Titan (or Saturn VI) is the largest natural satellite of Saturn. This satellite is the only natural satellite that has a dense atmosphere, and the only object other than Earth that proved to have liquid on the surface.
Titan is the sixth satellite of Saturn elipsoidal. These satellites are often described as similar planetary satellites and has a diameter that is 50% larger than the Moon, while its mass is 80% larger. This satellite is the second largest satellite in the Solar System, after Jupiter's satellite Ganymede in, and the volume is larger than the planet Mercury. Titan was first discovered in 1655 by the Dutch astronomer Christiaan Huygens, and is the fifth satellite in the solar system were found after four satellites of Jupiter.
Titan is mainly composed of water ice and rocky material. As Venus before the exploration of space, solid and opaque atmosphere complicate investigation of Titan's surface until the arrival of the Cassini-Huygens spacecraft at Saturn in 2004 which opened the new knowledge such as the discovery of liquid hydrocarbon lakes in the polar region of Titan. Its surface is geologically young, and though the mountains and some Cryovolcano been found, only a few craters collision encountered.
Titan's atmosphere consists mostly of nitrogen; small compounds result in the formation of methane and ethane clouds and fog nitrogen-rich organic. The climate-including wind and rain-yield similar to the Earth's surface, such as sand dunes, rivers, lakes, and seas (possibly composed of liquid methane and ethane), and delta, and is dominated by seasonal weather patterns such as on Earth. Because the surface containing liquid and nitrogen-rich atmosphere, Titan's methane cycle is considered similar to the water cycle on Earth, even though temperatures are much lower.
Discovery and naming.
Titan was discovered on March 25, 1655 by astronomer / physicist Christiaan Huygens Netherlands. Huygens was inspired by the discovery of the four largest satellites of Jupiter by Galileo in 1610 and updates telescope technology. Christiaan, with the help of his brother Constantijn Huygens, Jr., began to build a telescope around 1650. Christiaan Huygens discovered the first satellites orbiting Saturn with their first telescope built.
Huygens easily named his discovery saturni Luna (or Luna saturni, in Latin means "the moon"), and published it in his treatise in 1655, De saturni Luna Observatio Nova. After Giovanni Domenico Cassini published his discovery of the four satellites of Saturn other between 1673 to 1686, astronomers began to get used to name these satellites and Titan as Saturn I to V (with Titan in the fourth position). Another epithet originally used is "regular satellites of Saturn." Titan Saturn VI officially numbered because after the discovery in 1789, the numbering scheme was stopped to avoid confusion (Titan never be numbered II, IV, and VI).
The name "Titan" was proposed by John Herschel (son of William Herschel, discoverer of Mimas and Enceladus) in the publication Results of Astronomical Observations 1847nya made at the Cape of Good Hope. The name was derived from the Titans (Ancient Greek: Τῑτάν), which in Greek mythology is a race of gods strong and descendants of Gaia and Uranus and Kronos siblings.
Orbit and rotation.
Titan orbits Saturn every 15 days 22 hours. Like the other satellite, its rotation period equal to the period of its orbit; Titan lock ups and downs in synchronous rotation with Saturn, so that one hemisphere of the planet always faces. As a result, there is a point on the surface of sub-Saturn, and Saturn there would seem as hanging just above the head. Longitude on Titan was measured to the west of the meridian that passes through this point. The eccentricity of its orbit recorded at 0.0288, and 0.348 degrees orbital plane inclined relative to the equator of Saturn.
Hyperion satellites are small and irregularly shaped locked in orbit resonance 3: 4 with Titan. Evolution resonance slow-which should make Hyperion migrate from a chaotic orbit-considered unlikely based modeling. Hyperion probably formed in a stable orbit, while Titan big draw or remove objects approach.
The characteristics.
Titan diameter was recorded at 5,150 miles, than the planet Mercury is only 4879 km, which is only 3,474 km Moon, and Earth which amount 12 742 km. Before the arrival of Voyager 1 in 1980, Titan allegedly slightly larger than Ganymede (5,262 km diameter) and then calculated as the largest satellite in the Solar System; however, this is wrong, and the estimated Titan become excessive due to the dense and opaque atmosphere that can reach several kilometers above the surface. Titan's diameter and mass (and hence density) similar to the satellite Ganymede and Callisto on Jupiter. With a density of 1.88 g / cm3, is composed of half water ice and half rocky material. Although the composition is similar to Dione and Enceladus, this satellite is more dense due to gravitational compression.
