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.PAGE TWO-New Results
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. The winds on Titan are found to be flowing in the direction of Titan's rotation (from west to east) at nearly all altitudes. The maximum speed of roughly 120 metres per second (430 km/h) was measured about ten minutes after the start of the descent, at an altitude of about 120 km. The winds are weak near the surface and increase slowly with altitude up to about 60 km. This pattern does not continue at altitudes above 60 km, where large variations in the Doppler measurements are observed. Scientists believe that these variations may arise from significant vertical wind shear. That Huygens had a rough ride in this region was already known from the science and engineering data recorded on board Huygens. 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.
Data from the Gas Chromatograph and Mass Spectrometer (GCMS) indicate methane is evaporating from the surface (probably due to Huygens impacting at 4.5 meters per second).The data also shows that the probe passed through a dense methane cloud or haze at a height of 18 - 20 kilometres. These matches well with DISR's observations: at 25 km up the surface was still fuzzy, but below 18 km the clarity was near-perfect.
When the mission was designed, it was decided that the DISR's 20-Watt landing lamp should turn on 700 metres above the surface and illuminate the landing site for as long as 15 minutes after touchdown.
"In fact, not only did the landing lamp turn on at exactly 700 metres, but also it was still shining more than an hour later"
UPDATE: The communications failure occurred on Cassini, not Huygens, and was caused by an error "as simple as throwing a switch to, On. The science projects team at ESA did not switch on Cassini`s software; Doh!.
"In Space no one hears you scream"
The probe was to transmit data on two channels, A and B. A Doppler wind experiment was to use Channel A, a very stable frequency.
But the order to activate the receiver, or oscillator, for Channel A a signal was never sent, so the entire mission operated through Channel B, which is less stable. However, there is hope that some of the data survived. The doppler wind data from Huygens will need to be pieced together from the many ground telescopes that were tuning into the probes descent, due to the communications glitch.
"We do have Channel B data and although driven by a very poor and unstable oscillator, we may be able to get a little bit of data.
Some of the Channel A signal reached Earth and was picked up by radio telescopes. "We now have some of this data and lots of work to do to try to catch up."
The National Radio Astronomy Observatory's Very Long Baseline Array radio telescope, which is operated from Socorro, New Mexico, used eight of its 10 dishes to listen to the 10-watt transmissions from Huygens during the probe's descent.
The VLBA collected about 7 1/2 hours of data on magnetic discs beginning at about 2 a.m. Friday from the probe.
The craft had sent back three hours, 37 minutes and 26 seconds of data. Seventy minutes of this was transmitted from the surface.
Raw images from the Huygens probe descent ESA page 2 (Of 37)
This view from Cassini's second close flyby of Titan on Dec. 13, shows bright material within the large dark region west of Xanadu. The area in this image is a region that has not previously been seen at this high resolution. The image was taken with the narrow angle camera at a distance of approximately 125,900 kilometres from Titan, using a filter centred at 938 nanometres that emphasizes the moon's surface and clouds. The image scale is 735 meters per pixel.
for computer-rendered views from the Cassini
Saturday 25 December
Spacecraft operations will be run at NASAs Jet Propulsion Laboratory (JPL) in Pasadena, California.
05:08 CET - Separation of the Huygens probe from the Cassini orbiter.~07:00 CET - Status report upon successful separation from NASA/JPL.10:00 CET at the latest : ESA press release assessing the separation of the Huygens probe.~10:00 CET - ESA TV Video News Release produced at JPL during separation
Transmission details will be on http://television.esa.int12:00 CET - Replay of ESA TV Video News Release on separation
Thursday 13 January
17:00-17:30 CET - Press briefing at ESA/ESOC Control Centre in Darmstadt, Germany. Televised on ESA TV
Friday 14 January
Media briefings originated at ESA/ESOC will also be retransmitted to several ESA establishments and across Europe.
ESA TV Broadcast schedule for 14 January 2005
09:00-09:30 CET - ESA TV broadcast - Cassini turns to Huygens - Feeds from ESA/ESOC main Control Room. 11:00-12:15 CET - ESA TV Broadcast - Probe activation to parachute deployment and status of tracking by radio-telescope. 13:30-14:00 CET - Press briefing at ESA/ESOC: Huygens descent update (with results from ground radio telescope observations televised on ESA TV 14:30-15:00 CET - ESA TV broadcast: mission update. 16:00-16:30 CET - ESA TV broadcast: mission update. As of 17:15 CET - Press briefing: arrival of first data televised on ESA TV. 23:00-24:00 CET - Press briefing: presentation of first image if available) - Televised on ESA TV
and cover an area extending out to 30 kilometres.
