New surface images Mars , taken by the Mars Global Surveyor in December 2000, show layers of sediment that likely formed underwater in the distant past.

A group of specialists engaged in image research Mars received by the Mars Global Surveyor station, believes that these layers of sedimentary rocks indicate that once surface Mars was covered with numerous lakes and shallow seas . In Martian craters, rows of sediments are clearly visible, which could hardly have formed without the participation of water. Such layered rock structures are widespread on Earth in places where lakes once existed.

The photographs (see photographs in the “Image Gallery” section) show the western part of the deep gorge of the large Martian canyon Valles Marinaris. The homogeneous, repeating structure suggests that deposition occurred regularly. The same structures found on Earth are usually the result of long-term sedimentary layering of rocks that occurs underwater.

Areas covered with sedimentary layers are scattered throughout the surface Mars. They are mainly located within craters such as Western Arabia Terra, Terra Meridiani, Hellas and in the crevices of the great canyon Valles Marineris. Scientists compare these layers to similar terrestrial structures in the southwestern United States, such as the Grand Canyon and the Painted Desert in Arizona.

Researchers do not exclude another option for the formation of layered structures. In the distant past, Mars had a denser atmosphere with more dust. Frequent dust storms could lead to the formation of such structures, similar to fossilized sediments. It is necessary to continue research in order to solve the mystery of their origin.

While many of the layered deposits in craters and crevices on Mars appear as stepped cliffs made of similar materials, other layers have smooth, rounded outlines with alternating light and dark stripes. An example of this is the southern Holden Crater, which is 141 km wide. The Uzboi Vallis valley adjoins it on the southwestern side. Not far from this valley in the crater, the cameras of the Mars Global Surveyor station captured rounded inclined structures consisting of alternating light and dark stripes.

Surface topography

Telescopic research Mars discovered features such as seasonal changes in its surface. This primarily applies to the “white polar caps,” which begin to increase with the onset of autumn (in the corresponding hemisphere), and in the spring they “melt” quite noticeably, with “warming waves” spreading from the poles. It has been suggested that these waves are associated with the spread of vegetation over the surface Mars, however, later data forced us to abandon this hypothesis.

A significant part of the surface Mars represents lighter areas (“continents”) that have a reddish-orange color; 25% of the surface are darker “seas” of gray-green color, the level of which is lower than that of the “continents”. The elevation differences are quite significant and amount to approximately 14-16 km in the equatorial region, but there are also peaks that rise much higher, for example, Arsia (27 km) and Olympus (26 km) in the elevated Tarais region in the northern hemisphere.

Observations Mars satellites detect distinct traces volcanism and tectonic activity- faults, gorges with branching canyons, some of them are hundreds of kilometers long, tens of them wide and several kilometers deep. The most extensive of the faults - “Valley Marineris” - near the equator stretches for 4000 km with a width of up to 120 km and a depth of 4-5 km.

Impact craters on Mars are shallower than those on the Moon and Mercury, but deeper than those on Venus. However, volcanic craters reach enormous sizes. The largest of them - Arsia, Acreus, Pavonis and Olympus - reach 500-600 km at the base and more than two dozen kilometers in height. The diameter of the crater at Arsia is 100, and at Olympus - 60 km (for comparison, the largest volcano on Earth, Mauna Loa on the Hawaiian Islands, has a crater diameter of 6.5 km). The researchers came to the conclusion that the volcanoes were active relatively recently, namely several hundred million years ago.

The hope of people to find “brothers in mind” rose with renewed vigor after A. Secchi in 1859 and, especially, D. Sciparelli in 1887 (the year of the great confrontation) put forward a sensational hypothesis that Mars is covered with a network of man-made canals periodically filled with water. The appearance of more powerful telescopes, and then spacecraft, did not confirm this hypothesis. Surface Mars It appears to be a waterless and lifeless desert, over which storms rage, raising sand and dust to a height of tens of kilometers. During these storms, wind speeds reach hundreds of meters per second. In particular, the “warming waves” mentioned above are now associated with the transfer of sand and dust.

- the fourth planet in the solar system in terms of distance from the Sun. Its name comes from the name of the god of war, which is probably due to its association with the red color of the planet. Mars can be seen with the naked eye. The data obtained as a result of the research activities of interplanetary automatic stations allowed us to draw conclusions about the existing similarity of this planet with the Earth. The technical landing on Mars was carried out relatively recently.

One can note the similarities between the lunar and Martian surfaces, although the morphology of the latter’s landscape is more complex: there are a large number of craters, plains, canyons and volcanoes.

It should be noted the presence of water (especially in the polar regions) in the subsurface layers of the soil. This phenomenon is called permafrost.
Just like on Earth, due to the tilt of the rotation axis on Mars, the seasons change with changes in the temperature of the planet's surface. The average temperature is 40°C, in summer up to -14°C, in winter up to – 120°C.

The geological structure of Mars is not characterized by tectonic plates. Cooling and subsequent increase in crustal thickness did not contribute to the formation of tectonic plates. In other words, Mars is a single plate with endogenous, i.e. “internal” (for example, protrusions of lava-like rocks in the mantle, volcanoes), and exogenous characteristics (meteorite impacts that damaged the crust).

There is a significant difference between the two hemispheres of the planet: the northern hemisphere is dominated by smooth plains and has a moderate number of craters, while the southern hemisphere has 5 times more craters. These differences can be explained by the more ancient origin of the southern hemisphere - approximately 3.8 billion years ago, at which time there was active meteorite bombardment in the solar system.

Between both hemispheres there is a surface with a peculiar landscape morphology, its name is Tharsis. In this territory there are volcanic formations, the mountains of Arsia, Pavonis, Askreus, Olympus, as well as the Valles Marineris and a whole system of canyons.

River beds

On the surface of Mars, formations are visible that are similar to river beds on Earth. The width of some of them reaches 200 km.

The so-called channels are divided into two types: the first is small, winding formations with branching “rivers”. The second represents it as a deep channel, and its dimensions are the same throughout.

There are two hypotheses about the origin of this phenomenon. According to the first, we are talking about the existence of various rivers on the surface of the planet in a temperate climate. According to the second hypothesis, these channels represent a residual phenomenon after the sharp and sudden formation of water flows as a result of crustal fracture. As confirmation of this theory, the Valles Marineris are more than 5000 km long, cut by the channels of water streams that appeared, apparently, suddenly.

Oceans

Despite the current dry and cold climate of Mars, there is evidence of the destructive activity of water and ice on the planet. The beds of non-existent rivers, plains covered with ice, permafrost and ice caps - all this indicates that at some point in the geological history of Mars the climate was temperate, and, accordingly, there was water on the surface of the planet.

The first geological eras were characterized by impact meteorite bombardments and frequent volcanic eruptions. It is during this period that destruction and erosion of craters under the influence of water is observed, and at the same time river beds are formed. The availability of water necessary for erosive phenomena cannot be a consequence of melting and collecting water in permafrost alone.

It is likely that at some stage there will also be a hydrodynamic cycle, which is characterized by the presence of water vapor in the atmosphere. The visible river beds indicate that the climate was once temperate. In this regard, we can speculate about the existence in the distant past of oceans with a normal water cycle - meaning the evaporation of water, its condensation in the clouds and further eruption to the surface. The completion of this cycle and the subsequent adsorption of water by porous rocks may be associated with the small mass of the planet; it could not retain the gases that make up the atmosphere.

