Weight io. Discovery and name of Io's satellite

Brief information about Io

Orbit = 422,000 km from Jupiter
Diameter = 3630 km
Weight = 8.93*1022 kg

Io is the third largest and closest moon of Jupiter. Io is slightly larger than the Moon - Earth's satellite. Io was Zeus's (Jupiter's) first lover, whom he turned into a cow to try and hide from a jealous Hera. Io was discovered by Galileo and Marius in 1610.

Unlike most satellites in the outer solar system, Io and Europa are similar in composition to terrestrial planets, primarily in the presence of silicate rocks. The latest data from the Galileo satellite shows that Io has an iron core (perhaps a mixture of iron and iron sulfide) with a radius of at least 900 km.

The surface of Io is radically different from the surface of any other body in the solar system. This was a completely unexpected discovery made by scientists using the Voyager spacecraft. They expected to see a surface covered with craters, as on other solid-surface bodies, and to estimate the age of Io's surface from them. But very few craters have been found on Io, hence its surface is very young.

Instead of craters, Voyager 1 found hundreds of volcanoes. Some of them are active! Photographs of eruptions with plumes 300 km high were transmitted to Earth by Voyager and Galileo. This was the first real evidence that the cores of other terrestrial bodies are also hot and active. The material erupting from Io's volcanoes is some form of sulfur or sulfur dioxide. Volcanic eruptions change rapidly. In just the four months between Voyager 1 and Voyager 2, some of the volcanoes ceased to function, while others emerged.

Recent images from the NASA Infrared Telescope at Mauna Kea in Hawaii show a new and very large eruption. The Galileo images also show many changes since Voyager's flight. These observations confirm that Io's surface is indeed very active.

Io's landscapes are surprisingly diverse: pits up to several kilometers deep, lakes of molten sulfur (lower right), mountains that are not volcanoes, streams of some kind of viscous liquid (some kind of sulfur?) stretching for hundreds of kilometers, and volcanic vents. Sulfur and sulfur-containing mixtures give a wide range of colors that are observed in images of Io.

Analysis of images taken by Voyager led scientists to the assumption that the lava flows on the surface of Io consist mainly of molten sulfur with various impurities. However, consistent ground-based infrared studies indicate that they are too hot to be liquid sulfur. One idea about this is that the lava on Io is molten silicate rock. Recent observations indicate that this substance may contain sodium.

Some of the hottest spots on Io reach temperatures of 1500 K, although the average temperature is much lower, around 130 K.

The energy for all this activity Io probably receives from tidal interactions with Europa, Ganymede and Jupiter. Although Io, like the Moon, always turns the same side to Jupiter, the influence of Europa and Ganymede still causes slight fluctuations. These vibrations stretch and bend Io's surface by as much as 100 meters and generate heat, causing the surface to heat up.

Io crosses Jupiter's magnetic field lines, generating an electrical current. Although small compared to tidal heating, this current can carry more than 1 trillion watts. Recent data from Galileo indicates that Io may have its own magnetic field, like Ganymede. Io has a very thin atmosphere, consisting of sulfur dioxide and possibly some other gases. Unlike other moons of Jupiter, Io has very little or no water.

Volcanoes on Io are very hot and contain unfamiliar ingredients, according to the latest data from the Galileo spacecraft. A near-infrared spectrometer mounted on Galileo has detected extremely high temperatures inside volcanoes. They turned out to be much higher than previously thought. The spectrometer is able to detect the heat of a volcano and indicate the location of various materials on Io's surface.

Inside the Pele volcano, named after the mythological Polynesian goddess of fire, the temperature is much higher than the temperature inside any of the volcanoes on Earth - it is about 1500 ° C. It is possible that volcanoes on Earth were just as hot billions of years ago. Now scientists are interested in the following question: do all volcanoes on Io erupt such hot lava, or are most volcanoes like basalt volcanoes on Earth, which eject lava with lower temperatures - about 1200 ° C?

Even before Galileo flew close to Io in late 1999 and early 2000, Io was known to have two large, very hot volcanoes. Now, Galileo has found that there are more high-temperature regions on Io than remote observations indicated. This meant that there could be much smaller volcanoes on Io with very hot lava.

One of the most active volcanoes on Io is Prometheus. Its emissions of gas and dust have been recorded previously by the Voyager spacecraft and now by Galileo. The volcano is surrounded by a ring of bright sulfur dioxide.

As already mentioned, the spectrometer installed on board Galileo can recognize various substances by determining their ability to absorb or reflect light. In this way, hitherto unknown material was discovered. According to scientists, it could be an iron-containing mineral, such as pyrite, present in silicate lava. But further studies have shown that, most likely, this substance does not rise to the surface with lava, but rather is ejected by volcanic torches. It is possible that identifying this mysterious compound will require experimentation in the laboratory using spacecraft observational data.

Io has a solid metal core surrounded by a rocky mantle, similar to Earth's. But under the influence of the Moon's gravity, the shape of the Earth is slightly distorted. But the shape of Io under the influence of Jupiter is distorted much more. In fact, Io is permanently oval due to Jupiter's rotation and tidal influence. The Galileo spacecraft measured Io's polar gravity as it circled it in May 1999. With a known gravitational field, one can determine the internal structure of Io. The relationship between polar and equatorial gravity shows that Io has a large metallic core, mostly iron. The metal core of the Earth generates a magnetic field. It is not yet known whether Io's metallic core generates its own magnetic core.