8 kilometres above the surface ( Full Size Image)
A panorama of the surface. Scientists speculate that the white streaks are a ground 'fog' of methane or ethane vapour
click here for interactive panorama
Huygens is going to descend during `daylight hours`. Sunlight filtering through the casts an orange glow across the landscape "like 1000 full moons, and bright enough to read a newspaper, but still about 1000 times dimmer than a sunlit day on Earth. Just before Huygens lands it will turn on an intense flashlight to shine onto the terrain below. This is done to improve pictures of the landing site and help the probe's spectrometers get better readings of elements and minerals in the soil."The gods smiled on us." - ESA's space science director David Southwood,
Landing Site (Full Size Image)
The largest octagon is about 1,120 kilometres across and represents the field of view for the mosaic of images taken at an altitude of 150 kilometres. From that height, individual pixels in the centre of the image will be about 150 meters across, though haze between the ground and the camera at that height will likely degrade the resolution in those images.
The progressively smaller octagons are the anticipated fields of view from altitudes of 90 kilometres, 50 kilometres and 30 kilometres. In all, the camera is expected to acquire panoramic mosaics at a total of 20 different altitudes from 150 kilometres down to about 3 kilometres. The pixel size in the mosaic from 3 kilometres high will be about 3 meters across. In addition, the camera is expected to obtain individual images down to an altitude of about 200 meters with pixel size as small as 20 centimetres. The location of the anticipated landing site is based on modelling of Titan's winds, and the actual landing site will be different if the actual winds experienced by Huygens during descent differ from this model.
On 17 December the orbiter was placed on a controlled collision course with Titan in order to release Huygens on the proper trajectory, and on 21 December all systems were set up for separation and the Huygens timers set to wake the probe a few hours before its arrival at Titan.
The Huygens probe separated on the morning of 25 December at about 02:00 UTC (03:00 CET) . Since the Cassini orbiter will have to achieve precise pointing for the release, there will be no real-time telemetry available until it turns back its main antenna toward Earth and beams the recorded data of the release. This signal then took 1 hour and 8 minutes to cross the 1.2 billion kilometres separating the Cassini spacecraft and Earth. Separation was achieved by the firing of pyrotechnic devices. Under the action of push-off springs, ramps and rollers, the probe was released at a relative velocity of about 35 cm per second, and, to keep on track, will spin on its axis, making about 7 revolutions a minute.
Huygens drifted through space until it hits Titan's atmosphere on January 14 at about 1013 GMT moving at 10 miles a second. The dense air encountered by the probe rapidly slowed it down, allowing Huygens to drift downward under a deployed parachute for almost three hours. During the descent onto Titan, the Huygens probe scanned the surrounding atmosphere to analyse its composition and take more than 1,000 images as it heads toward the surface.
Huygens entered Titans atmosphere at a relatively steep angle of 65° and a velocity of about 6 km/s. The target was over the southern hemisphere, on the day side. Protected by an ablative thermal shield, the probe decelerated to 400 m/s within 3 minutes before it deploys a 2.6 m pilot chute at about 160 km. After 2.5 seconds this chute pulled away the probes aft cover and the main parachute, 8.3 m in diameter, was deploy to stabilise the probe. The front shield was then released and the probe, whose main objective is to study Titans atmosphere, opened inlet ports and deploy booms to collect the scientific data. All instruments will have direct access to the atmosphere to conduct detailed in-situ measurements of its structure, dynamics and chemistry. Imagery of the surface along the track was also acquired. The Descent Imager/Spectral Radiometer took pictures as the probe slowly spins. These data was transmitted directly to the Cassini orbiter, which, at the same time, will be flying over Titan at 60 000 km at closest approach. Earth-based radio telescopes have detect the signals tone directly.
15 minutes into the descent, at about 120 km, Huygens released its main parachute and a smaller 3 m drogue chute which took over to allow a deeper plunge through the atmosphere within the lifetime of the probes batteries.
The descent lasted about 140 minutes before Huygens impacted the surface at about 6 m/s. The probe has survives all this, and its extended mission will start, consisting in direct characterisation of Titans surface for as long as the batteries can power the instruments and the Cassini orbiter is visible over the horizon at the landing site, i.e. not more than 130 minutes.
At that time, the Cassini orbiter reoriented its main antenna dish toward Earth in order to play back the data collected by Huygens, which will be received by NASAs 70-m diameter antenna in Canberra, Australia, 67 minutes later. Three playbacks are planned, to ensure that all recorded data are safely transmitted to Earth. Then Cassini will continue its mission exploring Saturn and its moons, which includes multiple additional flybys of Titan in the coming months and years.
After release, Huygens did not communicate with Cassini for the whole period until after deployment of the main parachute following entry into Titans atmosphere. Titan's atmosphere, which is about 95% nitrogen and 5% methane, has a pressure near the surface that is one and a half times the Earth's sea level pressure.