Titan possibility differentiated into several layers with a diameter of 3,400 miles a rocky core surrounded by a layer consisting of various forms ice crystals. Parts of it may still be hot and contains a liquid layer consisting of "magma" of water and ammonia in the crust of ice Ih and ice deeper layers consisting of high-pressure ice. Presence of ammonia keep water liquid even in temperatures as low as 176 K (-97 ° C) (for a eutectic mixture with water). Evidence of the existence of the ocean has been demonstrated by the Cassini spacecraft in the form of very low frequency radio waves in the atmosphere of Titan. Titan's surface is allegedly not reflecting very low frequency waves are good, so that even supposedly reflecting liquid-ice boundary of a subsurface ocean. Cassini rides have some surface appearance shifted 30 km between October 2005 and May 2007, which showed that the crust is separated from the inside, and is additional evidence that supports the existence of a liquid layer on the inside.
Research in early 2000 by the DLR Institute of Planetary Research in Berlin-Adlershof placing Titan in the "big satelites" along with Callisto and Ganymede.
Formation.
Moons of Jupiter and Saturn supposedly formed through accretion, a process that is thought to have formed the planets in the Solar System. Once formed, a young gas giant surrounded by a disk of material that is slowly forming satellites. However, although Jupiter has four large satellites that orbit like planets and regular, Titan dominates Saturn system and has a very eccentric orbit which can not be explained by mere accretion. The model proposed for the formation of Titan is a model which explains that the system initially has a satellite Saturn like Galileo satellites of Jupiter. However, satellites are interrupted by a series of giant collisions that will form the Titan. Saturn's satellites are sized like Iapetus and Rhea formed from the rest of this collision. This may explain the eccentricity of the orbit of Titan.
The atmosphere.
Titan is the only satellite with a dense atmosphere. The atmosphere is rich in nitrogen, and observations of the atmosphere by Cassini in 2004 showed that Titan's atmosphere rotates faster than its surface (like Venus). Observations from the Voyager spacecraft have shown that Titan's atmosphere is more dense than Earth's atmosphere, with a pressure of about 1.45 times the Earth's surface. Overall the atmosphere of Titan, 1.19 times larger than the Earth's atmosphere, or 7.3 times greater based on surface area. Due to the low gravity, the atmosphere of Titan wider than Earth.
In Titan's atmosphere are opaque haze layer that blocks the light from the sun and other sources that create the appearance of the surface of Titan looks blurred. Titan's atmosphere is opaque in the visible range of wavelengths and hard surface reflectance spectra obtained from orbit. Only after the arrival of the Cassini-Huygens mission in 2004 the direct image of Titan's surface can be obtained.
The composition of the atmosphere in the stratosphere include 98.4% nitrogen with the remaining 1.6% is composed of methane (1.4%) and hydrogen (0.1-0.2%). There are trace elements of other hydrocarbons such as ethane, Diacetylene, metilasetilena, acetylene and propane, and other gases, such as Cyanoacetylene, hydrogen cyanide, carbon dioxide, carbon monoxide, cyanogen, argon and helium. The sun's ultraviolet rays solve this reaction to form methane and hydrocarbons in Titan's atmosphere, resulting in a thick orange haze. Titan spends 95% of his time in the magnetosphere of Saturn, which helps protect the Titan from the solar wind.
Energy from the Sun should have changed all traces of methane in Titan's atmosphere into more complex hydrocarbons in 50 million years - a short time compared to the age of the Solar System. This suggests that the methane must be replenished from Titan itself. Methane in Titan's atmosphere may come from within, which is released by the eruption Cryovolcano.
On April 3, 2013, NASA reported that organic chemistry might appear at Titan based on research that simulates Titan's atmosphere. Then, on June 6, 2013, scientists at the Institute of Astrophysics of Andalusia tracking reports polycyclic aromatic hydrocarbons in Titan's upper atmosphere
Climate.