As early as 1610, four spots on the disk were noticed by the Italian scientist Galileo Galilei. The spots appeared and then disappeared again. It was similar to the rotation of the planets around a star, like. So the first "moons" of Jupiter were discovered, named after the scientist - Galilean satellites. For almost four hundred years, scientists, astronomers and just amateurs have been sure that there are only four satellites. However, in the age of space technology, such devices as Pioneer and Voyager discovered dozens of Jupiter moons. All of them, together with a huge giant, form another, small "". If the mass of Jupiter were 4 times its real mass, then another star system would form. On the Earth's sky would be observed two stars: and .

All satellites rotate due to the huge gravity of Jupiter, their rotation is similar to rotation around. Each "moon" has its own orbits, which are distant from the gas planet at different distances. The closest satellite Metis is located 128 thousand km from the planet, while the most distant are 20-30 million km from their "owner". At the moment, the gaze of scientists and astronomers is directed precisely at the study of 4 Galilean satellites (Io, Europa, Ganymede, Calisto), since they are the largest and most unpredictable moons of Jupiter. These are the most interesting new worlds, each with its own history, mysteries and phenomena.

And about

Satellite name: And about;

Diameter: 3660 km;

Pov area: 41,910,000 km²;

Volume: 2.53×10 10 km³;
Weight: 8.93×1022 kg;
Density be: 3530 kg/m³;
Rotation period: 1.77 days;
Period of circulation: 1.77 days;
Distance from Jupiter: 350,000 km;
Orbital speed: 17.33 km/s;
equator length: 11,500 km;
Orbital inclination: 2.21°;
Accel. free fall: 1.8 m/s²;
Satellite : Jupiter

Io was discovered by Galileo on January 8, 1610. It is the closest Galilean satellite. Distance from And about to the outermost layers of Jupiter's atmosphere is almost the same as between and - about 350,000 thousand km. In many basic respects, the satellite is similar to the Moon. The mass and volume are almost the same, the radius of Io is only 100 km larger than the lunar radius, the forces of attraction of both satellites are also similar (Io - 1.8 m / s², the Moon - 1.62 m / s²). Due to the small distance from the planet and the large mass, the gravitational force rotates Io around the planet at a speed of 62,400 km / h (17 times the speed of rotation). Thus, the year on Io lasts only 42.5 hours, so you can observe the satellite almost every day.

A characteristic difference between Io and other satellites is the large volcanic activity on its surface. The Voyager space stations recorded 12 active volcanoes spewing hot lava flows up to 300 km high. The main emitted gas is sulfur dioxide, which then freezes on the surface as a white solid. Because of Io's thin atmosphere, such hot fountains of gas can be seen even with amateur telescopes. This majestic sight can be attributed to one of the wonders of the solar system. What is the reason for such a high volcanic activity of Io, because its neighbor Europe is a completely frozen world, the surface of which is covered with many kilometers of ice. This question is the main mystery for scientists and astronomers. The main version implies that the gravitational influence on Io, both itself and other satellites, has instilled two tidal humps on the surface of the satellite. Since Io's orbit is not an exact circle, as it rotates around Jupiter, the humps move slightly on Io's surface, which leads to heating of the interior. The nearest "moon" Jupiter is sandwiched in a gravitational ring between the planet itself and the rest of the satellites (mainly between and Europa). On this basis, it should be noted that Io is the most volcanically active body .

Volcanic activity is a fairly common occurrence on Io. Sulfur emissions can
rise to a height of 300 km, some of them fall to the surface, forming
lava seas, and some remain in outer space

Europe

Satellite name: Europe;

Diameter: 3122 km;

Pov area: 30,613,000 km²;

Volume: 1.59×10 10 km³;

Weight: 4.8×1022 kg;

Density be: 3013 kg/m³;

Rotation period: 3.55 days;

Period of circulation: 3.55 days;

Distance from Jupiter: 671,000 km;

Orbital speed: 13.74 km/s;

equator length: 9,807 km;

Orbital inclination: 1.79°;

Accel. free fall: 1.32 m/s²;

Satellite : Jupiter

Europe- This is the sixth satellite of Jupiter or the second of the Galilean group. Its nearly circular orbit is 671,000 kilometers away from the Gas Giant. The satellite needs 3 days 13 hours and 12 minutes to turn around, while Io manages to make two turns during this time.
At first sight Europe- this is a completely icy and devoid of any life world. There are no energy sources on its surface, and due to the large distance from the center, the satellite practically does not receive solar heat. This can also include too thin an atmosphere that is not able to retain heat for a long time. However, on the sixth moon there is something that not only other satellites of the planet do not have, but also all bodies (except). Jupiter's surface is covered by a 100 km layer water. This amount of water in volume exceeds the earth's oceans and seas combined. The atmosphere, although thin, is still entirely composed of oxygen (an element without which all Earthly creatures would die). It would seem that since there is oxygen and water, it means that life will be born. However, the upper layer, 10-30 km thick, is in a solid ice state, forming a very thick frozen bark, in which there are no active movements. But under its thickness, heat is enough to turn water into a liquid phase, in which a wide variety of inhabitants of the underwater world can live. In the near future, mankind plans to direct to Europe such a robot that could drill through a multi-kilometer layer of ice, plunge into the thickness of the water ocean and get acquainted with the local underwater inhabitants. At the end of its mission, such a device will have to rise to the surface of the satellite and deliver extraterrestrial beings to our planet.

