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Title: The reflectance spectrum of Titan's surface at the Huygens landing site determined by the Descent Imager/Spectral Radiometer
Author: S.E. Schröder, H.U. Keller

The Descent Imager/Spectral Radiometer aboard the Huygens probe successfully acquired images and spectra of the surface of Titan. To counter the effects of haze and atmospheric methane absorption it carried a Surface Science Lamp to illuminate the surface just before landing. We reconstruct the reflectance spectrum of the landing site in the 500-1500 nm range from Downward Looking Visual and Infrared Spectrometer data that show evidence of lamp light. Our reconstruction is a follow-up to the analysis by Tomasko et al. (2005), who scaled their result to the ratio of the up- and down flux measured just before landing. Instead, we use the lamp flux from the calibration experiment, and find a significantly higher overall reflectance. We attribute this to a phase angle dependance, possibly representing the opposition surge commonly encountered on solar system bodies. The reconstruction in the visible wavelength range is greatly improved. Here, the reflectance spectrum features a red slope, consistent with the presence of organic material. We confirm the blue slope in the near-IR, featureless apart from a single shallow absorption feature at 1500 nm. We agree with Tomasko et al. that the evidence for water ice is inconclusive. By modelling of absorption bands we find a methane mixing ratio of 4.5% ± 0.5% just above the surface. There is no evidence for the presence of liquid methane, but the data do not rule out a wet soil at a depth of several centimeters.

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Huygens mission
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Ten years at Titan

Celebrating the 10th anniversary of the pioneering Huygens mission to Saturn's moon Titan, the first successful landing on an outer Solar System world
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The Huygens experience

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The Huygens probe separated from the Cassini orbiter on December 25, 2004, and landed on Titan on January 14, 2005 near the Xanadu region. 
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Bouncing on Titan

ESA's Huygens probe bounced, slid and wobbled its way to rest in the 10 seconds after touching down on Saturns moon, Titan, in January 2005, a new analysis reveals. The findings provide novel insight into the nature of the moon's surface.
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First images from Titan

landing01_L2.jpg
First images from Titan

14 January 2005
This raw image was returned by the ESA Huygens DISR camera after the probe descended through the atmosphere of Titan.
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The Huygens Probe
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On 14 January, 2005, ESA's Huygens probe made an historic first ever descent to the surface of Titan, 1.2 billion kilometres from Earth and the largest of Saturn's moons.

The Huygens probe, supplied by the European Space Agency (ESA) and named after the Dutch 17th century astronomer Christiaan Huygens, was an atmospheric entry probe carried to Saturn's moon Titan as part of the Cassini-Huygens mission. The combined Cassini-Huygens spacecraft was launched from Earth on October 15, 1997. Huygens separated from the Cassini orbiter on December 25, 2004, and landed on Titan on January 14, 2005 near the Xanadu region.
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Huygens Probe Landing on Titan

The First 1000 Days: Cassini Explores The Saturn System



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Titan's Surface Revealed - Jan. 14, 2005





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Congratulations ESA!

aroback2.gif to page One

On 14 January, 2005, ESA's Huygens probe made an historic first ever descent to the surface of Titan, 1.2 billion kilometres from Earth and the largest of Saturn's moons. Huygens travelled to Titan as part of the joint ESA/NASA/ASI Cassini-Huygens mission. Starting at about 150 kilometres altitude, six multi-function instruments on board Huygens recorded data during the descent and on the surface. The first scientific assessments of Huygens' data were presented during a press conference at ESA head office in Paris on 21 January. New results were outlined at a press conference in Paris, France on Friday, 21 st Jan.

Liquid methane rain feeds river channels, lakes, streams, and springs on the surface of Saturn's moon Titan.

"Islands in the stream"... possible 'islands' on a dark plain

'islands'
 
These images from the Huygens DISR instrument show new features, such as evidence of flow around 'islands', deposits of water ice and channels which could have been created by methane springs.

