An unidentified emission in Titan's upper atmosphere

Dinelli, B. M.; López‐Puertas, M.; Adriani, A.; Moriconi, M. L.; Funke, B.; García‐Comas, M.; D’Aversa, E.

doi:10.1002/grl.50332

Cited by 50 publications

(24 citation statements)

References 28 publications

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“…Fullerenes have also been suggested as candidates for the negative ions [ Sittler et al , ]. An unidentified feature at 3.28 μm in mesospheric measurements from VIMS [ Dinelli et al , ] has been attributed to a collection of PAHs with an average mass of 430 Da [ López‐Puertas et al , ]. However, unambiguous identifications in this mass range will require a higher‐resolution mass spectrometer on a future mission.…”

Section: Titan's Atmospheric Structure and Compositionmentioning

confidence: 99%

Titan's atmosphere and climate

2017

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Titan is the only moon with a substantial atmosphere, the only other thick N2 atmosphere besides Earth's, the site of extraordinarily complex atmospheric chemistry that far surpasses any other solar system atmosphere, and the only other solar system body with stable liquid currently on its surface. The connection between Titan's surface and atmosphere is also unique in our solar system; atmospheric chemistry produces materials that are deposited on the surface and subsequently altered by surface‐atmosphere interactions such as aeolian and fluvial processes resulting in the formation of extensive dune fields and expansive lakes and seas. Titan's atmosphere is favorable for organic haze formation, which combined with the presence of some oxygen‐bearing molecules indicates that Titan's atmosphere may produce molecules of prebiotic interest. The combination of organics and liquid, in the form of water in a subsurface ocean and methane/ethane in the surface lakes and seas, means that Titan may be the ideal place in the solar system to test ideas about habitability, prebiotic chemistry, and the ubiquity and diversity of life in the universe. The Cassini‐Huygens mission to the Saturn system has provided a wealth of new information allowing for study of Titan as a complex system. Here I review our current understanding of Titan's atmosphere and climate forged from the powerful combination of Earth‐based observations, remote sensing and in situ spacecraft measurements, laboratory experiments, and models. I conclude with some of our remaining unanswered questions as the incredible era of exploration with Cassini‐Huygens comes to an end.

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Section: Titan's Atmospheric Structure and Compositionmentioning

confidence: 99%

Titan's atmosphere and climate

2017

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“…This is what motivated the development of the Titan Haze Simulation (THS) experiment at the NASA Ames Cosmic simulation facility (Ricketts and Salama, 2008), which had been initially developed for the study of PAHs in astrophysical context (Salama, 2008 and references therein). Furthermore, recent measurements from the Cassini Visible Infrared Mapping Spectrometer (VIMS) revealed an unidentified emission at 3.28 lm (Dinelli et al, 2013) detected between 600 km and 1250 km (with a maximum at 950 km) that could be an indication of the presence of aromatic hydrocarbon molecules such as PAHs in the upper atmosphere of Titan (Lopez-Puertas et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

The Titan Haze Simulation experiment on COSmIC: Probing Titan’s atmospheric chemistry at low temperature

Sciamma-O’Brien

Ricketts

Salama

2014

Icarus

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“…Recently, Dinelli et al (2013) and López-Puertas et al (2013) have attributed a daytime emission feature observed at 3.28 μm in Cassini/VIMS limb spectra to aromatic hydrocarbons contained in the haze at altitudes of 600−1250 km (with a maximum around 950 km). The predominant absorption by heavy alkane ices at ∼60−500 km altitude in the 1−5 μm VIMS solar occultation spectra seems at odds with their results.…”

Section: Resultsmentioning

confidence: 99%

Spectral characteristics of the Titanian haze at 1−5 micron fromCassini/VIMS solar occultation data

Kim

Courtin

2013

A&A

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We retrieved optical-depth spectra of the Titanian haze in the range 1−5 μm from solar occultation data obtained by the Cassini/Visual Infrared Mapping Spectrometer (VIMS) at altitudes of 59−502 km. Only limited wavelength intervals within this spectral range have been analyzed before. The haze spectra we retrieved are mostly similar to those of alkane particles (or powders), with three major absorption peaks typical of alkane powders at 2.3, 3.4, and 4.3 μm. This result suggests that at least in the ∼60−500 km altitude range, the Titanian haze is mostly composed of alkane particles, possibly with some trace impurities. The absence of the 3.0 and 4.6 μm features excludes the molecules containing NH and CN bonds that are typical of laboratory-made tholins reported in the literature. The alkane-like spectral characteristics of the haze we observed at ∼60−500 km differ from previous results obtained at different or overlapping altitudes: a) the presence of aromatic compounds derived from solar-pumped emissions observed at high altitude (600−1250 km) by Cassini/VIMS near 3.3 μm; and b) the detection of HCN and NH 3 in the cores of haze particles collected at low altitude (20−130 km) by the Huygens/Aerosol Collector and Pyrolyser (ACP). We suggest that these different characteristics arise from different structural layers formed by coagulation/coalescence during particle sedimentation.

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An unidentified emission in Titan's upper atmosphere

Cited by 50 publications

References 28 publications

Titan's atmosphere and climate

Titan's atmosphere and climate

The Titan Haze Simulation experiment on COSmIC: Probing Titan’s atmospheric chemistry at low temperature

Spectral characteristics of the Titanian haze at 1−5 micron fromCassini/VIMS solar occultation data

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