A spacecraft (in the artist's mind) that will pass through

ice crust of Europa and will begin to study the oceanic part of the satellite

Geological history of Europe has nothing to do with the history of other moons. It is one of the smoothest solids in . There are no hills more than 100 m high on Europa, and its entire surface looks like one large plain of frozen ice. Its entire young surface is covered with a network of light and dark narrow stripes of great length. Dark stripes thousands of kilometers long are traces of a global system of cracks that arose as a result of repeated heating of the ice crust from internal stresses and large-scale tectonic processes.

There are 63 known satellites revolving around Jupiter, which can be divided into two groups - inner and outer. The outer satellites of Jupiter could well be captured by the gravitational field of the planet: they all revolve around Jupiter in the opposite direction.

Galileo Galilei and his telescopes

These large satellites - Io, Europa, Ganymede and Callisto - were discovered at the beginning of the 17th century. almost simultaneously Galileo Galilei and Simon Marius. They are usually called the Galilean satellites of Jupiter, although the first tables of their movement were compiled by Marius.

The outer group consists of small satellites, 1 to 170 km in diameter, moving in elongated and highly inclined orbits to Jupiter's equator. While satellites close to Jupiter move in their orbits in the direction of the planet's rotation, most distant satellites move in the opposite direction. A number of small satellites move in almost identical orbits. Scientists suggest that all of them are the remains of Jupiter's larger moons, destroyed by its gravity.

Astrophysicists from the University of Arizona have been able to establish that in the past, Jupiter "swallowed" many of its satellites. Those moons that we currently observe represent only a small fraction of the objects that have lived around the gas giant during the entire time of its existence.

As part of their study, scientists were interested in four large satellites of the gas giant: Io, Europa, Ganymede and Callisto. The orbits of these objects indicate that they were formed from a disk of gas and dust, which was located in the equatorial plane of Jupiter.

When satellites were formed from the remnants of a protoplanetary cloud, flows of gas and dust from interplanetary space destabilized the orbits of the satellites, causing some of them to fall on Jupiter.

The moons currently observed are the latest generation of many moons that have existed around the gas giant. This fact, in particular, indicates the relative youth of Io, Europa, Ganymede and Callisto.

Let us dwell in more detail on four satellites from the inner group: the Galilean satellites. These are four satellites, which differ from the rest in their large size and mass. They move in almost circular orbits in the plane of the planet's equator.

Galilean satellites

Of the many moons of Jupiter listed in the table. 4 Galilean satellites are distinguished, known since the time of Galileo. These are Io, Europa, Ganymede and Callisto. They are distinguished by their large size and proximity to the planet. Satellites even closer to Jupiter are known: these are 3 very small bodies, and Amalthea, which has an irregular shape. Together with them, the Galilean satellites form the so-called regular system, which is characterized by coplanarity and almost circular orbits. If we compare them with the position of our Moon, then Io is 10% farther, and Callisto is 4.9 times farther than the Moon. But because of the huge mass of Jupiter, they spend only 1.8 and 16.7 days for one revolution around the planet.

Murphy's law: A brief history of space exploration is full of funny and sometimes sad incidents, misunderstandings and unexpected discoveries. Gradually, a certain folklore arose, which specialists exchange at meetings. Often it is associated with surprises in the behavior of spacecraft. Not without reason, in the circles of space explorers, a half-joking, half-serious formulation of the Murphy-Chiseholm law was born: “Everything that can go bad, goes bad. Anything that can't go bad, goes bad too." One of the purely scientific articles in the journal "Science" and began: "In accordance with Murphy's law. But fortunately, the opposite is also true. The case that we will tell about, rather refers to such amazing luck. It is difficult to say how much truth there is, but the scientific outline of this story is quite reliable.

In 1671, observing the eclipses of Jupiter's satellites, the Danish astronomer Ole Römer discovered that the true position of Jupiter's satellites did not coincide with the calculated parameters, and the magnitude of the deviation depended on the distance to the Earth. Based on these observations, Roemer concluded that the speed of light was finite and established its value - 215,000 km/s.

Exploration of Jupiter's moons from space

During its stay in orbit around Jupiter, the spacecraft "Galileo" approached a record close to the satellites of Jupiter: Europa - 201 km, Callisto - 138 km, Io - 102 km, Amalthea 160 km.

The glow of the aurora and hot volcanic springs on the shadowy side of Io. Two photographs of Jupiter's moon Io taken by Voyager in 1979 and Galileo in 1996. Distinguishable changes in the surface as a result of volcanic activity. At the time of filming on 7 Sept. 1996 Galileo was at a distance of approx. 487000 km. from Io. When synthesizing both color images, Voyager's green to violet filters were used to convert them to the same type.

The internal structure of Jupiter's moons

Sectional interiors of Jupiter's moons, modeled from images of the surface taken by the Voyager probe and measurements of gravitational and magnetic fields by the Galileo probe. The dimensions of the satellites are shown in relative proportion.

All satellites, with the exception of Callisto, have a metallic core, shown in relative size in gray, surrounded by a shell of rock. On Io, a rocky or silicate shell extends to the surface, while on Ganymede and Europa it is also surrounded by a watery shell in the form of liquid or ice.

