Titan News 2018


June 6, 2018 : What Are The Differences Between The Dunes Of Venus, The Earth, Mars, Titan And Pluto ?

The Earth is not the only world in the Solar System where we can encounter dunes. The numerous probes sent to other worlds, planets, moons, asteroids or comets have revealed that several worlds located in our Solar System unveil dunes. That's the case for Venus, Mars, Titan and Pluto. The planet Venus, which is almost as big as the Earth, is well known for its numerous big volcanoes, for its thick and opaque atmosphere containing clouds of sulfuric acid and for its extreme environmental temperatures. But we also have to keep in mind that Venus is a dry world unveiling dunes. The planet Mars is clearly a colder world than Venus or the Earth but it also unveils dunes in its dry environment. Saturn's largest moon, Titan, is even colder than Mars and it is rich in dune fields. The Dwarf Planet Pluto, which is largely smaller than Titan, Ganymede or Mercury, reveals dune fields as well. Many questions appear regarding the dunes of those worlds. What is the origin and the nature of those dunes ? What is their dynamics ? Are there differences between those dunes in terms of size or composition ?

Why are there significant dune fields on certain worlds and not on other worlds ? Have you ever wondered whether there are typical dunes on Mercury or on the Moon ? In fact, Venus, the Earth, Mars, Titan and Pluto have the common point of having an atmosphere which is not the case for Mercury, the Moon or Ganymede. Dunes are generally the outcome of erosion. Rainfall, snowfall, rivers, seas, oceans or winds engender erosion. That's why the presence of an atmosphere is required for the development of dunes on any world. Liquid water on Earth plays a major role in the formation or development of dunes. Meteorological phenomena such as evaporation, condensation and precipitation processes engender a dynamics which makes the development of dunes possible. Obviously, liquid water is not the only liquid which can engender dunes. Other liquids such as liquid methane, liquid ethane, liquid propane, liquid nitrogen, liquid ammonia or liquid carbon dioxide are likely to engender dunes on other worlds. Thanks to the exploration of Titan via the Cassini spacecraft, we know, now, that there can be exotic types of erosion produced by another type of liquid than liquid water. There is a meteorology involving liquid methane or liquid ethane on Titan and liquid methane or liquid ethane can be found on the surface of the Orange Moon.


The image in the upper part of this table unveils a portion of a radar swath of Titan's surface obtained with the Radar Mapper of the Cassini probe on October 28, 2005 during the T8 Flyby. One can notice, in particular, parallel and linear dunes extending over long distances. The Titanian dunes, reminiscent of the Seif Dunes found in the Namib Desert, are located in the low-albedo areas found at low or mid-latitudes. Topographic obstacles can be observed here.
The image in the lower part of the table, obtained via Google Earth, unveils an area of dunes located in the Taklamakan Desert in China. The chemistry of Titan's dunes may be completely different from the chemistry of typical dunes on our planet. The dunes of Saturn's largest moon may be rich in organics, hydrocarbons or tholins. Both images are 100 km wide and 100 km high and have the same scale. The color of the original image of the Taklamakan Desert has been removed.

Credit for the original radar view of Titan: NASA/JPL/Cassini RADAR Team/Jason Perry.
Credit for the original view of the Taklamakan Desert: Google Earth.
Credit for the montage and the image adjustments: Marc Lafferre, 2018.

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May 19, 2018 : Could We Put Pluto, Ganymede Or Titan Into The Category Of Planets ?

Today, there are officially eight planets in the Solar System. Prior to the major change of 2006 in the classification of planetary bodies, there were officially nine planets in the Solar System. The nine planets, from the Sun to the Outer Solar System, were Mercury, Venus, The Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Since the reclassification of planetary bodies performed by the International Astronomical Union (IAU) in 2006, Pluto is not part of the category of planets anymore. Yet, Pluto is quite big and is not the moon of another planetary body. Pluto is now part of the category of Dwarf Planets. From the discovery of Pluto by Clyde Tombaugh in 1930 to the revolution of 2006, Pluto had been considered a planet. Why is Pluto part of another category of planetary bodies ? Why aren't Pluto, Ganymede, Titan or Ceres planets ? To a certain extent, the current classification can be misleading for the general public since there are more than eight planetary bodies in the Solar System. Some moons like Io, Titan or Triton can be more interesting to study or explore than planets like Mercury, for instance.

