Mars is the 4th planet of the solar system. Mars is a red planet. Internal structure of Mars

Mars is the fourth planet from the Sun and the last of the terrestrial planets. Like the rest of the planets in the solar system (not counting Earth), it is named after the mythological figure - the Roman god of war. In addition to its official name, Mars is sometimes called the Red Planet, due to the brownish-red color of its surface. With all this, Mars is the second smallest planet in the solar system after.

For almost the entire nineteenth century, it was believed that life existed on Mars. The reason for this belief is partly error and partly human imagination. In 1877, astronomer Giovanni Schiaparelli was able to observe what he thought were straight lines on the surface of Mars. Like other astronomers, when he noticed these stripes, he assumed that such directness was associated with the existence of intelligent life on the planet. A popular theory at the time about the nature of these lines was that they were irrigation canals. However, with the development of more powerful telescopes in the early twentieth century, astronomers were able to see the Martian surface more clearly and determine that these straight lines were just an optical illusion. As a result, all earlier assumptions about life on Mars remained without evidence.

Much of the science fiction written during the twentieth century was a direct consequence of the belief that life existed on Mars. From small green men to towering invaders with laser weapons, Martians have been the focus of many television and radio programs, comic books, films and novels.

Despite the fact that the discovery of Martian life in the eighteenth century ultimately turned out to be false, Mars remained for scientific circles the most life-friendly planet (not counting Earth) in the solar system. Subsequent planetary missions were undoubtedly dedicated to the search for at least some form of life on Mars. Thus, a mission called Viking, carried out in the 1970s, conducted experiments on Martian soil in the hope of finding microorganisms in it. At that time, it was believed that the formation of compounds during experiments could be the result of biological agents, but it was later discovered that compounds of chemical elements could be created without biological processes.

However, even these data did not deprive scientists of hope. Having found no signs of life on the surface of Mars, they suggested that all the necessary conditions could exist below the surface of the planet. This version is still relevant today. At the very least, planetary missions of the present such as ExoMars and Mars Science involve testing all possible options for the existence of life on Mars in the past or present, on the surface and below it.

Atmosphere of Mars

The composition of the atmosphere of Mars is very similar to that of Mars, one of the least hospitable atmospheres in the entire solar system. The main component in both environments is carbon dioxide (95% for Mars, 97% for Venus), but there is a big difference - there is no greenhouse effect on Mars, so the temperature on the planet does not exceed 20°C, in contrast to 480°C on the surface of Venus . This huge difference is due to the different densities of the atmospheres of these planets. With comparable densities, Venus's atmosphere is extremely thick, while Mars has a rather thin atmosphere. Simply put, if the atmosphere of Mars were thicker, it would resemble Venus.

In addition, Mars has a very rarefied atmosphere - atmospheric pressure is only about 1% of the pressure on Earth. This is equivalent to a pressure of 35 kilometers above the Earth's surface.

One of the earliest directions in the study of the Martian atmosphere is its influence on the presence of water on the surface. Despite the fact that the polar caps contain solid water and the air contains water vapor resulting from frost and low pressure, all research today indicates that the “weak” atmosphere of Mars does not support the existence of liquid water on the surface planets.

However, based on the latest data from Mars missions, scientists are confident that liquid water exists on Mars and is located one meter below the surface of the planet.

Water on Mars: speculation / wikipedia.org

However, despite the thin atmospheric layer, Mars has weather conditions that are quite acceptable by terrestrial standards. The most extreme forms of this weather are winds, dust storms, frost and fog. As a result of such weather activity, significant signs of erosion have been observed in some areas of the Red Planet.

Another interesting point about the Martian atmosphere is that, according to several modern scientific studies, in the distant past it was dense enough for the existence of oceans of liquid water on the surface of the planet. However, according to the same studies, the atmosphere of Mars has been dramatically changed. The leading version of such a change at the moment is the hypothesis of a collision of the planet with another fairly voluminous cosmic body, which led to Mars losing most of its atmosphere.

The surface of Mars has two significant features, which, by an interesting coincidence, are associated with differences in the planet's hemispheres. The fact is that the northern hemisphere has a fairly smooth topography and only a few craters, while the southern hemisphere is literally dotted with hills and craters of different sizes. In addition to topographical differences, which indicate differences in the relief of the hemispheres, there are also geological ones - studies indicate that areas in the northern hemisphere are much more active than in the southern.

On the surface of Mars is the largest known volcano, Olympus Mons, and the largest known canyon, Mariner. Nothing more grandiose has yet been found in the Solar System. The height of Mount Olympus is 25 kilometers (that's three times higher than Everest, the tallest mountain on Earth), and the diameter of the base is 600 kilometers. The length of the Valles Marineris is 4000 kilometers, the width is 200 kilometers, and the depth is almost 7 kilometers.

The most significant discovery about the Martian surface to date has been the discovery of canals. The peculiarity of these channels is that, according to NASA experts, they were created by flowing water, and thus are the most reliable evidence of the theory that in the distant past the surface of Mars was significantly similar to the earth's.

The most famous peridolium associated with the surface of the Red Planet is the so-called “Face on Mars”. The terrain actually closely resembled a human face when the first image of the area was taken by the Viking I spacecraft in 1976. Many people at the time considered this image to be real proof that intelligent life existed on Mars. Subsequent photographs showed that this was just a trick of lighting and human imagination.

