ESA Science & Technology - Confirmation of Our Predictions, Based on Laboratory and Theoretical Studies, on the Findings of the Huygens Probe on Titan

Publication date: 28 May 2005

Authors: Bar-Nun, A., et al.

Journal: AGU, Spring Meeting 2005, abstract #P34A-06

1. The very low abundances of Ar, Kr and Xe in Titan's atmosphere can be easily explained by our experimental findings. These gases are trapped in the aerosols, which are formed by UV photolysis of acetylene in their presence. When the aerosols fall down to the surface, they clean the atmosphere of these gases. A continuous supply of the radiogenic produced ⁴⁰Ar from the interior can explain its small abundance in the atmosphere. 2. The originally soft and sticky photochemical aerosols, as found by us experimentally, were calculated to harden by spontaneous and radiation induces chemical cross-linking. Indeed the camera and other detectors were not covered by sticky aerosols and the intake ports were not clogged. 3. As we predicted, no lightning discharges were detected in the quiescent Titan atmosphere. Therefore, Titan's atmospheric chemistry is driven mainly by solar UV irradiation and not by electrical discharges. 4. The mixing ratios of the major gas phase species produced by UV photolysis of acetylene, as found experimentally: methylacetylene ; diacetylene ; divinyl ; and benzene were observed by the Cassini spacecraft in Titan's upper atmosphere, with an agreement within better than an order of magnitude. 5. The N:C ratio in Titan's aerosols was measured by the Huygens probe, but no results were published yet. UV photolysis of gas mixtures containing C₂H₂:HCN=10 yield aerosols with a ratio N:C=0.007 up to 0.01. Electrical discharges through a N₂:CH₄~10 gas mixtures yield a much higher N:C ratio. 6. We anticipate mountains not higher than 1900 m on Titan's surface.