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NASA's Cassini spacecraft data revealed that
seem to be giant dust storms in the equatorial regions of Titan, the moon of Saturn.
The discovery, described in an article published on September 24 in Nature Geoscience,
made Titan the third body of the solar system, in addition to the Earth and Mars, where
dust storms were observed.
Observation helps scientists to better
understand the fascinating and dynamic environment of the largest moon of Saturn.
"Titan is a very active moon," said
Sébastien Rodriguez, astronomer at the Paris Diderot University,
France and lead author of the newspaper. "We already know about his
geology and the exotic hydrocarbon cycle. Now we can add another analogy with the Earth
and Mars: the active cycle of dust, in which organic dusts can be
dune fields around the equator of Titan. "
Titan is an intriguing world – very similar to
Earth. In fact, it's the only moon in the solar system
atmosphere and the only celestial body other than our planet where stable
It is known that bodies of surface liquid still exist.
There is, however, a big difference: on Earth, such rivers,
the lakes and seas are filled with water, while on Titan, it's mainly methane
and ethane that passes through these liquid tanks. In this unique cycle,
the hydrocarbon molecules evaporate, condense in clouds and the rain comes back on
floor.
The weather on Titan varies from season to season as
well, like on Earth. In particular, around the equinox – the time
when the sun crosses the equator of Titan – massive clouds can form in the tropics
regions and cause powerful methane storms. Cassini observed such storms during
many of his Titan flybags.
When Rodriguez and his team first spotted three
unusual equatorial lightenings in the infrared images taken by Cassini around the
the north moon equinox in 2009, they thought that they could be of the same type as methane
clouds; However, an investigation revealed that they were something completely
different.
"From what we know about the formation of clouds on
Titan, we can say that such methane clouds in this region and at this time of
year are not physically possible, "said Rodriguez. Convection
methane clouds that can develop in this area and during this period
would contain huge droplets and should be at a very high altitude – much higher
that the 6 miles (10 kilometers) that modeling tells us that new features are
located. "
The researchers were also able to exclude
the features were actually on Titan's surface in the form of frozen methane
rain or frozen lava. Such surface stains would have a different chemical signature
and would remain visible much longer than the brilliant features of this study,
which were visible only 11 hours to five weeks.
In addition, modeling has shown that features must be
atmospheric but still near the surface – most likely forming a very thin
layer of tiny solid organic particles. Since they were located just above the
dune fields around Titan's equator, the only remaining explanation was that the
The spots were actually clouds of dust raised by the dunes.
Organic dust is formed when organic
molecules, formed by the interaction of sunlight with methane, develop
enough to fall to the surface. Rodriguez said that while
it's the first observation of a dust storm on Titan, the conclusion is not
surprising.
"We believe that the Huygens probe,
that landed on the surface of Titan in January 2005, raised a small amount of
organic dust on arrival because of its powerful aerodynamic wake, "said Rodriguez.
"But what we have seen here with Cassini is on a much larger scale.
the wind speed near the surface needed to raise such a quantity of dust that we see in
these dust storms should be very strong – about five times more
average wind speeds estimated by Huygens measurements near the surface
and with climate models. "
The existence of strong winds generating
dust storms imply that the underlying sand can also be set in motion, and
that the giant dunes covering the equatorial regions of Titan are still active and
change continuously.
The winds could carry the
the dust raised by the dunes over great distances, contributing to the
cycle of organic dust on Titan and causing effects similar to those that can be
observed on Earth and Mars.
The results were obtained with visual and infrared mapping of Cassini
Spectrometer. the
The mission of Cassini-Huygens is a cooperative project of NASA, ESA (European Space
Agency) and the Italian Space Agency. Jet Propulsion Laboratory of NASA, a
division of Caltech in Pasadena, California, manages mission for NASA
Directorate of Scientific Missions in Washington. The Cassini spacecraft deliberately
plunged into Saturn on September 15, 2017. JPL designed, developed and assembled
the Cassini orbiter. The radar instrument was built by the JPL and the Italian
Space Agency, working with members of American and European teams
countries.
For more information on Cassini, visit:
https://www.nasa.gov/cassini
https://saturn.jpl.nasa.gov
News Media Contact
Gretchen McCartney
Jet Propulsion Laboratory, Pasadena, California.
818-393-6215
[email protected]
Dwayne Brown / JoAnna Wendel
NASA Headquarters, Washington
202-358-1726 / 202-358-1003
[email protected] / [email protected]
Markus Bauer
Scientific communication officer of ESA
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
[email protected]
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