Like other terrestrial planets, the interior of Mars has three layers: crust, mantle and core.
Although precise measurements have not yet been made, scientists have made certain predictions about the thickness of the crust of Mars based on data on the depth of Valles Marineris. The deep, extensive valley system located in the southern hemisphere could not exist unless the crust of Mars was significantly thicker than that of Earth. Preliminary estimates indicate that the thickness of Mars' crust in the northern hemisphere is about 35 kilometers and about 80 kilometers in the southern hemisphere.

Quite a lot of research has been devoted to the core of Mars, in particular to determining whether it is solid or liquid. Some theories have pointed to the absence of a strong enough magnetic field as a sign of a solid core. However, in the last decade, the hypothesis that the core of Mars is at least partially liquid has gained increasing popularity. This was indicated by the discovery of magnetized rocks on the planet's surface, which may be a sign that Mars has or had a liquid core.

Orbit and rotation

The orbit of Mars is remarkable for three reasons. Firstly, its eccentricity is the second largest among all the planets, only Mercury has less. With such an elliptical orbit, Mars' perihelion is 2.07 x 108 kilometers, which is much further than its aphelion of 2.49 x 108 kilometers.

Secondly, scientific evidence suggests that such a high degree of eccentricity was not always present, and may have been less than Earth's at some point in the history of Mars. Scientists say the reason for this change is the gravitational forces of neighboring planets acting on Mars.

Thirdly, of all the terrestrial planets, Mars is the only one on which the year lasts longer than on Earth. This is naturally related to its orbital distance from the Sun. One Martian year is equal to almost 686 Earth days. A Martian day lasts approximately 24 hours and 40 minutes, which is the time it takes for the planet to complete one full revolution around its axis.

Another notable similarity between the planet and Earth is its axial tilt, which is approximately 25°. This feature indicates that the seasons on the Red Planet follow each other in exactly the same way as on Earth. However, the hemispheres of Mars experience completely different temperature regimes for each season, different from those on Earth. This is again due to the much greater eccentricity of the planet’s orbit.

SpaceX And ​​plans to colonize Mars

So we know that SpaceX wants to send people to Mars in 2024, but their first Mars mission will be the Red Dragon capsule in 2018. What steps is the company going to take to achieve this goal?

• 2018 Launch of the Red Dragon space probe to demonstrate technology. The goal of the mission is to reach Mars and do some survey work at the landing site on a small scale. Perhaps supplying additional information to NASA or space agencies of other countries.
• 2020 Launch of the Mars Colonial Transporter MCT1 spacecraft (unmanned). The purpose of the mission is to send cargo and return samples. Large-scale demonstrations of technology for habitat, life support, and energy.
• 2022 Launch of the Mars Colonial Transporter MCT2 spacecraft (unmanned). Second iteration of MCT. At this time, MCT1 will be on its way back to Earth, carrying Martian samples. MCT2 is supplying equipment for the first manned flight. MCT2 will be ready for launch once the crew arrives on the Red Planet in 2 years. In case of trouble (as in the movie “The Martian”) the team will be able to use it to leave the planet.
• 2024 Third iteration of Mars Colonial Transporter MCT3 and first manned flight. At that point, all technologies will have proven their functionality, MCT1 will have traveled to Mars and back, and MCT2 will be ready and tested on Mars.

Mars is the fourth planet from the Sun and the last of the terrestrial planets. The distance from the Sun is about 227940000 kilometers.

The planet is named after Mars, the Roman god of war. To the ancient Greeks he was known as Ares. It is believed that Mars received this association due to the blood-red color of the planet. Thanks to its color, the planet was also known to other ancient cultures. Early Chinese astronomers called Mars the “Star of Fire,” and ancient Egyptian priests referred to it as “Ee Desher,” meaning “red.”

The land masses on Mars and Earth are very similar. Despite the fact that Mars occupies only 15% of the volume and 10% of the mass of the Earth, it has a comparable land mass to our planet as a consequence of the fact that water covers about 70% of the Earth's surface. At the same time, the surface gravity of Mars is about 37% of the gravity on Earth. This means that you could theoretically jump three times higher on Mars than on Earth.

Only 16 of 39 missions to Mars were successful. Since the Mars 1960A mission launched by the USSR in 1960, a total of 39 landers and rovers have been sent to Mars, but only 16 of these missions have been successful. In 2016, a probe was launched as part of the Russian-European ExoMars mission, the main goals of which will be to search for signs of life on Mars, study the surface and topography of the planet, and map potential environmental hazards for future manned missions to Mars.

Debris from Mars has been found on Earth. It is believed that traces of some of the Martian atmosphere were found in meteorites that bounced off the planet. After leaving Mars, these meteorites for a long time, for millions of years, flew around the solar system among other objects and space debris, but were captured by the gravity of our planet, fell into its atmosphere and crashed to the surface. The study of these materials allowed scientists to learn a lot about Mars even before space flights began.

In the recent past, people were sure that Mars was home to intelligent life. This was largely influenced by the discovery of straight lines and grooves on the surface of the Red Planet by Italian astronomer Giovanni Schiaparelli. He believed that such straight lines could not be created by nature and were the result of intelligent activity. However, it was later proven that this was nothing more than an optical illusion.

