Study finds comets unlikely to have seeded early Earth with life's chemicals
A University of Cambridge team modelled whether comets could have delivered molecules such as hydrogen cyanide to early Earth. They found comets would likely vaporise on impact, so delivery would be at best a rare "one-off fluke".
The study is peer-reviewed and appears in Scientific Reports. The team found that Mars could have been a slightly more promising site for such delivery, though still highly unlikely. They say asteroids and chemistry on Earth itself are now seen as likelier sources of life's building blocks. The work is computer modelling, so its conclusions depend on the model's assumptions, and the authors say they cannot rule the scenario out completely.