After the first stages of the evolution of a planet with a characteristic temperate climate, other times come. It was during this period that the ocean formed on the surface of the planet. This could explain the origin of the Valles Marineris, water channels and other cracks that exist on the surface of Tharsis. The formation of an ocean on the surface of Mars can be argued by the permafrost fault as a result of volcanic activity. Canyons are also located close to volcanic structures.

The presence of water causes changes in the atmosphere - water vapor and carbon dioxide enter it from the surface. The greenhouse effect is progressing, resulting in rising temperatures, which is causing the melting of the planet's polar caps. As a consequence of these phenomena, water begins to be absorbed, slowly and over a long period of time, by the porous surface of the planet. Further events develop as follows - the reflectivity of the planet increases (due to the ice that covers the surface), its temperature decreases. The cycle ends. Water is absorbed by the surface of Mars.

Over time, the planet's internal temperature decreases and volcanic activity dies out. The climate is stabilizing.

Atmosphere

Thanks to research carried out using interplanetary automatic stations, the composition of the atmosphere of Mars was established - it consists of 96% carbon dioxide, 2.7% nitrogen and 1.6% argon. Oxygen is only 0.13% and water vapor is 0.03%. The surface pressure is low, six thousandths of the Earth's pressure. Suppose an astronaut lands on Mars. What will he see? The sky is reddish due to dust particles carried by the wind. Due to the low density, the sun's rays do not heat the planet; there is a significant difference in temperature between air flows. Martian clouds are composed of water and carbon dioxide, and they are similar in appearance to our cirrus clouds. Martian clouds basically follow the relief contours of the planet.

Mars is the fourth most distant planet from the Sun and the seventh (penultimate) largest planet in the solar system; The mass of the planet is 10.7% of the mass of the Earth. Named after Mars - the ancient Roman god of war, corresponding to the ancient Greek Ares. Mars is sometimes called the “red planet” because of the reddish tint of its surface given by iron oxide.

Mars is a terrestrial planet with a rarefied atmosphere (the pressure at the surface is 160 times less than that of Earth). Features of the surface relief of Mars can be considered impact craters like those on the Moon, as well as volcanoes, valleys, deserts and polar ice caps like those on Earth.

Mars has two natural satellites - Phobos and Deimos (translated from ancient Greek - “fear” and “horror” - the names of the two sons of Ares who accompanied him in battle), which are relatively small (Phobos - 26x21 km, Deimos - 13 km across ) and have an irregular shape.

Great Oppositions of Mars, 1830-2035

Mars is the fourth most distant from the Sun (after Mercury, Venus and Earth) and the seventh largest (exceeding only Mercury in mass and diameter) planet in the solar system. The mass of Mars is 10.7% of the mass of the Earth (6.423 1023 kg versus 5.9736 1024 kg for the Earth), its volume is 0.15 that of the Earth, and its average linear diameter is 0.53 the diameter of the Earth (6800 km).

The topography of Mars has many unique features. The Martian extinct volcano Mount Olympus is the highest mountain in the Solar System, and Valles Marineris is the largest canyon. Additionally, in June 2008, three papers published in the journal Nature provided evidence for the largest known impact crater in the solar system in the northern hemisphere of Mars. Its length is 10,600 km and its width is 8,500 km, which is about four times larger than the largest impact crater previously also discovered on Mars, near its south pole.

In addition to similar surface topography, Mars has a rotation period and seasonal cycles similar to Earth's, but its climate is much colder and drier than Earth's.

Until the first flyby of Mars by the Mariner 4 spacecraft in 1965, many researchers believed that there was liquid water on its surface. This opinion was based on observations of periodic changes in light and dark areas, especially in the polar latitudes, which were similar to continents and seas. Dark grooves on the surface of Mars have been interpreted by some observers as irrigation channels for liquid water. It was later proven that these grooves were an optical illusion.

Due to low pressure, water cannot exist in a liquid state on the surface of Mars, but it is likely that conditions were different in the past, and therefore the presence of primitive life on the planet cannot be ruled out. On July 31, 2008, ice water was discovered on Mars by NASA's Phoenix spacecraft.

In February 2009, the orbital exploration constellation orbiting Mars had three operational spacecraft: Mars Odyssey, Mars Express and Mars Reconnaissance Satellite, more than around any other planet besides Earth.

The surface of Mars has currently been explored by two rovers: Spirit and Opportunity. There are also several inactive landers and rovers on the surface of Mars that have completed exploration.

The geological data they collected suggests that most of the surface of Mars was previously covered by water. Observations over the past decade have revealed weak geyser activity in some places on the surface of Mars. According to observations from the Mars Global Surveyor spacecraft, parts of Mars' southern polar cap are gradually retreating.

Mars can be seen from Earth with the naked eye. Its apparent magnitude reaches 2.91m (at its closest approach to the Earth), second in brightness only to Jupiter (and not always during a great opposition) and Venus (but only in the morning or evening). Typically, during a great opposition, orange Mars is the brightest object in Earth's night sky, but this only occurs once every 15-17 years for one to two weeks.

Orbital characteristics

The minimum distance from Mars to the Earth is 55.76 million km (when the Earth is exactly between the Sun and Mars), the maximum is about 401 million km (when the Sun is exactly between the Earth and Mars).

The average distance from Mars to the Sun is 228 million km (1.52 AU), and the period of revolution around the Sun is 687 Earth days. The orbit of Mars has a fairly noticeable eccentricity (0.0934), so the distance to the Sun varies from 206.6 to 249.2 million km. The inclination of Mars' orbit is 1.85°.

Mars is closest to Earth during opposition, when the planet is in the opposite direction to the Sun. Oppositions are repeated every 26 months at different points in the orbit of Mars and Earth. But once every 15-17 years, oppositions occur at a time when Mars is near its perihelion; At these so-called great oppositions (the last one was in August 2003), the distance to the planet is minimal, and Mars reaches its largest angular size of 25.1" and brightness of 2.88m.

physical characteristics

Comparison of the sizes of Earth (average radius 6371 km) and Mars (average radius 3386.2 km)

In terms of linear size, Mars is almost half the size of the Earth - its equatorial radius is 3396.9 km (53.2% of the Earth's). The surface area of ​​Mars is approximately equal to the land area on Earth.

The polar radius of Mars is approximately 20 km less than the equatorial one, although the planet's rotation period is longer than that of the Earth, which gives reason to assume that the rotation speed of Mars changes over time.

The mass of the planet is 6.418·1023 kg (11% of the mass of the Earth). The acceleration of gravity at the equator is 3.711 m/s (0.378 Earth); the first escape velocity is 3.6 km/s and the second is 5.027 km/s.

The planet's rotation period is 24 hours 37 minutes 22.7 seconds. Thus, a Martian year consists of 668.6 Martian solar days (called sols).

