Andrew Yee[_1_]
January 12th 07, 06:38 PM
ESA News
http://www.esa.int
12 January 2007
Huygens's second landing anniversary -- the surprises continue
Two years ago, planetary scientists across the world watched as Europe and
the US did something amazing. The Huygens descent module drifted down
through the hazy atmosphere of Saturn's moon Titan, beaming its data back to
Earth via the Cassini mothership. Today, Huygens's data are still continuing
to surprise researchers.
Titan holds a unique place in the Solar System. It is the only moon covered
in a significant atmosphere. The atmosphere has long intrigued scientists as
it may be similar to that of the early Earth but the deeper mystery was:
what lies beneath the haze?
The European Space Agency built the Huygens spacecraft to find out. The
probe, carrying scientific investigations involving both sides of the
Atlantic, hitched a ride on NASA's Cassini spacecraft. Together Cassini and
Huygens make an unprecedented joint space mission -- as a major milestone,
Huygens parachuted to the surface of Titan on 14 January 2005.
While Cassini keeps flying by this moon of Saturn collecting new amazing
data, one can say that the data collected by Huygens's six instruments
during its 2.5-hour descent and touch-down have provided the most
spectacular view of this world yet and first dramatic change in the way we
now think about it.
"When you put all the data together, we get a very rich picture of Titan,"
says Atha Coustenis, Observatoire de Paris, France, "The Descent
Imager/Spectral Radiometer (DISR) pictures were an enormous surprise. We had
expected a much smoother landscape." Instead, they saw a varied landscape of
channels that had been formed by some kind of flowing liquid.
"At the landing site we also saw rounded ice pebbles," says Jonathan Lunine,
University of Arizona. The Surface Science Package (SSP) provided the final
piece in this particular puzzle. The impact it detected when Huygens touched
down indicated that the spacecraft had come to rest in compacted gravel.
"Put it all together and it is clear that Huygens landed in an outflow
wash," says Lunine.
The Gas Chromatograph and Mass Spectrometer (GCMS) instrument confirmed the
nature of the liquid that shapes the surface of Titan. It detected methane
evaporating from the Huygens landing site. "Methane on Titan plays the role
that water plays on Earth," concludes Lunine. But there are still mysteries.
It is not yet clear whether the methane falls mostly as a steady drizzle or
as an occasional deluge.
The GCMS also detected two isotopes of argon. Both have important stories to
tell. The Ar40 indicates that the interior of Titan is still active. This is
unusual in a moon and indicates that perhaps an insulating layer of water
ice and methane is buried in the moon itself, close to the surface, trapping
the heat inside it. Occasionally, this heat causes the so-called
cryo-volcanoes to erupt. Icy 'lava' flows from these cryo-volcanoes have
been seen from the orbiting Cassini spacecraft. Because Ar40 is so heavy, it
is mostly concentrated towards the base of the atmosphere, so having Huygens
on the surface was essential for its detection.
Daniel Gautier, Observatoire de Paris, France, thinks that the other
isotope, Ar36, is telling scientists that Titan formed after Saturn, at a
time when the primeval gas cloud that became the Solar System had cooled to
about 40 K (-233 C).
The atmosphere of Titan held surprises too. "Huygens made a fantastic and
unexpected discovery about the wind," says Gautier. At an altitude of around
60 kilometres, the wind speed dropped, essentially to zero. Explaining this
behaviour presents a challenge for theoreticians who are developing computer
models of the moon's atmospheric circulation.
The Huygens Atmosphere Structure Instrument (HASI) provided the temperature
of the atmosphere from 1600 kilometres altitude down to the surface. "This
has helped put all the other data into context," says Coustenis. Huygens
measured the composition profile of the atmosphere to be a mixture of
nitrogen, methane and ethane. The methane and ethane provide humidity, as
water does in Earth's atmosphere. At the surface of Titan, Huygens measured
the temperature to be 94 K (-179 C) with a humidity of 45 percent.
Even though the Huygens data set is now two years old, the discoveries have
not yet stopped. "There are lots of surprises still to come from this data,"
says Francesca Ferri, Universitdegli Studi di Padova. In addition, Huygens
gives planetary scientists a wealth of 'ground-truth' to complement and help
interpret the observations still coming from Cassini. At the beginning of
2007, Cassini showed that liquid methane is present on Titan in lakes.
Cassini, whose experiments also see a joint US and European participation,
will make another 22 fly-bys of Titan -- the first on 13 January -- between
now and the end of its scheduled mission in the summer of 2008. The
Cassini-Huygens scientists are discussing their options to extend the
mission. One idea, says Christophe Sotin, Universitde Nantes, France, would
be to use Cassini to study the newly discovered lakes.