The highest planetary mountain known in the solar system is on Mars. It is called Olympus Mons (Mount Olympus) and rises 21 kilometers in height. It is believed that this is a volcano that was formed billions of years ago. Scientists have found quite a lot of evidence that the age of the object's volcanic lava is quite young, which may be evidence that Olympus may still be active. However, there is a mountain in the solar system to which Olympus is inferior in height - this is the central peak of Rheasilvia, located on the asteroid Vesta, whose height is 22 kilometers.

Dust storms occur on Mars - the most extensive in the solar system. This is due to the elliptical shape of the planet's orbit around the Sun. The orbital path is more elongated than many other planets and this oval orbital shape results in ferocious dust storms that cover the entire planet and can last for many months.

The Sun appears to be about half its visual Earth size when viewed from Mars. When Mars is closest to the Sun in its orbit, and its southern hemisphere faces the Sun, the planet experiences a very short but incredibly hot summer. At the same time, a short but cold winter sets in in the northern hemisphere. When the planet is farther from the Sun, and the northern hemisphere points towards it, Mars experiences a long and mild summer. In the southern hemisphere, a long winter sets in.

With the exception of Earth, scientists consider Mars the most suitable planet for life. Leading space agencies are planning a series of space missions over the next decade to find out whether there is potential for life on Mars and whether it is possible to build a colony on it.

Martians and aliens from Mars have been the leading candidates for extraterrestrials for quite a long time, making Mars one of the most popular planets in the solar system.

Mars is the only planet in the system, other than Earth, that has polar ice. Solid water has been discovered beneath the polar caps of Mars.

Just like on Earth, Mars has seasons, but they last twice as long. This is because Mars is tilted on its axis at about 25.19 degrees, which is close to Earth's axial tilt (22.5 degrees).

Mars has no magnetic field. Some scientists believe that it existed on the planet about 4 billion years ago.

The two moons of Mars, Phobos and Deimos, were described in the book Gulliver's Travels by Jonathan Swift. This was 151 years before they were discovered.

Mars is the fourth planet from . Confidently takes first place in the hopes placed on it by those who want to find life in space. The planet is red because of iron oxides, which are very abundant in the sands. In the near future, Elon Musk plans to colonize Mars and is already preparing an expedition and ships. Aliens and life have not yet been discovered here. The mass of the planet is 10 times less than Earth. You can fly to Mars on a spaceship in 7 months.

Atmosphere

Back in the 19th century, astronomers realized that Mars has an atmosphere. This was determined during the moments of confrontation between the planet and the Earth, which occur every 15–17 years. The discovery gave rise to optimism about possible life on Mars, but all hopes were dashed after the composition of the atmosphere and its density were determined. Carbon dioxide (96%), nitrogen (2.7%), argon (1.6%) and insignificant amounts of oxygen and other gases did not become favorable conditions for the development of life on the planet. But, nevertheless, there are still clouds of carbon dioxide and water. In appearance they are similar to earthly ones, feathery, and their shapes follow the relief contours.

Surface

Martian landscapes are complex and picturesque. They are replete with volcanoes, canyons, plains and craters. The southern hemisphere has five times more craters than the northern.

The structure of the planet.

Since we don’t even know the detailed structure yet, it’s also impossible to speak with certainty about the structure of Mars. Most likely, it also has a metallic and liquid core, the mass of which is up to one-tenth the mass of the planet, and the radius is up to half the radius of the planet. Between the core and the crust (70 – 100 km) the mantle is located. It is silicate and contains a lot of iron, the red oxides of which determine the color of the Martian surface. Mars is a cooling planet, so its crust is in a stationary state; marsquakes and geological faults are a thing of the past.

Moons of Mars

Mars has 2 satellites: Phobos and Deimos. Visible from Earth only through a very powerful telescope. They appear as two dots, pale against the background of the bright disk of Mars. In shape and structure, these are two huge stones, consisting of the same substance as.

This giant “potato” (both satellites resemble this vegetable) has dimensions of 27x22x18.6 km. Distant from the center of the planet by 9400 km, Phobos manages to fly around the planet three times per day.

Photos of Phobos

It is believed that due to the gravity of Mars, the satellite will be torn apart in 50 million years. If its strong enough structure holds up, it will fall onto the Martian surface, but after 100 million years.

Deimos

The dimensions of this satellite are more modest: 16x12x10 km. But its orbital period is longer than a Martian day - 30 hours, and its distance from the center of the planet is 23,000 km. The surface of Deimos, like its brother, is dotted with craters from meteorite bombings.

The appearance of satellites on the planet is explained by the gravity of Mars, which captured them from the asteroid belt.

Features of the red planet

Compared to Earth's, the atmosphere of Mars is rarer, its pressure at the surface is 160 times less. The average temperature here is -40 °C. In summer, the surface of the red planet can warm up to +20 °C, and on winter nights it can drop to –125 °C.

Mars also has oases. The land of Noah, for example, has an area with a temperature range from –53 °C to +22 °C in summer and from –103 °C to –43 °C in winter. These parameters are quite comparable to ours in Antarctica.

Dust storms. Due to sudden changes in temperature, strong winds arise. Since gravity on the planet is low, millions of tons of sand rise into the air. Vast areas are caught in dust storms. Most often these storms occur near the polar ice caps.

Dust devils.Similar to earthly ones, but tens of times larger in size. They raise a lot of dust and sand into the air. Such a vortex cleaned the rover's solar panels in 2005.