Titan's surface temperature was recorded at 94 K (-179.2 ° C). At this temperature, ice water has a very low vapor pressure, so the atmosphere is almost free from moisture. Titan only about 1% of the amount of sunlight that is obtained Earth.
Methane atmospheric greenhouse effect on Titan's surface, and without that Titan will be much colder.
In contrast, in the atmosphere of Titan's haze resulted in an anti-greenhouse effect by reflecting sunlight back into space and cancel some of the warming effect of greenhouse so that the surface is colder than the upper atmosphere.
Titan clouds, which may consist of methane, ethane, or other simple organic materials, dispersed and diverse. The discovery by Huygens spacecraft show that Titan's atmosphere periodically rain down liquid methane and other organic compounds to the surface.
Typically 1% cloud cover disc of Titan, though sometimes clouds quickly expanded to include 8%. According to one hypothesis, the southern clouds are formed when an increase in the sun during the summer cause convection. The problem becomes more complicated due to the formation of clouds is not only observed during the solstice after the summer, but also during mid-spring. Increased moisture in the south polar methane possibly leading to a rapid expansion of the cloud. Titan southern hemisphere experiences summer until 2010, when the orbit of Saturn's northern hemisphere of Titan makes exposure to sunlight.
When the seasons change, estimated ethane will begin to condense in south pole.
The appearance of the surface.
Titan's surface is described a "complex, processed fluid, [and] geologically young." Titan has existed since the formation of the Solar System, but the surface is younger, with ages between 100 million to 1 billion years. Geological processes may have to reshape the surface of Titan. The atmosphere of Titan two times thicker than Earth, making it difficult for astronomical instruments to take the image of the surface in the visible light spectrum. The Cassini spacecraft using a infrared, radar altimetry, and synthetic aperture radar (SAR) to map Titan during the flyby. The first image shows the diverse geology, with rough and smooth areas. There seems to be caused by the appearance Cryovolcano activity, which may be a disgorge water mixed with ammonia. There are also some striped appearance, some of which reach hundreds of kilometers in length and appears to be caused by wind-blown particles. Studies have also shown that Titan's surface is relatively smooth; some object that appears to be a collision crater appears to have been filled, possibly by rain hydrocarbons or volcanoes. Radar altimetry shows that the variation of Titan low altitude, usually no more than 150 meters. However, changes in altitude up to 500 meters have been discovered and Titan has a high mountain between a few hundred meters to 1 kilometer.
Titan's surface filled with light and dark regions. One is Xanadu, in the equatorial region of the reflective and large the size of Australia. The region was first tracked through infrared images captured by the Hubble Space Telescope in 1994, and will be seen by the Cassini spacecraft. The region is filled with hills, valleys, and Chasma. In the region there is also a darker appearance similar topographic ridge or cracks. The appearance was probably caused by tectonic activity, which indicates that Xanadu is geologically young. Another explanation states that the appearance of a channel formed by the liquid, so that an old area that was interrupted by the flow. There is a dark area with a size similar to Titan; The alleged appearance of a sea of methane or ethane, but the observations from Cassini seem to indicate otherwise.
Liquid.
The possible existence of hydrocarbon seas on Titan were first estimated based on data from Voyager 1 and 2 which shows that Titan has a thick atmosphere with temperature and composition appropriate to support the existence of the ocean. However, the new direct evidence obtained in 1995 after data from Hubble and other observations indicate the presence of liquid methane on Titan, either separately or in a hole in the form of oceans, like water on Earth.
Cassini mission to prove this hypothesis, although indirectly. When the spacecraft arrives at Saturn system in 2004, expected hydrocarbon lakes or oceans can be tracked through the sunlight reflected by the surface of the liquid, but initially no reflection was observed.
In the near Titan's south pole, dark appearance of the so-called Ontario Lacus was found (and then the appearance confirmed as a lake). The coastline is also identified near the poles through the radar image.
