Compelling new evidence that comets helped seed life on earth has emerged from experiments mimicking the bombardment of early earth.
Scientists in Japan generated protein building blocks by recreating impacts by comets containing water, amino acids and silicate.
In the tests, a propellant gun was used to fire the frozen mixture and simulate the shock of a comet striking the Earth.
Analysis showed that some of the amino acids had linked together to form chained molecules called peptides.
Recurring lengths of peptide chains form proteins, the large, complex and bioactive molecules from which all living things are made.
Lead researcher Dr Haruna Sugahara said the experiment showed that the cold conditions of comets at the time impact were key to this synthesis.
"This finding indicates that comet impacts almost certainly played an important role in delivering the seeds of life to the early Earth," said Dr Sugahara, from the Japan Agency for Marine-Earth Science and Technology.
"It also opens the likelihood that we will have seen similar chemical evolution in other extraterrestrial bodies, starting with cometary-derived peptides."
While much of the story of life has been explained, what kicked off the first step in the chemical evolution of complex biomolecules remains a deep mystery.
Once the first short peptide chains are created, much less energy is needed to expand them further.
The icy moons of Jupiter and Saturn, such as Europa and Enceladus, are likely to have undergone similar cometary bombardment.
Scientists believe life could have developed in a liquid water ocean below Europa's icy surface.
The amino acid glycine had also been detected by the American space agency Nasa's Stardust mission, which collected dust samples from Comet 81P/Wild2.
The findings were presented at the Godschmidt geochemistry conference in Prague, Czech Republic.
Share