Water vapor There is very little water on Mars, but low pressure helps it gather into clouds. Of course, they differ from earthly ones in their inexpressiveness. Fog may well accumulate over low-lying areas, and snow may even fall.

Seasons. Earth and Mars are similar in many ways. The Martian day is only 40 minutes longer than the Earth's. Both planets have almost the same inclination of the rotation axis (Earth 23.5°, Mars 25.2°), as a result of which the seasons also change on Mars. This is expressed in changes in the Martian polar caps. The northern cap decreases by a third in summer, while the southern one loses almost half.

Olympus. It is no coincidence that this inactive volcano received such a significant name. With a base diameter of 600 kilometers, it has a height of 27 kilometers. This is almost three times higher than Earth's Everest. It is considered the largest mountain in the solar system.

The huge area occupied by the base of the volcano does not allow it to be completely visible from the surface of the planet. The diameter of Mars is half that of Earth, and therefore the horizon is lower.

Life on Mars

The position of the planet relative to the Sun, the presence of river beds, rather benign climatic parameters, all this allows us to hope for the existence of life on it in some form. If we assume that life on the planet once existed, then some organisms may survive even now. Some scientists even claim to have found evidence of this. They draw such conclusions after studying objects that came to Earth directly from Mars. They contained some organic molecules, but their presence alone does not prove the existence of life on Mars, even primitive ones.

But no one doubts the presence of water on the red planet. The polar caps change their size depending on the season, this serves as evidence of their melting. Consequently, water is present on Mars in at least a solid state.

It is the planet Mars that is the optimistic future of humanity. It is quite possible that life on Earth appeared by moving from the surface of its red neighbor. And humanity also connects its future fate with it, hoping to move there in the event of a cataclysm.

Mars exploration

The 1960s became the starting point for the launch of automatic stations. Mariner 4 was the first to go to Mars, and Mariner 9 became the first satellite of the planet. Since then, many spacecraft have reached the orbit of the red planet, exploring not only it, but also the satellites of Mars. The most recent was Curiosity, which is still operating today.

The most important discoveries were confirmation of the presence of water on the planet and the cyclical nature of climate change on the planet.

"Puzzles"

Flashes. From 1938 to the present time, several flares have been recorded on the surface of Mars. Their duration ranges from several seconds to several minutes. The glow is bright blue, not typical for volcanic eruptions. The brightness is similar to the explosions of thermonuclear bombs. These flares turned out to be the play of sunlight in the optics of devices

Martian Sphinx. In one of the first images of the planet's surface, you can see a face. A more detailed study showed that this was an ordinary mountain, and the outline of the face turned out to be a bizarre play of light and shadow. And the camera optics were imperfect at that time.

Pyramid of Molenaar. A pentagonal pyramid was also initially discovered next to the famous “mysterious sphinx”. Its dimensions were said to be up to 800 meters in height with a maximum diameter of 2.6 km. Modern high-resolution surface studies have shown that these are ordinary, unremarkable rocks.

Spindle-shaped object. Before its death, Phobos-2 sent a photograph of a strange object to Earth. Some even recorded the presence of a UFO 3 days before the satellite stopped working. In fact, it turned out to be a shadow from its natural satellite - Phobos.

Mars – from the Greek Mas - male power - the god of war, in the Roman pantheon he was revered as the father of the Roman people, the guardian of fields and herds, and later the patron of equestrian competitions. Mars is the fourth planet of the solar system. The glowing blood-red disk seen through a telescope must have terrified the astronomer who discovered this planet. That's why they called her that.

And the satellites of Mars have corresponding names - Phobos and Deimos (“fear” and “horror”). None of the planets in the solar system attracts so much attention and remains so mysterious. A “quiet” planet, according to its data, is more “aggressive” to outside invasion than Venus, the planet with the most severe conditions (among the planets of this group). Many call Mars “the cradle of a great ancient civilization,” others call it just another “dead” planet in the solar system.

General information about the planet

It is most convenient to explore Mars when the Earth is between it and the Sun. Such moments are called oppositions, they are repeated every 26 months. During the month when the opposition occurs, and for the next three months, Mars crosses the meridian near midnight, it is visible throughout the night and sparkles like a star - 1st magnitude, rivaling Venus and Jupiter in brilliance.

The orbit of Mars is quite elongated, so the distance from it to the Earth varies greatly from opposition to opposition. If Mars comes into opposition with the Earth at aphelion, the distance between them exceeds 100 million kilometers. If the confrontation occurs under the most favorable conditions, at the perihelion of the Martian orbit, this distance is reduced to 56 million kilometers. Such “close” confrontations are called great and are repeated after 15-17 years. The last great confrontation took place in 1988.

Mars has phases, but since it is located further from the Sun than the Earth, it (like other outer planets) does not have a complete change of phases - the maximum “damage” corresponds to the phase of the Moon three days before the full moon or three days after it.

The axis of rotation of Mars is inclined relative to the plane of its orbit by 22*, i.e. only 1.5* less than the Earth's rotation axis is inclined to the ecliptic plane. Moving in orbit, it alternately exposes the Sun to the southern and northern hemispheres. Therefore, on Mars, just like on Earth, the seasons change, only they last almost twice as long. But a Martian day is not much different from an Earth day: a day there lasts 24 hours. 37 min.

