TITAN'S BULK COMPOSITION CONSTRAINED BY CASSINI-HUYGENS: IMPLICATION FOR INTERNAL OUTGASSING
- Universite de Nantes, LPGNantes, UMR 6112, F-44322 Nantes (France)
- LESIA, Observatoire de Paris, F-92195 Meudon Cedex (France)
- Universite Bordeaux, LAB, UMR 5804, F-33270, Floirac (France)
In the present report, by using a series of data gathered by the Cassini-Huygens mission, we constrain the bulk content of Titan's interior for various gas species (CH{sub 4}, CO{sub 2}, CO, NH{sub 3}, H{sub 2}S, Ar, Ne, Xe), and we show that most of the gas compounds (except H{sub 2}S and Xe) initially incorporated within Titan are likely stored dissolved in the subsurface water ocean. CO{sub 2} is likely to be the most abundant gas species (up to 3% of Titan's total mass), while ammonia should not exceed 1.5 wt%. We predict that only a moderate fraction of CH{sub 4}, CO{sub 2}, and CO should be incorporated in the crust in the form of clathrate hydrates. By contrast, most of the H{sub 2}S and Xe should be incorporated at the base of the subsurface ocean, in the form of heavy clathrate hydrates within the high-pressure ice layer. Moreover, we show that the rocky phase of Titan, assuming a composition similar to CI carbonaceous chondrites, is a likely source for the noble gas isotopes ({sup 40}Ar, {sup 36}Ar, {sup 22}Ne) that have been detected in the atmosphere. A chondritic core may also potentially contribute to the methane inventory. Our calculations show that a moderate outgassing of methane containing traces of neon and argon from the subsurface ocean would be sufficient to explain the abundance estimated by the Gas Chromatograph Mass Spectrometer. The extraction process, implying partial clathration in the ice layers and exsolvation from the water ocean, may explain why the {sup 22}Ne/{sup 36}Ar ratio in Titan's atmosphere appears higher than the ratio in carbonaceous chondrites.
- OSTI ID:
- 22039432
- Journal Information:
- Astrophysical Journal, Vol. 752, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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