The internal structure of Callisto is shown as a mixture of comparable amounts of ice and silicates. Recent data point, however, to a more complex structure of the Callisto core. The surface layers of Callisto and Ganymede are thought to differ from the underlying glacial/silicate layers in terms of silicate percentage.

According to scientists, the ice surface on Europa may cover a liquid ocean. Studies of Galileo images allow us to conclude that under the ice cover of the satellite with a thickness of several to ten kilometers, there may be a liquid water ocean. But it has not yet been determined whether it currently exists.

Io satellite

The closest satellite of the planet Jupiter is Io, it is located at a scattering of 350 thousand km from the surface of the planet. The natural satellite of Io revolves around Jupiter at breakneck speed, making a revolution around it in 42.5 hours. Because of this, it is difficult to observe it through a telescope. almost every night it is on different sides of Jupiter relative to observers on Earth.

Although Io is a large satellite with a diameter of 3640 km, but due to its proximity to the planet, Jupiter's huge gravitational forces act on it, due to which tidal forces are formed that create enormous friction inside the satellite, so both the bowels of Io and its surface are heated. Some parts of the satellite are heated to three hundred degrees Celsius, twelve volcanoes have been discovered on Io, spewing magma to a height of up to three hundred kilometers.

In addition to Jupiter, Io is affected by the forces of attraction of other satellites of Jupiter closest to it. The Europa satellite has the main influence, providing its additional heating. In contrast to the Earth's volcanoes, which have a long “sleep” time and a relatively short period of eruptions, the volcanoes of a red-hot satellite are continuously active. The constantly flowing molten magma forms rivers and lakes. The largest molten lake is twenty kilometers in diameter and contains an island of solidified sulfur.

Volcanic activity on satellites is an extremely rare phenomenon in the solar system and Io in our system is the undoubted favorite in this indicator.

The surface of the satellite has a whole palette of colors, because the sulfur on the surface has a variety of shades at different temperatures and when combined with other substances, and also tends to retain color when cooled. The moon Io has no ice or water. According to the assumptions of scientists, this happened from the fact that Jupiter, at the stage of origin, was very hot and the liquid on the surface simply evaporated. The atmosphere on the satellite is rarefied. There are traces of sulfur dioxide and other gases.

The satellite has strong electrical discharges up to 1000 gigawatts. Electric current leaves the satellite at a high speed, several kilograms per second. This is due to the ionized atoms that are formed on the satellite due to the eruption. As a result, strong radio bursts occur that even reach the Earth. A plasma torus of charged particles is created along the orbit due to the rapid rotation of Jupiter's magnetic field. These particles then leave the torus and form an unusual magnetic sphere around Jupiter, which increases the radiation levels around the planet.

Sources: www.shvedun.ru, www.galspace.spb.ru, znaniya-sila.narod.ru, systemplanet.narod.ru, sevengalaxy.ru

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The most important astronomical discoveries in the history of space exploration are associated with the name of Galileo Galilei. It was thanks to this talented and persistent Italian that in 1610 the world first learned about the existence of four satellites of Jupiter. Initially, these celestial objects received a collective name - Galilean satellites. Later, each of them was given its own name: Io, Europa, Ganymede and Callisto. Each of the four largest satellites of Jupiter is interesting in its own way, but it is the satellite of Io that stands out among the other Galilean satellites. This celestial body is the most exotic and unusual among other objects in the solar system.

What is unusual about the moon Io?

Already with one observation through a telescope, the satellite of Io stands out among other satellites of the solar system with its appearance. Instead of the usual gray and muddy surface, the celestial body has a bright yellow disk. For 400 years, man could not find the reason for such an unusual coloring of the surface of the Jupiterian satellite. Only at the end of the 20th century, thanks to the flights of automatic space probes to the giant Jupiter, it was possible to obtain information about the Galilean satellites. As it turned out, Io is perhaps the most volcanically active object in the solar system in terms of geology. This was confirmed by the huge number of active volcanoes found on the moon of Jupiter. To date, about 400 of them have been identified, and this is on an area that is 12 times smaller than the area of ​​our planet.

The surface area of ​​the moon Io is 41.9 square meters. kilometers. The earth has a surface area of ​​510 million km, and today there are 522 active volcanoes on its surface.

In size, many of Io's volcanoes exceed the size of terrestrial volcanoes. In terms of the intensity of eruptions, their duration and power, volcanic activity on the satellite of Jupiter exceeds similar terrestrial indicators.

Some volcanoes of this satellite emit a huge amount of poisonous gases to a height of 300-500 km. At the same time, the very surface of the most unusual satellite of the solar system, Io, is a vast plain, in the center of which there is a huge mountain range, separated by huge lava flows. The average height of the mountain formations on Io is 6-6.5 km, but there are also mountain peaks more than 10 km high. For example, Mount South Boosavla has a height of 17-18 km and is the highest peak in the solar system.

Almost the entire surface of the satellite is the result of centuries of eruptions. According to instrumental studies carried out on board the space probes Voyager 1, Voyager 2 and other spacecraft, the main surface material of the Io satellite is frozen sulfur, sulfur dioxide and volcanic ash. Why are there so many multi-colored areas on the surface of the satellite. This is explained by the fact that active volcanism constantly forms a characteristic contrast in the color of the surface of the moon Io. The object may change from bright yellow to white or black for a short period of time. The products of volcanic eruptions form a thin and heterogeneous atmosphere of the satellite.