Since the revolution of 2006, a celestial body must satisfy three criteria to be considered a planet. First, the planetary body must turn around the Sun and it must not turn around any other celestial body than the Sun. In other words, if the planetary body is a moon or a natural satellite, it is not a planet by definition. Second, the celestial body must be large enough to be round, spherical or spheroid or the celestial body must have enough gravity to be round, spherical or spheroid and the celestial body must have a gravity which is too low to make fusion reactions possible in its interior. In other words, the gravity of the celestial or planetary body must be high enough to make the planetary body round, spherical or spheroid but it must be lower than that of a star like the Sun or Proxima Centauri. Third, the celestial body or planetary body must have  cleared its neighborhood  of debris, asteroids, comets or planetary bodies. Pluto doesn't meet the third criterion since Pluto is part of a family of planetary bodies, asteroids or comets evolving beyond Neptune in a ring of icy bodies known as the Kuiper Belt. Pluto is in fact a Kuiper Belt Object or KBO like Charon, Makemake and Haumea. Further collisions or aggregation and accretion processes are needed in the Kuiper Belt to turn the future Pluto into a planet according to the new definition.


The image above reveals the Earth, Ganymede, Titan and Pluto at scale. Ganymede, which is the largest moon of Jupiter, and Titan, which is the largest moon of Saturn, are the biggest moons in the Solar System. Pluto is the largest Dwarf Planet identified in the Solar System and the second most massive Dwarf Planet identified in the Solar System behind Eris. Pluto used to be considered a planet until the famous discovery of Mike Brown in 2005. Could we regard those planetary bodies as planets like the Earth, Mercury or Mars, due to their significant size ?

Credit for the original view of the Earth: DSCOVR.
Source of the original view of Ganymede: Wikipedia.
Source of the original view of Titan: Wikipedia.
Source of the original view of Pluto: Wikipedia.
Montage Credit: Marc Lafferre, 2018.

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April 24, 2018 : The Geology, The Chemistry And The Biology Of The Danakil Depression May Help Us Better Understand Mars And Titan

The study of the Danakil Depression, Dallol or the saline Lake Afrera is likely to allow us to better understand or analyze exotic places on Mars or Titan. The Danakil Depression, located in Ethiopia, represents an extreme environment where life has to withstand high temperatures, a high level of acidity or an hostile chemistry. That's why the area is a perfect place to study extremophiles. The hostile region of the Danakil Depression is also reminiscent of Io, the active moon of Jupiter whose surface looks like a pizza in terms of texture from outer space. A parallel can also be drawn between the conditions found in the Danakil Depression and the conditions found in sites made of nuclear waste. A few months ago, from January 20 to January 28, 2018, five groups of scientists and more than 30 support staff explored two places in the area to analyze the microbiology, the geology and the chemistry at the Dallol hydrothermal outcrop and the saline Lake Afrera in northern Ethiopia. The expedition performed by the scientists was supported by the Europlanet 2020 Research Infrastructure (RI) financed by the EU.

The Europlanet 2020 Research Infrastructure has organized several field campaigns over the past two years to carry out a comparative analysis between the environment of the region and the environment of other planetary bodies and to improve our knowledge or understanding in terms of biology or exobiology. The famous volcano Dallol, located in the Danakil Depression in Ethiopia, has been explored by the researchers Karen Olsson-Francis and Vincent Rennie from the Open University who study the ecosystem of that hostile environment. Dallol has a particularly low elevation since its mean elevation is lower than the sea level. The ground can be more than 100 meters below the sea level. Organisms or microorganisms in the environment of Dallol must be adapted to the extreme conditions which are characterized by high temperatures, an extreme salinity and an extreme acidity. The area is clearly active with upwelling water heated by magma near the ground. The liquid contains a large concentration of many different salts. The scenery is remarkable with brightly-colored, highly acidic lakes or pools. It is hard to breathe in that environment since there are toxic gases such as chlorine and sulfur vapor in the air close to the surface.