Mars rotates around its axis, inclined to the perpendicular to the orbital plane at an angle of 24°56?. The tilt of Mars' rotation axis causes the seasons to change. At the same time, the elongation of the orbit leads to large differences in their duration - for example, the northern spring and summer, taken together, last 371 sols, that is, noticeably more than half of the Martian year. At the same time, they occur in a section of Mars’ orbit that is distant from the Sun. Therefore, on Mars, the northern summer is long and cool, and the southern summer is short and hot.

Atmosphere and climate

The atmosphere of Mars, photo of the Viking orbiter, 1976. Halle's "smiley crater" is visible on the left

Temperatures on the planet range from -153 at the poles in winter to over 20 °C at the equator at midday. The average temperature is -50°C.

The atmosphere of Mars, consisting mainly of carbon dioxide, is very thin. The pressure at the surface of Mars is 160 times less than on Earth - 6.1 mbar at the average surface level. Due to the large difference in altitude on Mars, the pressure at the surface varies greatly. The approximate thickness of the atmosphere is 110 km.

According to NASA (2004), the atmosphere of Mars consists of 95.32% carbon dioxide; it also contains 2.7% nitrogen, 1.6% argon, 0.13% oxygen, 210 ppm water vapor, 0.08% carbon monoxide, nitrogen oxide (NO) - 100 ppm, neon (Ne) - 2, 5 ppm, semi-heavy water hydrogen-deuterium-oxygen (HDO) 0.85 ppm, krypton (Kr) 0.3 ppm, xenon (Xe) - 0.08 ppm.

According to data from the Viking lander (1976), about 1-2% argon, 2-3% nitrogen, and 95% carbon dioxide were determined in the Martian atmosphere. According to the data from the Mars-2 and Mars-3 satellites, the lower boundary of the ionosphere is at an altitude of 80 km, the maximum electron concentration of 1.7 105 electron/cm3 is located at an altitude of 138 km, the other two maxima are at altitudes of 85 and 107 km.

Radio illumination of the atmosphere at radio waves 8 and 32 cm by the Mars-4 AMS on February 10, 1974 showed the presence of the night ionosphere of Mars with the main ionization maximum at an altitude of 110 km and an electron concentration of 4.6 103 electron/cm3, as well as secondary maxima at an altitude 65 and 185 km.

Atmosphere pressure

According to NASA data for 2004, the atmospheric pressure at the average radius is 6.36 mb. Density at the surface ~0.020 kg/m3, total mass of the atmosphere ~2.5·1016 kg.
Changes in atmospheric pressure on Mars depending on the time of day, recorded by the Mars Pathfinder lander in 1997.

Unlike Earth, the mass of the Martian atmosphere varies greatly throughout the year due to the melting and freezing of the polar caps containing carbon dioxide. During winter, 20-30 percent of the entire atmosphere freezes on the polar cap, consisting of carbon dioxide. Seasonal pressure drops, according to various sources, are the following values:

According to NASA (2004): from 4.0 to 8.7 mbar at the average radius;
According to Encarta (2000): 6 to 10 mbar;
According to Zubrin and Wagner (1996): 7 to 10 mbar;
According to the Viking 1 lander: from 6.9 to 9 mbar;
According to the Mars Pathfinder lander: from 6.7 mbar.

The Hellas Impact Basin is the deepest place where the highest atmospheric pressure can be found on Mars

At the landing site of the Mars-6 probe in the Erythraean Sea, a surface pressure of 6.1 millibars was recorded, which at that time was considered the average pressure on the planet, and from this level it was agreed to calculate the heights and depths on Mars. According to the data of this apparatus, obtained during descent, the tropopause is located at an altitude of approximately 30 km, where the pressure is 5·10-7 g/cm3 (as on Earth at an altitude of 57 km).

The Hellas (Mars) region is so deep that the atmospheric pressure reaches about 12.4 millibars, which is above the triple point of water (~6.1 mb) and below the boiling point. At a high enough temperature, water could exist there in a liquid state; at this pressure, however, water boils and turns into steam already at +10 °C.

At the summit of the highest 27 km Olympus volcano, the pressure can range from 0.5 to 1 mbar (Zurek 1992).

Before the landing modules landed on the surface of Mars, the pressure was measured due to the attenuation of radio signals from the Mariner 4, Mariner 6 and Mariner 7 probes when they entered the Martian disk - 6.5 ± 2.0 mb at the average surface level, which is 160 times less than on Earth; the same result was shown by spectral observations of the Mars-3 spacecraft. Moreover, in areas located below the average level (for example, in the Martian Amazon), the pressure, according to these measurements, reaches 12 mb.

Since the 1930s. Soviet astronomers tried to determine atmospheric pressure using photographic photometry methods - by the distribution of brightness along the diameter of the disk in different ranges of light waves. For this purpose, French scientists B. Liot and O. Dollfus made observations of the polarization of light scattered by the atmosphere of Mars. A summary of optical observations was published by the American astronomer J. de Vaucouleurs in 1951, and they obtained a pressure of 85 mb, overestimated by almost 15 times due to interference from atmospheric dust.

Climate

Microscopic photo of a 1.3 cm hematite nodule taken by the Opportunity rover on March 2, 2004, shows the past presence of liquid water

The climate, like on Earth, is seasonal. During the cold season, even outside the polar caps, light frost can form on the surface. The Phoenix apparatus recorded snowfall, but the snowflakes evaporated before reaching the surface.

According to NASA (2004), the average temperature is ~210 K (-63 °C). According to the Viking landers, the daily temperature range is from 184 K to 242 K (-89 to -31 °C) (Viking-1), and wind speed: 2-7 m/s (summer), 5-10 m /s (autumn), 17-30 m/s (dust storm).

According to data from the Mars-6 landing probe, the average temperature of the troposphere of Mars is 228 K, in the troposphere the temperature decreases by an average of 2.5 degrees per kilometer, and the stratosphere located above the tropopause (30 km) has an almost constant temperature of 144 K.

According to researchers from the Carl Sagan Center, a warming process has been underway on Mars in recent decades. Other experts believe that it is too early to draw such conclusions.

There is evidence that in the past the atmosphere could have been denser, and the climate warm and humid, and there was liquid water and rain on the surface of Mars. Proof of this hypothesis is the analysis of the ALH 84001 meteorite, which showed that about 4 billion years ago the temperature of Mars was 18 ± 4 °C.

Dust devils

Dust devils photographed by the Opportunity rover on May 15, 2005. The numbers in the lower left corner indicate the time in seconds since the first frame.

Since the 1970s. As part of the Viking program, as well as the Opportunity rover and other vehicles, numerous dust devils were recorded. These are air vortices that arise near the surface of the planet and lift large amounts of sand and dust into the air. Vortexes are often observed on Earth (in English-speaking countries they are called dust devils), but on Mars they can reach much larger sizes: 10 times higher and 50 times wider than those on Earth. In March 2005, a whirlwind cleaned out the solar panels on the Spirit rover.

Surface

Two-thirds of the surface of Mars is occupied by light areas called continents, about a third are dark areas called seas. The seas are concentrated mainly in the southern hemisphere of the planet, between 10 and 40° latitude. In the northern hemisphere there are only two large seas - Acidalia and Greater Syrtis.

