Cassini Tracks Clouds Developing Over A Titan Sea

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Cassini Tracks Clouds Developing Over A Titan Sea

Post by bystander » Wed Aug 13, 2014 6:20 pm

Cassini Tracks Clouds Developing Over A Titan Sea
NASA | JPL-Caltech | Cassini Solstice Mission | CICLOPS | 2014 Aug 12
[imghover=http://s3.amazonaws.com/ciclops_ir_2014 ... 8928_2.png]http://s3.amazonaws.com/ciclops_ir_2014 ... 8927_2.png[/imghover]Northern Clouds Return to Titan - (Credit: NASA/JPL-Caltech/Space Science Institute)[/i][/b]
As NASA's Cassini sped away from Titan following a relatively close flyby, its cameras
monitored the moon's northern polar region, capturing signs of renewed cloud activity.

NASA's Cassini spacecraft recently captured images of clouds moving across the northern hydrocarbon seas of Saturn's moon Titan. This renewed weather activity, considered overdue by researchers, could finally signal the onset of summer storms that atmospheric models have long predicted.

A movie showing the clouds' movement is available at: Clouds Over Ligeia Mare on Titan.

The Cassini spacecraft obtained the new views in late July, as it receded from Titan after a close flyby. Cassini tracked the system of clouds developing and dissipating over the large methane sea known as Ligeia Mare for more than two days. Measurements of cloud motions indicate wind speeds of around 7 to 10 mph (3 to 4.5 meters per second).

For several years after Cassini's 2004 arrival in the Saturn system, scientists frequently observed cloud activity near Titan's south pole, which was experiencing late summer at the time. Clouds continued to be observed as spring came to Titan's northern hemisphere. But since a huge storm swept across the icy moon's low latitudes in late 2010, only a few small clouds have been observed anywhere on the icy moon. The lack of cloud activity has surprised researchers, as computer simulations of Titan's atmospheric circulation predicted that clouds would increase in the north as summer approached, bringing increasingly warm temperatures to the atmosphere there. ...
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Cassini Watches Mysterious Feature Evolve in Titan Sea

Post by bystander » Mon Sep 29, 2014 7:48 pm

Cassini Watches Mysterious Feature Evolve in Titan Sea
NASA | JPL-Caltech | Cassini Solstice Mission | CICLOPS | 2014 Sep 29
NASA's Cassini spacecraft is monitoring the evolution of a mysterious feature in a large hydrocarbon sea on Saturn's moon Titan. The feature covers an area of about 100 square miles (260 square kilometers) in Ligeia Mare, one of the largest seas on Titan. It has now been observed twice by Cassini's radar experiment, but its appearance changed between the two apparitions.
...
The mysterious feature, which appears bright in radar images against the dark background of the liquid sea, was first spotted during Cassini's July 2013 Titan flyby. Previous observations showed no sign of bright features in that part of Ligeia Mare. Scientists were perplexed to find the feature had vanished when they looked again, over several months, with low-resolution radar and Cassini's infrared imager. This led some team members to suggest it might have been a transient feature. But during Cassini's flyby on August 21, 2014, the feature was again visible, and its appearance had changed during the 11 months since it was last seen.

Scientists on the radar team are confident that the feature is not an artifact, or flaw, in their data, which would have been one of the simplest explanations. They also do not see evidence that its appearance results from evaporation in the sea, as the overall shoreline of Ligeia Mare has not changed noticeably.

The team has suggested the feature could be surface waves, rising bubbles, floating solids, solids suspended just below the surface, or perhaps something more exotic. ...
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Re: Cassini Tracks Clouds Developing Over A Titan Sea

Post by geckzilla » Mon Sep 29, 2014 10:29 pm

Weird. The circled feature may be the most conspicuous but there is a lot of change going on all over. Titan is a fascinating, dynamic world. I would much sooner send a myriad of probes to it than Mars.
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ESA: Titan polar vortex contains frozen HCN

Post by MargaritaMc » Wed Oct 01, 2014 7:49 pm

More interesting Titan information.
TITAN'S SWIRLING POLAR CLOUD IS COLD AND TOXIC

The international Cassini mission has revealed that a giant, toxic cloud is hovering over the south pole of Saturn’s largest moon, Titan, after the atmosphere has cooled in a dramatic fashion.

Scientists analysing data from the mission found that this giant polar vortex contains frozen particles of the toxic compound hydrogen cyanide.

