Comets unlikely delivered life's building blocks to Earth
A University of Cambridge study using computer modelling found that comets travel too fast and at too sharp angles to Earth's atmosphere for fragile organic molecules to survive impact, suggesting cometary delivery of prebiotic molecules would be "at best, a one-off fluke" rather than a steady source. The researchers focused on hydrogen cyanide, a prebiotic molecule found on comets, and found that even if HCN survived impact, useful concentrations would be extremely rare, with at most a handful of opportunities in Earth's early history. The study, published in Scientific Reports, suggests alternative sources such as synthesis following asteroid impacts or chemical processes occurring on Earth itself may better explain the molecular origins of life.