Such volcanic activity is caused by the peculiarities of the structure of the celestial body, which is constantly subjected to the tidal action of the gravitational field of the mother planet and the influence of other large satellites of Jupiter, Europa and Ganymede. As a result of the influence of cosmic gravity in the bowels of the satellite, friction arises between the crust and the inner layers, which generates natural heating of matter.

For astronomers and geologists who study the structure of objects in the solar system, Io is a real and active testing ground, where today there are processes characteristic of the early period of the formation of our planet. Scientists in many fields of science today are carefully studying the geology of this celestial body, making Jupiter's unique satellite Io the object of close attention.

The most geologically active celestial body in the solar system has a diameter of 3630 km. The size of Io is not so large, in comparison with other satellites of the solar system. In terms of its parameters, the satellite occupies a modest fourth place, skipping ahead of the huge Ganymede, Titan and Callisto. Io's diameter is only 166 km. exceeds the diameter of the Moon - Earth's satellite (3474 km).

The satellite is closest to the parent planet. The distance from Io to Jupiter is only 420 thousand km. The orbit has an almost regular shape, the difference between perihelion and apohelion is only 3400 km. The object rushes in a circular orbit around Jupiter at a tremendous speed of 17 km / s, making a complete revolution around it in 42 Earth hours. The orbit is synchronized with the rotation period of Jupiter, so Io is always turned to him by the same hemisphere.

The main astrophysical parameters of the celestial body are as follows:

• the mass of Io is 8.93x1022 kg, which is 1.2 times the mass of the moon;
• satellite density is 3.52 g/cm3;
• the magnitude of the free fall acceleration on the surface of Io is 1.79 m/s2.

By observing the position of Io in the night sky, it is easy to determine the swiftness of its movement. The celestial body is constantly changing its position relative to the planetary disk of the parent planet. Despite the moon's rather impressive gravitational field of its own, Io is unable to sustain a consistently dense and uniform atmosphere. A thin gaseous shell around the moon of Jupiter is practically a space vacuum, it does not prevent the ejection of eruption products into outer space. This explains the huge height of the columns of volcanic eruptions occurring on Io. In the absence of a normal atmosphere, low temperatures predominate on the surface of the satellite, down to -183 ° C. However, this temperature is not uniform for the entire surface of the satellite. Infrared images taken from the Galileo space probe showed the inhomogeneity of the temperature layer on Io's surface.

The main area of ​​the celestial body is dominated by low temperatures. On the temperature map, such areas are colored blue. However, in a number of places on the surface of the satellite there are bright orange and red spots. These are areas of the greatest volcanic activity, where eruptions are visible and clearly visible on ordinary photographs. Pele volcano and the Loque lava flow are the hottest areas on the surface of Io's moon. The temperature in these areas varies between 100-130° below zero on the Celsius scale. The small red dots on the temperature map are the craters of active volcanoes and fractures in the crust. Here the temperature reaches 1200-1300 degrees Celsius.

satellite structure

Unable to land on the surface, scientists today are actively working on modeling the structure of the Jovian moon. Presumably, the satellite consists of silicate rocks diluted with iron, which is characteristic of the structure of the terrestrial planets. This is confirmed by the high density of Io, which is higher than that of its neighbors - Ganymede, Callisto and Europa.

The current model, based on data obtained by space probes, is as follows:

• in the center of the satellite is an iron core (iron sulfide), which makes up 20% of the mass of Io;
• the mantle, consisting of minerals of an asteroid nature, is in a semi-liquid state;
• liquid subsurface layer of magma 50 km thick;
• the satellite's lithosphere consists of compounds of sulfur and basalt, reaching a thickness of 12-40 km.

Evaluating the data obtained during the simulation, the scientists came to the conclusion that the core of the satellite Io should have a semi-liquid state. If it contains sulfur compounds along with iron, its diameter can reach 550-1000 km. If it is a completely metallized substance, the size of the core can vary between 350-600 km.

In view of the fact that no magnetic field was detected during the studies of the satellite, there are no convection processes in the core of the satellite. Against this background, a natural question arises, what are the true reasons for such intense volcanic activity, where do the volcanoes of Io draw their energy from?

The small size of the satellite does not allow us to say that the heating of the bowels of a celestial body is carried out due to the reaction of radioactive decay. The main source of energy inside the satellite is the tidal effect of its space neighbors. Under the influence of the gravity of Jupiter and neighboring satellites, Io oscillates, moving along its own orbit. The satellite seems to sway, experiencing strong libration (uniform swaying) during movement. These processes lead to the curvature of the surface of a celestial body, causing thermodynamic heating of the lithosphere. This can be compared to the bending of a metal wire, which is very hot at the bend. In the case of Io, all of the above processes occur in the surface layer of the mantle at the boundary with the lithosphere.

The satellite is covered on top with deposits - the results of volcanic activity. Their thickness varies in the range of 5-25 km in the places of the main localization. In their color, these are dark spots, strongly contrasting with the bright yellow surface of the satellite, caused by outpourings of silicate magma. Despite the large number of active volcanoes, the total area of ​​volcanic calderas on Io does not exceed 2% of the moon's surface area. The depth of volcanic craters is insignificant and does not exceed 50-150 meters. The relief on most of the celestial body is flat. Only in some areas there are massive mountain ranges, for example, the Pele volcano complex. In addition to this volcanic formation, the Patera Ra volcano massif, mountain ranges and massifs of various lengths have been identified on Io. Most of them have names consonant with terrestrial toponyms.