After a flyby on July 22, 2006, which managed to capture the image of the northern latitudes of Titan (during the winter), and a large number of pieces that are found in the polar surface smooth. Based on the observations, scientists announced the "definitive proof of the existence of a lake that contains methane in Titan satellite" in January 2007. The team Cassini-Huygens concluded that the images were captured almost certainly a hydrocarbon lakes that have long sought, thus becoming the first surface of the fluid found outside Earth. Some seem to have a channel that is contained in a topographic depression. The appearance of fluid erosion looks just happened : the channel in some areas are surprisingly not much result in erosion, thus indicating that erosion on Titan took place very slowly, or other phenomena may have cleared the riverbed and landscape long. overall, the Cassini radar observations indicate that lakes covering only a few percent of the surface, so that Titan is much drier than Earth.
Although most of the lakes are concentrated near the poles (which is not much undergo evaporation due to lack of sunlight), a number of hydrocarbon lakes in the desert region of the equator also been found, including in the near region Shangri-La, the amount of approximately half of the Great Salt Lake of Utah. Lakes in the equatorial region of the possibility of an "oasis", or in other words the fluid coming from underground aquifers.
In June 2008, the Visual and Infrared Mapping Spectrometer (VIMS) on Cassini spacecraft confirmed the presence of liquid ethane in Ontario Lacus.
Later, on December 21, 2008, Cassini passed the Ontario Lacus directly and observe a strong reflection on the radar. The reflection shows that the lake does not vary more than 3 mm (which can mean surface wind was not much, or liquid hydrocarbons in the lake lumpy).
Cassini VIMS on July 8, 2009 to track the strong reflections that show the existence of smooth surfaces such as glass and in the northern polar region, which is now called Jingpo Lacus (Jingpo Lake), soon the winter for 15 years in the region is completed.
Radar measurements in July 2009 and January 2010 showed that the surface of Ontario Lacus is very shallow, with an average depth of between 0.4 to 3.2 m, and a maximum depth of between 2.9 to 7.4 m. Meanwhile, Ligeia Mare depth in the northern hemisphere exceed 8 m.
During the flyby on September 26, 2012, Cassini's radar to track the presence of the river in the north polar region of Titan with a length of more than 400 kilometers. River Nile is juxtaposed with much greater on Earth. This appearance ended in Ligeia Mare.
In six flyby between 2006 and 2011, Cassini collect radiometric tracking data and optical navigation can show changes in the shape of Titan. Titan density consistent with the celestial bodies consisting of 60 & rock and 40% water. Based on the analysis, the surface of Titan can go up and down to 10 meters each orbit. This indicates that the inside of Titan relatively volatile, and the most appropriate Titan models are models that estimate the possibility of the existence of a layer of ice that floats on the global ocean at a depth of more than a dozen kilometers. The findings, coupled with results of previous studies, also shows that the possibility of oceans of Titan is not more than 100 miles below the surface.
Comparison of the number of lakes in the northern hemisphere (left) and the southern hemisphere (right) Titan Titan's southern hemisphere Two images taken in 2004 and 2005, showed changes in lakes south pole
Crater collision.
Data from Cassini indicates the presence of several collision craters on Titan's surface. The collision crater seems relatively young when compared to the age of Titan. Examples of craters found is called the double-ring basin Menrva with a width of 440 km, which is tracked by Cassini as a light-dark concentric pattern. There is also a smaller craters and flat with a width of 60 km, called Sinlap and a crater with a peak in the middle and dark base with a width of 30 km, called Ksa. Cassini imaging radar and also find a number of round appearance at Titan's surface that may be caused by the collision, but do not have specific characteristics which ensure its status.For example, a bright ring width of 90 km, called Guabonito been observed by Cassini. The appearance is thought to be the collision crater filled by dark sediment carried by the wind. Another example is in the area of Shangri-La and Aaru dark. Observation of the radar also found some rounded appearance that may be a crater in the bright Xanadu region on April 30, 2006.
Many craters Titan with erosion and changes.
Most of the crater has a side that is not complete, although some craters on Titan has a bigger edge than elsewhere in the Solar System. However, there is much evidence to suggest the formation of palimpsest (crater which relief has disappeared due to the widening of the ice surface) through relaxation crust (which occurred in the other satellites of ice). Most of the crater does not have a peak in the middle and smooth base, which may be exacerbated by the eruption Cryovolcano. The number of craters on Titan itself is relatively less for a variety of geological processes replenish crater. In addition, the atmosphere also protects the surface of Titan, and estimated atmospheric reduce by half the number of craters.
