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South Pole Scientists Get View of Jupiter-Comet Clash

By Robert Lee Hotz
Los Angeles Times

In a frozen wilderness where explorers once died for the sake of a penguin's egg and chunks of petrified wood, Hien Nguyen is collecting spectacular images of a fire in the sky.

At the South Pole - atop an icepack two miles thick, where it is drier than the Sahara and colder than parts of Mars - astronomers such as Nguyen this week are getting what may be the clearest view on Earth as Jupiter and a comet clash in the heavens overhead. While their colleagues at other major observatories around the world contend with rain, fog, pollution and viewing opportunities constrained by daylight, Nguyen and his colleagues at the South Pole Station can be assured of pristine darkness throughout the celestial encounter.

At this time of year, the sun at the South Pole never rises and Jupiter never sets, because the station is centered on the axis of the earth's rotation.

As the death rattles of the comet Shoemaker-Levy 9 on Jupiter ignited blazing fireballs and dark storms larger than Earth itself, almost the entire staff of the station huddled together in the cold by Nguyen's small infrared telescope to marvel at the sight before them.

"For the first time, the whole station felt like we were together," Nguyen reported Tuesday via a satellite link.

Nguyen, who fled Vietnam to Southern California in 1981, is among 26 scientists spending the six months of continuous winter darkness under the blue geodesic dome of the National Science Foundation's South Pole Station. Now a research associate at the University of Chicago, he is the station science leader.

The spreading bruise of debris and superheated gases in Jupiter's southern hemisphere caused by Monday's explosion of a two-mile-wide comet fragment now rivals the 300-year-old "Great Red Spot" as the most prominent feature on the planet's immense surface, astronomers said. The red spot measures 20,000-by-8,000 miles.

Two more comet fragments hit Jupiter Tuesday. The white-hot glow from one impact - Fragment K - was at least three times the size of Earth. Starting Wednesday, three more large fragments were to slam into the planet's upper atmosphere, hitting the same spot repeatedly over a period of 20 hours.

"You'll have three - boom, boom, boom," said planetary scientist Heidi B. Hammel, who is leading the scientists analyzing the images from the Hubble space telescope. "You are going to have one heck of a mess."

By Tuesday, the South Pole Infrared Explorer Telescope that Nguyen is operating had detected five of the nine comet fragments that had struck Jupiter, he said in an interview conducted via electronic mail.

"For this particular event, our polar site is unique since the sky is continuously dark during the impact period," he said. "Had this occurred during the summertime, our detector would be immediately saturated by the shining sky background and probably would not be able to detect Jupiter itself, let alone the explosions."

Conditions are so extreme - the temperature Monday was minus 80 degrees Farenheit, with 25 mph winds drifting snow over the telescope - that the atmospheric impurities and water vapor that blur most astronomical images freeze out of the air.

The frigid atmosphere over the South Pole contains less than one-tenth the water vapor found over the Mauna Kea observatories in Hawaii, one of the best of all existing telescope sites.

Infrared light, an invisible form of light emitted by heat, is more easily detected in the bitter chill. Because the telescope also is more sensitive when it is refrigerated, the small 24-inch SPIREX instrument is yielding some of the most dramatic and important images of the impacts on Jupiter.

"The atmosphere at the Pole is many times more stable and transparent than for the best mid-latitude infrared observatories," said John P. Lynch, the NSF's director of polar aeronomy and astrophysics. "Because of the cold, dry atmosphere and the cold telescope itself, a two-foot telescope at the South Pole might be comparable to a 30-foot telescope - like the Keck at Mauna Kea - at those infrared wavelengths."

"That is an awfully extreme thing to say, but that is what the numbers show," Lynch said.