Due to its low mass, the gravity on Mars is almost three times lower than on Earth. Currently, the structure of the gravitational field of Mars has been studied in detail. It indicates a slight deviation from the uniform distribution of density on the planet. The core can have a radius of up to half the radius of the planet. Apparently, it consists of pure iron or an alloy of Fe-FeS (iron-iron sulfide) and possibly hydrogen dissolved in them. Apparently, the core of Mars is partially or completely liquid.

Mars should have a thick crust 70-100 km thick. Between the core and the crust there is a silicate mantle enriched in iron. Red iron oxides present in surface rocks determine the color of the planet. Now Mars continues to cool. The planet's seismic activity is weak.

Surface of Mars

The surface of Mars, at first glance, resembles the moon. However, in reality its relief is very diverse. Over the course of Mars' long geological history, its surface has been altered by volcanic eruptions and marsquakes. Deep scars on the face of the god of war were left by meteorites, wind, water and ice.

The planet's surface consists of two contrasting parts: ancient highlands covering the southern hemisphere, and younger plains concentrated in northern latitudes. In addition, two large volcanic regions stand out - Elysium and Tharsis. The difference in altitude between the mountainous and lowland areas reaches 6 km. Why different areas differ so much from each other is still unclear. Perhaps this division is associated with a very long-standing catastrophe - the fall of a large asteroid on Mars.

The high mountain part has preserved traces of active meteorite bombardment that took place about 4 billion years ago. Meteor craters cover 2/3 of the planet's surface. There are almost as many of them on the old highlands as on the Moon. But many Martian craters managed to “lose their shape” due to weathering. Some of them, apparently, were once washed away by streams of water. The northern plains look completely different. 4 billion years ago there were many meteorite craters on them, but then the catastrophic event, which has already been mentioned, erased them from 1/3 of the planet’s surface and its relief in this area began to form anew. Individual meteorites fell there later, but in general there are few impact craters in the north.

The appearance of this hemisphere was determined by volcanic activity. Some of the plains are completely covered with ancient igneous rocks. Streams of liquid lava spread over the surface, solidified, and new streams flowed along them. These fossilized "rivers" are concentrated around large volcanoes. At the ends of lava tongues, structures similar to terrestrial sedimentary rocks are observed. Probably, when hot igneous masses melted layers of underground ice, fairly large bodies of water formed on the surface of Mars, which gradually dried up. The interaction of lava and underground ice also led to the appearance of numerous grooves and cracks. In low-lying areas of the northern hemisphere far from volcanoes, sand dunes extend. There are especially many of them near the northern polar cap.

The abundance of volcanic landscapes indicates that in the distant past Mars experienced a rather turbulent geological era, most likely it ended about a billion years ago. The most active processes occurred in the regions of Elysium and Tharsis. At one time, they were literally squeezed out of the bowels of Mars and now rise above its surface in the form of enormous swellings: Elysium is 5 km high, Tharsis is 10 km high. Numerous faults, cracks, and ridges are concentrated around these swellings - traces of ancient processes in the Martian crust. The most ambitious system of canyons, several kilometers deep, the Valles Marineris, begins at the top of the Tharsis Mountains and stretches 4 thousand kilometers to the east. In the central part of the valley its width reaches several hundred kilometers. In the past, when Mars' atmosphere was denser, water could flow into the canyons, creating deep lakes in them.

The volcanoes of Mars are exceptional phenomena by earthly standards. But even among them, the Olympus volcano, located in the northwest of the Tharsis Mountains, stands out. The diameter of the base of this mountain reaches 550 km, and the height is 27 km, i.e. it is three times larger than Everest, the highest peak on Earth. Olympus is crowned with a huge 60-kilometer crater. Another volcano, Alba, was discovered east of the highest part of the Tharsis Mountains. Although it cannot rival Olympus in height, its base diameter is almost three times larger. These volcanic cones were the result of quiet outpourings of very liquid lava, similar in composition to the lava of the terrestrial volcanoes of the Hawaiian Islands. Traces of volcanic ash on the slopes of other mountains suggest that catastrophic eruptions have sometimes occurred on Mars.

In the past, running water played a huge role in the formation of the Martian topography. At the first stages of the study, Mars seemed to astronomers to be a desert and waterless planet, but when the surface of Mars was photographed at close range, it turned out that in the old highlands there were often gullies that seemed to have been left by flowing water. Some of them look as if they were broken through by stormy, rushing streams many years ago. They sometimes stretch for many hundreds of kilometers. Some of these “streams” are quite old. Other valleys are very similar to the beds of calm earthly rivers. They probably owe their appearance to the melting of underground ice.

Atmosphere of Mars

The atmosphere of Mars is more rarefied than the air envelope of the Earth. Its composition resembles the atmosphere of Venus and is 95% carbon dioxide. About 4% comes from nitrogen and argon. Oxygen and water vapor in the Martian atmosphere are less than 1%. The average temperature on Mars is much lower than on Earth, about -40*C. Under the most favorable conditions in summer, on the daytime half of the planet, the air warms up to 20 * C - a completely acceptable temperature for the inhabitants of the Earth. But on a winter night the frost can reach -125*C. Such sudden temperature changes are caused by the fact that the thin atmosphere of Mars is not able to retain heat for a long time. Strong winds often blow over the surface of the planet, the speed of which reaches 100 m/sec. Low gravity allows even thin air currents to raise huge clouds of dust. Sometimes quite large areas on Mars are covered in enormous dust storms. A global dust storm raged from September 1971 to January 1972, raising about a billion tons of dust into the atmosphere to a height of more than 10 km.

