Pass The Sugar? Er, It’s 400 Light Years Away...
By Nick OlleOctober 25, 2012
This week astronomers in Chile discovered the nearest planet outside our solar system, a trifling four light years away. Another observatory in Chile — the world’s largest — is looking much farther afield towards the “cosmic dawn”, transforming our understanding of the universe along the way.
In the thin air 5,000 metres above sea level, the Chajnantor plateau in Chile’s Atacama Desert is, in every sense of the word, breathtaking. The desolate landscape — reputedly the driest on earth — is hemmed on one side by snow-capped Andean peaks and tapers away to stark otherworldly plains on the other. It’s little wonder filmmakers favour these extreme Atacaman expanses to simulate Martian vistas. Indeed, scientists have compared the lifeless soil here to that on the red planet. Most people who venture to these dizzying heights do so with oxygen tanks in tow, but with or without plastic tubes pumping O2 directly into your nostrils, it’s a heady atmosphere.
And that’s just the natural environment.
Sprouting improbably from the Chajnantor plateau’s surface, like giant metallic mushrooms, are 46 antennas, their 12-metre diameter dishes tilted deferentially toward the heavens. Together, they form two-thirds of ALMA (the Atacama Millimeter/Submillimeter Array), which, when it is completed in 2013, will be the world’s biggest, most sensitive radio telescope. It may still be 20 antennae short of its final network, but ALMA is already looking farther into space than astronomers ever have before.
Exposing The Cosmic Dawn
That is to say, this facility — literally — looks farther back in time than has previously been possible. Its view takes us back billions of years, to just a couple of hundred million years after the Big Bang.
“We are looking back in time. Because of the limited velocity of light, we can look at galaxies that formed in the wake of the Big Bang,” grins German commissioning astronomer Rainer Mauersberger.
Mauersberger and his oxygen-deprived colleagues enjoy some of the most spectacular office views available anywhere in the world, but the work environment is not ideal. We’re talking a day (and night) job at the altitude of the Mt Everest base camps. With constant exposure, workers generally become less prone to altitude sickness, but even after five years Italian electronic engineer Lorenzo Martinez-Conde uses his personal oxygen tank inside the oxygenated building.
But these scientists know they are working at the cutting edge of astronomical enquiry. Not surprisingly, there is a constant, palpable sense of excitement among the people who work here.
This is the largest astronomical project in existence, an undertaking of such ambition — and cost — that it is only possible thanks to the expertise and funding (more than USD1billion) of an international consortium which combines North American, European and Asian partners with its Chilean host. At any given time about 500 people live on site at the 3,000m-altitude Operations Support Facility.
Coexisting with the scientists and technicians is a giant support staff — office assistants, caterers, medics. Everyone sleeps in the spartan but comfortable quarters, fashioned from converted shipping containers. Many work gruelling 12-hour shifts, some through the night, for eight or more days at a time. But far from complaining, everyone seems almost as excited about the cross-cultural exchange the facility allows, as at the prospect of unlocking the secrets of the universe.
Almost. Of course, it’s really all about the science. Even the water-cooler talk reflects this, as scientists and non-scientists alike gush at ALMA’s potential — “unbelievable”, “groundbreaking”, “revolutionary”.
In the words of the System Integration Manager, Dutchman Rieks Jager: “It’s amazing to think that even with the incomplete array that we have now, we’re producing science that is mind-boggling for the astronomers.
“We are seeing the origins of planet formation. We can see regions around other suns where planets are being formed and, of course, we hope to find evidence of planets that look a bit like our planet so that we know that we’re not alone.”
In the midst of the excitement it’s easy to forget the extraordinary feats of engineering behind the scenes. There are more engineers here than any other group of professionals. ALMA’s Instrument Group Manager David Rabanus, a German, attributes this to the enormous number of interacting hardware systems underpinning the entire operation.
“The instruments represent the whole signal chain, starting from the focal plane of the antennas,” he says. The antennas themselves are assembled in three different work areas, operated separately by European (ESO), North American (NRAO), and East Asian (NAOJ) teams.
The result is three visually distinct antennae, which all meet ALMA’s extremely strict design and operation specifications. Then there’s the small issue of installing the antennae once they’re built; safely moving the high-tech behemoths two kilometres uphill to stand alongside their kinsfolk on the plateau. Naturally, the Germans take care of this. Or to be more precise, Otto and Lore do. These two 28-wheeled, 20-metre long transporters were custom-built for the job.
Unlike the optical telescopes most commonly used in astronomy, which detect light, ALMA’s antennas work collectively to pick up sub-millimetre infrared and radio waves. The great advantage of this “interferometer” technology, Mauersberger explains, is that it can “see through” opaque cosmic dust into the centre of the Milky Way.
“With optical telescopes, the objects we look at need to be very hot, like stars and suns — but [here] we are exploring the cold universe. [ALMA] is like an infrared camera, we can see objects that have only a few hundred Kelvin, like planets and interstellar dust.”
It’s in these dark discs of dust that stars and planets are formed. The dust, you see, shrouds the interior of gas clouds, keeping the molecules sufficiently cold and immobile to collapse under their own gravity.
For the past five years, the oxygen-toting Italian Martinez-Conde has worked out of a building just across the plateau from the antennas, manning one of the world’s biggest, most powerful computers. The “correlator” is a beast of a thing, scarcely contained by the multiple stacked rows of shelves housing its seemingly interminable hardwiring. This extreme level of computing muscle is necessary to process the 120 gigabytes of information each of the antennas sends every second.
The atmosphere here might be tough for humans, but for the antennas there is nowhere better. Martinez-Conde explains: “The antennas were placed at this altitude of 5000m and in a very dry place because we [the earth] have an atmosphere and there is a lot of water in the middle of it.”
“The problem is that radio waves are absorbed by water, but here we have only a tiny amount of water between us and the open space, so there is the least [possible] attenuation of radio signals.”
From the correlator, the digitised data whizzes down to the control room where Mauersberger and other astronomers and astrophysicists eagerly set about deciphering and interpreting it. Recently, this process led to an astonishing discovery — space sugar. ALMA found sugar molecules — known as glycolaldehyde, which is one of the building blocks of life — in the gas surrounding the star IRAS 16293-2422, some 400 light years away. “The scientists who discovered this propose that these complex molecules, which could be the origin of life, might already have existed before the Earth was formed,” Mauersberger enthuses. “Everything we are doing now is new, it’s like walking through newly formed snow and you look back and you see your traces — that’s exciting.”
So pioneering is the science that it inspires — almost begs — the really big questions: Will we be able to see back to the Big Bang itself? Are there other life forms in the universe?
The scientists urge caution here. The answer to the former question, according to Mauersberger, is no. “We can get extremely close,” he says, “but there is a limit, and this is the cosmic background radiation a couple of hundred million years after the big bang. We can’t go back further.”
As for finding life in the universe, he thinks it is unlikely in the short term. “What we can find is the presence of planets around newly formed stars that look like earth, and complex molecules that provide clues to the formation of life — that would be a great step forward.”
“I would predict that the biggest discoveries with ALMA will be things that we cannot imagine now.
“Of course, we have objectives in mind, such as discovering complex prebiotic molecules like amino acids, and to see the black hole in the centre of the Milky Way,” he says.
Talking in ALMA’s control room, 2,000 metres closer to sea level than the antennas, Mauersberger’s giddy, and it’s clearly not from the oxygen deprivation: “I would predict we will find something even more exciting.”