Sucking Up Radiation from Outer Space in the Chilean Desert

The terrain at the high site is barren and extremely dry. Temperatures can range from +20 to -20 degrees C within a single day.

For most of the year, the village of San Pedro de Atacama in the northern Chilean desert plays host to the usual contingent of tourists drawn to the salt-flats and sand dunes nearby. The rundown adobe souvenir shacks dish out coca tea and Bob Marley necklaces to dreadlocked Aussie undergrads who come here for mountain bike expeditions—and the off chance they’ll be able to hook up with an American undergrad or two.

But every once in awhile, an altogether different crowd descends on the dust-choked village. It's a motley crew of some of the smartest people on the planet. That's because a half-hour up the road, and a kilometre higher into the sky, sits an installation that defies most of the superlatives used to explain it to plebs like you and me.

Five thousand metres above sea level, where the air is so thin that most visitors need one of those bingo-grandma oxygen tanks plugged into their nose just to keep from passing out, is an enormous scientific experiment called ALMA—short for the Atacama Large Millimetre/sub-Millimetre Array. It’s not exactly a catchy name, but what it lacks in clever branding it more than makes up for in mind-blowing scale and ambition. The goal of this megaproject, costing a billion dollars and involving participation from dozens of countries around the world, is to understand the fundamental structure of the universe.

The fine details of the detectors which pick up millimetre-wavelength radiation from space. It uses superconducting magnets which must be kept extremely cold with liquid helium

A few weeks ago, I was lucky enough to tag along to the official opening of ALMA with a group of scientists with a collective IQ that tops the figure on Lil' Wayne's Saturday night bar tab. After 30 years of development, their mindblowing project was about to be switched on for the first time—and they were ready to throw down.

However, a party with a group of astrophysicists and satellite engineers plays out a bit differently than the average night at your local hipster bar. Rather than chatter about SXSW and vintage Bianchi fixies, here are some actual phrases I overheard during my weeklong nerd-fest in the bone-dry desert air:

• "Can you believe it took us about 20 minutes to integrate a redshift of z = 7? That used to take a week. And forget about 5-sigma; all we have to worry about now is UV coverage"
• That must be the Large Magellanic Cloud! I'm not used to seeing it upside down"
• "Oh, that was during Wife 1.0."
• "I had a Starfleet uniform, too. Engineering yellow. My wife threw it out."

That was just the warm-up. I was in for a hell of a week.

Canada's contribution: the fine details of the detectors which pick up millimetre-wavelength radiation from space. It uses superconducting magnets which must be kept extremely cold with liquid helium.

The plane journey from Santiago to Atacama is only a couple of hours, but you might as well have landed on a different planet. The Chilean capital is cosmopolitan and chic; the desert in the north of the country is mostly barren rock. Coming in from sea level, the thin atmosphere is a shock. It brushes against you ineffectually and even a short jog leaves you winded. The air here is also incredibly dry. Not an ideal environment for humans, but it’s a great place to find millimetre-wavelength photons that have travelled across the cosmos for billions of years.

The group of scientists I was travelling with came to Atacama to switch on a giant, billion-dollar machine just to look for these little quantized bits of light. Why are they so important? It turns out they may hold the key to understanding the origin of life on Earth.

In order to get to the observatory where all this happens, the first step is a medical check in the tourist town of San Pedro. Dozens of journalists mill around a hotel dining room booked for the occasion. Before validating your accreditation, a paramedic checks your blood pressure and oxygen perfusion. The observatory is located 5,000 metres above sea level—that’s the same altitude as Everest Base Camp. I heard a little conspiratorial chatter about a wayward BP reading: “I have some pills that can help you bring that down.” Not exactly railing lines on a tour bus, but it was something.

The guts of the detector array that sits at the heart of each antenna. They are sensitive enough to pick up a single photon that has travelled trillions of kilometres.

But any notions of excess were quickly put to bed, along with myself, confined to a strict 9pm curfew and NO BOOZE. This is anathema to most journalism junkets and got me a bit depressed. But holy shit, am I ever glad they were strict with me the next morning: alcohol messes with your metabolism at high altitudes.

As our bus chugged skyward, I realized this trip was diametrically opposite to the recent Rhianna press tour in which a bunch of alcoholic entertainment bloggers were crammed into a 777 and forcefed douchebag-brand champagne. Everyone I was travelling with was hale, hearty, had at least one PhD and were filled with a positive, can-do attitude, which was especially useful on the morning’s climb.

