Light and Magic
On a clear night--with this telescope--you can see forever.
- By Eric Adams
- Air & Space magazine, July 2000
(Page 2 of 4)
From the ocean, the trip east entails a bone-jarring 75-mile drive into the Atacama Desert, a dusty plateau on the edge of the Andes that is virtually devoid of vegetation and animal life. There is little but gently sloping mountains and vast fields of boulders that sit evenly distributed, as if placed by a machine. The wide dirt road, called the Old Panamerican Highway, is mostly used by the observatory and by a nitrate and iodine mine about 20 miles beyond the telescopes. There is nothing along the way, and trouble (breakdown, blown tire, accident) means either a long walk or a long wait. Visitors who don't take the ESO's shuttle and elect to drive themselves are instructed to call the observatory before leaving. If you don't show up in three hours, they send someone out to find you.
Eventually, a large white sign materializes, announcing the presence of the VLT. Behind it, a freshly paved road vanishes into the hills-a 280-square-mile region that Chile donated to the ESO in exchange for telescope time. A slow first-gear ascent leads to the guard shack and the observatory base camp, which sit 7,750 feet above sea level. From here, you can visually follow a two-mile road up the mountain's remaining 900 feet to its perfectly flat top, where four giant silvery cubes perch, with rocks dribbling over the sides-debris produced when the builders blew 90 feet off the top of Paranal in 1990.
The base camp below is a clean, orderly village that is mostly made up of bright white ship cargo containers that have been converted into surprisingly nice offices and dorm rooms. On one side of the camp sit a helicopter pad and a soccer field; on the other, a parking lot filled with white four-wheel-drive trucks bearing ESO logos on the doors. Scattered throughout are a two-story telescope service building, a platform with eight 20-foot-tall water tanks that get replenished twice daily by trucks from Antofagasta, a power station, and a dormitory being built for staff and visitors.
Beyond this, there is nothing. As workplaces go, Paranal has little appeal. Though serene and beautiful, it is also hot and dry, and far from any diversions. "Personally, I consider Paranal to be one of the better places on the Earth to read books," says VLT staff astronomer Gianni Marconi, a friendly 39-year-old Italian who spends his nights on the mountaintop operating the telescopes for visiting astronomers. "I'm used to walking far from the base camp to where human-produced noise disappears and I am disturbed only by the wind." Visitors aren't encouraged to take such walks, though: Two who wandered off last year quickly became disoriented in the featureless hills and ended up lost for two days.
But for astronomers, the lonely desert site has several advantages: the dry air, which makes for clearer skies and a low risk of condensation collecting on telescope mirrors; the distance from any sources of the urban light pollution that plagues much of the world; and the roughly equatorial positioning, which gives it access to objects in both northern and southern skies.
When the sun goes down and the night sky emerges, any doubts about why someone would travel so far for this are squelched. Scrolling up from the east, the Milky Way shines steadily against the deep-black sky, with dozens of fuzzy nebulas and star clusters visible to the naked eye. Two galaxies, consuming startlingly large swaths of sky, hover in the south: The Large Magellanic Cloud spans the width of about 14 full moons; the Small Magellanic Cloud, six. On this mountain, you feel as if you are staring out into space, rather than merely up at the stars.
On the telescope platform at dusk, the four 100-foot-square silver enclosures, each containing a five-story telescope, await instructions to open their doors and commence their night's work, either observation or, for the unfinished scopes, calibration and testing. All are cast in a shimmery reddish yellow from the sunset. Massimo Tarenghi, the VLT's project manager, stands amid a somewhat treacherous network of half-finished concrete channels and open pits that will soon contain the interferometry hardware. He wonders if the project will end up spoiling his colleagues: "Will we ever be able to work on a telescope that isn't at least as big as this?" he asks.
Though it isn't quite dark yet, the doors to Unit Telescope 1 slowly crank open and the dome rotates around to face south. This process helps ensure that the temperature of the air inside of the dome equals that of the air outside; inequalities would produce turbulence, which would distort the observed images.