Comet-planet collisions can spawn life

The basic building blocks of life - amino acids - can spontaneously come into existence when icy comets smash into planets, a new study suggests.
Researchers said that these essential building blocks are also produced if a rocky meteorite crashes into a planet with an icy surface.
They suggest that this process provides another piece to the puzzle of how life was kick-started on Earth, after a period of time between 4.5 and 3.8 billion years ago when the planet had been bombarded by comets and meteorites.
"Our work shows that the basic building blocks of life can be assembled anywhere in the Solar System and perhaps beyond," Dr Zita Martins, co-author of the paper from the Department of Earth Science and Engineering at Imperial College London, said.

"However, the catch is that these building blocks need the right conditions in order for life to flourish. Excitingly, our study widens the scope for where these important ingredients may be formed in the Solar System and adds another piece to the puzzle of how life on our planet took root," said Martins.
"This process demonstrates a very simple mechanism whereby we can go from a mix of simple molecules, such as water and carbon-dioxide ice, to a more complicated molecule, such as an amino acid," Dr Mark Price, co-author from the University of Kent, added.

The abundance of ice on the surfaces of Enceladus and Europa, which are moons orbiting Saturn and Jupiter respectively, could provide a perfect environment for the production of amino acids, when meteorites crash into their surface, researchers said.

Their work further underlines the importance of future space missions to these moons to search for signs of life.
Researchers discovered that when a comet impacts on a world, it creates a shock wave that generates molecules that make up amino acids. The impact of the shock wave also generates heat, which then transforms these molecules into amino acids.
The team made their discovery by recreating the impact of a comet by firing projectiles through a large high speed gun.
This gun, located at the University of Kent, uses compressed gas to propel projectiles at speeds of 7.15 kilometres per second into targets of ice mixtures, which have a similar composition to comets. The resulting impact created amino acids such as glycine and D-and L-alanine.

The study was published in the journal Nature Geoscience.