“The discovery suggests that the atmosphere of Titan’s southern hemisphere is cooling much faster than we expected,” says Remco de Kok of Leiden Observatory and SRON Netherlands Institute for Space Research, lead author of the study published in the journal Nature.
Vortex on Titan close up
NASA/JPL–Caltech/Space Science Institute.

A true-colour image of the south pole vortex observed in Titan’s atmosphere at about 200–300 km altitude, as seen during a Cassini flyby of Saturn’s largest moon on 27 June 2012. ...
The images were obtained with the Cassini spacecraft narrow-angle camera at a distance of approximately 484,000 kilometres from Titan.


... As a gas, HCN is one of the molecules present in small amounts in the nitrogen-rich atmosphere of Titan. However, finding these molecules in the form of ice was very surprising, as HCN can condense to form frozen particles only if the atmosphere is as cold as –148ºC.

“This is about 100ºC colder than predictions from current theoretical models of Titan’s upper atmosphere,” explains co-author Nick Teanby from the University of Bristol, UK.

“To check whether such low temperatures were actually possible, we investigated a second set of observations from Cassini’s Composite Infrared Spectrometer, which allows us to measure atmospheric temperature at different altitudes.”

Unfortunately, no such readings were taken in 2012 at this cloud’s altitude, but the scientists looked at data from other dates, probing the atmosphere above and below the vortex.

These data showed that the southern hemisphere has been cooling rapidly, making it possible to reach the low temperature needed to form the giant toxic cloud seen on the south pole.
...
More details at: http://www.esa.int/Our_Activities/Space ... _and_toxic
NATURE: “HCN ice in Titan’s high-altitude southern polar cloud,” by R. J. de Kok et al
Titan’s middle atmosphere is currently experiencing a rapid change of season after northern spring arrived in 2009 (refs 1, 2). A large cloud was observed for the first time above Titan’s southern pole in May 2012, at an altitude of 300 kilometres. A temperature maximum was previously observed there, and condensation was not expected for any of Titan’s atmospheric gases. Here we report that this cloud is composed of micrometre-sized particles of frozen hydrogen cyanide (HCN ice). The presence of HCN particles at this altitude, together with temperature determinations from mid-infrared observations, indicate a dramatic cooling of Titan’s atmosphere inside the winter polar vortex in early 2012. Such cooling is in contrast to previously measured high-altitude warming in the polar vortex, and temperatures are a hundred degrees colder than predicted by circulation models. These results show that post-equinox cooling at the winter pole of Titan is much more efficient than previously thought.
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Re: ESA: Titan polar vortex contains frozen HCN

Post by bystander » Wed Oct 01, 2014 8:55 pm

MargaritaMc wrote:
Titan’s Swirling Polar Cloud is Cold and Toxic
ESA Space Science | Cassini-Huygens | 2014 Oct 01

HCN ice in Titan’s high-altitude southern polar cloud - R. J. de Kok et al

Swirling Cloud at Titan's Pole is Cold and Toxic
NASA | JPL-Caltech | Cassini | 2014 Oct 01
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NRAO: Organic Molecules in Titan's Atmosphere Are Skewed

Post by bystander » Thu Oct 23, 2014 5:26 pm

Organic Molecules in Titan's Atmosphere Are Intriguingly Skewed
National Radio Astronomy Observatory | ALMA | 2014 Oct 22
While studying the atmosphere on Saturn’s moon Titan, scientists discovered intriguing zones of organic molecules unexpectedly shifted away from its north and south poles. These misaligned features seem to defy conventional thinking about Titan’s windy atmosphere, which should quickly smear out such off-axis concentrations.

"This is an unexpected and potentially groundbreaking discovery," said Martin Cordiner, an astrochemist working at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the lead author of a study published online today in the Astrophysical Journal Letters. "These kinds of east-to-west variations have never been seen before in Titan’s atmospheric gases. Explaining their origin presents us with a fascinating new problem."

This discovery, made during a remarkably brief three-minute "snapshot" observation with the Atacama Large Millimeter/submillimeter Array (ALMA), may help astronomers better understand the processes that shape this world's complex chemistry.

Titan’s atmosphere has long been of interest because it acts as a chemical factory, using energy from the Sun and Saturn’s magnetic field to produce a wide range of organic molecules. Studying this complex chemistry may provide insights into the properties of Earth’s very early atmosphere, which may have shared many chemical characteristics with present-day Titan. ...

