A week with the stars
Barbara Burtscher, a 20-year-old Swiss student of physics at Zurich University, won the Special Donated Prize at the 16th European Young Scientists Contest in 2004 for her work on the 153P/Ikeya-Zhang comet. Her reward was a trip to the European Southern Observatory in Paranal, Chile. Read on…
7 March 2005, Zurich airport. I still couldn’t really believe it. Here I was, about to fly to Chile to discover the famous giant telescopes at the European Southern Observatory (ESA).
|Barbara on the road to the stars.|
Over the past four years I had spent many long nights gazing at the stars in the Swiss sky, dreaming of better weather conditions and larger expanses free of light pollution. Chile is an ideal country for astronomers, with its cloudless skies, large areas unpolluted by light, and mountains whose summits rise up high into the earth’s atmosphere. All good reasons why the Andes were chosen as the site for the large European observatories. From the plane I suddenly caught a glimpse of their cloud-shrouded summits rising up sharply from the plain, a mountain range that still presents an obstacle to man and animals. The longest mountain range in the world.
I was met at the airport by a member of the ESA staff who drove me to the guest residence in Santiago – a single-storey building with an ornamental pond in the interior courtyard and set in a garden. A haven of peace where I was really pampered.
It was there that I met Valentina Rodriguez, who had organised my visit to the observatory. It was she who drove me around, visiting all the installations and sites where the astronomers worked. I then went off to discover a little of Santiago, a city of 6 million inhabitants. Everything was new to me, from the beggars squatting in the streets to the incredible tangle of the power lines…
2. The VLT
The next day I was off to Antofagasta, 1 200 km to the north. Then on again, with a group of astronomers, along the rather bumpy roads to a platform sited high in the Cerro Paranal, at 2 635 metres in altitude, deep in the Atacama Desert – the site of the Very Large Telescope (VLT).
|Flying over the Andes.|
© Barbara Burtscher
The installation consists of four main telescopes – 'Antu', 'Kueyen', 'Melipal' and 'Yebup' – with a main lens of 8.2 m in diameter, and four auxiliary 1.8 m telescopes. This largest and most modern optical interferometric installation in the world has already enabled some spectacular scientific progress.
For two days I stayed at La Residencia, the accommodation for site staff and visitors. It is an underground building topped, at ground level, with a dome housing a swimming pool and miniature artificial jungle.
The astronomer Emmanuel Jehin took me to visit the VLT. After donning my protective helmet in the control room we passed along the passages hewn into the rock until we reached the main telescope. I visited the interior. It was really impressive! It was so big that it was impossible to photograph it all in a single frame.
3. A southern night
Astronomical observations are carried out at night and any artificial light is strictly forbidden. Cars drive on the mountain roads of the Cerro Paranal using sidelights only, guided by luminescent diodes found at the side and in the middle of the roads, like aircraft on a runway. In the total darkness, this is an incredible experience.
|Flames, ready to observe 150 stars at a time…|
© Barbara Burtscher
The night I was there was marvellously bright, nothing like the kind of sky I am used to. At first I was able to recognise hardly any of the stars, but finally I picked out the Southern Cross and Orion, with its head facing downwards.
During the day I had watched the telescope operators as they drew up their checklists. I had also been shown Flames, a device that enables you to observe 150 stars all at the same time and to make spectral analyses. I was excited at the prospect of being able to watch the astronomers at work during the night in the control room and the chance to ask them all my questions. However, after a few hours I was simply too tired to continue.
4. Star Track
The next day I followed the route known as Star Track to the VLT where I was treated to a guided tour of the interferometric installations (VLTI). The VLTI, with its four giant telescopes, together with four other smaller telescopes located on the platform, concentrates the light that enters the atmosphere in an underground tunnel. This produces an optical resolution of as much as 0.005 arc seconds, enough to pick out an astronaut on the Moon!
|Sunset over La Silla, seen from the control room. On the right, the NTT telescope.|
During the day, the weather conditions steadily worsened. The air humidity soon reached a critical level beyond which condensation could pose a threat to the telescope optics. A single droplet on the lens could be fatal, so they were all positioned to rule out any danger of this happening.
Clouds obscured the sky and it was clear that there would be no observation that night. We all took the road back to the Residencia to attend the station’s monthly party. Time just flew by.
5. La Silla in the rain
After a few hours’ sleep I took a last quick look at the telescope platform before taking the road back to Antofagasta. Then it was La Serena, the long road that borders the Pacific, and finally a dusty track. We came to a sign marked La Silla and there, on a distant mountain, we could just make out up ahead the dome of a telescope.
La Silla is the first of the ESA’s astronomical stations as you head south, located 160 km from La Serena at 2 400 m in altitude. It has 17 telescopes. It is here that the technological innovations intended for the giant telescopes (such as active and adaptive optics) are developed and tested before being used on the VLT.
It was raining and the wind was blowing. I was given a room and torch – part of the survival equipment for astronomers working at these altitudes. Fernando Selman then showed me around the installations which were simply incredible.
Most impressive of all the telescopes was the NTT (New Technology Telescope) with a diameter of 3.5 m, built in 1989. The structure housing the telescopes pivots along with the actual telescopes. Fernando organised a demonstration for my benefit so that I could see, from the inside, the movement of the telescope and that of the building itself.
We witnessed a magnificent sunset from the control room, affectionately known as ‘The Ritz’ by the astronomers, but the weather continued to deteriorate and the fog became so thick that nobody dared venture outside. The culmination of the evening’s events was a visit to the 1.2 m Geneva telescope used to detect planets beyond our solar system. Being Swiss, I understood why it was painted red and white.
The next morning, under a bright blue sky, I took the road back to Santiago and enjoyed a final excellent meal at the ESA guesthouse.
After – fortunately – finding stamps at the airport to send off about 30 postcards, it was time for the long flight back to Europe.