Scientists have also recovered much data from Huygens that had been thought lost due to a communications failure, that missing data could be recovered via a network of radio telescopes that listened for Huygens' signals

Huygens landed on Titan at around 1138 GMT at a leisurely speed of around 5m/s. Cassini received data from Huygens until 1250 GMT when the orbiter passed over the horizon and severed the communications link.


But the Parkes radio telescope was still receiving a signal from Huygens at 1555 GMT
spacer.gif
Two new Titan features

Two new Titan features - water ice and methane springs

The probes descent was bumpier than expected in the upper atmosphere. During its descent through high-altitude haze, it rocked about 10 - 20 degrees. But below the haze layer, the probe was more stable, tilting less than 3 degrees. The reason for this seems to be that the wind changed direction at about 25 kilometres altitude.

No data from any of the nine sensors was lost. More than 474 megabits of data were received.
When Huygens touched down it experienced deceleration of about 15g in 40 milliseconds.

CoastLineMoasic

Mosaic of river channel and ridge area on Titan

Image Credit: ESA
 

 

 

" The liquid was within a few centimetres of the surface. Our feeling is that in the place we landed it must have rained not that long ago "

The pattern of rainfall on Titan may be seasonal.

Visible are short, stubby dark channels that may have been formed by 'springs' of liquid methane rather than methane 'rain'
 
Titan landing site

Surface

Image Credit: ESA
 
New, stunning evidence based on finding atmospheric argon 40 indicates that Titan has experienced volcanic activity generating not lava, as on Earth, but water ice and ammonia.


"The area we landed in is more typical of arid regions. The river beds are dry most of the time. Then after rains you have open flowing liquid. There are pools and then they dry out and the liquid methane sinks into the surface."

"We see a ridge system with a peak 100 metres tall."
There is a hint of how the hills are built:
"In another region we see a white streaky pattern, evidence of water ice being extruded by the surface."

8 kilometres above the surface  titan

8 kilometres above the surface
( Full Size Image)

Image Credit: ESA
 

DISR surface images show small rounded pebbles in a dry riverbed. Spectra measurements (colour) are consistent with a composition of dirty water ice rather than silicate rocks. However, these are rock-like solid at Titan's temperatures.

Titan's soil appears to consist at least in part of precipitated deposits of the organic haze that shrouds the planet. This dark material settles out of the atmosphere. When washed off high elevations by methane rain, it concentrates at the bottom of the drainage channels and riverbeds contributing to the dark areas seen in DISR images.

 

Landing  panorama
Huygens panorama of titan
(
Full Size Image)
Image Credit: ESA
 

Scientists speculate that the white streaks are a ground 'fog' of methane or ethane vapour

 

Yes, click this! click here for interactive panorama

Yes, click this! click here for latest news

 
drainage channels
 
Titan drainage channels
 
Tidal Basin ? ( Titans orbit period of 15.95 days, and the moons position relative to Saturn would mean that the `tide` was rising.)

Titans orbit period of 15.95 days, and the moons position relative to Saturn would mean that the `tide` was rising.

"It looks like something has flowed at some time to make those channels. But is it something that has solidified?"

The drainage channels were either caused by falling rain or seepage of liquid hydrocarbons similar to lighter fuel or natural gas (CH4) which had soaked into the ground.

 

First Data from accelerometer
 
First Data from Penetrometer as it extended 15 cm into the surface.
Initial results show that Titan has a troposphere, At a height of 50 km up The probe measured a freezing 203°C as it passed through it, compared with a -179°C ground temperature.
One radio channel was lost so only 350 photos were taken, instead of the expected 700+.
The probe landed at a slight 20 degree tilt (Revised: 8° tilt) on to a `rock (of ice)` strewn surface that has a brittle surface crust, below which is a thicker layer with the consistency of wet sand or clay. Its composition,is mainly a mix of dirty water ice and hydrocarbon ice, resulting in a darker
soil than expected.
The atmospheric pressure is similar to earth.
titaantgreenbank.jpg
 
Data recorded from the Greeen Bank telescope
titaantilt.jpg
 
Data from the tilt sensor.
The ratio of carbon isotopes C12 and C13 in Titan's atmosphere, measured by the Huygen probe's Gas Chromatograph and Mass Spectrometer (GCMS) instrument, indicates that methane is being replenished on the freezing world. Previous evidence suggested that lighter isotopes of oxygen and nitrogen would have escaped from the atmosphere into space at a greater rate than the heavier isotopes. This would change the isotopic ratio of the elements - a process called fractionation. But the atmospheric carbon isotopes do not show the same trait, implying the gas is being replenished. Continuing geological activity beneath the surface is thought to be the most likely source.

