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Ground Zero

A Danish expedition begins searching frozen Greenland for the remains of a meteor
One person described "a giant millipede with yellow glowing legs on fire" overhead. A trawler captain reported a glowing ball that cast a bluish light over his wheelhouse and then exploded like lightning. Town folk in Fiskenaesset said they heard a loud crash and felt strong winds. And a surveillance camera in Nuuk recorded a mysterious streak.

In the end, there were more than 100 eyewitnesses who saw a meteor streak accross the early morning sky above southern Greenland on December 9, 1997. But no one has seen any trace of it since. Deep, wet snow has kept investigators from searching the region until now.

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LANDING SITE?

Astronomer Holger Pederson of the Niels Bohr Institute at the University of Copenhagen interviewed many of the eyewitnesses. And using these accounts, scientists quickly calculated that the extraplanetary intruder had landed within an 10-kilometer by 10-kilometer area near Frederikshaab Isblink, on the inland ice just 10 to 15 kilometers from the edge. American satellite images confirmed that the impact occured midway between Nuuk and Qaqortoq.

But later searches closer to home came up empty-handed. In January, Soren Norvang Madsen of the Danish Center for Remote Sensing (DCRS) scanned the ice by plane using special radar, called EMISAR. It was a careful survey, yet Madsen found nothing, probably because the radar could not detect objects smaller than 30 to 50 meters in diameter--which the impact site may well be.

So at last, on Wednesday, July 22, a seven-man team from the University of Copenhagen and Tycho Brahe Planetarium set forth by boat, helicopter and snow boot to spend three to four weeks canvasing the ice sheet. On Thursday, the expedition, christened The Tycho Brahe Expedition 1998, set up a base camp of yellow tents along the glacier just north of the Kangilia Nunataks. There, the team will be joined by Scientific American's Senior Writer Wayt Gibbs.

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Image: LARS LINDBERG CHRISTENSEN
COSMIC ROCKS. Scientists had to wait until the end of July--when the ground was relatively dry and warm--to begin looking for fragments of the Greenland meteor.

The group stands a good chance of finding the impact site and recovering fragments of the meteor. For one thing, at a latitude of almost 63 degrees North, they benefit from approximately 18 hours of light each day. Also, parts of the meteorite--what meteors are termed once they touch down--are probably quite big.

Based on the video and on eyewitness accounts, it is clear that the Greenland meteor entered the atmosphere at a velocity around 100,000 kilometers per hour and that it must have weighed at least several tons. So too, they know that the meteor exploded some 15 to 20 kilometers above the ground, pelting the ice with at least 20 cosmic rocks. Many of these rocks were large enough--and fell fast enough--that witnesses claimed to have tracked their glowing paths all the way down to the horizon.

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Image: LARS LINDBERG CHRISTENSEN
SUMMER CAMP. The Tycho Brahe Expedition 1998 has set up their base camp along the glacier just north of the Kangilla Nunataks
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Should the team find even one small fragment buried in the snow, they will be able to estimate where to look for more. Whatever the group finds will be sealed in sterile containers and flown back to Gronnedal. From there the samples--which according to Danish law remain the property of the Greenland Home Rule--will be sent to the Geological Museum in Copenhagen and distributed to research insititutes around the world for further analysis. By studying the mineral composition of the meteorite, the scientists will learn its celestial origins, how it was formed and when--information that in turn can offer clues about conditions that existed when the solar system was formed.

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