Volcanoes of the satellite of Io and its atmosphere

The most curious objects on Io's moon are its volcanoes. The sizes of areas with increased volcanic activity range from 75 to 300 km. Even the first Voyager during its flight recorded the process of eruption of eight volcanoes at once on Io. A few months later, images taken by the Voyager spacecraft in 1979 confirmed the information that eruptions continued at these points. At the place where the largest volcano Pele is located, the highest temperature on the surface was recorded, +600 degrees Kelvin.

Subsequent studies of information from space probes allowed astrophysicists and geologists to divide all the volcanoes of Io into the following types:

• the most numerous volcanoes, which have a temperature of 300-400 K. The speed of the emission of gases is 500 m / s, and the height of the emission column does not exceed 100 km;
• the second type includes the hottest and most powerful volcanoes. Here we can talk about temperatures of 1000K in the caldera of the volcano itself. This type is characterized by a high ejection speed - 1.5 km / s, a gigantic height of the gas plume - 300-500 km.

The Pele volcano belongs to the second type, having a caldera with a diameter of 1000 km. The deposits resulting from the eruptions of this giant occupy a huge area - one million kilometers. No less interesting is another volcanic object - Patera Ra. From orbit, this area of ​​the satellite's surface resembles a marine cephalopod. Serpentine lava flows extending from the eruption site stretched for 200-250 km. Spacecraft thermal radiometers do not allow us to accurately determine the nature of these flows, as is the case with the Loki geological object. Its diameter is 250 km and in all likelihood it is a lake filled with molten sulfur.

The high intensity of eruptions and the huge scale of cataclysms not only constantly change the relief of the satellite and the landscape on its surface, but also form a gaseous shell - a kind of atmosphere.

The main component of Jupiter's moon atmosphere is sulfur dioxide. In nature, it is a sulfur dioxide gas that has no color, but has a pungent odor. As a supplement, along with sulfur dioxide, sulfur monoxide, sodium chloride, sulfur and oxygen atoms were found in the gas layer of Io.

Sulfur dioxide on Earth is a common food additive that is actively used in the food industry as a preservative E220.

The thin atmosphere of the moon Io is uneven in its density and thickness. The atmospheric pressure of the satellite is also characterized by the same variability. The maximum value of Io's atmospheric pressure is 3 nbar and is observed in the equatorial region on the hemisphere facing Jupiter. The minimum atmospheric pressure values ​​were found on the night side of the satellite.

Sultans of hot gases are not the only hallmark of Jupiter's moon. Even in the presence of a highly rarefied atmosphere, auroras can be observed in the equatorial region above the surface of a celestial body. These atmospheric phenomena are associated with the effect of cosmic radiation on charged particles entering the upper atmosphere during the volcanic eruptions of Io.

Io satellite research

A detailed study of the planets of gas giants and their systems began in 1973-74 with the missions of the space automatic probes Pioneer-10 and Pioneer-11. These expeditions provided scientists with the first images of the Io satellite, on the basis of which more accurate calculations of the size of the celestial body and its astrophysical parameters have already been made. Following the Pioneers, two American space probes, Voyager 1 and Voyager 2, set off for Jupiter. The second device managed to get as close as possible to Io at a distance of 20 thousand km and take better pictures at close range. It was thanks to the work of the Voyagers that astronomers and astrophysicists received information about the presence of active volcanic activity on this satellite.

The mission of the first space probes to explore outer space around Jupiter was continued by NASA's Galileo spacecraft, launched in 1989. After 6 years, the ship reached Jupiter, becoming its artificial satellite. In parallel with the study of the giant planet, the automatic probe Galileo was able to transmit data on the surface of the moon Io to Earth. During orbital flights, valuable information about the structure of the satellite and data on its internal structure was received by the earth's laboratories from the board of the space probe.

After a short break in 2000, the baton in the study of the most unique satellite in the solar system was intercepted by the NASA and ESA space probe Cassini-Huygens. The apparatus was engaged in the study and examination of Io during its long journey to Titan, the satellite of Saturn. The most recent data on the satellite was obtained using the state-of-the-art New Horizons space probe, which flew near Io in February 2007 on its way to the Kuiper belt. A new batch of images was presented to scientists by ground-based observatories and the Hubble space telescope.

NASA's Juno spacecraft is currently orbiting Jupiter. In addition to studying Jupiter, his infrared spectrometer continues to study the volcanic activity of the moon Io. Data transmitted to Earth allows scientists to monitor active volcanoes on the surface of this most interesting celestial body.

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Many curious facts, stories, secrets of space and the unknown are constantly surrounding us. It is always interesting both from a scientific point of view and from the layman's side. However, if some space objects are interesting in themselves as extraterrestrial formations, then there are other truly unique objects whose behavior and nature are really unusual. Io, one of the four largest satellites of Jupiter, can be safely attributed to such celestial bodies.

Volcanic hell, cosmic underworld, hellish furnace - all these epithets refer to the satellite, bearing the meek female name Io, taken from ancient Greek mythology.

Behind the ordinary lies the extraordinary

Io, like the other three largest moons of Jupiter, was discovered in 1610. The discovery is attributed to Galileo Galilei, but the great scientist had a co-author. They became the German astronomer Simon Marius, who also managed to discover the satellites of Jupiter. Despite the fact that world science gave the palm of discovery to Galileo, it was at the suggestion of Marius that the newly discovered celestial bodies got their names: Io, Europa, Ganymede and Callisto. The German insisted that the entire cosmic retinue of Jupiter should also bear mythical names.

