A team of scientists has proposed a new hypothesis to explain how amino acids, the ultimate building blocks of life, might have arisen on Earth.
The new discovery is the result of a collaboration led by Drs. Zita Martins of Imperial College London, Mark Price of the University of Kent, and Nir Goldman of Lawrence Livermore National Laboratory. The researchers recreated an impact using an experimental setup at the University of Kent, in which projectiles were fired out of a high-speed gun. Propelled by compressed gas, the projectiles struck their targets at speeds of 7.15 kilometers per second. The targets were a series of ice mixtures, similar in composition to comets. The impacts created amino acids such as glycine and D- and L-alanine.
Between 4.5 and 3.8 billion years ago, Earth was bombarded by repeated comet and meteorite impacts. The new research has clarified part of the story of how life emerged in such an inhospitable environment. "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," Price explained in an Imperial College London press release. "This is the first step towards life. The next step is to work out how to go from an amino acid to even more complex molecules such as proteins."
The team's research has shown that amino acids can be formed when an icy comet strikes a planet's surface, and when a rocky meteor strikes a planet with an icy surface. When a comet or meteor smashes into a planetary surface, it generates a shock wave that produces the molecules that comprise amino acids. Heat from the impact then fuses these molecules into amino acids.
These findings could explain how the icy surfaces of Jupiter's moon Europa and Saturn's moon Enceladus might, with the help of rocky meteor impacts, provide a suitable setting for the generation of amino acids.
"Our work shows that the basic building blocks of life can be assembled anywhere in the Solar System and perhaps beyond," said Martins. "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."
The new research has been published in the journal "Nature Geoscience".
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