There is very little water vapor in the atmosphere of Mars, but at low pressure and temperature it is in a state close to saturation and often collects in clouds. Martian clouds are rather inexpressive compared to terrestrial ones, although they have a variety of shapes and types: cirrus, wavy, leeward (near large mountains and under the slopes of large craters, in places protected from the wind). There is often fog over lowlands, canyons, valleys, and at the bottom of craters during cold times of the day.

The change of seasons on Mars occurs in the same way as on Earth. Seasonal changes are most pronounced in the polar regions. In winter, the polar caps occupy a significant area. The boundary of the northern polar cap can move away from the pole by a third of the distance from the equator, and the boundary of the southern cap covers half of this distance. This difference is caused by the fact that in the northern hemisphere, winter occurs when Mars passes through the perihelion of its orbit, and in the southern hemisphere, when it passes through aphelion (i.e., during the period of maximum distance from the Sun). Because of this, winter in the southern hemisphere is colder than in the northern hemisphere.

With the onset of spring, the polar cap begins to shrink, leaving behind gradually disappearing islands of ice. Apparently none of the caps disappear completely. Before Mars was explored using interplanetary probes, it was assumed that its polar regions were covered with frozen water. More accurate studies have also discovered frozen carbon dioxide in the Martian ice. In summer it evaporates and enters the atmosphere. The winds carry it to the opposite polar cap, where it freezes again. This cycle of carbon dioxide and the different sizes of the polar caps explain the variability in the pressure of the Martian atmosphere. In general, at the surface it is approximately 0.006 of the pressure of the earth's atmosphere, but can rise to 0.01.

Phobos and Deimos

The hypothesis about the existence of two moons in the orbit of Mars was first expressed by the famous writer Jonathan Swift in his novel about the adventures of Gulliver. But real astronomical confirmation of this hypothesis was obtained only in 1877. The year 1877 was the year of the great opposition, in which Mars and Earth came very close to each other. Such favorable conditions could not be neglected by the experienced astronomer Esaph Hall (1829-1907), who had already earned himself considerable authority as one of the best observers and calculators at the Harvard Observatory and a professor of mathematics at the Naval Observatory (Washington), who was responsible for the discovery of two Martian moons.

Having learned about the discovery from the newspapers, one English schoolgirl suggested Hall names for new celestial bodies: the god of war in ancient myths is always accompanied by his offspring - Fear and Horror, so let the inner one of the satellites be called Phobos, and the outer one Deimos, for this is how these words sound in ancient Greek language. The names turned out to be successful and stuck forever.

In 1969, the same year when people landed on the Moon, the American automatic interplanetary station Mariner 7 transmitted to Earth a photograph in which Phobos accidentally appeared, and it was clearly visible against the background of the disk of Mars. Moreover, the photograph showed the shadow of Phobos on the surface of Mars, and this shadow was not round, but elongated! More than two years later, Phobos and Deimos were specially photographed by the Mariner 9 station. Not only were television films with good resolution obtained, but also the first results of observations using an infrared radiometer and an ultraviolet spectrometer. Mariner 9 approached the satellites at a distance of 5,000 km, so the images showed objects with a diameter of several hundred meters. Indeed, it turned out that the shape of Phobos and Deimos is extremely far from the correct sphere. Their shape resembles an elongated potato. Telemetric space technology has made it possible to clarify the dimensions of these celestial bodies, which will no longer undergo significant changes. According to the latest data, the semi-major axis of Phobos is 13.5 km, and that of Deimos is 7.5 km, while the minor axis is 9.4 and 5.5 km, respectively. The surface of the satellites of Mars turned out to be extremely rugged: almost all of them are dotted with ridges and craters, obviously of impact origin. Probably, the fall of meteorites onto a surface unprotected by the atmosphere, which lasted for an extremely long time, could lead to such furrowing.

Mars programs

Over the past 20 years, many flights have been made to Mars and its moons. Research was carried out by Russian and American stations. But most of the programs were disrupted. Here is their chronology:

November 1962. The Mars-1 probe passed 197,000 kilometers from the “red” planet. After 61 sessions the connection was lost.

July 1965 Mariner 4 passed at a distance of 10 thousand km. from Mars. Many photographs of the surface of this planet were obtained, craters were discovered, the mass and composition of the atmosphere were clarified.

1969 Mariner 6 and Mariner 7 were at a distance of 3,400 km. from the surface. Several dozen images were obtained with a resolution of up to 300 m.

May 1971 Mars 2 and Mars 3 and Mariner 9 are launched. “Mars-2,-3” conducted research from the orbits of artificial satellites, transmitting data on the properties of the atmosphere and surface of Mars based on the nature of radiation in the visible, infrared and ultraviolet spectral ranges, as well as in the radio wave range. The temperature of the northern cap was measured (below -110*C); the extent, composition, temperature of the atmosphere, surface temperature were determined, data on the height of dust clouds and a weak magnetic field were obtained, as well as color images of Mars. After the research, both stations were lost. Mariner 9 transmitted to Earth 7,329 images of Mars with a resolution of 100 m, as well as photographs of its satellites.