The reason we had to go up so high is because the kind of feeble radio waves the installation is looking for are easily absorbed by both dense air and water vapour. The signals are so weak because they are emitted by enormous clouds of interstellar dust a mind-bending distance away1. This light is intercepted by ALMA’s antennas. One of the world’s biggest computers crunches the information contained in these signals to determine the chemical composition of the dust grains. They’ve already found water and simple sugar molecules on these grains. According to a new theory, these biomolecules come together as the dust cloud collapses in on itself over the course of billions of years to form a planet. The seeds of life are sown in space, before the planet is born.

Each of the antennas at ALMA can be moved to different positions on the site to accommodate various experiments. They're lugged around by these enormous tractors.

Before I learned all this I finally had to get up there. Before the bus trip we were given oxygen canisters fitted with plastic masks. I thought I wouldn’t need mine until about halfway through the journey when I suddenly began to feel incredibly tired, like I was wearing a lead suit. I lost consciousness for a few seconds; when I snapped awake my first confused thought was that I needed to find Blanche from The Golden Girls. A couple of hoots off the oxygen can cleared away the sitcom hallucination, but for the next few hours any activity more strenuous than a brisk walk required a lengthy sit-down.

Intermittent rest stops were more than welcome because the scenery, and the scope of what we were taking in, was astonishing. Here at the Chajnantor plateau, silhouetted against the brilliant high-altitude sunshine, were dozens of parabolic dishes, about as high as a three-story house and as wide as a truck. These receivers are incredible feats of engineering: they maintain a perfectly parabolic shape over their entire surface to within the thickness of a sheet of paper. Each dish is capable of capturing a single photon of light, then converting that blip of radiation into signals that are processed by a supercomputer at 17 quadrillion operations per second. By teasing apart these calculations, the scientists at ALMA can examine a property of the incoming light called redshift, which reveals even more intriguing details about our universe.

Up at the high site, we come face-to-face with two of ALMA's 66 antennas. They are real engineering feats: 12 metres in diameter, shaped as perfect parabolas. The shape of the dish is accurate to within the diameter of a human hair across the entire surface.

When you’re on the street and an ambulance approaches, then races past, the pitch of the siren will increase as the ambulance gets closer, then drops sharply as it speeds away from you. This phenomenon is called the Doppler effect. The same principle applies to light waves, too: if an object is moving away from the Earth quickly, the light rays emanating from it will get stretched out. A longer wavelength means the light appears more red to a stationary observer: thus the degree of “redshift” indicates how fast an object is moving away from us. ALMA has already detected a number of surprising objects with very high redshift values, meaning they are sources of light that are so distant they are among the oldest known objects in the universe. This is because the older something is, the further it is away from us, caught up in the cosmic tide as the universe continually expands. When you’re looking at the cusp of that expansionary wave, you’re literally looking back in time, at the ghostly images of nebulae and bursts of radiation that died out when the universe was still a toddler.

A couple of days later, back in the delightfully dense air of Santiago, I sat on the rooftop bar of a boutique hotel, swirling a pisco sour.  I reminisced about the amazing intersection of raw intelligence, engineering savvy, and the quest for an understanding of the basic truths of the universe that I had witnessed over the past few days. A few tables over, a group of American college girls on spring break were braying like jackals about Botox and which clinics in L.A. deliver the best value for cellulite reduction. I found myself giving thanks I lived in a world where there was room for both the loftiest of cosmic thought and the quest for perfectly unsaggy flesh.

Paul Tadich is a journalist from Toronto. He’s working on a project about the 1993 Russian Constitutional Crisis. Please email him at paul.tadich@gmail.com.

1This is going to get a bit heavy, but you can handle it. We see objects in everyday life because light (from the sun or artificial sources) in the visible part of the electromagnetic spectrum bounces off these objects and strikes the photosensitive pigments in our retinas; our brain interprets this reflected light as the familiar things we see. However, all matter emits radiation that has nothing to do with the light that falls upon it from an external source. The colour—or frequency—of this emitted light changes with the object’s temperature. An iron in a fire will glow red at about 700 °C, and will radiate white light when white-hot at about 6,000 °C. This is due to an innate quantum-mechanical property of all matter. A human’s skin temperature is about 33°C. This temperature translates to an emission of light in the infrared portion of the electromagnetic spectrum; invisible to our eyes, but not to infrared cameras. The reason a far-off dust cloud appears dark to us here on Earth is because there’s no light bouncing off of it. To see the particles, observers must rely on light emitted by this quantum-mechanical process. The temperature of interstellar dust is about -230 °C, corresponding to light waves which have a frequency of about a millimetre which means they have very low energy. That’s why ALMA’s antennas need to be so sensitive. More science: The Science Behind Tripping Balls Stephen Harper Needs to Stop Gagging Canadian Scientists Science Will Justify Your One-Night Stands