The cometary connection with prebiotic chemistry

The latent heat of water ice has been established to control the sublimation of most cometary nuclei. The next most abundant molecules are CO and/or CO2, typically reaching 10-30 percent of the water content. The other species are in the range of 1-10 percent or less and include the newly discovered NH3. HCN and CH3CN are two other important prebiotic molecules present at a comparable (1 percent) level. Attention is drawn to similarities between these compositions and those inferred for the primordial earth.