Saturn's Satellites: Enceladus. Is there life on Enceladus

Saturn's satellites: Enceladus, Titan, Dion, Tethys and others differ in size, shape and structure. Large and icy moons coexist with small and stony moons. One of the most interesting objects in this system is Enceladus. Studies suggest that the sixth largest satellite of Saturn has a subsurface ocean. Scientists call Enceladus a real candidate to discover life in its simplest forms.

Gas giant

Saturn - the second largest planet in the solar system. By diameter, he is only slightly inferior to the leader in this regard, Jupiter. However, by mass Saturn is not so great. Its density is less than the analogous parameter 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 consist of ice and dust. Particles vary in size: the largest and rare occur reach tens of meters, most not more than a few sentiments.

Cassini

In 1997, for the study of Saturn and its moons, the Cassini-Huygens apparatus was launched. He became the first artificial satellite of the gas giant. "Cassini" showed the world an unknown Saturn: a photo of a hexagonal storm, data on new moons, Titan surface images substantially supplemented the knowledge of scientists about this gas giant. The device is still working and continues to provide researchers with information. A lot of "Cassini" also spoke 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 largest moon of the gas giant is Titan, followed by Ray. Saturn's satellites Enceladus, Dion, Iapetus, Tethys, Mimas, and a few others are also quite large in size. However, an impressive portion of the moons in diameter do not exceed 100 m.

Of course, among such a cluster there are also unique objects. Titan, for example, ranks second in size among all the satellites in the solar system (on the first - Ganymede from the "suite" of Jupiter). However, its main feature is a very dense atmosphere. Recently, astronomers are increasingly directing their telescopes to 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 in sixth place. In 1789 he was discovered by William Herschel with the help of his telescope. Perhaps, the satellite would have been open before (its dimensions and high albedo were very helpful), however, Enceladus could not be seen from the reflection of the rings and Saturn itself. William Herschel watched the gas giant at a good time - this made the discovery possible.

Options

Enceladus is the sixth largest satellite of Saturn. Its diameter is 500 km, which is about 25 times less than the analogous parameter of the Earth. By mass, the satellite yields to our planet almost 200,000 times. The size of Enceladus does not make it any outstanding cosmic object. A satellite is allocated by other parameters.

Enceladus has a high reflectivity, its albedo is close to unity. In the whole system, it is probably the lightest object after the Sun. The reason for the brightness of the star in the high surface temperature, in Enceladus is different. It reflects almost all the light that comes to it, because it is covered with ice. The average surface temperature on the satellite is -200 ºС.

The orbit of the satellite is located close enough to the rings of Saturn. From the gas giant it is separated by a distance of 237,378 km. One revolution around the planet the satellite makes in 32.9 hours.

Surface

Initially, scientists were not interested in so actively Enceladus. However, the device "Cassini", several times quite close to the satellite, conveyed to Earth extremely interesting data.

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 southern pole of the satellite. Parallel tectonic faults were detected by the Cassini apparatus in 2005. They were called "tiger stripes" for their similarity to the pattern of a mustached predator.

According to scientists, these cracks - 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, which flew past Enceladus in 1981, did not notice the faults at the south pole. The researchers suggest that the fissures are exactly less than a thousand years old, and it is quite possible that they appeared just ten years ago.

Temperature anomalies

The orbital station registered a non-standard temperature distribution on the surface of Enceladus. It turned out that the southern pole of the cosmic body heats up much more than the equator. The sun can not lead to such an anomaly: traditionally the poles are the coldest areas. Scientists involved in the study Enceladus, came to the conclusion that the cause of heating - an internal source of heat.

Here it is worth mentioning that the surface temperature in this place is large by the standards of such a remote part of the solar system. Saturn's satellites: Enceladus, Titan, Iapetus and others - can not boast of hot areas in the usual sense. The temperature in the anomalous zones is only 20-30º above the average, that is, about -180ºC.

Astrophysicists suggest that the reason for heating the southern 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 liquid that makes up it breaks out in the form of geysers through the "tiger stripes". Powerful jets were also seen by the Cassini probe in 2005. The device collected samples of the substance that makes up the streams. His analysis made two assumptions. Near the surface, particles that have escaped from the "tiger stripes" contain a large number of salts. It is they who point to the existence of a sea beneath the surface of Enceladus (and this is the first conclusion of scientists from the data of Cassini). With much higher speed, particles with a smaller salt content break out from the cracks. Hence the conclusion of the second: they form the ring E, on the "territory" of which the satellite of Saturn is actually located.

The subsurface ocean

An impressive fraction of the escaping particles is close in composition to sea water. They fly out at relatively low speeds and can not become material for ring E. Salty particles fall on the surface of Enceladus. The composition of the escaping ice indicates that its source can not be the frozen core of the satellite.

The researchers suggest that the salt sea is located at a depth of 50 miles below the surface of Enceladus. It is limited on the one hand by a solid core and an ice mantle on the other. Water in the interlayer is in a liquid state, despite the low temperature. It does not freeze because of the high content of salts, but also due to tidal energy, which creates the gravitational field of Saturn and some other objects.

The amount of evaporating water (about 200 kg per second) speaks for a huge ocean area. Jets of water vapor and ice break out onto the surface as a result of the formation of cracks that lead to pressure failure.

Atmosphere

The automatic interplanetary station "Cassini" discovered an atmosphere on Enceladus. For the first time it was registered by the magnetometer of the apparatus on the effect on the magnetosphere of Saturn. Some time later, "Cassini" directly recorded it, watching the eclipse by the companion of Gamma Orion. Studies of the probe made it possible to learn the approximate composition of the atmosphere of the icy moon of Saturn. At 65% it consists of water vapor, in second place concentrates molecular hydrogen (about 20%), carbon dioxide, carbon monoxide and molecular nitrogen are also found.

The source of the replenishment of the atmosphere is presumably geysers, volcanism or gas emissions.

Is there life on Enceladus?

Detection of water in a liquid state is a kind of pass to the list of potentially inhabited (the way only by the simplest organisms) planets. According to scientists, if the ocean beneath the surface of Enceladus has existed for a long time, since the inception of the solar system, the probability of finding life in it is high enough, provided that water is practically all this time maintained in a liquid state. If the ocean periodically freezes, which is quite possible because of the impressive distance to the luminary, the chance of habitability becomes extremely small.

Confirm or disprove the assumptions of researchers now only the information coming from the probe "Cassini" is capable. His mission was 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 the Earth to Enceladus is great, and similar projects require careful preparation and impressive funding.

The Cassini probe continues its work. He was on his way to study the gas giant and satellites of Saturn. Enceladus, however, did not appear on the list of main tasks. The detected features included it in the list of objects of primary importance. No one expected to find water in a liquid state in the solar system where Saturn is located. Photo geysers on Enceladus and a few years after the opening seem incredible. It is possible that the satellite's surprises do not end there and until the mission of Cassini is completed, astrophysicists will learn a lot more about this icy moon.