The nature of the dark areas is still a matter of debate. They persist despite dust storms raging on Mars. At one time, this supported the assumption that dark areas were covered with vegetation. Now it is believed that these are simply areas from which, due to their topography, dust is easily blown away. Large-scale images show that, in fact, the dark areas consist of groups of dark streaks and spots associated with craters, hills and other obstacles in the path of winds. Seasonal and long-term changes in their size and shape are apparently associated with a change in the ratio of surface areas covered with light and dark matter.

The hemispheres of Mars differ quite greatly in the nature of their surface. In the southern hemisphere, the surface is 1-2 km above average and is densely dotted with craters. This part of Mars resembles the lunar continents. In the north, most of the surface is below average, there are few craters, and the bulk is relatively smooth plains, probably formed by lava flooding and erosion. This hemispheric difference remains a matter of debate. The boundary between the hemispheres follows approximately a great circle inclined 30° to the equator. The boundary is wide and irregular and forms a slope towards the north. Along it are the most eroded areas of the Martian surface.

Two alternative hypotheses have been put forward to explain hemispheric asymmetry. According to one of them, at an early geological stage, lithospheric plates “moved together” (perhaps accidentally) into one hemisphere, like the continent of Pangea on Earth, and then “froze” in this position. Another hypothesis suggests a collision between Mars and a cosmic body the size of Pluto.
Topographic map of Mars, according to Mars Global Surveyor, 1999.

The large number of craters in the southern hemisphere suggests that the surface here is ancient - 3-4 billion years old. There are several types of craters: large flat-bottomed craters, smaller and younger bowl-shaped craters similar to the Moon, rimmed craters, and raised craters. The last two types are unique to Mars - rimmed craters formed where liquid ejecta flowed across the surface, and raised craters formed where a blanket of crater ejecta protected the surface from wind erosion. The largest feature of impact origin is the Hellas Plain (approximately 2100 km across).

In the area of ​​chaotic landscape near the hemispheric boundary, the surface experienced large areas of fracture and compression, sometimes followed by erosion (due to landslides or catastrophic release of groundwater), as well as flooding by liquid lava. Chaotic landscapes often lie at the head of large channels cut by water. The most acceptable hypothesis for their joint formation is the sudden melting of subsurface ice.

Valles Marineris on Mars

In the northern hemisphere, in addition to vast volcanic plains, there are two areas of large volcanoes - Tharsis and Elysium. Tharsis is a vast volcanic plain with a length of 2000 km, reaching an altitude of 10 km above the average level. There are three large shield volcanoes on it - Mount Arsia, Mount Pavlina and Mount Askrian. On the edge of Tharsis is Mount Olympus, the highest on Mars and in the solar system. Olympus reaches 27 km in height relative to its base and 25 km in relation to the average surface level of Mars, and covers an area of ​​550 km in diameter, surrounded by cliffs that in some places reach 7 km in height. The volume of Olympus is 10 times greater than the volume of the largest volcano on Earth, Mauna Kea. There are also several smaller volcanoes located here. Elysium - an elevation up to six kilometers above average, with three volcanoes - Hecate's Dome, Mount Elysium and Albor Dome.

According to other data (Faure and Mensing, 2007), the height of Olympus is 21,287 meters above ground level and 18 kilometers above the surrounding area, and the diameter of the base is approximately 600 km. The base covers an area of ​​282,600 km2. The caldera (the depression in the center of the volcano) is 70 km wide and 3 km deep.

The Tharsis Rise is also crossed by many tectonic faults, often very complex and extensive. The largest of them, the Valles Marineris, stretches in a latitudinal direction for almost 4000 km (a quarter of the planet’s circumference), reaching a width of 600 and a depth of 7-10 km; This fault is comparable in size to the East African Rift on Earth. The largest landslides in the solar system occur on its steep slopes. Valles Marineris is the largest known canyon in the solar system. The canyon, which was discovered by the Mariner 9 spacecraft in 1971, could cover the entire United States, from ocean to ocean.

Panorama of Victoria Crater taken by the Opportunity rover. It was filmed over three weeks, between October 16 and November 6, 2006.

Panorama of the surface of Mars in the Husband Hill area, taken by the Spirit rover November 23-28, 2005.

Ice and polar caps

The northern polar cap in summer, photo by Mars Global Surveyor. The long, wide fault cutting through the cap on the left is the Northern Fault

The appearance of Mars varies greatly depending on the time of year. First of all, the changes in the polar ice caps are striking. They wax and wane, creating seasonal patterns in the atmosphere and surface of Mars. The southern polar cap can reach a latitude of 50°, the northern one - also 50°. The diameter of the permanent part of the northern polar cap is 1000 km. As the polar cap in one hemisphere recedes in the spring, features on the planet's surface begin to darken.

The polar caps consist of two components: seasonal - carbon dioxide and secular - water ice. According to data from the Mars Express satellite, the thickness of the caps can range from 1 m to 3.7 km. The Mars Odyssey probe discovered active geysers on the southern polar cap of Mars. According to NASA experts, jets of carbon dioxide with spring warming burst upward to great heights, taking with them dust and sand.

Photos of Mars showing a dust storm. June - September 2001

The spring melting of the polar caps leads to a sharp increase in atmospheric pressure and the movement of large masses of gas to the opposite hemisphere. The speed of the winds blowing in this case is 10-40 m/s, sometimes up to 100 m/s. The wind lifts large amounts of dust from the surface, leading to dust storms. Severe dust storms almost completely obscure the surface of the planet. Dust storms have a noticeable effect on the temperature distribution in the Martian atmosphere.

In 1784, astronomer W. Herschel drew attention to seasonal changes in the size of the polar caps, by analogy with the melting and freezing of ice in the Earth's polar regions. In the 1860s. French astronomer E. Lie observed a wave of darkening around the melting spring polar cap, which was then interpreted by the hypothesis of the spreading of meltwater and the growth of vegetation. Spectrometric measurements that were carried out at the beginning of the 20th century. at the Lovell Observatory in Flagstaff by W. Slifer, however, did not show the presence of a line of chlorophyll, the green pigment of terrestrial plants.

From photographs of Mariner 7, it was possible to determine that the polar ice caps are several meters thick, and the measured temperature of 115 K (-158 °C) confirmed the possibility that it consists of frozen carbon dioxide - “dry ice”.

The hill, which is called the Mitchell Mountains, located near the south pole of Mars, looks like a white island when the polar cap melts, since glaciers in the mountains melt later, including on Earth.

Data from the Mars Reconnaissance Satellite made it possible to detect a significant layer of ice under rocky screes at the foot of the mountains. The glacier, hundreds of meters thick, covers an area of ​​thousands of square kilometers, and its further study could provide information about the history of the Martian climate.

"River" beds and other features

There are many geological formations on Mars that resemble water erosion, particularly dry river beds. According to one hypothesis, these channels could have been formed as a result of short-term catastrophic events and are not evidence of the long-term existence of the river system. However, recent evidence suggests that the rivers flowed over geologically significant periods of time. In particular, inverted channels (that is, channels raised above the surrounding area) were discovered. On Earth, such formations are formed due to the long-term accumulation of dense bottom sediments, followed by drying and weathering of the surrounding rocks. In addition, there is evidence of shifting channels in the river delta as the surface gradually rises.

