The collision of icy comets with planetary bodies could result in the formation of complex amino acids, the building blocks of proteins, reports a study published online in Nature Geoscience.

The organic precursors of amino acids have been previously detected in a comet, but an energetic process is needed to synthesize the complex amino acids required for life from these simpler ingredients.

Mark Price and colleagues conducted laboratory experiments in which they fired a steel projectile at high velocities into an ice mixture similar to those found in comets. The impacts produced several amino acids, including d- and l-alanine, which are important components of proteins. From this, the researchers suggest that an icy impact - whether from an icy comet onto a rocky planet or a rocky asteroid onto an icy moon - could have been the pathway towards life in our Solar System.