On 28 December Cassini will then manoeuvre off collision course to resume its mission and prepare itself to receive Huygens data, which it will record, to later relay back to Earth.
These images show the surface of Titan at two different infrared wavelengths. They were captured by the visual and infrared mapping spectrometer onboard Cassini as the spacecraft flew by at an altitude of 1200 kilometres - Cassini's closest approach yet to the hazy moon. The image on the left, taken at a wavelength of 2 microns, is the most detailed picture to date of the Titan's surface. It reveals complex landforms with sharp boundaries, which scientists are eager to further study. The image on the right was taken at a wavelength of 1 micron and shows approximately what a digital camera might see. It seems from the pictures received that this area is geologically alive, possibly with liquids moving on its surface.
However, synthetic aperture radar images of the surface, captured on Oct. 26, when the Cassini spacecraft flew approximately 2,500 kilometres above the surface, show that the dark regions may represent areas that are smooth, made of radar-absorbing materials, or are sloped away from the direction of illumination. A striking bright feature stretches from upper left to lower right across this image, with connected 'arms' to the East. The fact that the lower (southern) edges of the features are brighter is consistent with the structure being raised above the relatively featureless darker background. Comparisons with other features and data from other instruments has determined that this is a cryovolcanic flow, where water-rich liquid has welled up from Titan's warm interior.Previous Photometric profiles showed considerable variations across dark areas that were identified as possible lakes or seas. A liquid surface would have been more uniform. "There is no evidence of oceans," But it turns out that there is hydrocarbon flows and lakes. Most of the features seem to be volcanic in nature, produced by flowing ice rather than molten rock.
View from ten miles up:Seen are streams, valleys and to the right a coastline.
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.
On Christmas day Huygens began its final journey to Titan
At 1.25 billion kilometres from Earth, and after a 7-year journey, ESAs Huygens probe separated from the Cassini orbiter to fall towards Titan, the largest moon of Saturn, to enter its atmosphere on 14 January 2005, 1013 GMT, and landing on the surface at 1234 GMT.
This was the first man-made object to land on a this strange world, whose chemistry was assumed to be very similar to that of the early Earth just before life began, 3.8 billion years ago.
The Cassini orbiter, carrying the Huygens strapped to its belly, entered orbit around Saturn on 1 July 2004, and began a four year mission to explore strange new worlds. The Cassini space probe carries two cameras, one with a narrow angle (0.35 degrees field of view) and the other with a wide angle (3.5 degrees).
Landing Site false colour (Full Size Image)
This image shows a full 360-degree view around Huygens. The left-hand side, behind Huygens, shows a boundary between light and dark areas. The white streaks seen near this boundary could be ground 'fog' of methane or ethane vapour, as they were not immediately visible from higher altitudes. As the probe descended, it drifted over a plateau (centre of image) and was heading towards its landing site in a dark area (right). This dark area is possibly a drainage channel which might still contain liquid material. From the drift of the probe, the wind speed has been estimated at around 6-7 metres per second.
Landing Site Location
Geothermal activity from underground heat sources on titan may generate methane through the oxidation of iron contained in hot basaltic rocks. The process releases hydrogen which combines with carbon to form methane.
Landing polar panorama (Full Size Image)
The `Airstrip` Detail
Click to Expand the Images!
This is an improved (Better than the ESA offering below) image of the surface.
8 kilometres above the surface( Full Size Image) 216 kb
These images were taken with a resolution of about 20 metres per pixel and cover an area extending
A billion miles from Earth, a small saucer-shaped spacecraft emerged from the fiery turmoil of an atmospheric entry.Seconds later, a set of explosive bolts fired, and its charred heat-shield fell away. A parachute then opened and the craft slowly began its descent, gently buffeted by winds.With temperatures hovering at a chilly -180C, it finally touched down on the freezing surface of this distant world.Not the opening chapter of a science fiction novel, but an accurate description of the extraordinary moment on 14 January 2005 when the European Space Agency's Huygens probe landed on the surface of Saturn's largest moon, Titan.Read more
A billion miles from Earth, a small saucer-shaped spacecraft emerged from the fiery turmoil of an atmospheric entry.Seconds later, a set of explosive bolts fired, and its charred heat-shield fell away. A parachute then opened and the craft slowly began its descent, gently buffeted by winds.With temperatures hovering at a chilly -180C, it finally touched down on the freezing surface of this distant world.Not the opening chapter of a science fiction novel, but an accurate description of the extraordinary moment on 14 January 2005 when the European Space Agency's Huygens probe landed on the surface of Saturn's largest moon, Titan.
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.