In the southwestern hemisphere, in the Eberswalde crater, a river delta with an area of ​​about 115 km2 was discovered. The river that washed out the delta was more than 60 km long.

Data from NASA's Mars rovers Spirit and Opportunity also indicate the presence of water in the past (minerals were found that could only have formed as a result of prolonged exposure to water). The Phoenix apparatus discovered ice deposits directly in the ground.

In addition, dark streaks were discovered on the hillsides, indicating the appearance of liquid salt water on the surface in modern times. They appear soon after the onset of summer and disappear by winter, “flow around” various obstacles, merge and diverge. “It is difficult to imagine that such structures could have formed from something other than fluid flows,” said NASA scientist Richard Zurek.

Several unusual deep wells have been discovered on the Tharsis volcanic upland. Judging by the image of the Mars Reconnaissance Satellite taken in 2007, one of them has a diameter of 150 meters, and the illuminated part of the wall goes no less than 178 meters deep. A hypothesis has been put forward about the volcanic origin of these formations.

Priming

The elemental composition of the surface layer of Martian soil, according to data from landers, is not the same in different places. The main component of the soil is silica (20-25%), containing an admixture of iron oxide hydrates (up to 15%), giving the soil a reddish color. There are significant impurities of sulfur, calcium, aluminum, magnesium, and sodium compounds (a few percent for each).

According to data from NASA's Phoenix probe (landing on Mars on May 25, 2008), the pH ratio and some other parameters of Martian soils are close to those on Earth, and it would theoretically be possible to grow plants on them. “In fact, we found that the soil on Mars meets the requirements and also contains the necessary elements for the emergence and maintenance of life both in the past, present and future,” said the lead chemist on the project, Sam Coonaves. Also, according to him, many people can find this alkaline type of soil in “their backyard,” and it is quite suitable for growing asparagus.

There is also a significant amount of water ice in the ground at the landing site. The Mars Odyssey orbiter also discovered that there are deposits of water ice beneath the red planet's surface. Later, this assumption was confirmed by other devices, but the question of the presence of water on Mars was finally resolved in 2008, when the Phoenix probe, which landed near the planet’s north pole, received water from the Martian soil.

Geology and internal structure

In the past, on Mars, as on Earth, there was movement of lithospheric plates. This is confirmed by the characteristics of the magnetic field of Mars, the locations of some volcanoes, for example, in the province of Tharsis, as well as the shape of the Valles Marineris. The current state of affairs, when volcanoes can exist for a much longer time than on Earth and reach gigantic sizes, suggests that now this movement is rather absent. This is supported by the fact that shield volcanoes grow as a result of repeated eruptions from the same vent over a long period of time. On Earth, due to the movement of lithospheric plates, volcanic points constantly changed their position, which limited the growth of shield volcanoes, and perhaps did not allow them to reach heights like on Mars. On the other hand, the difference in the maximum height of volcanoes may be explained by the fact that due to the lower gravity on Mars, it is possible to build taller structures that would not collapse under their own weight.

Comparison of the structure of Mars and other terrestrial planets

Current models of the internal structure of Mars suggest that Mars consists of a crust with an average thickness of 50 km (and a maximum thickness of up to 130 km), a silicate mantle with a thickness of 1800 km and a core with a radius of 1480 km. The density at the center of the planet should reach 8.5 g/cm2. The core is partially liquid and consists mainly of iron with an admixture of 14-17% (by mass) sulfur, and the content of light elements is twice as high as in the Earth's core. According to modern estimates, the formation of the core coincided with the period of early volcanism and lasted about a billion years. The partial melting of mantle silicates took approximately the same time. Due to the lower gravity on Mars, the pressure range in the Martian mantle is much smaller than on Earth, which means there are fewer phase transitions. It is assumed that the phase transition of olivine into the spinel modification begins at fairly large depths - 800 km (400 km on Earth). The nature of the relief and other features suggest the presence of an asthenosphere, consisting of zones of partially molten matter. A detailed geological map has been compiled for some areas of Mars.

According to observations from orbit and analysis of a collection of Martian meteorites, the surface of Mars consists mainly of basalt. There is some evidence to suggest that on parts of the Martian surface the material is more quartz-rich than ordinary basalt and may be similar to andesitic rocks on Earth. However, these same observations can be interpreted in favor of the presence of quartz glass. Much of the deeper layer consists of granular iron oxide dust.

Magnetic field of Mars

A weak magnetic field has been detected near Mars.

According to the readings of the magnetometers of the Mars-2 and Mars-3 stations, the magnetic field strength at the equator is about 60 gamma, at the pole 120 gamma, which is 500 times weaker than the earth’s. According to AMS Mars-5 data, the magnetic field strength at the equator was 64 gammas, and the magnetic moment was 2.4 1022 oersted cm2.

The magnetic field of Mars is extremely unstable; at different points on the planet its strength can differ from 1.5 to 2 times, and the magnetic poles do not coincide with the physical ones. This suggests that the iron core of Mars is relatively immobile in relation to its crust, that is, the planetary dynamo mechanism responsible for the Earth’s magnetic field does not work on Mars. Although Mars does not have a stable planetary magnetic field, observations have shown that parts of the planetary crust are magnetized and that the magnetic poles of these parts have changed in the past. The magnetization of these parts turned out to be similar to strip magnetic anomalies in the world's oceans.

One theory, published in 1999 and retested in 2005 (with the help of the unmanned Mars Global Surveyor), these stripes show plate tectonics 4 billion years ago before the planet's dynamo ceased to function, causing a sharp weakening magnetic field. The reasons for this sharp weakening are unclear. There is an assumption that the functioning of the dynamo 4 billion. years ago is explained by the presence of an asteroid that revolved at a distance of 50-75 thousand kilometers around Mars and caused instability in its core. The asteroid then fell to the Roche limit and collapsed. However, this explanation itself contains ambiguities and is disputed in the scientific community.

Geological history

Global mosaic of 102 images of the Viking 1 orbiter from February 22, 1980.

Perhaps in the distant past, as a result of a collision with a large celestial body, the rotation of the core stopped, as well as the loss of the main volume of the atmosphere. The loss of the magnetic field is believed to have occurred about 4 billion years ago. Due to the weakness of the magnetic field, the solar wind penetrates almost unhindered into the Martian atmosphere, and many of the photochemical reactions under the influence of solar radiation that occur in the ionosphere and above on Earth can be observed on Mars almost at its very surface.

The geological history of Mars includes the following three eras:

Noachian Epoch (named after the "Noachian Land", a region of Mars): Formation of the oldest surviving surface of Mars. Lasted from 4.5 billion to 3.5 billion years ago. During this era, the surface was scarred by numerous impact craters. The Tharsis plateau was probably formed during this period, with intense water flow later.

Hesperia era: from 3.5 billion years ago to 2.9 - 3.3 billion years ago. This era is marked by the formation of huge lava fields.

Amazonian Era (named after the "Amazonian Plain" on Mars): 2.9-3.3 billion years ago to the present day. The areas formed during this era have very few meteorite craters, but are otherwise completely different. Mount Olympus was formed during this period. At this time, lava flows were spreading in other parts of Mars.

