An Eye For Cosmic Clues

By KURT LOFT The Tampa Tribune

Published: Aug 6, 2007

TAMPA - High atop a mountain in the Atacama Desert of Chile, the driest region on Earth, a giant eye will gaze at the heavens.

Nearly 100 feet across, it will peer through a crystal clear sky at the wonders of the universe, always focused and never blinking on its perch far from lights, clouds and rain.

This remote and desolate place may be inhospitable, but astronomers prize its pristine conditions - few places in the world offer such an unprecedented field of view. For this reason, scientists next year will break ground on the largest telescope of its kind, one designed to see distant objects through a "peep hole" in the spectrum of light and energy flowing through the cosmos.

If all goes according to plan, the $100 million Cornell Caltech Atacama Telescope will become one of the world's highest observatories, sitting at 18,400 feet on a dormant volcano known as Cerro Chajnantor. The observatory literally is high and dry, away from the clutter of water vapor, says Simon Radford, deputy project manager at the California Institute of Technology in Pasadena.

"In Tampa, there's a lot of humidity, and you can't really see out into space," he says by telephone. "But in the desert or on a high mountain, there's less water in the atmosphere."

The Higher The Better

The telescope will see in a narrow part of the spectrum called the submillimeter wavelength, which astronomers use to study distant objects that don't emit much visible light. But humidity in the air absorbs the radiation from these sources, making them hard to detect. The solution is to go as high as possible.

"Telescopes are being put in increasingly higher and dryer sites," Radford says. "And in Chile, the combination is ideal."

But building the observatory will be an engineering challenge. At 3½ miles above sea level, breathing is difficult, so construction could pose health risks. Air pressure at that altitude drops to 7.3 pounds per square inch, and the lungs struggle to draw oxygen from the air.

"It's always a challenge to work at high altitude because workers are prone to mistakes," Radford says.

Without portable air tanks, telescope workers would lose 15 percent to 20 percent of blood oxygen, leading to an altitude sickness known as hypoxia.

"So we are paying a lot of attention to the design of the telescope to simplify assembly and construction," says project engineer Tom Sebring. "At this altitude, we will require all the workers and staff to use [supplemental] oxygen."

Mars Comes To Mind

The Atacama Desert of northern Chile is a rainless region and considered the driest area on the planet. The Andes and coastal mountains block the desert from incoming clouds, which rise, cool and condense outside the mountain ranges. Vegetation is almost nonexistent. Geologists say the terrain is not unlike that found on Mars.

"The Atacama Desert is very dry, and some areas haven't seen rain in recorded history," Sebring says. "It's a fabulous place."

Once completed, in six years, the observatory will be self-contained with its own oxygen-rich atmosphere. However, only a few people will work there. Instead, observations will be made remotely, with much of the hardware controlled robotically.

The telescope won't "see" light from stars and planets like your average optical variety. It will operate in a part of the spectrum - the microwave region - that is invisible to the human eye.

By focusing its bank of 210 segmented mirrors on relatively cool cosmic objects, scientists expect the telescope to offer a wealth of new clues about the evolution of the universe, formation of stars and interstellar matter, and how distant planets came to be.

Reporter Kurt Loft can be reached at (813) 259-7570 or kloft@tampatrib.com.