Cassini-Huygens Working at Titan

Data
Operations

Data

Titan is by far largest Saturn's moon and like Ganymede at Jupiter one of the largest in the solar system. It features no plate tectonics. Moreover it's the sole solar system's moon with an atmosphere. Its atmosphere is organic compounds-rich as such organic molecules at Titan are resulting from the interaction of Sun's ultraviolet with the atmosphere's methane and nitrogen. Once formed the prebiotic molecules are falling on Titan's surface where liquefied ethane and methane might be found under the form of hydrocarbons lakes and oceans. Due to some impacts or ice volcanism such deposits of organics might turn into amino acids as liquid water would be provided during time spans of thousands of years. Some even think that life might be readily found at Titan or that life could have appeared through a chemistry of the hydrocarbons only. Or that lightning in Titan's atmosphere are the catalyst which binds molecules together into DNA precursors. "Titan is like a time machine taking us to the past to see what Earth might have been like," said Dr. Dennis Matson, Cassini project scientist at NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif. "The hazy moon may hold clues to how the primitive Earth evolved into a life-bearing planet." Hence Titan is a place of choice for astrobiologists. During its two and a half hour parachuting descent the European ESA Huygens probe will take 1,100 pictures as it will gather data during 30 minutes once on the surface if it survives the 16 mph impact. In case it would touch down at a lake or an ocean, it would float among slow, tall, waves seven times higher than at Earth. On the other hand data from afar will be acquired and mapped by Cassini during its 45 flybys at Titan. The atmosphere of Titan had been noticed containing prebiotics as soon as by the Voyager missions. see more data about Titan

Once it's hydrogen fuel is almost exhausted, the Sun will begin to expand into its red giant phase, becoming much more luminous. When this happens Titan will awaken from its state of hibernation and life on Titan May become a reality. This phase will unfortunately exist for only a brief time. Once the Sun's core is hot enough, it will begin to burn helium. This leads into a second stable phase but with a much higher luminosity than the present-day Sun. This in turn moves the solar system's habitable zone from Earth out to Titan

Operations

Titan Seen by Cassini-Huygens (Pre-Insertion, and Insertion Flyby)
Cassini Titan Flybys
Titan Seen by ESA Huygens

->It Really Rains Methane at Titan!
An observation, by April 2009, by a terrestrial telescope, of a large, tropical storm at Titan is showing that methane really rains at Titan, likely helping to replenish the lakes!

->Titan Crust's Rotation Decoupled from the Rocky Core, Through an Underlying Ocean? (March 2008)
Titan has been found with maybe an underground ocean of water and ammonia. That was infered from shifts seen up to 19 miles (30 km) for surface features, hinting to that Titan's icy crust is decoupled from its core by an internal ocean. The ocean might be 62 miles (100 km) beneath the surface. Such a process is at work too at Jupiter's Europa and needs a sufficiently thin crust, and an ocean deep enough, decoupling the crust's rotation from the moon's rocky core. An alternate explanation might be the effect of the winds of an extremely dense atmosphere, creating a moment of inertia of the crust. The differences in position have been measured at Titan on a timespan of 2 and a half years

->A Better Idea About The Internal Structure of the Moon Brings More Explanation About the Methane and The Methane-Related Surface Features at Titan
Using Cassini-Huygens data, a model of how the methane production evolved at Titan has been built by March 2006
- a first supply of the gas was provided following the accretion and differentiation period of Saturn's moon, when the moon got a rocky, silicate core, a water-ammonia mantle and an icy crust during the first 1 billion or maybe just some hundreds million years in the history of Titan. The methane which was released then was reabsorbed into the interior however as what could manage its way into the atmosphere was photochemically destroyed in a timespan of 1 billion years
- then came the radioactive heating of the silicate core, 2 billion years ago. The softened core was the place of convection, this natural, heat-dissipating motion in a liquid body. Heat headed up into the liquid mantle, thence into the icy crust, which thinned, leading to another episode of methane release
- the most recent -and last- episode occurred 500 million years ago from solid-state convection in the outer crust cooling the moon
This leads to a view of the current geology of Titan's interior, with a methane-rich ice crust existing atop an ocean of liquid water mixed with ammonia, lying a few tens of kilometers below the surface. A rocky core, at last, shoud be found in the depths of the moon. It's thermal anomalies, generated by the crystallisation in the internal ocean that yield the cryo-volcanism, leading to the outgassing of the methane. This explains why the atmosphere of Titan is constantly replenished with the gas as this accounts too for the river-like features seen at the surface. Flows of methane are also released by the process. The quantity of methane released now, however, is just enough to replenish the atmosphere, though not enough to allows for the famed widespread methane seas which were expected to be found at the surface of Titan. The production of methane won't go further, on the other hand, leading in the next few hundred million years to the end of the cryo-volcanism, with, the haze clearing, and photochemistry destroying the surface methane and drying Titan up. Cryo-volcanism and the search for evidences of the subsurface liquid ocean should be the main targets of the remaining work of Cassini about Titan

