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What is Eating Ozone? Thermal Reactions between SO2 And O3: Implications for Icy EnvironmentsLaboratory studies are presented, showing for the first time that thermally driven reactions in solid H2O+SO2+O3 mixtures can occur below 150 K, with the main sulfur-containing product being bisulfate (HSO4(-)). Using a technique not previously applied to the low-temperature kinetics of either interstellar or solar system ice analogs, we estimate an activation energy of 32 kJ per mol for HSO4(-) formation. These results show that at the temperatures of the Jovian satellites, SO2 and O3 will efficiently react making detection of these molecules in the same vicinity unlikely. Our results also explain why O3 has not been detected on Callisto and why the SO2 concentration on Callisto appears to be highest on that world's leading hemisphere. Furthermore, our results predict that the SO2 concentration on Ganymede will be lowest in the trailing hemisphere, where the concentration of O3 is the highest. Our work suggests that thermal reactions in ices play a much more important role in surface and sub-surface chemistry than generally appreciated, possibly explaining the low abundance of sulfur-containing molecules and the lack of ozone observed in comets and interstellar ices.
Document ID
20170002494
Document Type
Reprint (Version printed in journal)
Authors
Loeffler, Mark J. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Hudson, Reggie L. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
March 23, 2017
Publication Date
December 5, 2016
Publication Information
Publication: The Astrophysical Journal Letters
Volume: 833
Issue: 1
Subject Category
Inorganic, Organic and Physical Chemistry
Geophysics
Report/Patent Number
GSFC-E-DAA-TN40310
Distribution Limits
Public
Copyright
Other