What was the Tagish Lake meteorite?
Tagish Lake is a fragile, carbon-rich meteorite that fell on a frozen lake in Canada on 18 January 2000 and was collected frozen, preserving unusual organic material.
On the morning of 18 January 2000, a brilliant fireball lit up the sky over northern British Columbia and Yukon in Canada. It was seen widely, detected by satellites and followed by loud booms.
The find. On 25 January, a local resident, Jim Brook, found black fragments scattered on the frozen surface of Tagish Lake in British Columbia. He collected them in clean plastic bags without touching them with his hands and kept them frozen. More fragments were collected later in the spring, when the ice began to melt. In total, about 10 kilograms were recovered.
What it is. Tagish Lake is an unusual carbonaceous chondrite, sometimes classed as ungrouped or related to CI and CM chondrites. It is very fragile, porous and rich in carbon, about 4 to 5 per cent, with abundant carbonates and organic matter.
Pristine samples. Because the first fragments were collected frozen and never thawed, they are some of the most pristine carbonaceous samples available. They contain organic molecules, including amino acids, and nanoglobules of organic material.
Orbit. Camera and satellite data allowed its orbit to be estimated, showing it came from the asteroid belt.
Parent body. Its spectrum resembles some D-type asteroids, dark reddish bodies in the outer asteroid belt, suggesting it may sample a type of asteroid not otherwise represented among meteorites.
Tagish Lake showed the value of careful collection and opened a window on the organic chemistry of outer asteroids.