to the balmy air—and get a taxi to Banyan Drive and a large bed.
Hilo is a small American town dropped into a tropical jungle—everything is surrounded by foliage I’m more used to seeing in a greenhouse. Hilo is also one of the wettest places on Earth, with 128 inches of rainfall a year. But I don’t have time to enjoy it as I have to head up the mountain.
The Big Island is made of five separate shield volcanoes rising from the bottom of the Pacific. One is extinct, two are dormant—officially this includes Mauna Kea, but we tell our students it’s extinct to make them feel safer—and two are active. One of these, Kilauea, is very active, and has been constantly erupting since 1983. You can see its dull glow from the observatory and sometimes it produces a sulfurous vog—volcanic smog—that blows into Hilo. The biggest volcanoes are Mauna Kea and Mauna Loa. These form the bulk of the island. To get to either you have to ascend the infamous Saddle Road that runs between them.
Starting in Hilo the car climbs into thicker jungle as the houses get further and further apart. Soon we hit clouds and a thick mist, almost rain, coats the windshield. We’ve left the jungle behind and are in the cloud forest. Oddly-shaped trees stand on either side of the road, with wispy foliage and thin white trunks emerging from the black volcanic rock.
Eventually we break into bright sunshine and get our first clear view of the mountains. On the left the huge bulk of Mauna Loa dominates, its vast flanks scarred by lava flows. On the right, smaller but higher, is Mauna Kea with the observatory’s white domes clustering on the top.
The road flattens out as it meanders through the lava flows until we take a right turn onto the steep Mauna Kea Access Road. We go across a cattle grid and enter grassy ranching country, complete with signs warning us of ’Invisible Cows’ in the frequent fog.
By this point I can feel the altitude. I’m breathing faster, my ears have been popping as the car climbs and, if I try anything strenuous, I get light-headed.
A few more turns through rust red cinder cones and the astronomers’ residence, Hale Pohaku, comes into view.
The first part of my ascent is complete.
I’ll be driven to the summit by my telescope operator. They don’t let anybody control the telescopes, and they want to make sure I don’t break anything. The operators come from a huge range of backgrounds. My driver used to be a sonar officer on US submarines, while another is a part-time DJ at a Hilo radio station.
The operators also look after the observers. You lose a few points of intelligence for every thousand feet of altitude. At 14000 feet everyone is stupid, but it affects you in strange ways. I’ve taken an IQ test at the telescope (maybe in itself a sign of stupidity!) and got the result you might expect for someone with an astrophysics PhD. But I’ve also spent thirty minutes failing to work out how to get an instrument properly aligned.
There are stories from the construction of one telescope about an angry call received at sea level.
“There’s a problem with these parts you sent up.”
“Oh yes?” said the sea level manager.
“Yes! I’ve cut the things three times and they’re still too short!”
“Come down to sea level,” said the manager. “Now!”
There are other odd effects. On my first observing run I was typing away when I got an odd feeling that I was forgetting something very important. I looked round to make sure the telescope was working and checked the observation was progressing. Everything fine. Had some new email come in? No. Any bad weather? No. I sat back and scratched my head because the feeling wouldn’t go away. Then I realized.
Yes, that’s it—I’d forgotten to breathe, and a few deep breaths later I was feeling much better.
Any exertion really hits you. You learn this quickly when you come back from the toilet and run up stairs that look perfectly innocuous to anyone who’s just come up from sea level. If you’re lucky you can struggle to the top before you have to stop, lungs heaving and vision compressing to a dark tunnel as oxygen starvation sets in.
My observations are part of a large area survey of the submillimetre sky. This part of the spectrum, also called terrahertz waves, sits between radio and infrared wavelengths. The submillimetre has only been opened up in the last couple of decades and we’re still in the earliest stages of exploring its potential. My particular interest is the study of dust-dominated galaxies which are very powerful emitters of submillimetre radiation.
In the local universe luminous dusty galaxies are rare but observations with the COBE satellite in the early 90s confirmed hints that dusty galaxies were much more numerous at earlier epochs of the universe. They’re so numerous, in fact, that roughly half the total energy emitted by stars in the history of the universe came from such objects, where the light was absorbed by dust and re-emitted in the far-infrared and submillimetre bands. The history of galaxy formation we get from optical telescopes, such as the Hubble Space Telescope or the giant Kecks, is thus biased. It can’t show us the obscured emission that comes out in the submillimetre so half the story is missing.
Uncovering this hidden history is hard work as it takes many hours to detect just one of the dusty galaxies responsible and we need hundreds of them to properly understand where they are, what powers them and what role they play in the bigger picture of galaxy evolution.
I’m here to add some more nights of data to this survey.
