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Prebiotic Chemistry and Atmospheric Warming of Early Earth by an Active Young SunNitrogen is a critical ingredient of complex biological molecules. Molecular nitrogen, however, which was outgassed Into the Earth's early atmosphere, is relatively chemically inert and nitrogen fixation into more chemically reactive compounds requires high temperatures. Possible mechanisms of nitrogen fixation include lightning, atmospheric shock heating by meteorites, and solar ultraviolet radiation. Here we show that nitrogen fixation in the early terrestrial atmosphere can be explained by frequent and powerful coronal mass ejection events from the young Sun -- so-called superflares. Using magnetohydrodynamic simulations constrained by Kepler Space Telescope observations, we find that successive superflare ejections produce shocks that accelerate energetic particles, which would have compressed the early Earth's magnetosphere. The resulting extended polar cap openings provide pathways for energetic particles to penetrate into the atmosphere and, according to our atmospheric chemistry simulations, initiate reactions converting molecular nitrogen, carbon dioxide and methane to the potent greenhouse gas nitrous oxide as well as hydrogen cyanide, an essential compound for life. Furthermore, the destruction of N2, C02 and CH, suggests that these greenhouse gases cannot explain the stability of liquid water on the early Earth. Instead, we propose that the efficient formation of nitrous oxide could explain a warm early Earth.
Document ID
20170003495
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Airapetian, V. S. (Sigma Space Corp. Lanham, MD, United States)
Glocer, A. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Gronoff, G. (Science Systems and Applications, Inc. Hampton, VA, United States)
Hebrard, E. (Universities Space Research Association Columbia, MD, United States)
Danchi, W. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
April 17, 2017
Publication Date
May 23, 2016
Publication Information
Publication: Nature Geoscience
Volume: 9
Issue: 6
ISSN: 1752-0894
Subject Category
Geophysics
Report/Patent Number
GSFC-E-DAA-TN41221
Funding Number(s)
CONTRACT_GRANT: NNG12PL17C
CONTRACT_GRANT: NNX15AE05G
Distribution Limits
Public
Copyright
Other