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Science, People & Politics, Volume 1, 14.5.06.

What concerns astronomers in Chile,
when they are not doing astronomy

by Helen Gavaghan

Windswept, barren and shaken by Earthquakes that could crumble a European town; that is Cerro Paranal in Chile, home to four of the world's largest telescopes. When the Moon is full one could read a paper by its light and a night sky illuminated by the stars of the galactic centre. On dark nights if one is on the summit one can just about discern the outline of the telescopes. For astronomers like George Meylan, a professor of astrophysics at L'Ecole Polytechnique Federale de Lausanne, the Southern sky is magical.

Meylan is a regular visitor to the European Southern Observatory's (ESO) Very Large Telescopes at Paranal deep in the Atacama Desert -- one of the driest places on Earth, and with the clearest of skies. That is why some 15-plus years ago ESO chose the 2635-metre high mountain as the host site of its state-of-the-art hardware, and construction of the telescopes began in 1997.

Not all professional astronomers see the romance that Meynal observes when he looks upwards. To Jason Spyromilio, ESO's outgoing director in Chile - who is to head ESO's work on the Extra Large Telescope - the sky is a giant physics laboratory. Spyromilio has played a significant part, even in his pre director days, in bringing the VLT to fruition.

Unlike Meylan, who sees little of the Country because he must squeeze his work into exhausting three-day observing trips, Spyromilio has lived in Chile. Though he has shuttled between ESO's Chilean sites and between Chile and the ESO's headquarters in Germany, he has had a chance to see some of the surrounding country, including the adobe homes of ghost towns that once housed nitrate miners in the early 20th century.

Spyromilio has driven the 1000 miles from Santiago to the coastal port of Antofagasta and from there to Paranal. In the days before the Paranal Residencia opened he and visiting astronomers stayed in the make-shift accommodation of uninsulated shipping containers. These large metal boxes, about 12 metres long, divide roughly into a bedroom and bathroom. For anyone having to sleep during the day after a long night's observing the heat and dryness were uncomfortable. Rarely now do visitors need to sleep in the container units.

Since observing through the night is what life at Cerro Paranal is all about, getting out of the shipping containers and into rooms where the astronomers could sleep was as important to the success of the Observatory as was building the telescopes. Now astronomers luxuriate in a residence of one-hundred-plus rooms, each with en-suite bathrooms. A swimming pool in an atrium with surrounding balcony provides both relaxation and humidification to improve their quality of life.

Every day three or four water trucks make the trip to the observatory, others supply the diesel needed to keep the 3-MW generator working. Only a third of the road is yet paved, and when trucks brought in the mirrors for the telescopes they crept along at 3 miles an hour.

A gym, library and cinema provided the ESO staff with relaxation and entertainment. It is needed because the nearest town, Paposo, is one, says Spyromilio, of only 300 souls, and it is located about 50 miles south of the observatory. Antofagasta, a port city of nearly a quarter of a million people, is 100 miles away (the airport is near Antofagasta). The first has no entertainment to offer and the latter is too far away to visit given the tight schedule for the astronomers.

There is beauty though, of a stark nature, at Paranal. A distance of 12-kilometres in one direction one can see the Pacific, and so clear is the sky that 190 kilometres in the opposite direction one can see the 6700 metre high peak of Llullaillaco, the world's second highest active volcano. It straddles the Argentine-Chilean border and in Europe, where the furthest one could see is 30-kilometres, says ESO astronomer, Ferdinando Patat, it would not be visible.

Patat has made perhaps 10 trips to Paranal. He is an experimentalist and one of the ESO staff. Most of the time that he is in Chile he is supporting the work of other astronomers, sometimes doing his own work and other times commissioning an instrument.

Though he can almost guarantee clear nights - the sky is clear for 330 of 365 nights - he cannot guarantee the site will be free from Earthquakes, and there is a routine for closing down the telescope if quakes reach more that 6 on the Richter scale. Patat has not experienced one of these, but he has worked though lesser quakes. I asked him what that was like. Safe, he said. Both residence and observatory are designed and built to high standards, something reflected in a special acclamation by the jury awarding the Dedalo Minosse prizes in 2003-2004.

Still, though, the distinctive tremor has power to cause fear in Patat, who, as a 10-year old, lived through the Earthquake in the Friuli region of northern Italy in 1976. Some 1000 were killed, and 40 in his village died. So when the computer monitors shake, despite the quality of the building he can not quite suppress his fear.

In compensation there are magical moments, such as when those going to the summit gather in the car park. Typically they will have had dinner together. There will be one operator and one astronomer per telescope, a minimum of 8 people. Cars take them up the two to three kilometres to the summit and the telescopes. There, says Patat, most hope to see the Sun's distinctive green flash as it sinks below the horizon. It is the last lingering tentacle of the Sun's refracted light, and more likely to be visible in the clear Atacama desert against the sharp horizon of the Pacific than in Europe. But there is no time to linger. For from Sunset to Sunrise he and his colleagues must work. Having flown thousands of miles to some of the World's most powerful telescopes every second is precious. With only an hour for a meal they monitor conditions, reordering the work as dictated by science and weather. And then it is time to sleep.

With Sunrise they return to the Residencia. If it is the last day they have only six hours to sleep before the cars take them back to the airport. Nor are they encouraged to stay awake and explore the region on foot, lest they get lost. Occasionally there is a little mutiny.

As, for example, when Meylan - who in 1987 discovered the first double quasar - defied the security guards and hiked for a few hours around the desert. It reminded him of pictures of Mars, and what he noticed most was the quiet. No distant traffic, no aircraft, only silence and a barren brown landscape which quickly hid the observatory from view. Except that to his surprise the landscape was less barren than he thought. When bending to tie his shoelace he found that what he thought was a small stone was actually an insect, eking out its existence in an unpromising environment. He was so surprised he forgot to take a photograph, and he still does not know what it was.

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