Moons of Mars

The natural satellites of Mars are Phobos and Deimos. Both of them were discovered by American astronomer Asaph Hall in 1877. Phobos and Deimos are irregular in shape and very small in size. According to one hypothesis, they may represent asteroids like (5261) Eureka from the Trojan group of asteroids captured by the gravitational field of Mars. The satellites are named after the characters accompanying the god Ares (that is, Mars), Phobos and Deimos, personifying fear and horror who helped the god of war in battles.

Both satellites rotate around their axes with the same period as around Mars, so they always face the same side towards the planet. The tidal influence of Mars gradually slows down the movement of Phobos, and will ultimately lead to the satellite falling onto Mars (if the current trend continues), or to its disintegration. On the contrary, Deimos is moving away from Mars.

Both satellites have a shape approaching a triaxial ellipsoid, Phobos (26.6x22.2x18.6 km) is slightly larger than Deimos (15x12.2x10.4 km). The surface of Deimos appears much smoother due to the fact that most of the craters are covered with fine-grained material. Obviously, on Phobos, which is closer to the planet and more massive, the substance ejected during meteorite impacts either caused repeated impacts on the surface or fell on Mars, while on Deimos it remained in orbit around the satellite for a long time, gradually settling and hiding uneven terrain.

Life on Mars

The popular idea that Mars was inhabited by intelligent Martians became widespread at the end of the 19th century.

Schiaparelli's observations of the so-called canals, combined with Percival Lowell's book on the same topic, popularized the idea of ​​a planet whose climate was becoming drier, colder, dying and in which there existed an ancient civilization carrying out irrigation works.

Numerous other sightings and announcements by famous people have given rise to the so-called “Mars Fever” around this topic. In 1899, while studying atmospheric interference in radio signals using receivers at the Colorado Observatory, inventor Nikola Tesla observed a repeating signal. He then suggested that it could be a radio signal from other planets, such as Mars. In a 1901 interview, Tesla said that he had the idea that interference could be caused artificially. Although he could not decipher their meaning, it was impossible for him that they arose completely by chance. In his opinion, this was a greeting from one planet to another.

Tesla's theory aroused the enthusiastic support of the famous British physicist William Thomson (Lord Kelvin), who, visiting the United States in 1902, said that in his opinion Tesla had caught the signal from the Martians sent to the United States. However, Kelvin then began to strongly deny this statement before leaving America: “In fact, I said that the inhabitants of Mars, if they existed, could certainly see New York, especially the light from electricity.”

Today, the presence of liquid water on its surface is considered a condition for the development and maintenance of life on the planet. There is also a requirement that the planet's orbit be in the so-called habitable zone, which for the Solar System begins behind Venus and ends with the semimajor axis of the orbit of Mars. During perihelion, Mars is inside this zone, but a thin atmosphere with low pressure prevents the appearance of liquid water over a large area for a long period. Recent evidence suggests that any water on the surface of Mars is too salty and acidic to support permanent Earth-like life.

The lack of a magnetosphere and the extremely thin atmosphere of Mars are also a challenge to supporting life. There is a very weak movement of heat flows on the surface of the planet; it is poorly insulated from bombardment by solar wind particles; in addition, when heated, water instantly evaporates, bypassing the liquid state due to low pressure. Mars is also on the threshold of the so-called. "geological death". The end of volcanic activity apparently stopped the circulation of minerals and chemical elements between the surface and interior of the planet.

Evidence suggests that the planet was previously much more prone to supporting life than it is now. However, to date, no remains of organisms have been found on it. The Viking program, carried out in the mid-1970s, conducted a series of experiments to detect microorganisms in Martian soil. It has produced positive results, such as a temporary increase in CO2 emissions when soil particles are placed in water and growing medium. However, then this evidence of life on Mars was disputed by some scientists[by whom?]. This led to their lengthy dispute with NASA scientist Gilbert Levin, who claimed that Viking had discovered life. After re-evaluating the Viking data in light of current scientific knowledge about extremophiles, it was determined that the experiments conducted were not advanced enough to detect these life forms. Moreover, these tests could even kill the organisms even if they were contained in the samples. Tests conducted as part of the Phoenix program showed that the soil has a very alkaline pH and contains magnesium, sodium, potassium and chloride. There are enough nutrients in the soil to support life, but life forms must be protected from intense ultraviolet light.

It is interesting that in some meteorites of Martian origin formations were found that are shaped like the simplest bacteria, although they are inferior in size to the smallest terrestrial organisms. One such meteorite is ALH 84001, found in Antarctica in 1984.

Based on observations from Earth and data from the Mars Express spacecraft, methane was discovered in the atmosphere of Mars. Under Mars conditions, this gas decomposes quite quickly, so there must be a constant source of replenishment. Such a source could be either geological activity (but no active volcanoes have been found on Mars) or the activity of bacteria.

Astronomical observations from the surface of Mars

After the landing of automatic vehicles on the surface of Mars, it became possible to conduct astronomical observations directly from the surface of the planet. Due to the astronomical position of Mars in the solar system, the characteristics of the atmosphere, the orbital period of Mars and its satellites, the picture of the night sky of Mars (and astronomical phenomena observed from the planet) differs from that on Earth and in many ways appears unusual and interesting.

The color of the sky on Mars

During sunrise and sunset, the Martian sky at the zenith has a reddish-pink color, and in the immediate vicinity of the solar disk - from blue to violet, which is completely opposite to the picture of earthly dawns.

At noon, the sky of Mars is yellow-orange. The reason for such differences from the colors of the earth's sky is the properties of the thin, rarefied, dust-containing atmosphere of Mars. On Mars, Rayleigh scattering of rays (which on Earth is the reason for the blue color of the sky) plays an insignificant role, its effect is weak. Presumably, the yellow-orange color of the sky is also caused by the presence of 1% magnetite in dust particles constantly suspended in the Martian atmosphere and raised by seasonal dust storms. Twilight begins long before sunrise and lasts long after sunset. Sometimes the color of the Martian sky takes on a purple hue as a result of light scattering on microparticles of water ice in the clouds (the latter is a rather rare phenomenon).

Sun and planets

The angular size of the Sun observed from Mars is smaller than that visible from Earth and is 2/3 of the latter. Mercury from Mars will be virtually inaccessible to observation with the naked eye due to its extreme proximity to the Sun. The brightest planet in the sky of Mars is Venus, Jupiter is in second place (its four largest satellites can be observed without a telescope), and Earth is in third place.

The Earth is an inner planet to Mars, just as Venus is to the Earth. Accordingly, from Mars, the Earth is observed as a morning or evening star, rising before dawn or visible in the evening sky after sunset.

