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Complex organic materials may exist as haze layers in the atmosphere of Titan and as dark coloring agents on icy satellite surfaces. Laboratory measurements of optical constants of plausible complex organic materials are necessary for quantitative evaluation from remote sensing observations, and to document the existence of complex organic materials in the extraterrestrial environments. The recent...
Titan, Saturn's largest moon, has a thick nitrogen/methane atmosphere. The temperature and pressure conditions in Titan's atmosphere are such that the methane vapor should condense near the tropopause to form clouds. Several ground-based measurements have observed sparse cloud-like features in Titan's atmosphere, while the Cassini mission to Saturn has provided large scale images of the clouds. However,...
One of the key components controlling the chemical composition and climatology of Titan's atmosphere is the removal of reactive atomic hydrogen from the atmosphere. A proposed process of the removal of atomic hydrogen is the heterogeneous reaction with organic aerosol. In this study, we investigate the effect of heterogeneous reactions in Titan's atmospheric chemistry using new measurements of the...
In Titan's atmosphere consisting of N 2 and CH 4 , large amounts of atomic hydrogen are produced by photochemical reactions during the formation of complex organics. This atomic hydrogen may undergo heterogeneous reactions with organic aerosol in the stratosphere and mesosphere of Titan. In order to investigate both the mechanisms and kinetics of the heterogeneous reactions, atomic...
The goal of this study was to explore prebiotic chemistry in a range of plausible early Earth and Mars atmospheres. To achieve this laboratory continuous flow plasma irradiation experiments were performed on N 2 /H 2 /CO/CO 2 gas mixtures chosen to represent mildly reducing early Earth and Mars atmospheres derived from a secondary volcanic outgassing of volatiles in chemical...
Titan, the largest satellite of Saturn, has a thick nitrogen/methane atmosphere with a thick global organic haze. A laboratory analogue of Titan's haze, called tholin, was formed in an inductively coupled plasma from nitrogen/methane=90/10 gas mixture at various pressures ranging from 13 to 2300 Pa. Chemical and optical properties of the resulting tholin depend on the deposition pressure in cold plasma...
Haze particles exert a significant influence over the thermodynamics and radiation absorption properties of the Titan haze, as well as its complex organic chemistry. Characterization of both the molecular and the submicrometer components of the haze is therefore vital for understanding the global properties of Titan. We have carried out a Titan tholin synthesis experiment and measured the time variation...
We present new spectra of the leading and trailing hemispheres of Iapetus from 2.4 to 3.8 μm. We have combined the leading hemisphere spectra with previous observations by others to construct a composite spectrum of the dark side (leading) hemisphere from 0.3 to 3.8 μm. We review attempts to deduce the composition of the dark material from previously available spectrophotometry. None of them (numbering...
To simulate experimentally the production of aerosols in the atmospheres of Titan andTriton, we have studied organic material (tholins) obtained by inductively coupled plasma fromCH4 : N2 gas mixtures, with ratios 10 : 90 for Titan simulations and 0.1 : 99.9 for Tritonsimulations. Observation of tholins by high performance scanning electron microscopy showsthat tholin morphology varies with the chemical...
Organic heteropolymers that we call here ice tholin II have been produced by plasma discharge irradiation of water/methanol/carbon dioxide/ethane cocondensed ices in a rough simulation of cometary chemistry. The radiation yield of these organic heteropolymers is approximately 10 −26 g/eV. Intermediate products including polyalcohols, ethers, esters, carboxylic acids, and hydrocarbons are also...
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