High-resolution data from the radar (however limited, only 22%) in 2007 showed the heterogeneity of the distribution of the crater. The number of craters in the region of Xanadu 2-9 times more than other regions. The front parts of the crater density 30% greater than the rear hemisphere. Meanwhile, the density of craters in the desert region and the north pole khatilistiwa lower.
Path modeling and collision angle pre-Cassini showed that when a collision pierced crust of ice water, some fractions (ejecta) of the collision is still liquid inside the crater for centuries or even longer, time enough for the synthesis of simple molecules that will be the trigger going life.
Kriovolkanisme and mountains.
Scientists have long suspected that Titan circumstances similar to Earth, although temperatures are much lower. Tracking Argon 40 in the atmosphere in 2004 showed that the volcano has issued a "lava" which consists of water and ammonia. Map of the distribution of lakes on Titan's surface also shows that the amount of methane on the surface is not enough to remain in the atmosphere, so that the possibility of portion of the methane comes from volcanic processes.
There are some surface appearance that can be interpreted as a Cryovolcano. One of the appearance shown by the Cassini radar observations in 2004, called Ganesa Macula. The appearance is similar to the appearance of "pancake domes" on Venus, and consequently initially mistaken as a Cryovolcano, although the American Geophysical Union against this hypothesis in December 2008. In the end, the appearance was not the dome, but is the result of a combination of light and dark pieces unintentional.
In 2004, Cassini also track the appearance of light (called Tortola Facula) which is interpreted as a dome Cryovolcano. There is no appearance of the type found since 2010. In December 2008, astronomers announced the discovery of two "bright spots" are temporary but long-lived in the atmosphere of Titan, which apparently can not be explained by mere weather patterns, so it may be caused by events Cryovolcano.
In March 2009, a structure similar to lava flows were announced found in a region called Hotei Arcus, which fluctuates in brightness for a few months. Although there are many phenomena that can cause these fluctuations, the lava flow has appeared 200 meters above the surface of Titan, which may erupt from beneath the surface.
Mountains along the 150 km long, 30 km wide and as high as 1.5 km also discovered by Cassini in 2006. These mountains are in the southern hemisphere and is thought to consist of icy material and coated by snow methane. The movement of tectonic plates that may be affected by the collision basin around can open a gap which results in the buildup of material mountains. Before Cassini, scientists assumed that most of Titan's topography consists of the structure of the collision, but instead Cassini discoveries indicate that (just like the Earth) mountains are formed through geological processes. In December 2010, the team announced the discovery of the Cassini mission Cryovolcano convincing. Cryovolcano was named Sotra Patera and is part of a series of three mountains, each height range between 1000 to 1500 m, and on top of some mountain there is a large crater. The soil around the base appears to be met by frozen lava flows.
If volcanism exists on Titan, according to the hypothesis that the process is driven by the energy released by the decay of radioactive elements in the mantle, as it does on Earth. The magma in the Earth is made of molten rock, which is less dense than the rocky crust it. Because the ice is not more dense than water, magma aqueous Titan is denser than ice crust. Consequently, kriovolkanisme at Titan requires great energy, the possibility of stretching the tides of Saturn.
Alternatively, the pressure required to push Cryovolcano produced by ice Ih formed under the outer crust of Titan. Low-pressure ice that coats the lining of liquid ammonium sulfate went up due to the buoyant force. It is this process that coats the back of Titan and help generate landscapes and dunes are formed by winds.
In 2008, Jeffrey Moore (planetary geologist at Ames Research Center) propose an alternative viewpoint. Taking into account that there is no appearance of volcanic clearly identified to date, he stressed that the Titan is a world that is not geologically active, and its surface is formed by a collision, fluvial and aeolian erosion, bulk waste, and other eksogenik process. According to this hypothesis, methane is produced by volcanoes, but slowly diffuses from the inside of Titan were cold and hard. Ganesa Macula may constitute a collision that eroded crater with dark sand dunes in the middle. Mountainous ridge observed in some regions can be considered as a double ring structure escarpment collision results highly degraded or as a result of the global contraction caused by cooling the inside slowly. In this hypothesis, Titan can still have an ocean on the inside of which consists of a eutectic mixture of water-ammonia at a temperature of 176 K (-97 ° C), which is low enough to be caused by the decay of radioactive elements in the core of Titan. Bright Xanadu region may be an area that is highly cratered and degraded like on the surface of Callisto. Indeed, if Callisto had the atmosphere, Callisto can be a geological model of Titan. Even Jeffrey Moore calls Titan "Callisto who climates".