Huygens has exceeded expectations and shown Titan to be an 'alien earth',
giving planetary scientists a new world of fascination to explore.
Note to editors:
Cassini-Huygens is a project of international collaboration between NASA,
ESA and ASI.
For more information:
Jean-Pierre Lebreton, ESA Huygens Project Scientist
Email : jean-pierre.lebreton @ esa.int
[NOTE: Images supporting this release are available at
http://www.esa.int/esaCP/SEM7QJRMTWE_index_1.html ]
More about ...
* At Saturn and Titan
http://www.esa.int/SPECIALS/Cassini-Huygens/index.html
* More on Cassini-Huygens spacecraft
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=35026
Related articles
* Titan has liquid lakes!
http://www.esa.int/esaSC/SEMXJIRMTWE_index_0.html
* Tallest mountains ever seen on Titan imaged by Cassini
http://www.esa.int/esaSC/SEMAJIZTIVE_index_0.html
* Vast polar ethane cloud observed on Titan's north pole
http://www.esa.int/esaSC/SEMCI08LURE_index_0.html
* Huygens Scientific Archive data set released
http://www.esa.int/esaCP/SEM8TYIZBQE_index_0.html
* How the world watched Huygens
http://www.esa.int/esaCP/SEMJ83EQMPE_index_0.html
* Titan's pebbles 'seen' by Huygens radio
http://www.esa.int/esaCP/SEM23SVT0PE_index_0.html
* Cassini's radar spots 'Great Lakes' on Titan
http://www.esa.int/esaCP/SEMR8OBUQPE_index_0.html
* Landing on Titan -- the new movies
http://www.esa.int/esaSC/SEMKVQOFGLE_index_0.html
* Movie of Titan's surface in the infrared
http://www.esa.int/esaSC/SEMLMXLVGJE_index_0.html
* A simulated view from Huygens
http://www.esa.int/esaSC/SEMA7UMZCIE_index_0.html
Related links
* Titan lakes -- JPL podcast
http://www.jpl.nasa.gov/multimedia/podcast/cassini-20070103/
* ESA Planetary Science archive (PSA)
http://www.rssd.esa.int/PSA
* Cassini-Huygens at JPL
http://saturn.jpl.nasa.gov/home/index.cfm
* Cassini-Huygens at NASA
http://www.nasa.gov/cassini
* Italian Space Agency (ASI)
http://www.asi.it
http://www.esa.int
12 January 2007
Huygens's second landing anniversary -- the surprises continue
Two years ago, planetary scientists across the world watched as Europe and
the US did something amazing. The Huygens descent module drifted down
through the hazy atmosphere of Saturn's moon Titan, beaming its data back to
Earth via the Cassini mothership. Today, Huygens's data are still continuing
to surprise researchers.
Titan holds a unique place in the Solar System. It is the only moon covered
in a significant atmosphere. The atmosphere has long intrigued scientists as
it may be similar to that of the early Earth but the deeper mystery was:
what lies beneath the haze?
The European Space Agency built the Huygens spacecraft to find out. The
probe, carrying scientific investigations involving both sides of the
Atlantic, hitched a ride on NASA's Cassini spacecraft. Together Cassini and
Huygens make an unprecedented joint space mission -- as a major milestone,
Huygens parachuted to the surface of Titan on 14 January 2005.
While Cassini keeps flying by this moon of Saturn collecting new amazing
data, one can say that the data collected by Huygens's six instruments
during its 2.5-hour descent and touch-down have provided the most
spectacular view of this world yet and first dramatic change in the way we
now think about it.
"When you put all the data together, we get a very rich picture of Titan,"
says Atha Coustenis, Observatoire de Paris, France, "The Descent
Imager/Spectral Radiometer (DISR) pictures were an enormous surprise. We had
expected a much smoother landscape." Instead, they saw a varied landscape of
channels that had been formed by some kind of flowing liquid.
"At the landing site we also saw rounded ice pebbles," says Jonathan Lunine,
University of Arizona. The Surface Science Package (SSP) provided the final
piece in this particular puzzle. The impact it detected when Huygens touched
down indicated that the spacecraft had come to rest in compacted gravel.
"Put it all together and it is clear that Huygens landed in an outflow
wash," says Lunine.
The Gas Chromatograph and Mass Spectrometer (GCMS) instrument confirmed the
nature of the liquid that shapes the surface of Titan. It detected methane
evaporating from the Huygens landing site. "Methane on Titan plays the role
that water plays on Earth," concludes Lunine. But there are still mysteries.
It is not yet clear whether the methane falls mostly as a steady drizzle or
as an occasional deluge.