1973 The Mars-4, -5, -6, -7 spacecraft reached the vicinity of Mars in early 1974. Due to a malfunction of the on-board braking system, Mars-4 passed at a distance of about 2200 km from the surface of the planet, having only photographed it. Mars-5 carried out remote sensing of the surface and atmosphere from the orbit of an artificial satellite. Mars 6 made a soft landing in the southern hemisphere. Data on the chemical composition, pressure and temperature of the atmosphere were transmitted to Earth. Mars 7 passed at a distance of 1,300 km from the surface without completing its program.

1975 Two American Vikings were launched. The Viking 1 landing block made a soft landing on the Chryss Plain on July 20, 1976, and the Viking 2 soft landing on the Utopia Plain on September 3, 1976. Unique experiments were carried out at the landing sites to detect signs of life in the Martian soil.

1988 The Soviet stations "Phobos-2, -3", which were supposed to explore Mars and its satellite Phobos, were, unfortunately, unable to implement the main program. Contact was lost on March 27, 1989.

1992 The American Mars Observer spacecraft also failed to complete its task; contact with it was lost on August 21, 1993.

JULY 1997“Mars Pathfinder” is the most interesting of the Mars exploration programs, and it is worth telling about it in more detail. On July 4, 1997, the automatic Earthling vehicle Pathfinder (Pathfinder) landed on the surface of the Red Planet. The “pathfinder” covered the entire path to Mars, which was half a billion kilometers long, at a speed of more than one hundred thousand kilometers per hour. The American specialists who created the interplanetary probe and sent it on such a long and dangerous journey showed miracles of ingenuity to ensure that the Pathfinder reached its destination safe and sound. They were especially worried about the last stage - landing the probe on the surface. The greatest danger to the probe was the violent storms on Mars. Before landing, a violent storm was spotted about a thousand kilometers from the landing point.

For the first time, Pathfinder was supposed to reach the Red Planet without entering orbit. To do this, the braking rockets were activated, and the probe entered the Martian atmosphere at a reduced speed of 7.5 km. per second. To further slow down the descent, a parachute with a garland of inflatable balloons was released. The parachute reduced the speed to 100 meters per second. 8 seconds before landing the cylinders were filled with gas. Immediately before touching the rocky ground, the parachute was “shot”, the cylinders hit the ground, springing back, jumped to a height of 15 meters. And so, after jumping several times, the entire complex froze only 20 kilometers from the planned location. And here a small problem occurred: one of the inflatable cylinders got caught on the edge of the “petal” (section of the open solar battery) and prevented the self-propelled six-wheeled robot “Sojourner” (“Fellow Traveler”) from exiting the womb of the apparatus. On command from the Earth, we had to raise the solar battery section by 45 degrees and keep it in that position for 10 minutes. During this time, the balloon was lowered, which made it possible for the “Fellow Traveler” to roll out onto the rocky ground and begin research.

90 minutes after the probe landed, NASA specialists received the first weak radio signals from an antenna mounted on one of the lobes. This meant that the landing was successful. The signals were transmitted in dead silence at a temperature of minus 220 Celsius! There was a long wait of several hours for the Martian sunrise to be able to recharge the solar panels. Then signals will come from a more powerful antenna, and along with them pictures of the planet’s surface.

The first stereoscopic images obtained showed that the landing was made in the area of ​​​​the ancient Ares Vallis canal, which once carried thousands of times more water than our current Amazon. As you know, “canals” were discovered from Earth a hundred years ago and gave rise to hypotheses about intelligent Martians who deployed a powerful irrigation system on their planet. Meteorite experts keen on searching for evidence of life on Mars said the images show a wide variety of rocks that deserve serious attention from geologists. Some rocks bear obvious traces of past impacts of water masses.

The Pathfinder interplanetary probe is the precursor to an ambitious series of further Mars missions. Particular interest in them was sparked by last year's discovery of traces of primitive life forms in a Martian meteorite that fell to Earth more than 1,300 years ago.

Mars is best observed during periods of its approach to the Earth. They occur on average every 2 years and 2 months, or more precisely, every 780 days. During such “meetings”, Mars, Earth and the Sun line up almost in one straight line. When Mars approaches us, it is located in the side of the sky opposite the Sun, and therefore is especially convenient for observations throughout the night. This position of the outer planet when, when observed from Earth, it opposes the Sun is called opposition.

However, due to the elongation of the Martian orbit, not all oppositions of Mars are equivalent. The “closest” approaches of the “red planet” to the Earth - great oppositions - are repeated after 15-17 years. The last such “handshake” of the two planets occurred on August 28, 2003, at a distance of about 56 million km. The next one will happen on July 27, 2018.

If you look at Mars through a telescope during its great opposition, then instead of a “fiery star” we will see an orange disk. And although the image is blurred by our turbulent atmosphere and shakes, the impression is nevertheless powerful, especially if one is observing the planet for the first time.

The first thing that attracts attention is the white spot at the top of the disk. This is the south polar cap of Mars. (Recall that the telescope gives an inverted image: north is below, and south is above.) It so happens that during periods of great oppositions, the southern hemisphere of the planet is tilted towards us, and therefore, before the start of space exploration of Mars, it was better studied than the northern.