Dark field.
Images of Titan's surface that is perpetuated by telescopes on Earth in the early 2000s showed that a large dark field at the equator of Titan. Prior to the arrival of Cassini, the region is thought to be a sea of organic material such as tar or liquid hydrocarbons. Image radar is perpetuated by the Cassini spacecraft in fact proves that the region is a plateau covered by sand dunes that stretches to a height of 330 meters, a width of about one kilometer, and the length from tens to hundreds of kilometers. The dunes are longitudinal (or transverse) supposedly formed by winds that follow the direction of the average or alternated between two different directions. The dunes of this kind are usually in line with the average wind direction. At Titan, heading east winds combined with wind tidal change (approximately 0.5 meters per second). Wind ups and downs caused by the tidal forces of Saturn, which is 400 times more powerful than the power of the Earth and the Moon receding tide tends to direct the wind to the equator. As a result, the dunes are formed in parallel lines long and composed west to east. The series ended in the sand dunes around the mountains because the wind direction changed.
Sand on Titan is not made of the possibility of such silicate grains of sand on Earth, but are formed when liquid methane rain eroded Titan and icy rock (possibly through the flood). According to another possibility, sand derived from organic solids produced by photochemical reactions in Titan's atmosphere. Study the composition of the dunes in May 2008 showed that the dunes have less water than in the other Titan, and the possibility of come from organic material collected after showering the surface.
Observation and exploration.
Titan is not visible to the naked eye, but can be observed through a small telescope. Amateur observation difficult because Titan is located close to the planet Saturn and the rings; occulting bar can be used to block the Saturn. Titan has an apparent magnitude of +8.2 maximum, and the average magnitude of the opposition 8.4.
For comparison, the apparent magnitude Ganymede similar size was recorded at + 4.6.
Observations of Titan before future space exploration is not much done. In 1907, astronomers Spain Josep Comas Sola edge darkening observed on Titan, thus becoming the first evidence that the satellite has atmosphere. In 1944, Gerard P. Kuiper using spectroscopic techniques to track atmospheric methane.
The first rides visiting the Saturn system was Pioneer 11 in 1979. This facility ensures that Titan is too cold for life. In addition, Pioneer 11, also perpetuate the image of Titan and Saturn in the late to mid 1979. The picture quality is inferior to the two Voyager spacecraft, but it gives the data in preparation.
Titan investigated by Voyager 1 in 1980 and 2 in 1981. Line Voyager 1 is amended in order to be close to the current passing through Titan. Unfortunately, the vehicle does not have a tool that can penetrate Titan's haze, something that was not expected. A few years later, the image processing is perpetuated by Voyager 1 orange filter digitally indicates the presence of light and dark appearance which is now called Xanadu and Shangri-La, but now it has been observed both in the form of infrared by the Hubble Space Telescope. Voyager 2 only see Titan in passing. Voyager 2 team confronted by two choices: to direct the vehicle to see Titan in detail or follow another path that will visit Uranus and Neptune. Since at least the appearance of the surface that can be seen by Voyager 1, the second plan was the one who carried out.
Cassini-Huygens.
Forum for the Cassini-Huygens reached Saturn on July 1, 2004, and has begun to map the surface of Titan using radar. Rides which is a joint project of the European Space Agency (ESA) and NASA is very successful in its mission. Cassini flew through Titan rides on October 26, 2004 and perpetuate the image of the surface of Titan by far the largest resolution of 1,200 km distance that shows light and dark pieces that can not be seen by the naked eye on Earth. Huygens landed at Titan on 14 January 2005 and found a lot of surface appearance that may have formed by liquid flowing in the past. On July 22, 2006, Cassini flew past his first from a distance of 950 km from Titan; The closest flyby done from a distance of 880 km on June 21, 2010.