The maximum elongation of the Earth in the sky of Mars will be 38 degrees. To the naked eye, the Earth will be visible as a bright (maximum visible magnitude about -2.5) greenish star, next to which the yellowish and fainter (about 0.9) star of the Moon will be easily visible. Through a telescope, both objects will show the same phases. The revolution of the Moon around the Earth will be observed from Mars as follows: at the maximum angular distance of the Moon from the Earth, the naked eye can easily separate the Moon and the Earth: after a week, the “stars” of the Moon and Earth will merge into a single star, inseparable by the eye; after another week, the Moon will again be visible at its maximum distance, but on the other side from the Earth. From time to time, an observer on Mars will be able to see the passage (transit) of the Moon across the Earth's disk or, conversely, the covering of the Moon by the Earth's disk. The maximum apparent distance of the Moon from the Earth (and their apparent brightness) when observed from Mars will vary significantly depending on the relative positions of the Earth and Mars, and, accordingly, the distance between the planets. In eras of opposition it will be about 17 minutes of arc, at the maximum distance between Earth and Mars - 3.5 minutes of arc. The Earth, like other planets, will be observed in the band of Zodiac constellations. An astronomer on Mars will also be able to observe the passage of the Earth across the disk of the Sun, the closest one occurring on November 10, 2084.

Satellites - Phobos and Deimos

Passage of Phobos across the solar disk. Photos from Opportunity

Phobos, when observed from the surface of Mars, has an apparent diameter of about 1/3 of the Moon's disk in the Earth's sky and an apparent magnitude of about -9 (approximately the same as the Moon in its first quarter phase). Phobos rises in the west and sets in the east, only to rise again 11 hours later, thus crossing the Martian sky twice a day. The movement of this fast moon across the sky will be easily noticeable throughout the night, as will the changing phases. The naked eye will be able to discern the largest relief feature of Phobos - the Stickney crater. Deimos rises in the east and sets in the west, appears as a bright star without a noticeable visible disk, about magnitude -5 (slightly brighter than Venus in Earth's sky), slowly crossing the sky over the course of 2.7 Martian days. Both satellites can be observed in the night sky at the same time, in this case Phobos will move towards Deimos.

Both Phobos and Deimos are bright enough for objects on the surface of Mars to cast clear shadows at night. Both satellites have a relatively low orbital inclination to the equator of Mars, which precludes their observation in the high northern and southern latitudes of the planet: for example, Phobos never rises above the horizon north of 70.4° N. w. or south of 70.4° S. sh.; for Deimos these values ​​are 82.7° N. w. and 82.7° S. w. On Mars, an eclipse of Phobos and Deimos can be observed as they enter the shadow of Mars, as well as an eclipse of the Sun, which is only annular due to the small angular size of Phobos compared to the solar disk.

Celestial sphere

The North Pole on Mars, due to the tilt of the planet's axis, is located in the constellation Cygnus (equatorial coordinates: right ascension 21h 10m 42s, declination +52° 53.0? and is not marked by a bright star: the closest to the pole is a dim sixth magnitude star BD +52 2880 (others its designations are HR 8106, HD 201834, SAO 33185).The south celestial pole (coordinates 9h 10m 42s and -52° 53.0) is located a couple of degrees from the star Kappa Parus (apparent magnitude 2.5) - its, in principle, , can be considered the South Pole Star of Mars.

The zodiacal constellations of the Martian ecliptic are similar to those observed from Earth, with one difference: when observing the annual movement of the Sun among the constellations, it (like other planets, including the Earth), leaving the eastern part of the constellation Pisces, will pass for 6 days through the northern part of the constellation Cetus in front of how to re-enter western Pisces.

History of Mars exploration

The exploration of Mars began a long time ago, 3.5 thousand years ago, in Ancient Egypt. The first detailed reports on the position of Mars were compiled by Babylonian astronomers, who developed a number of mathematical methods to predict the planet's position. Using data from the Egyptians and Babylonians, ancient Greek (Hellenistic) philosophers and astronomers developed a detailed geocentric model to explain the motion of the planets. Several centuries later, Indian and Islamic astronomers estimated the size of Mars and its distance from Earth. In the 16th century, Nicolaus Copernicus proposed a heliocentric model to describe the solar system with circular planetary orbits. His results were revised by Johannes Kepler, who introduced a more accurate elliptical orbit of Mars, coinciding with the observed one.

In 1659, Francesco Fontana, looking at Mars through a telescope, made the first drawing of the planet. He depicted a black spot in the center of a clearly defined sphere.

In 1660, two polar caps were added to the black spot, added by Jean Dominique Cassini.

In 1888, Giovanni Schiaparelli, who studied in Russia, gave the first names to individual surface features: the seas of Aphrodite, Erythraean, Adriatic, Cimmerian; lakes Sun, Lunnoe and Phoenix.

The heyday of telescopic observations of Mars occurred at the end of the 19th - mid-20th centuries. It is largely due to public interest and well-known scientific controversies surrounding the observed Martian canals. Among the astronomers of the pre-space era who carried out telescopic observations of Mars during this period, the most famous are Schiaparelli, Percival Lovell, Slifer, Antoniadi, Barnard, Jarry-Deloge, L. Eddy, Tikhov, Vaucouleurs. It was they who laid the foundations of areography and compiled the first detailed maps of the surface of Mars - although they turned out to be almost completely incorrect after automatic probes flew to Mars.

Colonization of Mars

Estimated appearance of Mars after terraforming

Natural conditions relatively close to those on Earth make this task somewhat easier. In particular, there are places on Earth in which natural conditions are similar to those on Mars. The extremely low temperatures in the Arctic and Antarctica are comparable to even the coldest temperatures on Mars, and the equator of Mars can be as warm (+20°C) in the summer months as on Earth. There are also deserts on Earth that are similar in appearance to the Martian landscape.

But there are significant differences between Earth and Mars. In particular, Mars' magnetic field is approximately 800 times weaker than Earth's. Together with a rarefied (hundreds of times compared to the Earth) atmosphere, this increases the amount of ionizing radiation reaching its surface. Measurements carried out by the American unmanned spacecraft The Mars Odyssey showed that the background radiation in Mars orbit is 2.2 times higher than the background radiation on the International Space Station. The average dose was approximately 220 millirads per day (2.2 milligrays per day or 0.8 grays per year). The amount of radiation received as a result of being in such a background for three years is approaching the established safety limits for astronauts. On the surface of Mars, the background radiation is somewhat lower and the dose is 0.2-0.3 Gy per year, varying significantly depending on the terrain, altitude and local magnetic fields.

The chemical composition of minerals common on Mars is more diverse than that of other celestial bodies near Earth. According to the 4Frontiers corporation, there are enough of them to supply not only Mars itself, but also the Moon, Earth and the asteroid belt.

The flight time from Earth to Mars (with current technologies) is 259 days in a semi-ellipse and 70 days in a parabola. To communicate with potential colonies, radio communication can be used, which has a delay of 3-4 minutes in each direction during the closest approach of the planets (which repeats every 780 days) and about 20 minutes. at the maximum distance of the planets; see Configuration (astronomy).

To date, no practical steps have been taken to colonize Mars, but development of colonization is underway, for example, the Centenary Spaceship project, the development of a habitable module for staying on the planet Deep Space Habitat.

The red planet - Mars - is named after the ancient Roman god of war of the same name, similar to Ares among the Greeks. It is the fourth planet in the solar system in terms of distance from the Sun. It is believed that the blood-red color of the planet, which is given to it by iron oxide, influenced its name.