A sound file generated from the communication between the Cassini spacecraft and the Huygens probe has been released by ESA. This was converted to an audio file to show the descent profile indicating how the Huygens probe moved through the atmosphere of Titan.
Click to listen! To Listen:

As the Huygens probe plunged through Titans atmosphere, it sent back scientific data. It landed on Titan at around 1138 and transmitted a signal until at least 1555 GMT.
Scientists will comb the data sent back for the chemical signature of life in a bid to identify the moon's source of methane.
Methane is constantly destroyed by UV light so there must be a source within Titan to replenish the atmosphere.
Life could be a possible source of this hydrocarbon along with geological processes.
Titan is too cold for surface biology, but microbes could survive deep within Titan.
Methane can also be released from a trapped form called clathrate and can be produced by a geological process called "serpentisation".
Neither of these involves biology.
Dominated by nitrogen, methane and other organic molecules, Titan resembles a deep-frozen version of Earth 4.6 billion years ago.
Liquid methane rains down on Titan into river channels carved between hills of water ice. Reservoirs of this hydrocarbon probably lie on or just below the surface.
But UV light would destroy all the methane on Titan within 10 million years if it were not being constantly renewed.

"We cannot say there is absolutely no chance for life. Models of Titan's interior show there should be an ocean about 100km deep at around 300km below the surface."

If the models are correct, this ocean would be composed mostly of liquid water with about 15% ammonia at a temperature of about -80°C.

"We have liquid water, organics not so far away; we have everything on Titan to make life.

If methane-producing microbes had colonised this habitable zone, scientists might detect its chemical signature by looking at the relationship of two forms (or isotopes) of the element carbon - C12 and C13.
Living cells preferentially incorporate C12. So compounds produced by living things should be depleted of "heavier" isotopes such as C13, and have a high C12/C13 ratio.
Scientists should be able to measure this ratio in data sent back by the Gas Chromatograph Mass Spectrometer (GCMS) instrument on Huygens.

"The GCMS can directly detect the C12/C13 carbon ratio. We haven't done that yet, but we're working on it".

"It's one factor we can take into account to figure out how methane is getting replenished."

However, scientists favour the geological process of serpentisation as a more likely source of the moon's methane.
In serpentisation, geothermal activity generates methane through the oxidation of metals such as iron, chromium and magnesium which could be contained in crustal rocks below Titan's surface.
Another possibility is that methane molecules are trapped in a water-ice matrix called clathrate (or methane hydrate).

Watch real player streamUnveiling Titan: February 2005
We have seen the surface of Titan, one of the most mysterious bodies in the Solar System. Patrick Moore talks to the project's lead scientist, Professor John Zarnecki, about the first results from the Huygens probe.
Watch real player streamLord of the Rings: January 2005
Patrick Moore discusses the spacecraft Cassini, which has been at Saturn for six months, and Cassini's probe Huygens, which was sent to Titan.

BACK TO TOP

All images credits go to ESA and JPL and University of Arizona



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22:07 End of first full playback of all Probe data

 

Huygens control room
 
Huygens control room Webcam

Saturday

07:07 AM (+01d02h) - Power on of orbiter instruments
08:30 AM (+01d03h) - End nominal playback of Probe data

 

Saturday 15 January

10:00-11:00 GMT - Press conference at ESA/ESOC: presentation of the first image, sounds, etc. - not broadcast live on ESA TV. Though, a video news release with the highlights will be available on ESA TV for broadcasters immediately at the end of the press conference.

hygenscontrolroom.jpg
 
Control room wall
On the Web

You can follow all main Cassini/Huygens mission events on the ESA website at: http://saturn.esa.int

Here you will find information on Cassini-Huygens and its status, and the latest updates from January 13, with continuous coverage during the the descent on 14 January, with the first image arriving on 14 January.

