A new analysis of radar data from the Cassini mission for NASA, conducted in partnership with the European Space Agency and the Italian Space Agency, revealed regional variations between the various sand dunes of Titan, the largest moon (It Moon calls any natural satellite of a planet, but the moon, with a capital L, is the only natural satellite of Earth. By its visibility and its eccentricities, the Moon has always ...) from Saturn.  The results provide new clues to climate history and geology of the moon.

 

After the Plains of uniform appearance, the dune fields are the dominant feature of relief (Relief is the difference in height between two points. However, this word is often used to characterize the shape of the Earth's surface.) of Titan and therefore give an overview of large-scale of the environment (The environment is everything around us. It is all natural and artificial elements within which human life takes place. With the current environmental issues, the term environment is tending to take a ...) especially of the moon.  The dunes cover about 13 percent of the area (there are many meanings to the word surface, sometimes geometric object, sometimes physical border, often wrongly confused with its extent - the area ...) and cover an area (The area or the area is the size of a surface. By metonymy, this dimension is often referred to as "surface" itself ...) 10 million kilometers (The meter (symbol m, the Greek metron, measure) is the basic unit of length in the International System. It is defined as the distance traveled by light in ...) squares.  On Earth (Earth, home of mankind, is called the blue planet. This is the third planet in the solar system from the Sun.), that's about the size of the United States.

Although similar in shape to linear dunes on Earth found in Namibia and in the Arabian Peninsula, the dunes of Titan are in our giant scale.  They are in average (There are many ways to calculate an average of a set of numbers. It should be remembered that it depends on the physical quantity represented by these numbers. ,...) When one to two kilometers wide, hundreds of kilometers long and 100 meters high.  However, their size and extent varies across the surface, betraying the environment in which they were formed and evolved.

Using data from the radar (Radar is a system that uses radio waves to detect and determine the distance and / or speed of objects such as aircraft, ships, or the rain. A transmitter sends waves .. .) of the probe (A space probe is an unmanned spacecraft sent by humans to explore closer to the solar system objects, and for some, the space that is beyond. It covers ... ) Cassini, Alice Le Gall, who worked at the Jet Propulsion Laboratory (The Jet Propulsion Laboratory (JPL), Pasadena based in the United States, is a joint venture between NASA and Caltech is responsible for construction and the ...) in Pasadena, California and is currently a researcher (Researcher (female researcher) means a person whose job is to do research. It is difficult to clearly define the profession of researcher as the areas of research are diverse ...) in the laboratory LATMOS to Paris (Paris is a French city, capital of France and the capital of the region of Ile de France. This city is built on a loop of the Seine, the center of ...), found that the size of Titan's dunes is controlled by two factors: altitude and latitude.

In terms of altitude, the highest dunes tend to be thinner and more widely separated.  The differences between the dunes appear on the Cassini radar indicates a thin cover of sand (sand or arena, is a soft sedimentary rock consisting of small particles from the disintegration of other rocks whose size is between 0.063 and 2 mm.).  This suggests that the sand needed to build the dunes comes mainly from the plains of Titan.

Scientists believe that the sand on Titan is made up of silicates as on Earth, but of solid hydrocarbons, resulting in precipitation of the atmosphere (atmospheric The word can mean many things:).  These have resulted in aggregates of grains of about 1 millimeter by a process still unknown.

In terms of latitude, the sand dunes of Titan are confined to the equatorial region, in a band between 30 degrees latitude south (the South is a name) and 30 degrees latitude north (North is a cardinal point, as opposed to the south.).  However, the dunes tend to be less bulky in the north.  Le Gall and colleagues believe that this may be due to the orbit (in celestial mechanics, an orbit is the path that describes a body in space around another body under the influence of gravity.) elliptical Saturn.

Titan is orbiting Saturn, and the seasons of the moon are controlled by the trajectory (the trajectory is the line described by any point of a moving object, including its center of gravity.) Saturn around the Sun ((weight percent)).  As Saturn takes about 30 years to complete an orbit, each season (the season is a period of one year has been a relative constancy of the climate and temperature. Over a period of approximately three months (see Table Solstice Equinox and below), the ...) on Titan lasts approximately seven years.  The nature of the slightly elliptical orbit of Saturn implies that the southern hemisphere summer has shorter but more intense.  And southern regions are probably drier, which means less moisture in the soil.  More sand grains are dry, they can be more easily transported by winds and build dunes.  "Soil moisture is likely to increase towards the north, making the sand particles less mobile and, therefore, the development of dunes more difficult."  Le Gall suppose.

In support of this hypothesis, the fact that lakes and seas (The term covers several realities Wed.) Titan are not symmetrically distributed in latitude.  These reserves ethane and methane (methane (R50) is a hydrocarbon of the alkane family.) liquid (the liquid phase is a state of matter.) occur mainly in the northern hemisphere, which suggests again that the soil is wetter and, again, that the sand grains are less easily transported by wind in these regions.

"Understanding how dunes form, explain their shape, size and distribution on the surface of Titan is of great importance for the understanding of Titan's climate and geology, because the dunes are an interface (An interface is an area, real or virtual between two elements. The interface is so that each element needs to know the other to function properly.) significant trade-surface atmosphere, "said Nicolas Altobelli, scientific (A scientist is a person devoted to the study of a science or science and dedicated to the study of a field with the rigor and ...) of the project (a project - in a professional context - a temporary adventure company in order to create a unique product or service:) Cassini-Huygens at ESA.  "In particular, as they are made from hydrocarbons atmospheric frozen dunes could provide us with important clues about the cycle methane / ethane is still a mystery of Titan, though in many respects comparable to the cycle of water (water (which can also be called dihydrogen monoxide, hydrogen hydroxide or acid hydroxyque) is a simple chemical compound, but with complex properties because of its ...) on Earth. "