->Long Winter Night Concentrates Primordial Molecules Above Titan's North Pole!
A study by the Composite Infrared Spectrometer instrument (CIRS) principal investigator at NASA's Goddard Space Flight Center, Greenbelt, Md., published May 13, 2005 in the Journal Science, is showing how strong circumpolar winds around Titan's North Pole are isolating the atmosphere around there during the long polar night. This produces a polar vortex similar to the one that occurs on Earth. The vortex features raised walls. At Earth, this isolation, at the South Pole, allows the formation of polar stratospheric clouds which, in turn, lead to the famous "ozone hole". At Titan, this seems to concentrate over the pole the organic (carbon-containing) molecules which are manufactured in the moon's atmosphere. Polar clouds, should they exist at Titan too, could further react with these molecules. Titan's axis of rotation tilt combined with the long orbital period of Saturn is yielding a winter night which lasts many Earth years. It's currently early winter in Titan's northern hemisphere

Titan Seen by Cassini-Huygens (Pre-Insertion, and Insertion Flyby)

from left to right: view of Titan general surface features, striking details view of Titan southern hemisphere, Titan neutral hydrogen cloud, a map of Titan. pictures courtesy from left to right): based on picture NASA/JPL/University of Arizona, NASA/JPL/Space Science Institute, NASA/JPL/JHU/APL/Max-Plank-Institut für Aeronomie/University of Maryland/University of Kansas/University of Arizona/CESR/Bell Laboratories. Map courtesy NASA/JPL/Space Science Institute

Cassini began imaging Titan mid-April 2004 as it was approaching Saturn. Its first pictures were already rivalling best Earth-based images and were showing features already observed by the Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) in 1997 and 1998. Further pictures gave an improved vision of Saturn's larger moon. Eventually Cassini performed it first flyby at Titan just following its Saturn orbit insertion maneuver on July, 1st 2004 (June, 30th EDT). The craft flew 211,000 miles (340,000 km) over moon's south pole, showing the moon's surface with unprecedented clarity. Picture 1 is showing general composite and specific views of Titan (areas of water ice (dark), of hydrocarbons (light) as methane clouds are white or light (like the neat spot near the South Pole)) as picture 2 is a striking close view of Titan southern hemisphere (probably color-inverted; a cloud pile is visible near the South Pole). Lack of craters suggest active geological processes. Picture 3 is showing the neutral hydrogen gas cloud, 44,000 miles wide (70,000 km) Cassini discovered surrounding Titan. A further region, as wide as the whole Saturn's ring, is surrounding it! This is due to energetic ions from Saturn's radiation belts knocking out hydrogen from Titan's atmosphere. As Titan makes a complete 360-degree orbit around Saturn, the relative influence of the sun's illumination and the hot ionized gas trapped in Saturn's magnetic bubble changes. Previously to the Saturn Orbit Insertion, Cassini team had released a most recent map of Titan built on pictures taken June, 2nd-22nd 2004, and showing shadowy features and mysterious markings which might be related to tectonics. The bright region "Xanadu" is seen too (bright) on the map, as might be impact craters

	First pictures of Titan taken by Cassini mid-April, with a Hubble-based map. Xanadu, the brightest albedo feature at Titan is seen (red on Hubble's map) with darker features (left). picture courtesy NASA/JPL/Space Science Institute
	Titan snapped on May, 5th 2004. More details are seen as Cassini had come to 29.3 million kilometers (18.2 million miles) from the moon. What is seen of Titan is comprised between 180 and 250° of longitude. picture courtesy NASA/JPL/Space Science Institute
	An improved view of the surface, June, 14th 2004 using infrared and a polarizing filter. Distance is 6.5 million miles (10.4 million km). picture courtesy NASA/JPL/Space Science Institute
	Seen in visible light, Titan is remaining an enigma. Picture was taken on May 23, 2004, from a distance of 13.4 million miles (21.6 million km). picture courtesy NASA/JPL/Space Science Institute
	Two tones atmosphere seen at Titan in methane sensitive filter. Such a feature had already been seen by Voyager 23 years ago but it is now inverted due an opposite seasons pattern. picture courtesy NASA/JPL/Space Science Institute
	Titan as seen in color in visible light June, 10th 2004. picture courtesy NASA/JPL/Space Science Institute
	Two layers of atmospheric haze seen at Titan. Such haze is made of organic molecules manufactured by ultraviolet breaking down nitrogen and methane. Outer layer is hard to see in this unprocessed picture. picture processed from picture courtesy NASA/JPL/Space Science Institute
	Titan's atmosphere is seen being one sixth the diameter of the globe as Cassini capture methane (green) and carbon mooxyde (red) emissions in the infrared. An alien at Titan would see the atmosphere glowing even at night! Leftmost view is mostly Titan's surface. picture courtesy NASA/JPL/Space Science Institute