The image in the upper part of this table reveals the area of Dallol in Ethiopia. The view corresponds to a black-and-white portion generated on the basis of a Google Earth view. The portion is 100 km wide and 100 km high. The image in the lower part of the table represents a radar portion of a radar swath of Titan's surface taken from the Cassini spacecraft on October 26, 2004. The radar portion of Titan's surface is 100 km long. Therefore, the scale is the same for each image. The radar view of Titan's surface unveils brigh and linear features which may be related to a cryovolcanic activity. Can we find similarities between that area and the area of Dallol or the Danakil Depression ?

Credit for the original view of the Dallol area: Google Earth.
Credit for the radar portion of Titan: NASA/JPL/Cassini Radar team/Jason Perry.
Credit for image adjustments: Marc Lafferre, 2018.

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April 21, 2018 : The Discovery Of Two Subglacial Lakes At A High Altitude And Depth Beneath The Devon Ice Cap Demonstrates The Potential Existence Of Subsurface Lakes Or Seas Beneath The Presumed Icy Crust Of Europa Or Titan

A new study entitled  Discovery of a hypersaline subglacial lake complex beneath Devon Ice Cap, Canadian Arctic  and appearing in the April 11 edition of Science Advances reveals the finding of two subglacial lakes at a high altitude and at a relatively high depth beneath the Devon Ice Cap, one of the largest ice caps in the Canadian Arctic. The two lakes identified by Anja Rutishauser, a PhD student at the University of Alberta, may represent the first isolated hypersaline subglacial lakes in the world. The subsurface bodies of liquid water are hidden beneath 550 to 750 meters of ice at an altitude between 1,200 meters and 1,700 meters above sea level and are located in long basins in a mountain range. The discovery was performed thanks to radar data acquired from radar antennae mounted to the wings of an aircraft, over a four-year period. The radar data had been collected by NASA and the University of Texas Institute for Geophysics (UTIG) with the purpose of analyzing the bedrock conditions beneath the Devon Ice Cap.

How can we see beneath the layer of ice ? In fact, ice penetrating radar sounding measurements are performed on the basis of electromagnetic waves that are steered towards the surface, that penetrate through the surface and that are reflected back at contrasts in the underground materials, fundamentally allowing researchers to discern subsurface features through the ice. It was really a surprise to identify pockets of liquid water beneath the ice due to the low level of environmental energy. Anja Rutishauser pointed out :  We weren't looking for subglacial lakes. The ice is frozen to the ground underneath that part of the Devon Ice Cap, so we didn't expect to find liquid water. She added :  We saw these radar signatures telling us there's water, but we thought it was impossible that there could be liquid water underneath this ice, where it is below -10C. Water can remain liquid below 0 degree Celsius if the liquid is salty like in our seas or oceans. That's why the subsurface lakes are likely salty but that's not always the case. Some subsurface lakes can exist thanks to hot springs or geothermal activity.


The raw image appearing in the upper part of this table reveals a portion of Titan's surface. The black-and-white view whose file name is W00039716.jpg was obtained on December 5, 2007 from the Cassini orbiter using the IR2 and IR1 filters. The view had not been validated or calibrated and a validated/calibrated view was going to be archived with the Planetary Data System of NASA. The image found in the lower part of the table represents the same view with an artificial color. The surface of Titan can be identified in the infrared or near-infrared spectrum. Are there pockets or seas of liquid water beneath the bright areas observed in that view ?

Credit for the raw image: NASA/JPL-Caltech/Space Science Institute.
Credit for the incorporation of the artificial color into the original image: Marc Lafferre, 2018.

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April 5, 2018 : Scientists Resort To Artificial Intelligence To Assess The Potential For Life On Alien Worlds Like Titan

A group of researchers from the University of Plymouth reveals the potential interest of artificial intelligence in our search for extraterrestrial life on alien worlds in the Solar System and around other stars. Artificial intelligence that is rapidly developing in various sectors can also help us identify exoplanets which have the ingredients or the environmental conditions to host life, from typical lifeforms to more exotic lifeforms. The project mobilizing artificial intelligence to find potential biospheres, here, is proposed by the PhD student Christopher Bishop and his supervisor Angelo Cangelosi who is a Professor in Artificial Intelligence and Cognition. Both specialists are developing an artificial neural network (ANN) based on multiple parameters linked to potential habitability. Their system allows them to classify planetary bodies into five types. Once the researchers have identified the type of world, they are in a position to evaluate the probability of life.

