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Pluto’s implications for a Snowball Titan

Wong, Michael L. and Yung, Yuk L. and Gladstone, G. Randall (2015) Pluto’s implications for a Snowball Titan. Icarus, 246 . pp. 192-196. ISSN 0019-1035.

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The current Cassini–Huygens Mission to the Saturn system provides compelling evidence that the present state of Titan’s dense atmosphere is unsustainable over the age of the Solar System. Instead, for most of its existence, Titan’s atmosphere might have been in a Snowball state, characterized by a colder surface and a smaller amount of atmospheric CH_4, similar to that of Pluto or Triton. We run a 1-D chemical transport model and show that the rates of organic synthesis on a Snowball Titan are significantly slower than those on present-day Titan. The primary method of methane destruction—photosensitized dissociation in the stratosphere—is greatly dampened on Snowball Titan. The downward flux of higher-order molecules through the troposphere is dominated not by hydrocarbons such as ethane, as is the case on Titan today, but by nitriles. This result presents a testable observation that could confirm the Snowball Titan hypothesis. Because Pluto’s atmosphere is similar to Titan’s in composition, it serves as a basis for comparison. Future observations of Pluto by the New Horizons Mission will inform photochemical models of Pluto’s atmosphere and can help us understand the photochemical nature of paleo-Titan’s atmosphere.

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Additional Information:© 2014 Elsevier Inc. Received 22 January 2014, Revised 21 April 2014, Accepted 14 May 2014, Available online 3 June 2014. This research was supported in part by the Cassini UVIS program via NASA Grant JPL.1459109, NASA NNX09AB72G grant to the California Institute of Technology. YLY was supported in part by the New Horizons Mission. We thank J. Kammer, C. Li, P. Gao, P. Kopparla, X. Zhang, D. Piskorz, and H. Ngo for helpful comments. Special thanks are due to C. Sotin for making available their model prior to publication. We are grateful for the comments and suggestions from our two anonymous reviewers.
Funding AgencyGrant Number
New Horizons MissionUNSPECIFIED
Subject Keywords:Pluto, atmosphere; Titan, atmosphere; Pluto; Titan; Photochemistry
Record Number:CaltechAUTHORS:20140714-081046063
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Official Citation:Michael L. Wong, Yuk L. Yung, G. Randall Gladstone, Pluto’s implications for a Snowball Titan, Icarus, Volume 246, 15 January 2015, Pages 192-196, ISSN 0019-1035, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:47155
Deposited By: Ruth Sustaita
Deposited On:14 Jul 2014 18:46
Last Modified:01 Nov 2017 17:22

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