The names of the satellites were given in accordance with the arrangement. The first, closest to Jupiter satellite of the whole four, was given the name in honor of Io - the secret beloved of the Thunderer Zeus. This combination was not accidental. Like the ancient myth, in which the beautiful Io was always under the influence of her master, in reality, the giant planet constantly dominates its nearest satellite. Jupiter's huge gravitational force field has endowed the satellite with the secret of eternal youth - increased geological activity.

The absence of powerful optical instruments for a long time did not allow a close view of the distant satellite. Only at the beginning of the 20th century, powerful new telescopes made it possible to see the amazing processes taking place on the surface of Io.

The satellite is a spherical body, slightly flattened at the poles. This is clearly seen in the difference between the equatorial and pole radii - 1830 km. against 1817 km. This unusual shape is explained by the constant impact on the satellite of the gravitational forces of Jupiter and two other neighboring satellites of Europa and Ganymede. Large dimensions correspond to the mass and rather high density of the first of the four Galilean satellites. So the mass of the object is 8.94 x 10 ²² kg. with an average density of 3.55 g / m³, which is slightly less than that of Mars.

The density of other satellites of Jupiter, despite their rather large size, decreases with distance from the parent planet. So for Ganymede, the average density is 1.93 g / m³, and for Callisto this figure is 1.83 g / m³.

The first of the famous four has the following astrophysical characteristics:

• the period of revolution around the parent planet is 1.77 days;
• the period of rotation around its own axis is 1.769 days;
• at perihelion, Io approaches Jupiter at a distance of 422,000 km;
• the apohelion of the satellite is 423,400 km;
• a celestial body rushes along an elliptical orbit at a speed of 17.34 km / s.

It should be noted that the satellite Io has the same period of revolution and the period of rotation, so the celestial body is always turned to its owner on one side. In this position, the fate of the satellite is not visible. Yellow-green poisonous Io makes its run around Jupiter, literally clinging to the upper edge of the giant planet's atmosphere at an altitude of 350-370 thousand km. The satellite Io and its neighbors act on it, periodically approaching it, since the orbits of the three satellites - Io, Europa and Ganymede - are in orbital resonance.

What is the main feature of Io?

Mankind is accustomed to the idea that the Earth is the only cosmic body in the solar system that can be called a living organism that has a turbulent geological biography. In fact, it turned out that in addition to us, there is Io in the solar system, a satellite of Jupiter, which can be called the most volcanically active object in near space. The surface of the moon Io is constantly exposed to active geological processes that change its appearance. In terms of the intensity of volcanic eruptions, in terms of strength and power of emissions, poisonous, yellow-green Io is ahead of the Earth. This is, in a way, a constantly boiling and bubbling cauldron, sheltered near the side of the largest planet in the solar system.

For such a small celestial body, such geological activity is an unusual phenomenon. For the most part, the natural satellites of the solar system are stable formations of a planetary type, the period of geological activity of which ended many millions of years ago or is in its final stage. Unlike other Galilean satellites of Jupiter, nature itself determined the fate of Io, placing it in the immediate vicinity of the mother planet. Io is roughly the size of our moon. The diameter of the Jupiter satellite is 3660 km, at 184 km. larger than the moon's diameter.

Active volcanism on the moon Io is a constantly ongoing geological process that is not associated either with the age of the celestial body or with the features of its internal structure. Geological activity on the satellite is caused by the presence of its own heat, which is born as a result of the action of kinetic energy.

Secrets of Io's Volcanism

The main secret of Jupiter's volcanic activity lies in its nature, which is caused by the action of tidal forces. It has already been said above that the giant gas giant Jupiter and two other satellites, the giant Europa and Ganymede, simultaneously act on the beautiful yellow-green captive. Due to its close proximity to the parent planet, the surface of Io is distorted by a tidal hump, the height of which reaches several kilometers. Io's slight eccentricity is influenced by Io's sister neighbors Europa and Ganymede. All together leads to the fact that the tidal hump wanders over the surface of the satellite, causing deformation of the crust. The deformation of the crust, the thickness of which is no more than 20-30 km, is of a pulsating nature and is accompanied by a colossal release of internal energy.

Under the influence of such processes, the bowels of Jupiter's moons are heated to high temperatures, turning into a molten substance. High temperatures and enormous pressure lead to the eruption of the molten mantle to the surface.

Currently, scientists have been able to calculate the intensity and strength of the heat flow that occurs on Io under the influence of tidal forces. In the hottest areas of the satellite, the generation of thermal energy is 108 MW, which is ten times more than all the energy facilities of our planet generate.

The main products of eruptions are sulfur dioxide and sulfur vapours. The following figures speak of the emission power:

• the speed of the gaseous emission is 1000 km per second;
• gas sultans can reach a height of 200-300 km.

Every second, up to 100 thousand tons of volcanic material is erupted from the satellite's interior, which would be enough to cover the surface of the satellite with a ten-meter layer of volcanic rock in millions of years. Lava spreads over the surface, and sedimentary rocks complete the formation of the relief of the beauty. In this regard, only craters of volcanic origin are represented on Io. The changing relief is evidenced by light and dark spots, which cover the surface of the satellite with enviable constancy. According to scientists, dark spots are most likely volcanic calderas, lava riverbeds and fault marks.