The artificial neural network developed by Christopher Bishop and Angelo Cangelosi, who are based in the Centre for Robotics and Neural Systems, can clearly play a major role in future missions towards other stars like Proxima Centauri or Sirius. We know, now, that there is a planetary body evolving in the Habitable Zone of Proxima Centauri. Are there pools or oceans of liquid water on the surface of that exoplanet known as Proxima Centauri b ? Christopher Bishop, who is also a Lecturer in Radio and Telecomms at the Britannia Royal Naval College in Dartmouth, had to describe his work at the European Week of Astronomy and Space Science (EWASS) in Liverpool. The artificial neural network developed by Christopher Bishop and his collaborator has been trained to classify planetary bodies on the basis of their type or category. The different types of planetary bodies identified by both specialists are the type of the present-day Earth, the type of the early Earth, the type of Mars, the type of Venus and the type of Saturn's largest moon Titan.

This composite view, generated on the basis of infrared data acquired with the Visual and Infrared Mapping Spectrometer of the Cassini orbiter during the T-114 flyby or the flyby of November 13, 2015, reveals surface features on Saturn's largest moon Titan. One can notice in particular the dark regions Fensal and Aztlan which mark a sharp contrast with the surrounding area whose mean albedo is higher. The Opaque Moon may have the highest habitability rating among known planetary bodies beyond the Earth, on the basis of parameters such as availability of energy and several surface and atmospheric characteristics. The artificial neural network developed by Christopher Bishop and his collaborator may help us better identify potential biospheres or key candidates for habitability. Image Credit: NASA/JPL/University of Arizona/University of Idaho.

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March 28, 2018 : What Do We Know About Titan Today ?

Titan, the largest moon of the Gas Giant Saturn, was discovered in 1655 by the Dutch astronomer Christiaan Huygens. There are numerous moons in the Solar System and Titan appears to be the second largest moon in the Solar System. The largest moon of the Gas Giant Jupiter is a little bit bigger than Titan. Titan draws the whole attention of the general public because the giant natural satellite of the Ringed Planet is covered by a significant atmosphere. The astronomer Gerard Kuiper had identified the presence of methane in Titan's atmosphere as soon as 1944. We know today that the atmosphere of the Orange Moon is dominated by molecular nitrogen like the atmosphere of the Earth. However, oxygen is absent or quasi-absent in the atmosphere of the Opaque Moon. Methane, whose chemical formula is CH4, is the second most abundant gas in Titan's atmosphere. A complex haze of organics prevents us from discerning surface features in the visible spectrum from any spacecraft.

The atmosphere of Titan is clearly one of the most striking features of the Orange Moon. Titan is relatively small compared to Earth but the atmospheric pressure on Titan's surface is higher than that of the Earth at sea level. At first sight, Titan seems to have the right combination of gravity and environmental temperature to allow the presence of a significant atmosphere over the presumed icy surface. The Huygens lander, proposed by the European Space Agency, had recorded a surface temperature of minus 179 degrees Celsius or minus 290 degrees Fahrenheit and an atmospheric pressure of 1,467 hPa at the level of the ground on January 14, 2005. Researchers believe that the Titanian atmosphere looks like the atmosphere of the Early Earth. The atmosphere of the Opaque Moon is particularly deep, thick and dense. The gas blanket extends about 370 miles or 600 kilometers high which is significantly higher than the atmosphere of the Blue Planet.

The composite image above reveals a giant ethane cloud system engulfing the north polar region of Titan during the flyby of December 29, 2006. At the time of the observation, the northern hemisphere of Saturn's largest moon was experiencing the Winter season. The image was produced on the basis of data obtained with the Visual and Infrared Mapping Spectrometer of the Cassini spacecraft. A south polar vortex composed of hydrogen cyanide or HCN was also observed in 2012 during the Autumn season of the southern hemisphere. Image Credit: NASA/JPL/University of Arizona/LPGNantes.

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March 10, 2018 : Does Titan Represent A Biosphere With Life Evolving In The Area Of The Ceiling Of The Icy Crust In The Presumed Subsurface Ocean Of Liquid Water ?

