Cassini watches mysterious feature evolve in Titan sea

September 29, 2014 by Preston Dyches
These three images, created from Cassini Synthetic Aperture Radar (SAR) data, show the appearance and evolution of a mysterious feature in Ligeia Mare, one of the largest hydrocarbon seas on Saturn's moon Titan. Credit: NASA/JPL-Caltech/ASI/Cornell

(Phys.org) —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 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 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 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.

The researchers suspect that the appearance of this feature could be related to changing seasons on Titan, as summer draws near in the moon's northern hemisphere. Monitoring such changes is a major goal for Cassini's current extended mission.

"Science loves a mystery, and with this enigmatic feature, we have a thrilling example of ongoing change on Titan," said Stephen Wall, the deputy team lead of Cassini's radar team, based at NASA's Jet Propulsion Laboratory in Pasadena, California. "We're hopeful that we'll be able to continue watching the changes unfold and gain insights about what's going on in that alien sea."

Explore further: Cassini nears 100th Titan flyby with a look back

More information: Images of the feature taken during the Cassini flybys are available at: photojournal.jpl.nasa.gov/catalog/PIA18430

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12 comments

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baudrunner
1.8 / 5 (5) Sep 29, 2014
We are being told that the atmosphere of Titan rains nitrogen-rich heteropolymer hydrocarbon molecules down upon its surface, creating the hydrocarbon seas whose shorelines are currently being analyzed. Those seas are likely a rich mixture of soluble and not so soluble fluids, the surface more apt to contain liquid methane and other non-persisting substances which can alter the refractivity and transparency in appearance from above. We are probably looking through a surface with changing properties.
Torbjorn_Larsson_OM
5 / 5 (5) Sep 29, 2014
Mind that we now know those seas are almost pure methane. It comes from measuring the deepest seas to be 200+ m deep, modeling then gives almost no ethane. (I'm not hip to the papers, mind.)

But "surface waves, rising bubbles, floating solids, solids suspended just below the surface, or perhaps something more exotic" hints at some expected fraction of solids. Of course, a more mundane explanation since it is summer season is algae blooms (if it had been Earth). =D

[I'm just half joking, McKay has written about how life predicts the surface deficit of ethane and excess of hydrogen IIRC that no atmosphere model can yet predict.]
Shitead
not rated yet Sep 29, 2014
The "land" mass near the new island looks more like a dendritic growth feature than an erosional feature.
HannesAlfven
1.1 / 5 (12) Sep 29, 2014
Recall that these radar images are peculiarly flat to infer lakes of anything. If the radar image looks smooth as glass, make sure you leave room for the possibility that it *IS* glass. We see bits of glass all over the Moon as well. What created it? Might it have been flat at some point, before it was bombarded?

As for features coming and going, recall that we've recently seen the exact same thing on Venus.
saila
5 / 5 (2) Sep 29, 2014
Several shapes have change in the picture, it seems.
Not only the one that appear within the circle.
tonybudz
not rated yet Sep 29, 2014
Looks like the downwind of a chemical combination maybe or chunks sticking together to form links deep under the current.
cantdrive85
1 / 5 (11) Sep 30, 2014
The apparition was a cloud of swamp gas from Enceladus trapped in a methane pocket and reflected the light from Saturn's F-ring.
barakn
4.4 / 5 (7) Sep 30, 2014
Recall that these radar images are peculiarly flat to infer lakes of anything. If the radar image looks smooth as glass, make sure you leave room for the possibility that it *IS* glass. We see bits of glass all over the Moon as well. What created it? Might it have been flat at some point, before it was bombarded?
We had this conversation here http://phys.org/n...tan.html just before your mysterious 3-month absence in which you appear to have suffered some sort of amnesiac state, judging from the fact that you've forgotten your glass argument was easily dispensed with.
big_hairy_jimbo
2.3 / 5 (3) Sep 30, 2014
It's a Monolith
javjav
4 / 5 (1) Sep 30, 2014
They could be hydrocarbon icebergs. We know that there is methane rain, which can be easily frozen at those temperatures. Then the mountains around could produce the equivalent of earth glaciers, bringing the ice down and extending it trough the sea, finally creating icebergs made of hydrocarbon.

Uncle Ira
4.2 / 5 (5) Sep 30, 2014
your mysterious 3-month absence


It is not so mysterious no. Sometimes they put you in a place that doesn't allow the interweb for peoples in there. Sometimes peoples aren't supposed to be on the interweb even if he is not in there so Hanne-Skippy better be more careful him.
DeliriousNeuron
1 / 5 (5) Sep 30, 2014
Piss off aunt ira no brain skippy

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