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South Pole telescope peers heavenward for dark energy

The giant instrument seeks clues that might identify the most powerful, plentiful but elusive substance in the universe.

March 30, 2008|William Mullen | Chicago Tribune

AMUNDSEN-SCOTT STATION, ANTARCTICA — Anywhere on Earth this would be a big telescope, as tall as a seven-story building, with a main mirror measuring 32 1/2 feet across. But here at the South Pole, it seems especially large, looming over a barren plain of ice that gets colder than anywhere else on the planet.

Scientists built the instrument at the end of the world so they can search for clues that might identify the most powerful, plentiful but elusive substance in the universe: dark energy.

First described just nine years ago, dark energy is a mysterious force so powerful that it will decide the fate of the universe. Having already overruled the laws of gravity, it is pushing galaxies away from one another, causing the universe to expand at an ever faster rate.

Though dark energy is believed to account for 70% of the universe's mass, it is invisible and virtually undetectable. Nobody knows what it is, where it is or how it behaves.

"If you see it in your basement," jokes University of Chicago cosmologist Rocky Kolb, "you better get back on your medication." But he knows better than most the high priority the world's governments and scientists have placed on gaining a fuller understanding of the invisible force.

"Many think dark energy is the most important problem in physics today," said Kolb, who recently served as chairman of the Dark Energy Task Force, convened in 2005 by the U.S. Department of Energy, NASA and the National Science Foundation.

Figuring out what dark energy is would explain the history and future of the universe and generate new understanding of physical laws that, applied to human invention, almost certainly would change the way we live -- just as breakthroughs in quantum mechanics brought the computer chip.

Swinging its massive mirror skyward, the South Pole Telescope has begun to search the southern polar heavens for shreds of evidence of the elusive stuff. Controlled remotely from the University of Chicago, the $19.2-million telescope has quickly succeeded in its first mission: finding unknown galaxy clusters, clues to the emergence of dark energy.

Ambitious project

The Chicago university has a stronger astronomy presence at the pole than perhaps any other institution, having built several smaller experimental telescopes there over the last 20 years. This scope, however, was the most ambitious project by far.

Its components had to be custom-built by scientists and craftsmen in several different parts of the world, then shipped to Antarctica in pieces for final assembly. The largest sections of the telescope were carefully designed so each could fit into ski-equipped military transport planes. It took 25 flights in all to ferry 260 tons of telescope components.

Late last year, a crew mostly made up of graduate students spent eight hours a day outdoors to help put them all together.

"It gets really, really cold, because you aren't moving much," said Joachin Vieira, 28, a graduate student in physics. "There's steel behind you, steel in front of you, and you're holding steel tools." His crew was assembling a 10-meter aluminum mirror and attaching it to a carbon-fiber backing designed to keep the mirror rigid in the powerful South Pole winds.

Earlier they had spent three months doing a dry run on the mirror assembly in the blazing summer heat of Kilgore, Texas. At the pole, temperatures never exceeded 20 degrees below zero Fahrenheit. Crew members said it took hours indoors before their fingers limbered up enough to type on their computers.

"We have to get these pieces into place to within 1/2,000th of an inch of accuracy," said Jeff McMahon, 29, a postdoctoral physics student. "If you move, you risk screwing it up, so you stand motionless at 20 degrees below zero."

Also out there, slinging two-by-fours alongside ironworkers putting together the telescope's main structure, was John E. Carlstrom, a veteran South Pole astronomer and University of Chicago astrophysicist who is heading up the international team that designed and constructed the telescope.

Senior scientists at six other institutions are collaborating with Carlstrom's Chicago team, including the University of Illinois at Urbana-Champaign, UC Berkeley, NASA's Jet Propulsion Laboratory, and Harvard, Case Western Reserve and McGill universities. The project is funded mainly by the National Science Foundation with additional money coming from two California donors, the Kavli Foundation and the Gordon and Betty Moore Foundation.

A thoughtful, soft-spoken man, Carlstrom honed his skills at physical labor by working in construction during his college-student days. He seems genuinely excited to be in the middle of the hunt for an elusive quarry, but still flummoxed by the astonishing new realities that dark energy represents.

"It's odd that we find ourselves missing the density of 70% of the universe," he said. "It's a hard pill to swallow, that this thing dominates the universe, but there is a lot of evidence to say that it is there."

Old-time methods

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