Hale Pohaku, ’stone hut’ in Hawaiian, is a halfway house between sea-level and the high altitude of the observatory. Astronomers stay here for 24 hours of acclimatization before being allowed up to the summit and then come back to sleep during the day. There are dorms, a library, TV room, canteen, where you can get ice-cream 24 hours a day, and hot and cold running internet.
Weather is the great enemy. All too often it can send you home empty handed. Cloud, fog, wind, humidity, rain, ice and snow all bring problems. Snowfall means the summit has to be evacuated as it’s all too easy to be stranded. In the early days some astronomers stuck on the summit in a storm had to burn furniture to keep warm.
Once I’ve unpacked and settled in, I have a little walk. HP is surrounded by cinder cones but their stark shapes are softened by bushes and clumps of grass. On one side the mountain slopes down to the Saddle Road with Mauna Loa rising beyond. On the other the summit road continues, leading upwards into an arid red landscape. Above that is the clear, deep blue sky only seen at the best observatories.
At the summit, like giant mushrooms growing on an ancient stump of mahogany, are the domes of the telescopes. Most are round and white, reflecting as much of the day’s heat as they can. Beneath the summit ridge, in Millimetre Valley, are the JCMT and the two other submillimetre telescopes. One of these, the Submillimetre Array, consists of eight small dishes sitting open to the elements on individual plinths. The other, the Caltech Submillimetre Observatory, hides inside a spherical reflective ball, only revealing itself for observations. The JCMT rises like a giant cylindrical gun turret, but its dish can’t be seen from outside as it’s covered by a giant Goretex membrane, shading it from the sun during daytime operation and protecting it from dust.
Everything except the telescopes is brick red. The ground is a mixture of volcanic cinders, larger rocks and a fine pervasive dust. And there are no signs of life. Apollo astronauts trained here for the moon landings, but the landscape is closer to Mars than the moon—it would be familiar to anyone who’s looked at images from the Mars rovers.
It isn’t entirely lifeless. Apart from astronomers and tourists, there are a few tufts of vegetation. There’s even a native insect. They consume less hardy insects blown up the mountain from sea level and unable to cope in the thin air—a unique ecological niche.
And most of the observatories have mice.
Our big four wheel drive pulls up to the JCMT and we settle into the control room surrounded by desks and computer screens. Once the sun sets there’s nothing to see outside so we close the small window and concentrate on the observations. The operator looks after the telescope and I make sure the data coming in looks right. We keep ourselves going with sandwiches from HP. I graze on food throughout the night as it helps keep me awake. I also drink lots—tea, water, fruit-juice – anything to make sure I stay hydrated and prevent altitude sickness.
The night wears on. I try to keep my attention on the observations but it’s hard. The hum of the computers and humidifier lull us to sleep when the CDs run out, but at least the humidifier is working. The best data comes when it’s very dry. The human body can’t cope with this so when the humidifier breaks you get nose bleeds. Some of the best data I’ve ever got at the JCMT was taken with my hand clamped to my nose stemming a stream of blood. My lab book and the observing log still have the stains.
By 6am the sun has started to rise and we get our second wind. But it all starts again ’tomorrow’ when we get up at 4pm, for ’dinner’ as breakfast, and head back.
Several exhausting days later and our final night is nearing its end. I take special care to clear my stuff out of the control room and there’s an extra spring to my step. The last night of the run is like the night before Christmas, or the end of school. I’m always a little excited about being let out of this scientific monastery and back to sea level.
I don’t really know what results my data will bring. Some observing runs, perhaps the most exciting, bring instant gratification with something interesting appearing on the screens immediately the data is read out. Extragalactic submillimetre surveys aren’t like that. My nights of data will have to be carefully combined with many others before we know what we’ve seen and the data must then be compared to datasets at other wavelengths before we can really understand what the submillimetre galaxies are doing. No instant gratification this trip, but I know the data is sound and that this run has been another useful step towards sorting out the hidden history of the universe.
After breakfast and a few hours sleep I meet up with another astronomer who’s driving me down to Hilo. I have sunglasses and a hat, but I still blink in the unaccustomed brightness. Below us are the tops of the clouds we’ll pass through on our way. Then we’re in the car and off.
As the car heads downhill, away from HP and its dry volcanic landscape, we soon reach the ranchland. Smells of grass and pine woods come through the windows. My head begins to clear as my body drinks in the richer supply of oxygen. This just keeps going all the way to sea level. You never realize it when you’re there, but your body works hard for every breath on the mountain. For days my lungs have been pumping further and faster than they’re used to. But now they can relax. With every breath I taste the richness of the air at the bottom of the atmosphere. The feeling won’t last, but for now slow breathing is a welcome relaxation.
My data has been downloaded. My work is done and I can look forward to a couple of days in Hilo catching up with friends. As the car descends into the mists of the cloud forest it all catches up with me and I fall asleep.