Conversation so far:
what real life mission returned a sample from a comet
The Stardust mission collected samples of a comet and returned them to Earth for laboratory analysis.
what did the scientists find out about the nature of the particles of comet wild 2 after the stardust mission
In 2009 it was announced by NASA that scientists had identified one of the fundamental chemical building blocks of life in a comet for the first time, glycine

Question: what does the discovery mean
Self-contained rewrite: what does comet wild 2 being made of glycine mean