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. Read more (1022kb, PDF)
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 worldRead more
Celebrating the 10th anniversary of the pioneering Huygens mission to Saturn's moon Titan, the first successful landing on an outer Solar System world
The Huygens experience
The Huygens probe separated from the Cassini orbiter on December 25, 2004, and landed on Titan on January 14, 2005 near the Xanadu region. Read more
The Huygens probe separated from the Cassini orbiter on December 25, 2004, and landed on Titan on January 14, 2005 near the Xanadu region.
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. Read more
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.
First images from Titan
14 January 2005This raw image was returned by the ESA Huygens DISR camera after the probe descended through the atmosphere of Titan.Source
This raw image was returned by the ESA Huygens DISR camera after the probe descended through the atmosphere of Titan.
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.Read more
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.
Huygens Probe Landing on Titan
The First 1000 Days: Cassini Explores The Saturn System
Titan's Surface Revealed - Jan. 14, 2005
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
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.
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.
Mosaic of river channel and ridge area on Titan
" 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.
"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 ( Full Size Image)
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.
Scientists speculate that the white streaks are a ground 'fog' of methane or ethane vapour
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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.
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. 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).
All images credits go to ESA and JPL and University of Arizona
07:07 AM (+01d02h) - Power on of orbiter instruments08:30 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.
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
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
Press conference 2Press conferenceStatus report 6Status report 5Status report 4Status report 3Status report 2Status report 1Overview 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 .
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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 File of Descent (1.2Mb .swf)
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.
98 Frame Animation - 5.4Mb
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
File 1 : acoustic during descent (443Kb mp3)
File 2 : radar conversion (441Kb mp3)