A visit to the Chajnantor plateau is a breath-taking experience – and not just because it’s 5,100 metres up. Perched in the Andes mountains in one of the driest places on earth, where clear skies and the thin atmosphere guarantee perfect viewing conditions, 66 house-sized antennae are spread across the featureless landscape.
As I emerged from our bus into the harsh light, the antennae stood sentinel, angled towards the heavens. Suddenly they started to swing upwards and turn, silently and in unison, in a balletic movement choreographed by an unseen force. It was a moment of pure theatre – and easy to imagine they were responding to a signal from another world.
From this barren spot the next chapter in the exploration of the universe and the search for extra-terrestrial life will be launched today with the official inauguration of the world’s most powerful radio telescope.
The antennae, which each weigh 100 tons and cost $6m to build, are linked in a network enabling them to probe the most distant parts of the universe. Together, they will enable astronomers to search in greater detail than ever before and seek answers to the question: are we alone?
The Atacama Large Millimetre Array (Alma) radio telescope has taken a decade to build and cost $1.4bn. Yet although it is operating at less than a 10th of its capacity – it will be up to a year before it is used at maximum power – it is already yielding new insights into the origins of galaxies, stars and planets.
Most scientists believe that statistically it is likely that life exists somewhere else in the universe, based on the number of stars like our own Sun.
More than 2,700 candidate planets orbiting other stars have been identified – the vast majority are expected to be confirmed as true “exoplanets”.
It is possible to work only for limited periods at the site of the world’s most powerful radio telescope, to be inaugurated by the President of Chile today, but it is too high for people to live there. Engineers go up and down from the base station, working with oxygen cylinders on their backs, spend no more than eight hours at the top, and work eight weeks on and six weeks off.
An ambulance followed our bus and there were two hyperbaric chambers waiting at the top for serious cases of altitude sickness. Two of our party felt faint and were given extra oxygen and ferried back down to base. The symptoms of altitude sickness – headache, nausea, vomiting – can strike suddenly when an ascent is made rapidly without time to acclimatise.
As we lumbered up the dirt road, two paramedics asked if we felt any symptoms. In my case only a slight light-headedness – as if the top of my scalp had been lifted two inches clear of my skull.
Astronomers using Alma have already identified sugar molecules in the gas surrounding a young Sun-like star – the first time sugar has been found in space. “The discovery shows that the building blocks of life are in the right place at the right time to be included in planets forming around the star,” the Joint Alma Observatory says.
The project is an international collaboration in which the European Southern Observatory (ESO), a consortium of 15 countries including the UK, whose subscription is paid via the UK Science and Technology Facilities Council , has played a leading role.
Valentin Ivanov, a staff astronomer with ESO from Bulgaria, said there had been “enormous advances” in astronomy in the last decade and Alma opened a new era with its ability to detect and analyse the chemical composition of molecules in space. But he is cautious about finding life outside our own solar system. “Our best bet is the moons of Jupiter and Saturn. It is very difficult to prove the existence of life on planets around other stars.” he said.
Douglas Pierce-Price, spokesman for ESO, said Alma’s advantage over optical telescopes was its ability to penetrate dust clouds to look at galaxies further away and observe the formation of stars. “If you want to understand the history of the universe you have to look further back in time.”
In addition, Alma is designed to observe longer wavelengths beyond the visible light spectrum and it is in this part of the spectrum that the chemicals essential to life such as water can be detected through spectroscopic analysis.
The Atacama desert has drawn astronomers for decades and several of the world’s biggest telescopes are sited here. The Chajnantor plateau lies on ancient Inca trading routes and the mountains and volcanoes of the high Andes were a place of pilgrimage centuries ago. In more recent times, the area around San Pedro de Atacama, the nearest settlement to Chajnantor, has lured people in search of spiritual enlightenment, drawn to the “window on the heavens”.
The slogan of the Alma observatory – “in search of our cosmic origins” – is one that could equally be applied to these latter-day pilgrims.
During the military dictatorship of President Pinochet in the 1970s and 1980s, when tens of thousands of ordinary Chileans were incarcerated in concentration camps in the Atacama desert or “disappeared”, an astronomer called Dr Alvarez taught a group of internees in the Chacabuco camp how to identify the constellations at night. They described “a feeling of great freedom” as they studied the cosmos with its distant stars. But the military quickly banned the lessons, fearing the prisoners could escape using the stars as their guide.
The story forms part of the 2010 Chilean documentary Nostalgia for the Light which juxtaposed interviews with astronomers searching humanity’s astronomical past with film of women searching the Atacama desert for remains of their loved ones, who were slaughtered during the Chilean terror. Their bodies still turn up preserved in the moisture-free environment.
One of those featured in the film was Valentina Rodriguez, now head of communications at ESO in Chile, who lost her parents during the terror, and was raised by her grandparents. She described how the military threatened to harm her, unless her grandparents disclosed where her parents were hiding, how in desperation they eventually complied, and how her parents were taken away. Today, instead of searching the desert floor, she is helping explore the skies above.
“Astronomy has give me another dimension to the pain and loss,” she said. “We, like the stars, are part of a cycle in which matter and energy are continuously recycled, but never lost.”
Vital signs: An astronomical puzzle
One of the earliest discoveries made with Alma, which has greatly excited astronomers, is the detection of glycolaldehyde – a primitive form of sugar – in the gas surrounding a young star.
Glycolaldehyde is one of the building blocks of ribonucleic acid (RNA), which in turn is one of the foundations of life.
In the search for extraterrestrial creatures or plants, the first step is to identify where the conditions are right for life to occur. The discovery of complex molecules such as sugar gives scientists confidence that they are looking in the right place.
Other molecules essential to life that have been discovered elsewhere in the universe include ethanol (alcohol), formaldehyde, carbon monoxide and ammonia.
Given the spectrum of radio waves within which it operates, Alma is able to spot these complex molecules and direct astronomers to where life may be formed.