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Impact Generation of Sugar Molecules and Survival of Glycolaldehyde
  • Nicolle Zellner
Nicolle Zellner
Albion College

Corresponding Author:nzellner@albion.edu

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Glycolaldehyde (GLA), a two-carbon sugar precursor, has been detected in multiple regions in our galaxy and on comets in our solar system. Impact experiments conducted at the Experimental Impact Laboratory at NASA’s Johnson Space Center have shown that samples of GLA and GLA mixed with montmorillonite clays can survive impact delivery in the pressure range of 4.5 GPa to 25 GPa. When extrapolated to amounts of GLA observed in the comae and in situ on the nucleus of individual comets and assuming a monotonic impact rate in the first billion years of solar system history, these experimental results show that up to 1023 kg of cometary GLA could have survived impact delivery, even if comets made up just 20% of the total impactor population. Substantial amounts of threose, erythrose, glycerol, glycolic acid, and ethylene glycol would also have been produced or delivered, depending on initial amounts and impact conditions. During the era of heavy bombardment (~4.2 to ~3.7 billion years ago), when life may have been developing on Earth, cometary impacts were likely prevalent throughout the solar system. They would have delivered these sugar molecules to Mars and to the icy moons of Jupiter and Saturn, providing additional intriguing evidence that biomolecules would have been abundant on these planetary bodies, too. The presence and availability of these biomolecules under the right conditions may have driven prebiotic chemical reactions that lead to, for example, ribose, the five-carbon sugar in RNA. In short, because experimental evidence shows that GLA survives impact, understanding impact delivery of biomolecules (in general, and including amino acids) may be important for answering questions about the origin of life as we know it. A diverse and wide-ranging approach that includes not only practices of investigation (i.e., experiments, observations, modeling) but also experiences and perspectives of the investigators, will be key to addressing the issues related to the origin of life on Earth and potentially elsewhere.