Mars has always been of interest not only to scientists, but to ordinary people of various professions. All because humanity had high hopes for this planet, because most people hoped that life also existed on the surface of Mars. Most science fiction novels are written specifically about the planet Mars. Trying to penetrate the secrets and unravel its mysteries, people rapidly studied the surface and structure of the planet. But so far we have not been able to get an answer to this question that worries everyone: “is there life on Mars?” Mars rotates in its slightly elongated orbit around the Sun in 687 Earth days, at a speed of 24 km/s. Its radius is 1.525 astronomical units. The distance from Earth to Mars is constantly changing from a minimum of 55 million km to a maximum of 400 million km. Great oppositions are those periods of time that repeat once every 16–17 years, when the distance between these two planets becomes less than 60 million km. A day on Mars is only 41 minutes longer than on Earth and is 24 hours 62 minutes. The change of day and night, as well as the seasons, also practically repeats those on earth. There are also climatic zones, but due to the greater distance from the Sun, they are much more severe than on our planet. Thus, the average temperature is about –50 °C. The radius of Mars is 3397 km, which is almost half the radius of the Earth - 6378.

Surface and structure of Mars

Mars, along with other terrestrial planets, consists of a crust up to 50 km thick, a mantle up to 1800 km thick and a core with a diameter of 2960 km.

In the center of Mars, the density reaches 8.5 g/m3. In the course of long-term research, it was found that the internal structure of Mars and its current surface consists mainly of basalt. It is assumed that several million, maybe billions of years ago, the planet Mars had an atmosphere. Accordingly, the water was in a liquid state. This is evidenced by numerous riverbeds - meanders, which can still be observed. The characteristic geological formations at their bottom indicate that they occurred over a very long period of time. Now, there are no necessary conditions for this and water is found only in the soil layers, under the very surface of Mars. This phenomenon is called permafrost (permafrost). Descriptions of Mars and its characteristics are often found in reports of famous researchers of the Red Planet.

The rest of the surface of Mars and its relief have no less unique finds. The structure of Mars is characterized by deep craters. At the same time, on this planet, there is the highest mountain in the entire solar system - Olympus - an extinct Martian volcano with a height of 27.5 km and a diameter of 6000 m. There is also a grandiose system of Marineris canyons with a length of about 4 thousand km and an entire region ancient volcanoes - Elysium.

Phobos and Deimos are natural, but very small, satellites of Mars. They have an irregular shape, and according to one version, they are asteroids captured by the gravity of Mars. The satellites of Mars Phobos (fear) and Deimos (horror) are heroes of ancient Greek myths, in which they helped the god of war, Ares (Mars), win battles. In 1877, they were discovered by American astronomer Asaph Hall. Both satellites rotate along their axis with the same period, as around Mars, due to this they always face the same side towards the planet. Deimos is gradually being pulled away from Mars, and Phobos, on the contrary, is being attracted even more. But this happens very slowly, therefore, it is unlikely that our next generations will be able to see the fall or complete disintegration of the satellite, or its fall onto the planet.

Characteristics of Mars

Weight: 6.4*1023 kg (0.107 Earth mass)
Diameter at equator: 6794 km (0.53 Earth's diameter)
Axis tilt: 25°
Density: 3.93 g/cm3
Surface temperature: –50 °C
Period of rotation around the axis (days): 24 hours 39 minutes 35 seconds
Distance from the Sun (average): 1.53 a. e. = 228 million km
Orbital period around the Sun (year): 687 days
Orbital speed: 24.1 km/s
Orbital eccentricity: e = 0.09
Orbital inclination to the ecliptic: i = 1.85°
Gravity acceleration: 3.7 m/s2
Moons: Phobos and Deimos
Atmosphere: 95% carbon dioxide, 2.7% nitrogen, 1.6% argon, 0.2% oxygen

The surface of Mars is a subject of interest to many scientists, astronomers and ordinary people not related to research. The public's interest is understandable, since Mars is one of the closest neighbors of the Earth, the 4th planet from the Sun. The age-old question: “Is there life on Mars?” is still relevant, research on the surface and atmosphere of the planet continues. The mysterious planet hides a lot on its surface interesting facts about the surface of Mars, accessible to human understanding.

1. According to studies of soil and the number of craters, the age of the planet’s surface reaches 4 billion years. Moreover, the southern hemisphere formed earlier than the northern, as evidenced by the different nature of the soil.
2. Mars is a planet like Earth. The solid surface is constantly changing under the influence of factors such as contact with cosmic bodies, movement of the earth's crust, dust storms and volcanic eruptions.
3. There is no area of ​​the stratosphere most enriched in ozone. There is no ozone layer on the planet, which allows large doses of radiation to penetrate when the sun rises.
4. The unusual coloring of the planet is given by iron oxides, which are present in large quantities in the soil..
5. The surface of the planet consists of dark and light areas, which are called seas and continents, respectively. Despite constant exposure to dust storms, the dark spots remain unchanged. Their character is being studied, the opinions of scientists are divided. Some believe that the dark color corresponds to the presence of dense vegetation, others are of the opinion that the color of the spot depends on the nature of the relief and the degree of dust deposition.
6. Different surface in the southern and northern hemisphere. The southern part is located above average, and resembles the relief of the Moon due to the frequent occurrence of craters. The northern hemisphere is flat, with sparse depressions. The smooth nature of the surface could have been formed due to the destruction of the soil by water and wind. Some scientists explain such a different asymmetrical relief of the hemispheres by the convergence of lithospheric plates, like what happened with Pangea. Another version suggests a collision of Mars with a body whose dimensions are similar to the size of Pluto.
7. There are a wide variety of craters on the surface of Mars, differing in size and shape.. Some depressions are characteristic only of Mars. Craters with a shaft are a consequence of the flow of liquid masses, and elevated depressions appeared in places protected from the action of winds.

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8. There are 2 areas on the planet where volcanoes are located. Tharsis and Elysium are the areas where the most active processes were observed.
9. The surface of the planet contains the Valles Marineris canyon, larger in size than the American Grand Canyon, and Mount Olympus. The mountain is larger than Everest and is the highest mountain in the solar system.

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10. The surface of Mars contains evidence that in ancient times the territory was dotted with rivers. Evidence is provided by dry riverbeds, the appearance of stones, and the presence of special rocks that are formed only under the influence of water.
11. The surface of the planet hides water resources that increase over time. Scientists have discovered a flow of thermal particles that may indicate that there is water in the ground.
12. On the territory of Mars there is a substance consisting of dust and ice, dating back several million years. Ice substances retain their original appearance without melting under the influence of ultraviolet rays. The number of such structures increases every year. Scientists studied the composition of the new substance and gave it the name dry ice.
13. The composition of the planet's soil is close to that of Earth's soil.. Scientists have conducted a number of studies, as a result of which it was found that, from a theoretical point of view, it is possible to grow plants on Mars. However, not only soil influences the growth process of living organisms. The predominantly cold climate, frequent sandstorms, and other negative aspects prevent favorable cultivation.
14. On the Tharsis Hill there are specific wells with a depth of about 200 m. Experts believe that the occurrence of depressions is associated with the action of volcanoes.
15. The composition of the atmosphere and other unfavorable components allow us to judge that today life on the Red Planet is excluded from the perspective that is familiar to society. The scientists’ tasks include studying the planet’s capabilities for normal life support in the future, as well as studying the past of Mars.

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