Saturn's moons: Enceladus, Titan, Dione, Tethys and others - differ in size, shape and structure. Large and icy moons coexist with small and rocky ones. One of the most interesting objects in this system is Enceladus. Research suggests that Saturn's sixth largest moon has a subsurface ocean. Scientists call Enceladus a real candidate for discovering life in its simplest forms.
Gas giant
Saturn is the second largest planet in the solar system. In diameter, it is only slightly inferior to the leader in this regard, Jupiter. However, in terms of mass, Saturn is not so large. Its density is less than that of water, which is no longer characteristic of any planet in the system.
Saturn, like Jupiter, Uranus and Neptune, belongs to the class of gas giants. It consists of hydrogen, helium, methane, ammonia, water and a small amount of heavy elements. Saturn has the brightest rings in the solar system. They are made of ice and dust. Particles are differentsizes: the largest and rarest reach tens of meters, most are no more than a few sentiments.
Cassini
In 1997, the Cassini-Huygens apparatus was launched to study Saturn and its moons. It became the first artificial satellite of the gas giant. Cassini showed the world an unknown Saturn: photos of a hexagonal storm, data on new moons, images of the surface of Titan significantly supplemented the knowledge of scientists about this gas giant. The device is still working and continues to provide researchers with information. Cassini also told a lot about Enceladus.
Satellites
The gas giant has at least 62 moons. Not all of them received their own names, some, due to their small size and other factors, are indicated only by numbers. The gas giant's largest moon is Titan, followed by Rhea. Saturn's moons Enceladus, Dione, Iapetus, Tethys, Mimas and a few others are also fairly large. However, an impressive part of the moons in diameter does not exceed 100 m.
Of course, there are unique objects among such clusters. Titan, for example, ranks second in size among all the satellites in the solar system (on the first - Ganymede from the "retinue" of Jupiter). However, its main feature is a very dense atmosphere. Recently, astronomers have been increasingly pointing their telescopes at Saturn's moon Enceladus, a brief description of which is given below.
Opening
Enceladus is one of the largest moons of Saturn. It was opened sixth in a row. It was discovered by William Herschel in 1789 with his telescope. Perhaps the satellite would have been discovered earlier (its size and high albedo greatly contributed to this), but the reflection of the rings and Saturn itself prevented seeing Enceladus. William Herschel observed the gas giant at the right time, which made the discovery possible.
Parameters
Enceladus is Saturn's sixth largest moon. Its diameter is 500 km, which is about 25 times smaller than that of the Earth. By mass, the satellite is inferior to our planet by almost 200 thousand times. The size of Enceladus does not make it any outstanding space object. A satellite is selected according to other parameters.
Enceladus has a high reflectivity, its albedo is close to unity. In the entire system, it is probably the brightest object after the Sun. The reason for the brightness of the star is the high surface temperature, Enceladus is different. It reflects almost all the light that reaches it, because it is covered with ice. The average surface temperature on the satellite is -200 ºС.
The satellite's orbit is close enough to Saturn's rings. It is separated from the gas giant by a distance of 237,378 km. The satellite makes one revolution around the planet in 32.9 hours.
Surface
Initially, scientists were not so actively interested in Enceladus. However, the Cassini apparatus, which approached the satellite quite close several times, transmitted extremelyinteresting data.
The surface of Enceladus is not rich in craters. All available traces from the fall of meteorites are concentrated in small areas. A feature of the satellite are numerous faults, folds and cracks. The most amazing formations are located in the region of the south pole of the satellite. Parallel tectonic faults were discovered by the Cassini spacecraft in 2005. They are called "tiger stripes" for their resemblance to the pattern of a mustachioed predator.
According to scientists, these cracks are a young formation, indicating the internal geological activity of the satellite. "Tiger stripes" 130 km long are separated by intervals of 40 km. The Voyager 2 spacecraft that flew past Enceladus in 1981 did not notice the faults at the south pole. The researchers suggest that the cracks are definitely less than a thousand years old, and it is quite possible that they appeared only ten years ago.