Messages from earthlings and pop music heading to Titan

Second Titan Targeted Flyby #3
 
Cassini launch

Before the mission was launched, ESA offered Europeans a unique opportunity to send a message to the unknown. Over 80 000 people wanted to share the excitement of this mission and wrote or drew a message that was engraved on a CD-ROM put on board the Huygens probe. The messages can be seen on http://television.esa.int/Huygens/index.cfm

FIRST PHOTO
 
First Photo of Surface of Titan . The `rocks` seen may actually be composed of ice.The true colour of the rocks is probably "black and gray".
(Full Size Image)
 

ESAASIBLACKicon.jpg
Press conference 2
Press conference
Status report 6
Status report 5
Status report 4
Status report 3
Status report 2
Status report 1
Overview of events

The same CD ROM carries four pop songs, composed by French musicians Julien Civange and Louis Haéri. More about this project at http://www.music2titan.com


Message from me .

Thanks ESA!

(BTW -Was this page helpful? Feedback/complains Here)

 

surfacepa203body.jpg
 
Pale orange surface
(Full Size Image)

New, refined pictures released on Saturday 14 January 2005 show a pale orange surface covered by a thin haze of methane and what appears to be a methane sea complete with islands and a mist-shrouded coastline. It shows the boundary between the lighter-coloured uplifted terrain, marked with what appear to be drainage channels, and darker lower areas. These images were taken from an altitude of about 8 kilometres with a resolution of about 20 metres per pixel.


"They are river-sized, not merely little trickles - probably hundreds of metres across."

Shockwave MOVIE Shockwave File of Descent (1.2Mb .swf)

"The probe's parachute disappeared from sight on landing, so the probe probably isn't pointing east, or we would have seen the parachute,"
First Colour Picture

Titan First Colour Picture The true colour of the rocks is probably "black and gray".
(Full Size Image)

 

This is the coloured view, following processing to add reflection spectra data, gives a better indication of the actual colour of the surface. Initially thought to be rocks or ice blocks, they are more pebble-sized. The two rock-like objects just below the middle of the image are about 15 centimetres (left) and 4 centimetres (centre) across respectively, at a distance of about 85 centimetres from the probe.

The surface is darker than originally expected, consisting of a mixture of water and hydrocarbon ice. There is also evidence of erosion at the base of these objects, indicating possible fluvial activity.

"The probe is absolutely rock solid, there's no motion at all.

Animated gif MOVIE 98 Frame Animation - 5.4Mb

Animated gif  MOVIE Animated gif (11.7Mb)

Raw Images at Lyle.org

Open University scientists after running experiments simulating the data returned by the Huygens landers Penetrometer have concluded that an ice pebble was almost certainly the first thing the probe struck as it landed on Titan. This penetrometer on the underside, was the first part to touch the Saturnian moon and drove about 10cm into the surface. Water-ice particles (ranging in size up to 8mm) mixed with a significant amount of hydrocarbon ice creates a sort of `sand and gravel` mix with cricket ball sized water-ice pebbles strewn on the surface.
"A crust and a pebble will give you an initial peak but the match looks better with a pebble and if we're seeing lots of them in the ground image it's hardly fanciful that we've bashed one of them." - Professor John Zarnecki

Mosaics and compositions created by ESA can be found here.
 Period (days) Radius
(km)
Mass
(kg)
Distance
(km)
Discoverer Date
Titantitan15.95 2,575 1.35e+23 1,221,850 TitanC. Huygens 1655

 

sound.jpg
Audio data collected by the Huygens Atmospheric Structure Instrument (HASI) during Huygens' descent
 
hygenPicture4L.jpg
 
Llocation of landing site

 

 

 


File 1 : acoustic during descent (443Kb mp3)

File 2 : radar conversion (441Kb mp3)


Sounds released are reconstructed from snippets.


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