Cassini Titan Flybys

all Titan flybys are to be found on a dedicated page

Titan Seen by ESA Huygens

see pictures below

The European ESA probe Huygens' successfully descended into Saturn's largest moon's atmosphere and landed there last January 14th, 2005, adding to unveiling Titan's atmosphere and surface! The landing site resembled a dried lakebed with channels and valleys nearby, hinting at the sporadic presence of surface liquid. A year later the presence of liquid-filled lakes was confirmed at Titan
Titan, like most of its faraway siblings is an icy moon as, on the other hand, it's the only moon of the solar system with an atmosphere. It's these both elements which explain Titan's topology. The methane is Titan's main erosion agent, akin to what water is making at Earth, yielding precipitation, erosion, and fluvial activity. Methane, on the other hand is acting on ice instead of rocks! All those eroded plateaus, those elevated terrains with drainage channels, those fluvial shapes or carved out islands, all are the result of the erosion process. Another type of Earth-like geological process at Titan is the one which produced cobblestones or other polished rocks at the mouth of riverbeds coming from some neighbouring -or distant- relief. Flash flooding of liquid methane and ethane carved and tumbled such elements from water ice, which constitute Titan's rocks, at about minus 180 degrees Celsius (minus 290 degrees Fahrenheit). A bright region in Xanadu is thought to be packed with such spherical rocks. Cryo-volcanism is at work too at Titan, on the other hand, spewing water ice and ammonia. It might that heat be trapped inside a layer of water ice and methane close to the surface. The heat, at interval, produces cryo-volcanism. This was seen as Huygens detected the presence of the isotope Argon 40. All these eroding mechanisms are explaining why mostly no impact craters have been seen at Titan. The presence of the Argon 36, on the other hand, is showing that Titan formed after Saturn, at a moment with the primeval gas cloud which gave birth to the Sun and the planets had cooled down to about 40°K (-420°.F; -233°.C). Titan' soil is loose sand possibly due to methane rains falling over eons or to liquids percolating from below, as it's covered by a thin, solid crust, the origin of which is still unknown. A new analysis of how Huygens landed on Titan, some years after landing, reveals that if something put little pressure on the surface, the surface was hard, but if an object put more pressure on the surface, it sank in significantly. The surface was soft enough to allow the probe to make a sizeable depression, but hard enough to support Huygens rocking back and forth. The impact also threw up a 'fluffy' dust-like material –most likely organic aerosols- which remained suspended in the air for around four seconds after the impact. Since the dust was easily lifted, it was most likely dry, suggesting that there had not been any rain of liquid ethane or methane for some time prior to the landing. It's still ill-known whether the lakes seen at Titan are of a permanent nature or whether some dry and rain seasons are alternating at the moon. Huygens, further, just dropped unto an outflow wash, with the soil made of compacted gravel
What for the atmosphere now? First, the cycle of the methane, like at Earth, is providing for the weather at Titan, with clouds appearing at intervals at some latitudes. The methane-ethane cycle is to Titan what water's is to Earth. Titan's atmosphere is an uniform mix of nitrogen and methane in the stratosphere as the methane proportion steadily is increasing in the troposphere, down to the surface. Ethane, too, is part of the atmosphere, as it's the methane and ethane which provide humidity, being the equivalent there of the water in the Earth's atmosphere. Clouds of methane at 12.5 miles (20 km) of altitude have been detected, as was methane or ethane fog nearer to the ground. Aerosols were collected between 78 and 12.5 miles (125-20 km) of altitude. The probe's descent was more bumpy than expected. As the probe descended at 110 mph (50 m/s) in the upper atmosphere, it then slowed down to 1.5 m/s in the lower atmosphere whith a lateral drift of 3.3 mph (1.5 m/s). The more noticeable is that Huygens rocked a lot in the upper atmosphere, tilted by 10 to 20° as it was more stable below the haze layer, with a tilt of less than 3°. Such a behavior might be traced back to a change in wind profile at about 15.5 miles of altitude (25 km). An ensueing report, stating measurements of winds made through a global network of radio-telescopes receiving the probe's signal, showed that winds are actually ranging from weak near the surface to rough, with strong vertical wind shear above 37 miles of altitude (60 km) -which is ill-explained, as a slow increase with altitude is seen up to that high only. Strong westerly wind of up to 250 mph (400 km/h) were seen at high altitude. The haze, on the other hand, was expected to disappear between 43-30-mile high (70-50 km). The probe did emerge from the haze at 19 miles of altitude (30 km) only however. At an altitude of 317 miles (510 km), further, a jet stream exists, similar to that of Earth, with a temperature inversion. It's moving at 447 mph (720 km/h) at a latitude of 50°N. In addition scientists saw the probe drifted two degrees North of East, while dropping from 90 to 31 miles (145 to 50 km). Between altitudes of 19-12,5 miles (30-20 km) , it turned five degrees South before resuming its eastward motion. At 4 miles (6.5 km), it reversed to a West-northwest direction before turning back to a southeast drift at 0.4 miles (0.7 km). Some low-lying, ground fog, of perhaps ethane or methane, might have been seen -that is fog like the one seen Earth when the surroundings are masked but the sky above may be seen -or it might be snow. Winds up to 370 mph (600 km/h) were recorded at high altitude with temperatures as low as - 330°F (-200°C). Around an altitude of about 12 miles (20 km), scientists further found that the probe endured a 20-minute period of turbulences likely due to some cloud layer there. The temperature of the landing site was -290°F (-179°C), with a humidity of 45 percent. Due to the high degree of "vapor" in Titan's atmosphere, one has to expect intense showers there. Methane (CH4) is what everybody knows under the name of "natural gas". Methane is much more fluid than water, with half the density of it. Winds at the surface are predominantly West-East
As far as the life-prone particles in the atmosphere as concerned, these hydocarbon particles forming in Titan's haze are concerned, they just settle out onto the landscape features, from where they are washed away by the rain, running through the drainage channels and rivers, down to the lower areas, which due to this material, are turning darker than the surrounding relief features, leading to that the potential for life is, at the same time, an element of landscape-forming at Titan
Surprisingly, the components of the atmosphere of Titan analyzed by the probe were found to contain ammonia-like structures albeit there is little or no ammonia in the atmosphere from which the particles form. The atmosphere of Titan, generally is mostly nitrogen with 2 to 3 percent methane as what replenish methane is unknown


