Evolution of Titan s high-altitude aerosols under ultraviolet irradiation

Abstract

The Cassini-Huygens space mission revealed that Titan s thick brownish haze is initiated high in the atmosphere at about 1000 km of altitude, before a slow transportation down to the surface. Close to the surface at altitudes below 130 km, the Huygens probe provided information on the chemical composition of the haze. So far we do not have insights on a possible photochemical evolution of the aerosols composing the haze during their descent. We address here this atmospheric aerosol aging process, simulating in the laboratory how solar vacuum-ultraviolet (VUV) irradiation affects the aerosol optical properties as probed by infrared spectroscopy. An important evolution is found, which could explain the apparent contradiction between the nitrogen-poor infrared spectroscopic signature observed by Cassini below 600 km of altitude in Titan s atmosphere, and a high nitrogen content as measured by the Aerosol Collector and Pyroliser of Huygens probe at the surface of Titan.

References in corpus (4)

• Titan's Atmosphere and Climate
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• Molecular Isomer Identification of Titan Tholins Organic Aerosols by Photoelectron/Photoion Coincidence Spectroscopy Coupled to VUV Synchrotron Radiation
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Cited by in corpus (8)

• Interaction dust-plasma in Titan's ionosphere: an experimental simulation of aerosols erosion
• The 3.4 μm absorption of the Titan's stratosphere: contribution of ethane, propane, butane and complex hydrogenated organics
• FUV Photoionization of Titan atmospheric aerosols
• Interaction dust-plasma in Titan's ionosphere: feedbacks on the gas phase composition
• Photochemical Haze Formation on Titan and Uranus: A Comparative Review
• Open Questions and Future Directions in Titan Science
• Science goals and new mission concepts for future exploration of Titan's atmosphere geology and habitability: Titan POlar Scout/orbitEr and In situ lake lander and DrONe explorer (POSEIDON)
• Quantifying the temperature-dependent yields of N${}_2$ and N${}_2$H${}_4$ formation in vacuum-ultraviolet-irradiated NH${}_3$ ice