Most of the Martian surface is occupied by yellowish-orange “continents.” Their color is the reason why Mars is visible in the sky as a fiery luminary. Taking a closer look, you can distinguish grayish-blue spots - “seas” - against the light background of the “continents”. It was no coincidence that astronomers who observed Mars in the 17th-19th centuries called the dark spots seas. They indeed considered them to be vast bodies of water, similar to the seas of the earth. And the orange color of the “continents” was perceived as the color of deserts.

But why do the spots lose their outlines as they move away from the center of the disk of Mars, and become completely shaded at its edges? But this is the influence of atmospheric haze! It intensifies as it approaches the edges of the disk, where the gas thickness increases. Mars, like Earth, has an atmosphere!

If you observe several nights in a row, you will notice that the spots slowly move from right to left and disappear behind the left edge of the planet’s disk. And because of its right edge, new spots appear (we are talking about an inverted image).

There is no doubt! The planet rotates around its axis in the forward direction (from west to east), that is, the same way as our Earth. Observations have established that Mars completes a full revolution around its axis in 24 hours 37 minutes 23 seconds. This determines the length of the Martian solar day to be 24 hours 39 minutes 29 seconds. Consequently, the days and nights in the neighboring world are slightly longer than ours on Earth.

On the eve of the great opposition, when Mars turns its southern hemisphere towards the Earth, spring begins there.

And the lucky observer is presented with the most impressive picture of seasonal changes on the planet.

Back in 1784, the English astronomer W. Herschel drew attention to periodic changes in the size of the polar caps of Mars. In winter they grow as if accumulating snow and ice, and with the arrival of spring they quickly melt. As the melting intensifies, those near the “sea” seem to come to life: they darken and acquire grayish-blue tones. Gradually, the “wave of darkening” spreads towards the equator. And in the next Martian half-year, the same wave moves towards the equator from the opposite pole of the planet.

Many observers attributed these regular seasonal changes to the spring awakening of Martian vegetation due to an increase in the influx of moisture and heat. Only if here on Earth spring spreads from south to north, then on Mars it moves from the poles to the equator! And although it looks strange, it is very tempting. One would think: there is life on the neighboring planet!

Natural conditions on Mars are determined not only by the change of day and night, but also by the change of seasons. The climatic features of the seasons depend on the inclination of the planet’s equator to the plane of its orbit. And the greater this tilt, the more contrasting the changes in the length of day and night and in the irradiation of the planet’s surface by solar rays.

The equator of Mars is inclined to the plane of its orbit at an angle of about 25 degrees, while at Earth it is 23 degrees 26 minutes of arc: the difference is almost imperceptible. Therefore, when the seasons change on Mars, the apparent movement of the Sun above the horizon should be approximately the same as on Earth. The only difference is the length of the seasons. They are much longer there. After all, Mars is on average 1.524 times farther from the central body than our Earth, and orbits in 687 Earth days. In other words, a Martian year is almost two Earth years.

The climate of Mars is harsh, perhaps harsher than in Antarctica. And spring on Mars is completely different from what we have on Earth.

In 1877, the scientific world was shocked by an unexpected discovery: there are canals on Mars! This was the year of the great opposition of Mars. Italian astronomer G. Schiaparelli decided to make a detailed map of the surface of Mars. Under the clear sky of Milan, he diligently made sketches of Mars and, of course, did not suspect that these observations would bring him worldwide fame. Schiaparelli had excellent eyesight and noticed something on Mars that other astronomers did not notice, and if they did notice, they did not pay attention. These were long and thin straight lines. They connected the polar caps of Mars with the equatorial regions of the planet, forming a complex network against the orange background of the Martian “continents”. Schiaparelli called them channels. “Every channel,” he reported about his discovery, “ends in the sea or is connected to another channel, and not a single case is known where the channel was interrupted among the land.”

The idea of ​​canals as structures created by thinking beings especially captured the American astronomer P. Lovell. In 1894, he built an observatory in Arizona (near Flagstaff at an altitude of 2200 m above sea level) designed specifically for observing Mars.

Even then, scientists realized that the climate of Mars was extremely dry and that most of its surface was occupied by vast deserts. And Lovell comes to the conclusion: the intelligent inhabitants of Mars, who have more advanced technology than we do, are attacking the desert: on the surface of the thirsty planet they are building grandiose irrigation structures...

The debate about the amazing canals lasted about 70 years. And only space research has shown that there are no artificial canals on Mars. And the effect of solid lines observed on Mars in small telescopes is an optical illusion. However, faith in intelligent Martians did not end there. Human minds began to be excited by the nature of the tiny satellites of Mars, Phobos and Deimos. Let us remember: it was hypothesized that they were artificial. And if so, then the satellites were created by Martians.

In the middle of the 20th century, it was noticed that something strange was happening to Phobos. For some reason, its movement is accelerating, and its orbit is gradually shrinking. In other words, the satellite is spiraling towards the planet. If this continues, then in 20 million years Phobos must certainly fall on Mars!

At first, scientists did not delve into the essence of this phenomenon. But now the Earth has artificial satellites. Braking in the upper atmosphere caused them to spiral and descend. This is where the Soviet astrophysicist Joseph Samuilovich Shklovsky (1916-1985) remembered the strange movement of Phobos. Its acceleration could be caused by a similar reason - the resistance of the Martian atmosphere. The scientist calculated that braking is possible only if the average density of the satellite is a thousand times less than the density of water. This means Phobos is empty inside! But only an artificial satellite can be hollow. Some have accepted this conclusion in favor of the existence of intelligent Martians...