Exploring the surface of the moon Io

The first data on Io were obtained during the flight of the Pioneer 10 automatic probe, which, back in 1973, provided information about the ionosphere of the Jupiter satellite. Subsequently, the study of the distant object continued with the help of AMS "Galileo". Today we can say with certainty that Io's atmosphere is thin and constantly under the influence of Jupiter. The giant planet seems to lick its companion, removing the air-gas layer from it.

The composition of the atmosphere of the yellow-green celestial body is almost uniform. The main component - sulfur dioxide - is a product of constant volcanic emissions. Unlike terrestrial volcanism, where volcanic emissions contain water vapor, Io is a sulfur factory. Hence the characteristic yellowish hue of the planetary disk of the satellite. As such, the atmosphere of this celestial body has negligible density. Most of the products of volcanic emissions fall immediately to a great height, forming the satellite's ionosphere.

As for the relief of the surface of the Jupiter satellite, it is mobile and constantly changing. This is evidenced by a comparison of images taken at different times from the two space probes Voyager 1 and Voyager 2, which flew near Io in 1979 with a difference of four months. Comparison of images made it possible to fix changes in the landscape of the satellite. The eruption processes continued with almost the same intensity. 16 years later, during the mission of the AMS "Galileo", cardinal changes in the relief of the satellite were revealed. New volcanoes have been noted in fresh images of previously explored areas. Changed the scale and lava flows.

More recent studies have made it possible to measure the temperature on the surface of an object, which on average varies between 130-140⁰С below zero. However, there are also hot regions on Io, where the temperature ranges from zero to 100 degrees with a plus sign. As a rule, these are areas of cooling lava, spreading after the next eruption. In the volcanic patera, the temperature can reach +300-400⁰ C. The small lakes of red-hot lava on the surface of the satellite are boiling cauldrons in which the temperature rises to 1000 degrees Celsius. As for the volcanoes themselves - the visiting card of the satellite of Jupiter, they can be divided into two types:

• the first are small, young formations, the height of the emissions is 100 km, with a gas emission velocity of 500 m/s;
• the second type is volcanoes, which are very hot. The height of ejecta during eruptions varies between 200-300 km, and the ejection velocity is 1000 m/s.

The second type includes the largest and oldest volcanoes of Io: Pele, Surt and Aten. Curious for scientists is such an object as Father Loki. Judging by the images taken from the Galileo AMS, the formation is a natural reservoir filled with liquid sulfur. The diameter of this boiler is 250-300 km. The dimensions of the patera and the relief surrounding it indicate that during the eruption a real apocalypse occurs here. The power of the erupting Loki exceeds the power of the eruptions of all active volcanoes on the Earth.

The intensity of Io's volcanism perfectly characterizes the behavior of the Prometheus volcano. This object continues to erupt continuously for 20 years since the start of fixation processes. Lava does not stop flowing from the crater of another Io volcano - Amirani.

Exploration of the most volcanically active object in the solar system

The most significant contribution to the study of the first of the Galilean satellites was made by the results of the AMS Galileo mission. The spacecraft, having reached the region of Jupiter, became an artificial satellite of the beautiful Io. In this position, the surface of Jupiter's satellite was surveyed during each orbital flight. The device completed 35 orbits around this hot object. The value of the information received led scientists from NASA to extend the mission of the probe for another three years.

Flight path of Galileo

The flight of the Cassini probe added important information for scientists, which, on the way to Saturn, managed to take several photographs of the yellow-green satellite. Exploring the satellite in the infrared and in the ultraviolet, the Cassini probe provided NASA scientists with data on the composition of the ionosphere, on the plasma torus of a distant celestial body.

The Galileo space probe, having completed its mission, burned up in September 2003 in the hot embrace of Jupiter's atmosphere. Further study of the most curious object of the solar system was carried out with the help of terrestrial telescopes and with the help of observations from the Hubble orbital telescope.

Flight of "New Horizons"

Fresh information about the moon Io began to arrive only after the automatic New Horizons probe reached this region of the solar system in 2007. The result of this work was pictures that confirmed the version of endlessly continuing volcanic processes that change the appearance of this distant celestial body.

Great hopes for the subsequent study of the Io satellite are associated with the flight of the new space probe "Juno", which set off on a long journey in August 2011. Today, this ship has already reached the orbit of Io and became its artificial satellite. The company AMC "Yunona" for the study of space around Jupiter, should be a whole flotilla of automatic probes:

• "Jupiter Europa Orbiter" (NASA);
• "Jupiter Ganymede Orbiter" (ESA - European Space Agency);
• "Jupiter Magnetospheric Orbiter" (JAXA - Japanese space agency);
• "Jupiter Europa Lander" (Roskosmos).

Flight of the Juno

Studies of Io's volcanism continue to interest scientists, but the general interest in this space object has weakened a bit. This is due to the fact that the practical side of studying the satellite of Jupiter has little in common with the plans of earthlings regarding the exploration of outer space. Much more interesting in this regard are other space objects that are in the sphere of influence of Jupiter and Saturn. Studying the behavior of Io gives scientists information about the natural mechanisms that exist in space. Whether information about the most volcanically active object in the solar system will be useful, time will tell. At the moment, the applied aspect of studying Jupiter's satellite Io is not being considered.