The liquid in the form of lakes and oceans also discovered by Cassini in the northern polar region.
In addition, thanks to the Cassini-Huygens mission, Titan is the second satellite in Tata solar and most distant object from Earth which has lander on its surface.
Huygens landing site.
On January 14, 2005, Huygens spacecraft landed on Titan's surface, in the east end of the bright region called Adiri. The rides take pictures pale hills with "river" dark flow into the dark plains. According to current understanding, the hills (which is also called the highlands) is composed mostly of water ice. Dark organic compounds produced in the upper atmosphere by solar ultraviolet radiation may bombard the atmosphere of Titan. The compound flowing down hill with methane rain and settles in geological time period.
After landing, Huygens took the image of the dark plains are covered with small rocks, which consist of water ice. The two stone in the center of the image on the right looks smaller than it actually is: the left of length 15 cm, and the right side length 4 cm, while the Huygens preserve it from a distance of 85 cm. There is evidence of erosion at the base of the rocks, which may be caused by fluvial activity. Surface appears darker than previously thought, and consists of a mixture of ice water and hydrocarbons. Based on the assumption, "soil" which looks at the picture on the right is the precipitation of hydrocarbon haze above.
In March 2007, NASA, ESA, and COSPAR decided to name the Huygens landing site "Hubert Curien Memorial Station" in memory of the former chairman of the ESA.
Future missions.
Titan Saturn System Mission (TSSM) is proposed joint NASA / ESA will explore Saturn's satellites. In the mission, will air balloons fly in the atmosphere of Titan during the six months. The project is competing with the Europa Jupiter System Mission (EJSM) to obtain funds. In February 2009, it was announced that ESA / NASA will prioritize EJSM, although TSSM still being considered. Since NASA out of TSSM in 2012, this plan was postponed.
There is also proposed Titan Mare Explorer (TIME), which is a low-cost lander will land on a lake near Titan's north pole and float on the surface for three to six months. The mission could be launched as early as 2016 and arrived in 2023. However, in 2012, NASA chose to fund Insight probe missions to Mars, so the future of the mission time is still unclear.
Other lake lander project proposed in late 2012 in Europe. The spacecraft dubbed Titan Lake In-situ Sampling Propelled Explorer (Talise).
The main difference with rides Time is the driving system.
Another proposed mission is Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR), which is an unmanned aircraft that will fly through the atmosphere of Titan and perpetuate the image of Titan's surface in high definition.
State of the prebiotic and the search for life.
Titan is thought to be a prebiotic environment that is rich in organic chemicals complex with the possibility of the existence of a liquid ocean beneath the surface into the biotic environment.
Although Cassini-Huygens mission is not equipped with the tools to find Biosignature or other organic compounds, this vehicle find an environment similar (in some cases) with ancient Earth. Scientists suspect that the ancient Earth's atmosphere composition similar to Titan's atmosphere today, although Titan's atmosphere has no water vapor.
The formation of complex molecules.
Miller-Urey experiment showed that the atmosphere similar to Earth and with the addition of ultraviolet radiation, complex molecules and substances such polymers can be produced Tholin. The reaction was started from the dissociation of nitrogen and methane, which form hydrogen cyanide and acetylene. Further reactions have been studied.
In October 2010, Sarah Horst of the University of Arizona makes simulation ultraviolet radiation and charged particles that pierced through the upper atmosphere of Titan with a thrust of energy to the gas collection compositionally similar to the atmosphere of Titan. In these simulations, he managed to find the five nucleotide bases-the building block of DNA and RNA and amino acids-the building blocks of proteins. According to him, this is the first time the nucleotide and amino acid found in the state without the presence of water.
On April 3, 2013, NASA reported that organic chemistry might appear at Titan based on research that simulates Titan's atmosphere.
The possible existence of subsurface habitats.
Laboratory simulations show that there is sufficient organic matter to start the chemical evolution similar to what happens on Earth. Although the analogy assumes the presence of water for a longer period, according to some theories water from the collision can be stored under a layer of frozen isolation. In addition, ocean liquid ammonia may exist below the surface; while the , based on other models, there is a solution of ammonia-water at a depth of 200 km below the crust of ice water that can support life, even by the standards of life of the earth is a harsh environment. The transfer of heat between the inside and the top layer plays an important role in supporting life The subsurface ocean. The discovery of microbial life itself depends on its biogenic effects (eg, investigation of methane and nitrogen in the atmosphere as a result of biological events).