Temperature anomalies
The orbital station registered a non-standard temperature distribution on the surface of Enceladus. It turned out that the south pole of the cosmic body heats up much more than the equator. The sun is not capable of causing such an anomaly: traditionally the poles are the coldest areas. Scientists involved in the study of Enceladus have come to the conclusion that the reason for the heating is an internal heat source.
Here it is worth mentioning that the surface temperature in this place is high precisely by the standards of such a remote part of the solar system. Satellites of Saturn: Enceladus, Titan, Iapetus and others - cannot boasthot areas in the usual sense. The temperature in the anomalous zones is only 20-30º above the average, that is, it is approximately -180 ºС.
Astrophysicists suggest that the reason for the heating of the south pole of the satellite is the ocean located under its surface.
Geysers
The subsurface ocean on Enceladus makes itself felt not only by heating the south pole. The fluid that makes it up erupts in the form of geysers through the "tiger stripes". Powerful jets were also seen by the Cassini probe in 2005. The apparatus collected samples of the substance that makes up the streams. His analysis led to two assumptions. Near the surface, the particles escaping from the "tiger stripes" contain a large amount of s alts. They indicate the existence of the sea under the surface of Enceladus (and this is the first conclusion of scientists from the Cassini data). With a much higher speed, particles with a lower s alt content break out of the cracks. Hence the second conclusion: they form the ring E, on the "territory" of which the satellite of Saturn is actually located.
Subsurface ocean
An impressive proportion of ejected particles is close in composition to sea water. They fly out at relatively low speeds and cannot become material for the E ring. S alty particles fall on the surface of Enceladus. The composition of the escaping ice suggests that the moon's frozen crust cannot be its source.
Researchers suggest that the s alty sea is located 50 miles below the surface of Enceladus. It is bounded on one side by a solid core and an icymantle - on the other. The water in the interlayer is in a liquid state, despite the low temperature. It does not freeze due to the high s alt content, as well as due to the tidal energy that the gravitational field of Saturn and some other objects creates.
The amount of water evaporating (approximately 200 kg per second) indicates a huge area of the ocean. Jets of water vapor and ice erupt to the surface as a result of the formation of cracks, which lead to a violation of pressure.
Atmosphere
Automatic interplanetary station "Cassini" discovered the atmosphere on Enceladus. For the first time it was registered by the magnetometer of the device by the influence on the magnetosphere of Saturn. Some time later, Cassini directly recorded it, observing an eclipse by Gamma Orion's satellite. The research of the probe made it possible to find out the approximate composition of the atmosphere of the icy moon of Saturn. At 65% it consists of water vapor, in second place in concentration is molecular hydrogen (about 20%), carbon dioxide, carbon monoxide and molecular nitrogen are also found.
Atmospheric replenishment is suspected to come from geysers, volcanism or gas emissions.
Is there life on Enceladus?
Detection of liquid water is a kind of a pass to the list of potentially habitable (only by simplest organisms) planets. According to scientists, if the ocean under the surface of Enceladus has existed for a long time, since the origin of the solar system, then the probability of detecting life in it is quite high, provided that water is maintained in liquid almost all this time.condition. If the ocean periodically freezes, which is quite possible due to the impressive distance to the sun, then the chance of habitability becomes extremely small.
Only information coming from the Cassini probe can now confirm or refute the assumptions of researchers. Its mission has been extended until 2017. It is not known how soon other interplanetary stations will be able to go to Saturn and its satellites. The distance from Earth to Enceladus is great, and such projects require careful preparation and impressive funding.
The Cassini probe continues its work. He was on his way to study the gas giant and Saturn's moons. Enceladus, however, did not appear on the list of main tasks. The features found included it in the list of objects of paramount importance. No one expected to find liquid water in the region of the solar system where Saturn is located. Photos of geysers on Enceladus and a few years after the discovery seem incredible. Quite possibly, the surprises of the satellite do not end there, and before the completion of the Cassini mission, astrophysicists will learn a lot more interesting things about this icy moon.
