'Ultra-primitive' Particles Found In Comet Dust

Dust samples collected from the stratosphere have yielded an unexpectedly rich trove of relicts from the ancient cosmos, scientists report.

The dust includes presolar grains and material from interstellar molecular clouds. This "ultra-primitive" material likely wafted into the atmosphere after the Earth passed through the trail of an Earth-crossing comet in 2003, giving scientists a rare opportunity to study cometary dust in the laboratory.