Origin and Evolution of Titan's Nitrogen and Methane Atmosphere: A Post Cassini-Huygens Perspective
- Paper number
IAC-07-A3.I.A.25
- Author
Prof. Sushil Atreya, University of Michigan, United States
- Year
2007
- Abstract
Origin and Evolution of Titan’s Nitrogen and Methane Atmosphere: A Post Cassini-Huygens Perspective
SUSHIL K. ATREYA (a), HASSO B. NIEMANN (b), ELENA Y. ADAMS (a) (a) University of Michigan, Ann Arbor, MI 48109-2143 USA (b) Goddard Space Flight Center, Greenbelt, MD 20771, USA
Titan acquired its nitrogen originally in the form of nitrogen compounds, most likely ammonia, as did the Earth. The extremely low upper limit of the heavy noble gases, especially xenon, found by the Cassini-Huygens GCMS [1] supports this assertion. The conversion of ammonia to nitrogen must have taken place by photolysis by the solar UV early in Titan’s accretionary heating phase [2], again as on primordial Earth. Production of N2 by shock induced dissociation of NH3 triggered by an impact [3] is less likely. The present day nitrogen atmosphere of 1.5 bars is the remnant of a much thicker 5-8 bars of N2 in the past, as indicated by the 14N/15N ratio [1,4]. Methane, the second most abundant gas on Titan, comprises 5References: [1] H.B. Niemann, et al., Nature 438, 779, 2005 [2] S.K. Atreya, et al., Science 201, 611, 1978; [3] C.P. McKay et al., Nature 332, 520, 1988 [4] H.W. Waite, et al., Science 308, 982, 2005 [5] Atreya et al., Planet. Space Sci. 54, 1177, 2006. [6] F. Hersant, et al., 52, 623, 2004) [7] Baines et al., Planet. Space Sci. 54, 1552, 2006.
- Abstract document
- Manuscript document
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