It is estimated that there is life in the lakes of liquid methane on Titan, the same as on Earth organisms that live in water. The creature would inhale from the H2 O2, its metabolization with acetylene instead of glucose, and remove methane from carbon dioxide.
Although all life on Earth (including methanogens) using water as a solvent, an estimated life on Titan using liquid hydrocarbons, such as methane or ethane. Water is the solvent that is stronger than methane. However, water is also more chemically reactive , and can break down large organic molecules in the process of hydrolysis.
As a result, the life of the use of hydrocarbons as solvents are not at risk of destruction of biomolecules.
Astrobiologist Christopher McKay in 2005 states that if there is life on Titan's surface methanogens, life is supposed to affect the ratio of Titan's troposphere: the content of hydrogen and acetylene should be lower than expected.
In 2010, Darrell Strobel of Johns Hopkins University found more molecular hydrogen in the atmosphere on Titan than the atmosphere below it, and proposes the downward flow at a rate of 1025 per second and the loss of molecular hydrogen near Titan's surface; as stated by Strobel, the findings in line with the expected effect of Chris McKay when methanogenic life does exist.
In the same year, another study showed that low levels of acetylene on Titan's surface, which according to Chris McKay appropriate with the hypothesis that organisms consume hydrocarbons in Titan. However, McKay warned that another explanation is more likely, such as physical or chemical processes that have not been identified (as the catalyst surface which receives hydrocarbons or hydrogen), or deficiencies in the current material flow model . The data composition and flow models need to be proved, and, in accordance with the principle of Occam knife, physical or chemical explanation is selected a priori rather than a biological explanation for chemical catalysts simpler explanation than the complexity of biological life. However, McKay stressed that the discovery of one of them, including an effective catalyst at a temperature of 95 K (-180 ° C), is an important discovery.
As expressed by NASA in an article about the discovery in June 2010, "until now, methane-based life is still hypothetical. Scientists still do not find this kind of life form." NASA also said that "some scientists believe that the (discovery) is supports the argument for the existence of primitive and exotic life or a precursor of life on Titan's surface."
Challenge.
While it may be biologically, there is a challenge for life on Titan. At large distances from the Sun, Titan is a cold satellite, and do not have a CO2 atmosphere. On the surface of Titan, water is only present in solid form. Because of these difficulties, scientists like Jonathan Lunine assume Titan less likely to have a life and just experiment to test theories about the state of the Earth before the emergence of life. Although life may not exist, the state of Titan prebiotics and organic chemicals associated still interesting because can be used to understand the early history of the Earth's biosphere. The study, using the Titan as a prebiotic experiments not only done through observation spacecraft, but also through laboratory experiments and modeling chemical and photochemical on Earth.
Panspermia hypothesis.
Large asteroid and comet collisions can cause thrown her fractions containing microbes of planet Earth, which enables the transpermia. Based on the calculations, some fragments can achieve various objects in the Solar System, including Titan. On the other hand, Jonathan Lunine that life on Titan's hydrocarbon lakes cryogenic should be chemically very different from Earth life so that both can not be related.
Future state.
Going forward, Titan may be more habitable. Five billion years from now, when the Sun becomes a red giant, the surface temperature will rise up to support the existence of water on the surface. In addition, due to solar ultraviolet reduced, fog in the upper atmosphere of Titan will be lost, thus reducing the anti-greenhouse effect takes place on the surface and increase the greenhouse effect caused by methane in the atmosphere. Two things can make Titan more habitable for several hundred million years, enough time for the evolution of the simple life, despite the presence of ammonia on Titan may slow chemical reactions. Thank you for reading this article. Written and posted by Bambang Sunarno.
sunarnobambang86@gmail.com
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Bambang Sunarno.
http://www.primadonablog.blogspot.com/2014/12/know-satellite-titan.html
DatePublished: December 2, 2014 at 11:21
Tag : Know satellite Titan.
Code : 7MHPNPADAEFW
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