A recent study entitled  The Possible Emergence of Life and Differentiation of a Shallow Biosphere on Irradiated Icy Worlds : The Example of Europa , proposed by the astrobiologist Michael Russell of NASA's Jet Propulsion Laboratory in Pasadena, California and published in the journal Astrobiology, suggests that an alien life could evolve in the area of the ceiling of the icy crust of presumed ocean moons like Europa or Titan. Europa is thought to harbor a subsurface ocean of salty liquid water. Some moons like the moons of Jupiter, Ganymede and Callisto or the moons of Saturn, Enceladus and Titan, may also contain the same kind of subsurface ocean. Michael Russell and his collaborators advance that an exotic lifeform can potentially develop in the particular environment found at the boundary between the liquid and the icy layer of the crust thanks to the interactions between chemical energy going up from hydrothermal vents found on the ocean floor and oxidants going down from the surface and the icy crust.

The Earth appears to be the only world in the Solar System containing pools or oceans of liquid water on its surface because there is the right combination of environmental temperatures and atmospheric pressure on the surface at sea level for water to appear in its liquid form on the surface. The main source of energy of our biosphere is sunlight even if some ecosystems can benefit from the energy emanating from internal sources, volcanoes, geysers or hydrothermal springs and evolve in the absence of solar radiations. In the presumed subsurface ocean of liquid water of Europa or Titan, the creatures, from microorganisms to more complex organisms, can't rely on sunlight to evolve or metabolize. As a result, the hypothetical creatures may be mainly based on the heat or the energy rising from hydrothermal vents located in the seafloor. Researchers imagine a configuration involving chemical reactions between molecules or elements from hydrothermal vents or the seafloor and seawater. The heat generated by hydrothermal vents is likely to facilitate complex chemical reactions, to engender key molecules or key building blocks of life and to push microbes and nutrients upward.


The image above corresponds to a composite view of Saturn's moon Titan and Jupiter's moon Europa represented at scale. The original view of Titan represents a natural-color image obtained on January 30, 2012 from the Cassini orbiter. The original view of Europa was obtained from the Galileo probe on September 7, 1996. Europa and Titan may harbor a subsurface ocean dominated by water beneath the external crust. Are there hydrothermal vents fueling hypothetical ecosystems inside those hypothetical oceans ?

Credit for the original image of Titan: NASA/JPL-Caltech/Space Science Institute.
Credit for the original image of Europa: NASA/JPL/DLR.
Montage credit: Marc Lafferre, 2018.

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February 26, 2018 : The Identification Of Seif Dunes At Low Latitudes And Of Lakes Or Seas At High Latitudes On Titan Were Marking Discoveries During The Cassini Mission

Prior to the Cassini-Huygens mission, Saturn's largest moon Titan gathered all the ingredients to draw the attention of researchers and of the general public. The opaque atmosphere of the giant moon prevented us from discerning surface features in the visible spectrum. Some researchers had hypothesized the presence of oceans or seas of methane or ethane on the presumed icy crust of the natural satellite. Some surface features of the Hazy Moon could be identified in the infrared or near-infrared spectrum. The Cassini spacecraft was going to bring new clues or answers regarding surface features or atmospheric features on Titan thanks to the Radar Mapper or the Visual and Infrared Mapping Spectrometer.

As soon as the first part of the Cassini-Huygens mission in 2004, the infrared or near-infrared images acquired from the Cassini orbiter revealed a remarkable contrast between low-albedo areas and high-albedo areas on the Orange Moon. Low-albedo areas were mostly found at low latitudes or at mid-latitudes. Some planetologists believed that the low-albedo regions represented seas or oceans of methane because the atmosphere of Titan, mainly composed of nitrogen like the atmosphere of the Earth, contains a significant fraction of methane. Researchers knew that the environmental temperature at  sea level  was around minus 180 degrees Celsius, minus 292 degrees Fahrenheit or 93 Kelvin. They also knew that the atmospheric pressure on the ground was higher than that of the Earth at sea level.


The image in the upper part of this table represents a raw image of Titan unveiling the area of Ontario Lacus. The view was acquired on June 6, 2005 from the Cassini spacecraft using the IRP0 and the CB3 filters. The file name of the image is N00035074.jpg. The photo has not been validated or calibrated. A validated and calibrated view will be archived with the NASA Planetary Data System. One can notice a system of bright clouds in the upper left part of the image. One can also notice the dark and uniform patch of Ontario Lacus which looks like a foot. The image in the lower part of the table represents the same view with an artificial color and a higher contrast in order to better discern key surface features.