The GCMS also detected two isotopes of argon. Both have important stories to
tell. The Ar40 indicates that the interior of Titan is still active. This is
unusual in a moon and indicates that perhaps an insulating layer of water
ice and methane is buried in the moon itself, close to the surface, trapping
the heat inside it. Occasionally, this heat causes the so-called
cryo-volcanoes to erupt. Icy 'lava' flows from these cryo-volcanoes have
been seen from the orbiting Cassini spacecraft. Because Ar40 is so heavy, it
is mostly concentrated towards the base of the atmosphere, so having Huygens
on the surface was essential for its detection.
Daniel Gautier, Observatoire de Paris, France, thinks that the other
isotope, Ar36, is telling scientists that Titan formed after Saturn, at a
time when the primeval gas cloud that became the Solar System had cooled to
about 40 K (-233 C).
The atmosphere of Titan held surprises too. "Huygens made a fantastic and
unexpected discovery about the wind," says Gautier. At an altitude of around
60 kilometres, the wind speed dropped, essentially to zero. Explaining this
behaviour presents a challenge for theoreticians who are developing computer
models of the moon's atmospheric circulation.
The Huygens Atmosphere Structure Instrument (HASI) provided the temperature
of the atmosphere from 1600 kilometres altitude down to the surface. "This
has helped put all the other data into context," says Coustenis. Huygens
measured the composition profile of the atmosphere to be a mixture of
nitrogen, methane and ethane. The methane and ethane provide humidity, as
water does in Earth's atmosphere. At the surface of Titan, Huygens measured
the temperature to be 94 K (-179 C) with a humidity of 45 percent.
Even though the Huygens data set is now two years old, the discoveries have
not yet stopped. "There are lots of surprises still to come from this data,"
says Francesca Ferri, Universitdegli Studi di Padova. In addition, Huygens
gives planetary scientists a wealth of 'ground-truth' to complement and help
interpret the observations still coming from Cassini. At the beginning of
2007, Cassini showed that liquid methane is present on Titan in lakes.
Cassini, whose experiments also see a joint US and European participation,
will make another 22 fly-bys of Titan -- the first on 13 January -- between
now and the end of its scheduled mission in the summer of 2008. The
Cassini-Huygens scientists are discussing their options to extend the
mission. One idea, says Christophe Sotin, Universitde Nantes, France, would
be to use Cassini to study the newly discovered lakes.
Huygens has exceeded expectations and shown Titan to be an 'alien earth',
giving planetary scientists a new world of fascination to explore.
Note to editors:
Cassini-Huygens is a project of international collaboration between NASA,
ESA and ASI.
For more information:
Jean-Pierre Lebreton, ESA Huygens Project Scientist
Email : jean-pierre.lebreton @ esa.int
[NOTE: Images supporting this release are available at
http://www.esa.int/esaCP/SEM7QJRMTWE_index_1.html ]
More about ...
* At Saturn and Titan
http://www.esa.int/SPECIALS/Cassini-Huygens/index.html
* More on Cassini-Huygens spacecraft
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=35026
Related articles
* Titan has liquid lakes!
http://www.esa.int/esaSC/SEMXJIRMTWE_index_0.html
* Tallest mountains ever seen on Titan imaged by Cassini
http://www.esa.int/esaSC/SEMAJIZTIVE_index_0.html
* Vast polar ethane cloud observed on Titan's north pole
http://www.esa.int/esaSC/SEMCI08LURE_index_0.html
* Huygens Scientific Archive data set released
http://www.esa.int/esaCP/SEM8TYIZBQE_index_0.html
* How the world watched Huygens
http://www.esa.int/esaCP/SEMJ83EQMPE_index_0.html
* Titan's pebbles 'seen' by Huygens radio
http://www.esa.int/esaCP/SEM23SVT0PE_index_0.html
* Cassini's radar spots 'Great Lakes' on Titan
http://www.esa.int/esaCP/SEMR8OBUQPE_index_0.html
* Landing on Titan -- the new movies
http://www.esa.int/esaSC/SEMKVQOFGLE_index_0.html
* Movie of Titan's surface in the infrared
http://www.esa.int/esaSC/SEMLMXLVGJE_index_0.html
* A simulated view from Huygens
http://www.esa.int/esaSC/SEMA7UMZCIE_index_0.html
Related links
* Titan lakes -- JPL podcast
http://www.jpl.nasa.gov/multimedia/podcast/cassini-20070103/
* ESA Planetary Science archive (PSA)
http://www.rssd.esa.int/PSA
* Cassini-Huygens at JPL
http://saturn.jpl.nasa.gov/home/index.cfm
* Cassini-Huygens at NASA
http://www.nasa.gov/cassini
* Italian Space Agency (ASI)
http://www.asi.it