A newly published study shows that the basic building blocks of life as we know it can be assembled anywhere in the Solar System, confirming that life on Earth really could have come from out of this world.
Scientists have discovered a ‘cosmic factory’ for producing the building blocks of life, amino acids, according to research.
The team from Imperial College London, the University of Kent, and Lawrence Livermore National Laboratory have discovered that when icy comets collide into a planet, amino acids can be produced. These essential building blocks are also produced if a rocky meteorite crashes into a planet with an icy surface.
The researchers 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.
The research is published today in the journal Nature Geoscience.
Dr. Zita Martins, co-author of the paper from the Department of Earth Science and Engineering at Imperial College London, says: “Our work shows that the basic building blocks of life can be assembled anywhere in the Solar System and perhaps beyond. 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.”
Dr. Mark Price, co-author from the University of Kent, adds: “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. 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 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, say the researchers. Their work further underlines the importance of future space missions to these moons to search for signs of life.
The 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 kilometers 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.
Reference: “Shock synthesis of amino acids from impacting cometary and icy planet surface analogues” by Zita Martins, Mark C. Price, Nir Goldman, Mark A. Sephton and Mark J. Burchell, 15 September 2013, Nature Geoscience.
Source: Colin Smith, Imperial College London
More Information from Lawrence Livermore National Laboratory
A group of international scientists including a Lawrence Livermore National Laboratory researcher have confirmed that life really could have come from out of this world.
The team shock compressed an icy mixture, similar to what is found in comets, which then created a number of amino acids — the building blocks of life. The research appears in advanced online publication September 15 on the Nature Geosciences journal website.
This is the first experimental confirmation of what LLNL scientist Nir Goldman first predicted in 2010 and again in 2013 using computer simulations performed on LLNL’s supercomputers, including Rzcereal and Aztec.
Goldman’s initial research found that the impact of icy comets crashing into Earth billions of years ago could have produced a variety of prebiotic or life-building compounds, including amino acids. Amino acids are critical to life and serve as the building blocks of proteins. His work predicted that the simple molecules found in comets (such as water, ammonia, methanol and carbon dioxide) could have supplied the raw materials, and the impact with early Earth would have yielded an abundant supply of energy to drive this prebiotic chemistry.
In the new work, collaborators from Imperial College in London and University of Kent conducted a series of experiments very similar to Goldman’s previous simulations in which a projectile was fired using a light gas gun into a typical cometary ice mixture. The result: Several different types of amino acids formed.
“These results confirm our earlier predictions of impact synthesis of prebiotic material, where the impact itself can yield life-building compounds,” Goldman said. “Our work provides a realistic additional synthetic production pathway for the components of proteins in our solar system, expanding the inventory of locations where life could potentially originate.”
Comets are known to harbor simple ices and the organic precursors of amino acids. Glycine — the simplest amino acid — was recently confirmed to be present in comet Wild-2.
Goldman’s original work used molecular dynamics simulations to show that shock waves due to planetary impact passing into representative comet mixtures could theoretically drive amino acid synthesis. This synthetic mechanism could yield a wide variety of prebiotic molecules at realistic impact conditions, independent of the external features or pre-existing chemical environment on a planet.
“These results present a significant step forward in our understanding of the origin of the building blocks of life,” Goldman said.
The team found that icy bodies with the same compounds created from comet impacts also may be found in the outer solar system. For example, Encleadus (one of Saturn’s moons) contains a mix of light organics and water ice. The team concluded that it is highly probable that the impact of a comet traveling with a high enough velocity would impart enough energy to promote shock synthesis of more complex organic compounds, including amino acids, from these ices.
“This increases the chances of life originating and being widespread throughout our solar system,” Goldman said.