A comet is a huge ball of frozen gas and dust that often releases a long trail of material as it nears the sun.

VOA: special.2009.09.30

Once frozen, the material was placed in a freeze-dryer that removed all the water from it over the course of four days.

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They even exhumed the bodies of flu victims buried in the permanently frozen ground of the Norwegian island of Spitzbergen, in the hope that traces of virus genetic material might have been preserved.

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