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Ice Cloud Heralds Autumn at Titan's South Pole

An ice cloud taking shape over Titan's south pole is the latest sign that the change of seasons is setting off a cascade of radical changes in the atmosphere of Saturn's largest moon. Made from an unknown ice, this type of cloud has long hung over Titan's north pole, where it is now fading, according to observations made by the composite infrared spectrometer (CIRS) on NASA's Cassini spacecraft.
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NASA Team Investigates Complex Chemistry at Titan

A laboratory experiment at NASA's Jet Propulsion Laboratory, Pasadena, Calif., simulating the atmosphere of Saturn's moon Titan suggests complex organic chemistry that could eventually lead to the building blocks of life extends lower in the atmosphere than previously thought. The results now point out another region on the moon that could brew up prebiotic materials. The paper was published in Nature Communications this week.
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Title: Nitrogen in the stratosphere of Titan from Cassini CIRS infrared spectroscopy
Authors: Conor A. Nixon, Nicholas A. Teanby, Carrie M. Anderson, Sandrine Vinatier

In this chapter we describe the remote sensing measurement of nitrogen-bearing species in Titan's atmosphere by the Composite Infrared Spectrometer (CIRS) on the Cassini spacecraft. This instrument, which detects the thermal infrared spectrum from 10-1500 cm-1 (1000-7 microns) is sensitive to vibrational emissions of gases and condensates in Titan's stratosphere and lower mesosphere, permitting the measurement of ambient temperature and the abundances of gases and particulates. Three N-bearing species are firmly detected: HCN, HC3N and C2N2, and their vertical and latitudinal distributions have been mapped. In addition, ices of HC3N and possibly C4N2 are also seen in the far-infrared spectrum at high latitudes during the northern winter. The HC(15)N isotopologue has been measured, permitting the inference of the 14N/15N ratio in this species, which differs markedly (lower) than in the bulk nitrogen reservoir (N2). We also describe the search in the CIRS spectrum, and inferred upper limits, for NH3 and CH3CN. CIRS is now observing seasonal transition on Titan and the gas abundance distributions are changing accordingly, acting as tracers of the changing atmospheric circulation. The prospects for further CIRS science in the remaining five years of the Cassini mission are discussed.

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Title: Upper limits for PH3 and H2S in Titan's Atmosphere from Cassini CIRS
Authors: Conor A. Nixon, Nicolas A. Teanby, Patrick G.J. Irwin, Sarah M. Horst

We have searched for the presence of simple P and S-bearing molecules in Titan's atmosphere, by looking for the characteristic signatures of phosphine and hydrogen sulfide in infrared spectra obtained by Cassini CIRS. As a result we have placed the first upper limits on the stratospheric abundances, which are 1 ppb (PH3) and 330 ppb (H2S), at the 2-sigma significance level.

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The International Astronomical Union (IAU) has approved new names for two features on Titan.

Sionascaig Lacus for a 143.2-km-wide lacus (lake) located at -41.52°, 278.12°.
The feature was named after a loch in Scotland.

Urmia Lacus for a 28.6-km-wide lacus (lake) located at -39.27°, 276.55°.
The feature was named after a lake in Iran.



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Icy Titan spawns tropical cyclones

With a maximum surface temperature of -180 °C, Saturn's icy moon Titan is no tropical paradise, at least by earthly standards. But it may still have tropical cyclones, and at what sounds like the unlikeliest of places - near its north pole.
These mini-hurricanes have never been observed anywhere but Earth. If they exist on Titan, that would add to a growing list of features that the distant moon shares with our planet, from lakes, hills, caves and sand dunes to fog, mist, smoggy haze and rain clouds.
 
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The International Astronomical Union (IAU) has approved a new name for a flumen feature on Titan.

Vid Flumina for a 158-km-wide flumen (channel) located at 72.9°, 242.25°.
The feature was named after one of the eleven venomous frozen rivers in Ginnungagap (In Norse mythology).



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Cassini Sees Titan Cooking up Smog

A paper published this week using data from NASA's Cassini mission describes in more detail than ever before how aerosols in the highest part of the atmosphere are kick-started at Saturn's moon Titan. Scientists want to understand aerosol formation at Titan because it could help predict the behaviour of smoggy aerosol layers on Earth.
According to the new paper, published this week in the Proceedings of the National Academy of Sciences, Titan's trademark reddish-brown smog appears to begin with solar radiation on molecules of nitrogen and methane in the ionosphere, which creates a soup of negative and positive ions. Collisions among the organic molecules and the ions help the molecules grow into bigger and more complex aerosols. Lower down in the atmosphere, these aerosols bump into each other and coagulate, and at the same time interact with other, neutral particles. Eventually, they form the heart of the physical processes that rain hydrocarbons on Titan's surface and form lakes, channels and dunes.
 
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Titan Gets a Dune 'Makeover'

pia16638-640.jpg

While most of Saturn's moons display their ancient faces pockmarked by thousands of craters, Titan - Saturn's largest moon - may look much younger than it really is because its craters are getting erased. Dunes of exotic, hydrocarbon sand are slowly but steadily filling in its craters, according to new research using observations from NASA's Cassini spacecraft.
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Cassini Suggests Icing on a Lake

It's not exactly icing on a cake, but it could be icing on a lake. A new paper by scientists on NASA's Cassini mission finds that blocks of hydrocarbon ice might decorate the surface of existing lakes and seas of liquid hydrocarbon on Saturn's moon Titan. The presence of ice floes might explain some of the mixed readings Cassini has seen in the reflectivity of the surfaces of lakes on Titan.
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