.top: color panoramic view of Titan from 5 mi (8 km), colorized site 'Amateur Astronomy'; left of the view is behind the probe
.first row (from left to right): Titan seen on Saturn's background (picture "Celestia", solar system simulator); Titan's seen from the vertical during ESA Huygens descent (pictures taken from 8 to 5 miles high (13-8 km)) -the area is about 19-mile (30 km) wide, and matches the color panorama; original black-and-white panorama (5 miles (8 km) of altitude); detailed part of the panorama (5 miles (8 km) of altitude) showing a plateau; the same plateau seen from a vertical vantage point; detailed view of the left part of the panoramic view with a raised, drainage channels-featured terrain along a low area, and with possibly ground fog; the same view from the vertical; the same view, from the vertical, more detailed still (colorized site 'Amateur Astronomy')
.second row (from left to right): islands carved out from a dark plain (colorized site 'Amateur Astronomy'); a bright, long, feature is likely ice extruded on the surface as stubby dark channels might be the marks of methane springs (colorized site 'Amateur Astronomy'); two same views of Titan's surface, one of them ESA-colored (pebbles -in fact dirty ice blocks- at the foreground are 6 x 1.5 inches (15 x 4 cm), lying at 2.8 ft (85 cm) as the scattered ones (about the same size, barely smaller), further, are at 7.9 ft (2.4 m). The horizon is lying at about 290 ft (88 meters)); landing area as seen from 9,800 ft -3,000 m (colorized site 'Amateur Astronomy'); landing area as seen from 2,600 ft -800 m with the area being 4,300-feet wide and dark channels 100-130 ft in width (30-40 meters) (colorized site 'Amateur Astronomy'); landing area closeup (released by ESA in November 2005, North is up; white points are probe's ground track; other draining channels are seen as the surface, rocky view seen by Huygens might show the effect of the outlet of such a channel)
.third row (from left to right): perspective view of the ridge and valleys (total relief about 500ft -150 m; blue is lowest, red is highest) with steep sides ranging up to 30°.;perspective view of the dark plains along with bright features (same color-coding than previous, relief is reaching 150 ft -50 m)

all pictures ESA/NASA/University of Arizona, except colorized panorama (top), colorized vertical view (first row, second picture), colorized drainage channels area (first row, last picture), colorized islands and ice and springs, colorized views of the landing area (second row, two last pictures) site 'Amateur Astronomy',langing area closeup, picture ESA/NASA/JPL/University of Arizona, and two perspective views of the third row, pictures ESA/NASA/JPL/University of Arizona/USGS

->see data about the Huygens probe's descent