Morning light : the secret history of the Tagish Lake Fireball

Abstract

[Spoiler alert:] On January 18, 2000, a meteoroid 4 meters in diameter hit the Earth's atmosphere and exploded over the Yukon Territory in northern Canada. The size of the fireball and the contrail that it left behind caught the attention of meteoriticists, who suspected it was a carbonaceous chondrite. Amongst the public, however, reactions to the event were varied, and conspiracy theorists emerged, claiming that the meteor had been a failed weapons test conducted by the United States military. A week after the fall, outdoorsman Jim Brook discovered black meteorites on the frozen surface of Tagish Lake, in northern British Columbia. He kept the stones pristine: frozen and untouched-a first for any meteorite fall. He made his discovery known to a few scientists only after they agreed to confidentiality, and those scientists confirmed that he had found a carbonaceous chondrite. Alan Hildebrand and Peter Brown put together an expedition to recover more fragments of the rare meteorite, interviewing eyewitnesses to reconstruct the trajectory of the bolide, but recovery efforts were hampered by deep snow. A second expedition returned in the spring when, for a short window, the fragile chondrites were exposed on the melting lake ice, and collection was successful. The secrecy surrounding these expeditions contributed to the idea that a cover-up was taking place; that the meteorite was not real. But scientific analysis, conducted by Mike Zolensky and many others, has proven otherwise. The Tagish Lake Meteorite appears to be a new type of meteorite, with ties to CI and CM type chondrites, possibly from the D type asteroids. It has the highest concentrations of carbon observed in any extraterrestrial sample, and an abundance of presolar grains. Rich in extraterrestrial organic compounds and containing distinct hollow organic globules, the primitive meteorite has brought a mini revolution to the field of meteoritics. It may help us understand the beginnings of the solar system and the origins of life on Earth. The story of the fall, recovery and the study of this meteorite highlights the necessary uncertainties of the scientific method, and the relationship between science and the general public.