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Date: August 13, 2014 3:15:54 PM CDT
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Subject: FW: Cassini Tracks Clouds Developing Over a Titan Sea
From:
Subject: FW: Cassini Tracks Clouds Developing Over a Titan Sea
Date: Wed, 13 Aug 2014 09:15:45 -0500
Cassini Tracks Clouds Developing Over a Titan Sea
This animated sequence of Cassini images shows methane clouds moving above the large methane sea on Saturn's moon Titan known as Ligeia Mare.
› Full image and captionAugust 12, 2014
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:
http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18420
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.
"We're eager to find out if the clouds' appearance signals the beginning of summer weather patterns, or if it is an isolated occurrence," said Elizabeth Turtle, a Cassini imaging team associate at the Johns Hopkins University Applied Physics Lab in Laurel, Maryland. "Also, how are the clouds related to the seas? Did Cassini just happen catch them over the seas, or do they form there preferentially?"
A year on Titan lasts about 30 Earth years, with each season lasting about seven years. Observing seasonal changes on Titan will continue to be a major goal for the Cassini mission as summer comes to Titan's north and the southern latitudes fall into winter darkness.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory (JPL) in Pasadena, California, manages the mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the United States, England, France and Germany. The imaging team is based at the Space Science Institute in Boulder, Colorado.
More information about Cassini is available at the following sites:
http://www.nasa.gov/cassini
http://saturn.jpl.nasa.gov
Preston Dyches
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-7013
preston.dyches@jpl.nasa.gov
2014-274
Images
As NASA's Cassini spacecraft sped away from Titan following a relatively close flyby, its cameras monitored the moon's northern polar region, capturing signs of renewed cloud activity.
› Full image and captionenlarge image
Spacecraft Stormchasing: Titan Clouds Swirl As Saturn Moon Approaches Northern Summer
by Elizabeth Howell on August 12, 2014Swoosh! At long last, and later than models predicted, clouds are starting to appear on Titan's nothern hemisphere. The region is just starting to enter a seven-year-long summer, and scientists say this could be an indication of coming summer storms there.Clouds swirl on the Saturn moon Titan, over the methane Ligeia Mare, in this picture sequence taken by the Cassini spacecraft. Credit: NASA/JPL-Caltech/Space Science Institute
This moon of Saturn is of particular interest to astrobiologists because it has hydrocarbons (like ethane and methane), which are organic molecules that are possible precursors to the chemistry that made life possible. But what is also neat about Titan is it has its own weather system and liquid cycle — which makes it closer to Earth than to our own, nearly atmosphere-less Moon.
"The lack of northern cloud activity up til now has surprised those studying Titan's atmospheric circulation," wrote Carolyn Porco, the imaging lead for Cassini, in a message distributed to journalists.
"Today's reports of clouds, seen a few weeks ago, and other recent indicators of seasonal change, are exciting for what they imply about Titan's meteorology and the cycling of organic compounds between northern and southern hemispheres on this unusual moon, the only one in our solar system covered in liquid organics."The pictures were taken by the Cassini spacecraft, which has been orbiting Saturn and its moons since 2004. The satellite arrived at the system in time to see clouds forming in the southern hemisphere, but the moon has been nearly bereft of clouds since a large storm occurred in 2010.Clouds swirl near Titan's north pole in this annotated still image from the Cassini mission. Credit: NASA/JPL-Caltech/Space Science Institute
This particular cloud system occurred over Ligeia Mare, which is near Titan's north pole, and included gentle wind speeds of about seven to 10 miles per hour (11 to 16 kilometers per hour.)
The sequence takes place between July 20 and 22, with most of the pictures separated by about 1-2 hours (although there is a 17.5-hour jump between frames 2 and 3.)
Sources: NASA Jet Propulsion Laboratory and Cassini Imaging Central Laboratory for Operations (CICLOPS)
At last! Cassini spies methane clouds on Saturn's moon Titan
Pale methane clouds traverse across the dark hydrocarbon lakes in the northern polar region of Saturn's moon Titan. The winds were clocked at about 7 to 10 mph. (NASA/JPL-Caltech/Space Science Institute)
Cloudy with a chance of more clouds? Scientists hope the forecast for Saturn's moon Titan holds true
Flying past Saturn's moon Titan, NASA's Cassini spacecraft has caught a few glimpses of methane clouds speeding over the enormous moon's hydrocarbon seas in its northern polar region.
Clouds developed and dissipated over Ligeia Mare, a roughly 310-mile-wide sea of methane and ethane that ranks as Titan's second-largest lake. Tracked for more than two days in late July, the pale apparitions' movements revealed wind speeds of 7 to 10 mph.
"It was exciting to see them because we have been waiting for a while now," said Elizabeth Turtle, a planetary scientist working with the Cassini imaging team at the Johns Hopkins University Applied Physics Lab in Laurel, Md.
It's been a long time since such floating clumps of methane gas have been spotted in the icy moon's nitrogen-rich atmosphere. Ever since a major storm blew through Titan's midsection near the end of 2010, the skies on this Saturnian satellite have remained largely clear, Turtle said. But this sunny weather caught some scientists off guard: According to their models, more clouds should have started to crop up as Titan approached its summer season.
Such seasonal changes are more challenging to track far out in the solar system, given that a year on Titan lasts some 30 years on Earth (and each season is about seven years long). It takes a while to establish "annual" patterns on such long time scales, and so it becomes particularly disconcerting when the atmosphere's behavior doesn't fit the predicted models.
The clouds then are a welcome sign that perhaps the planetary scientists' long-held theories are not too far off base. Here's an animation showing their movement across the moon's surface.
"It's just a tantalizing hint that the summer storms are starting," Turtle said, "but we'll have to keep observing to see."
Cassini is scheduled for another flyby in late August that could reveal whether clouds are building for some summer tempests, as they predict.
Scientists want to understand Titan in part because it helps them refine atmospheric models that they could then apply to far-off exoplanets and other as-yet impenetrable worlds. It is, after all, the only world in our neighborhood with a thick atmosphere and stable bodies of liquid on its surface.
It's also one of the few spots in our solar system very rich in complex organic molecules, giving it some potential for life-friendly environments. (The chances of any form of life ever having existed are still very low, however – as low as the surface temperature, which sits at about 290 degrees below zero.)
Copyright © 2014, Los Angeles Times
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