Image credit for the original view: NASA/JPL-Caltech/Space Science Institute.
Image credit for the technical adjustments: Marc Lafferre, 2018.


The image in the upper part of this table corresponds to an unprocessed view of a portion of Titan obtained on September 11, 2017. One can clearly discern the shape of a sea or lake found in the high latitudes of Titan's northern hemisphere. The pool of liquids appears dark and uniform. The eye of the Cassini probe can see surface features in the infrared or near-infrared spectrum. The image in the lower part of the table corresponds to a colorized view of the black and white image.

Image credit for the original view: NASA/JPL-Caltech/Space Science Institute.
Image credit for the technical adjustments: Marc Lafferre, 2018.

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February 9, 2018 : Scientists From Washington State University Simulate An Alien Sea Of Hydrocarbons To Test An Exploration Submarine Of NASA

Researchers from Washington State University have performed a laboratory simulation of the alien sea or lake that one may encounter on Saturn's largest moon Titan. The experiments regarding the dynamics or the composition of the seas or lakes are needed to build a suitable submarine for the exploration of the north polar lakes or seas on the Opaque Moon. NASA is planning a new mission to Titan within the next twenty years and there are several projects involving probes, drones, boats or even submarines. The engineers or scientists re-created the presumed seas or lakes of hydrocarbons in the laboratory and simulated an environment where the environmental temperature is around minus 300 degrees Fahrenheit. Let's recall that the surface temperature recorded from the Huygens probe on January 14, 2005 after landing was minus 179 degrees Celsius that is to say minus 290 degrees Fahrenheit or 94 Kelvin. The lakes or seas of Titan are likely composed of a mixture of methane and ethane.

The laboratory experiment was fundamentally designed to simulate the behavior of any submarine beneath the surface of a sea or a lake on the giant moon of the Gas Giant Saturn. The simulation was developed by Ian Richardson who is a former graduate student in the School of Mechanical and Materials Engineering. The experiment in the cryogenic laboratory of Washington State University is described in a paper released in the journal Fluid Phase Equilibria. The behavior of liquid hydrocarbons in the pools of Titan's surface may be quite surprising and may be more difficult to manage than in the oceans or seas of liquid water on Earth. Researchers are ambitious for the next step in the exploration of the Hazy Moon. Any probe sent to Titan will have to study the atmospheric conditions where complex organics or hydrocarbons can take shape and will have to study the environment of the lakes or seas as well as the internal phenomena related to the pools of liquids. Will the heat generated by the submarine and its movement engender the emergence or the development of nitrogen bubbles inside the lake or sea explored ?

This mosaic based on near-infrared data taken from the Cassini spacecraft during the T104 Flyby of August 21, 2014 clearly reveals the lakes or seas located in the high latitudes of the northern hemisphere of Saturn's largest moon Titan. Data obtained from the Visual and Infrared Mapping Spectrometer were used to produce this global view. There is a meteorological cycle implying evaporation processes, condensation processes, cloud formation and precipitation on the Hazy Moon. The properties of the liquids on Titan's surface represent a big question mark. Image Credit: NASA/JPL-Caltech/University of Arizona/University of Idaho.

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February 2, 2018 : Researchers Confirm The Presence Of Vinyl Cyanide High In Titan's Atmosphere And Suggest It May Play A Key Role In The Development Of A Potential Methane-Based Life

Scientists from NASA have confirmed, on the basis of data obtained from the Atacama Large Millimeter/submillimeter Array (ALMA) located in the desert of Chile, the presence of vinyl cyanide at a high altitude in the atmosphere of Saturn's largest moon Titan. Vinyl cyanide is an organic molecule whose chemical formula is C3H3N. The identification of vinyl cyanide in the opaque atmosphere of the Hazy Moon is captivating because researchers believe that vinyl cyanide may represent a key molecule in the development of a potential methane-based life on the giant moon. Molecules of vinyl cyanide in an hypothetical methane-based life on Titan may represent the equivalent of well-known phospholipids in the structure of typical cell membranes in our biosphere. The data from ALMA were in line with the data obtained from the mass spectrometer of the Cassini spacecraft which had led researchers to deduce the presence of vinyl cyanide in the environment of Titan.