Image Credits: NRAO/AUI/NSF; M. Cordiner (NASA) et al.
The globe outline represents Titan's orientation at the time of the observations.

ALMA measurements of the HNC and HC3N distributions in Titan's atmosphere - M. A. Cordiner et al
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NASA Finds Methane Ice Cloud in Titan's Stratosphere

Post by bystander » Sat Oct 25, 2014 12:20 am

NASA Finds Methane Ice Cloud in Titan's Stratosphere
NASA | JPL-Caltech | GSFC | Solar System Exploration | 2014 Oct 24
NASA scientists have identified an unexpected high-altitude methane ice cloud on Saturn's moon Titan that is similar to exotic clouds found far above Earth's poles.

This lofty cloud, imaged by NASA's Cassini spacecraft, was part of the winter cap of condensation over Titan's north pole. Now, eight years after spotting this mysterious bit of atmospheric fluff, researchers have determined that it contains methane ice, which produces a much denser cloud than the ethane ice previously identified there.

"The idea that methane clouds could form this high on Titan is completely new," said Carrie Anderson, a Cassini participating scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study. "Nobody considered that possible before."

Methane clouds were already known to exist in Titan's troposphere, the lowest layer of the atmosphere. Like rain and snow clouds on Earth, those clouds form through a cycle of evaporation and condensation, with vapor rising from the surface, encountering cooler and cooler temperatures and falling back down as precipitation. On Titan, however, the vapor at work is methane instead of water.

The newly identified cloud instead developed in the stratosphere, the layer above the troposphere. ...

Subsidence-induced methane clouds in Titan's winter polar stratosphere and upper troposphere - C.M. Anderson et al
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Cassini Sees Sunny Seas on Titan

Post by bystander » Thu Oct 30, 2014 8:39 pm

Cassini Sees Sunny Seas on Titan
NASA | JPL-Caltech | Cassini | 2014 Oct 30
As it soared past Saturn's large moon Titan recently, NASA's Cassini spacecraft caught a glimpse of bright sunlight reflecting off hydrocarbon seas.

In the past, Cassini had captured, separately, views of the polar seas and the sun glinting off them, but this is the first time both have been seen together in the same view.

Also in the image:
  • An arrow-shaped complex of bright methane clouds hovers near Titan's north pole. The clouds could be actively refilling the lakes with rainfall.
  • A "bathtub ring," or bright margin, around Kraken Mare -- the sea containing the reflected sunglint -- indicates that the sea was larger at some point, but evaporation has decreased its size.

Titan's seas are mostly liquid methane and ethane. Before Cassini's arrival at Saturn, scientists suspected that Titan might have bodies of open liquid on its surface. Cassini found only great fields of sand dunes near the equator and lower latitudes, but located lakes and seas near the poles, particularly in the north.

The new view shows Titan in infrared light. It was obtained by Cassini's Visible and Infrared Mapping Spectrometer (VIMS) on Aug. 21.
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Cassini Sails into New Ocean Adventures on Titan

Post by bystander » Mon Nov 10, 2014 9:30 pm

Cassini Sails into New Ocean Adventures on Titan
NASA | JPL-Caltech | Cassini | 2014 Nov 10
NASA's Cassini mission continues its adventures in extraterrestrial oceanography with new findings about the hydrocarbon seas on Saturn's moon Titan. During a flyby in August, the spacecraft sounded the depths near the mouth of a flooded river valley and observed new, bright features in the seas that might be related to the mysterious feature that researchers dubbed the "magic island."

The findings are being presented this week at the Division for Planetary Sciences Meeting of the American Astronomical Society held in Tucson, Arizona.

To the delight of Cassini scientists, two new bright features appeared in Titan's largest sea, Kraken Mare, during the August 21 flyby. In contrast to a previously reported bright, mystery feature in another of Titan's large seas, Ligeia Mare, the new features in Kraken Mare were observed in both radar data and images from Cassini's Visible and Infrared Mapping Spectrometer (VIMS). Having observations at two different wavelengths provides researchers with important clues to the nature of these enigmatic objects.

The VIMS data suggest the new features might have similarities to places in and around the seas that the Cassini team has interpreted as waves or wet ground. The observations support two of the possible explanations the team thinks are most likely -- that the features might be waves or floating debris. ...
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