Thanks to radar data acquired from the Cassini spacecraft, in particular, we have discovered exotic environments on Titan which are reminiscent of typical environments on Earth. There are mountains, hills, canyons, lakes, seas, rivers and islands on the Opaque Moon. Most lakes or seas are found at high latitudes on the giant moon. The high latitudes of the northern hemisphere appear to be the most humid areas at the present time with major seas or lakes like Kraken Mare, Ligeia Mare or Punga Mare. The first body of surface liquids clearly identified on Titan was Ontario Lacus, a kidney-shaped lake or sea located in the high latitudes of the southern hemisphere. Titan unveils a methane cycle implying evaporation processes, condensation processes, cloud formation and rainfall. Water can't appear in its liquid form on the surface of Titan since the environmental temperature is around minus 179 degrees Celsius or minus 290 degrees Fahrenheit. Can liquid methane play the same role as liquid water on Earth for the development of a biosphere on Titan ? Is there a methane-based life on the Orange Moon ?

The image above represents a portion of a radar swath captured from the Radar Mapper of the Cassini spacecraft during the T29 Flyby of April 26, 2007. One can notice the sharp contrast between the land which appears irregular or bright and the pools of liquids which appear dark and relatively uniform. A remarkable network of large interconnected drainage channels can be seen in particular. Some islands can be observed as well. Is there a life form based on liquid methane or liquid ethane in that humid environment ? Do the hypothetical creatures mobilize vinyl cyanide in their metabolism ? Image Credit: NASA/JPL/Cassini RADAR Team/Jason Perry.

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January 20, 2018 : Researchers Produce A New Global Topographic Map Of Titan Revealing That The Main Seas Have The Same Height And May Be Interconnected With A Subsurface Network Of Liquids

Some new studies unveiled in Geophysical Review Letters on December 2, 2017 reveal that the main seas located in the high latitudes of the northern hemisphere on Saturn's largest moon Titan have the same level similar to our sea level on Earth. This finding implies that the three seas may be interconnected via a subsurface network of liquid hydrocarbons or that the drainage channels between the pools redistribute the liquids so that the level of each sea is similar to the level of the other seas. The new analyses were published in two papers of Geophysical Research Letters. The first paper entitled  Titan's Topography and Shape at the End of the Cassini Mission  was proposed by Paul Corlies, the first author of the paper. The second paper entitled  Topographic Constraints on the Evolution and Connectivity of Titan's Lacustrine Basins  was proposed by Alex Hayes, assistant professor of astronomy.

Researchers managed to produce a new global topographic map of the Opaque Moon which unveils new features such as new mountains that don't exceed the height of 700 meters. The topographic map clearly shows variations in altitude of surface features such as hills or depressions on the entire globe of the Orange Moon. Planetologists were in a position to determine that there are two areas representing depressions in the equatorial region. The depressions may correspond to ancient seas or dried seas or they may represent cryovolcanic flows. The global map also shows that the Hazy Moon is a little bit flatter or more oblate than previously thought. That configuration implies that the thickness of the crust may vary to a larger extent than previously believed. The second paper reveals that the three seas unveil a common equipotential surface that is to say the equivalent of the common sea level on Earth.

There may be a subsurface reservoir of liquid hydrocarbons in the area of Kraken Mare and Ligeia Mare or the channels connecting the seas may balance the level of each sea. The well known seas of Titan's northern hemisphere may communicate or interact via the presumed subsurface reservoir. The analytical work reveals that most lakes represent sharp-edged depressions. Some high ridges can be observed in some locations. Is the environment of Titan's lakes and seas similar to the environment of karstic terrain or limestone areas on Earth ? Are there caves engendered by dissolution processes or erosion ? Liquid water is absent on the surface of Titan due to extremely harsh conditions. The lakes and seas of Titan may be mainly composed of methane and ethane. So, what are their properties or interactions with the soil or crust of the giant moon ? Why do the lakes studied unveil a process of uniform scarp retreat ?

The image above represents a colorized radar map of Titan's northern hemisphere unveiling, in particular, the famous seas or lakes Kraken Mare and Ligeia Mare. The bodies of surface liquid in this view appear blue or dark. There may be a subsurface reservoir of methane or ethane fueling the seas or lakes found in the high latitudes of the northern hemisphere of the Hazy Moon. Image Credit: NASA/JPL-Caltech/ASI/USGS.

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