Mars is the fourth farthest from the Sun and the seventh largest planet in the solar system, named after Mars, the ancient Roman god of war, corresponding to the ancient Greek Ares. Mars is sometimes referred to as the "red planet" because of the reddish hue of the surface given to it by iron oxide.

Mars is a planet terrestrial group with a rarefied atmosphere. The features of the surface relief of Mars can be considered impact craters like those of the moon, as well as volcanoes, valleys, deserts and polar ice caps like those of the 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 and have an irregular shape. They may be asteroids captured by the gravitational field of Mars, similar to the asteroid (5261) Eureka from the Trojan group.

The relief of Mars has many unique features. Martian extinct volcano Mount Olympus high mountain in solar system, and the Mariner Valley is the largest canyon. In addition, in June 2008, three papers published in the journal Nature presented evidence for the existence of the largest known impact crater in the solar system in the northern hemisphere of Mars. It is 10,600 km long and 8,500 km wide, about four times larger than the largest impact crater previously discovered on Mars, near its south pole. In addition to similar surface topography, Mars has a rotation period and seasons 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 polar latitudes, which were similar to continents and seas. Dark furrows on the surface of Mars have been interpreted by some observers as irrigation channels for liquid water. It was later proven that these furrows were an optical illusion.

Due to the 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, water in the state of ice was discovered on Mars by NASA's Phoenix spacecraft.

In February 2009, the orbital research constellation in Mars orbit had three functioning spacecraft: Mars Odyssey, Mars Express and Mars Reconnaissance Satellite, more than around any other planet except Earth. The surface of Mars is currently explored by two rovers: "Spirit" and "Opportunity". There are also several inactive landers and rovers on the surface of Mars that have completed research. The geological data they collected suggests that most of the surface of Mars was previously covered with water. Observations over the past decade have made it possible to detect weak geyser activity in some places on the surface of Mars. According to observations from NASA's Mars Global Surveyor, parts of the south polar cap of Mars are gradually receding.

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

In 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 about 20 km less than the equatorial one, although the planet's rotation period is longer than that of the Earth, which suggests a change in the rotation rate of Mars over time. The mass of the planet is 6.418 × 1023 kg (11% of the mass of the Earth). The free fall acceleration at the equator is 3.711 m/s² (0.378 Earth); first space velocity is 3.6 km/s and the second is 5.027 km/s. Mars rotates around its axis, which is inclined to the perpendicular plane of the orbit at an angle of 24°56′. 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 salts). The tilt of the axis of rotation of Mars causes the change of seasons. In this case, the elongation of the orbit leads to large differences in their duration. Thus, 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 fall on the part of Mars' orbit that is farthest from the Sun. Therefore, on Mars, northern summers are long and cool, while southern summers are short and hot.

The temperature on the planet ranges from -153°C at the pole in winter to over +20°C at the equator at noon. The average temperature is -50 °C.

Atmosphere of Mars.

The atmosphere of Mars, which consists mainly of carbon dioxide, is very rarefied. The pressure at the surface of Mars is 160 times less than the earth's - 6.1 mbar at the average surface level. Due to the large elevation difference on Mars, the pressure near the surface varies greatly. The maximum value reaches 10–12 mbar in the Hellas basin at a depth of 8 km. Unlike the Earth, the mass of the Martian atmosphere varies greatly during the year due to the melting and freezing of the polar caps containing carbon dioxide.

The atmosphere is 95% carbon dioxide; it also contains 2.7% nitrogen, 1.6% argon, 0.13% oxygen, 0.1% water vapor, 0.07% carbon monoxide. There are traces of methane.

The Martian ionosphere extends from 110 to 130 km above the surface of the planet.

There is evidence that in the past the atmosphere could be denser, and the climate warm and humid, and liquid water existed on the surface of Mars and it rained. The Mars Odyssey orbiter has discovered that there are deposits of water ice under the surface of the red planet. 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.

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

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

The Opportunity rover recorded numerous dust whirlwinds. These are air turbulences that occur near the surface of the planet and raise a large amount of sand and dust into the air. They are often observed on Earth, but on Mars they can reach much large sizes.

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

The nature of the dark areas is still a matter of controversy. They persist despite the fact that dust storms rage on Mars. At one time, this served as an argument in favor of the assumption that the dark areas are covered with vegetation. Now it is believed that these are just areas from which, due to their relief, dust is easily blown out. Large-scale images show that in fact, the dark areas consist of groups of dark bands and spots associated with craters, hills and other obstacles in the path of the 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 are quite different in the nature of the surface. In the southern hemisphere, the surface is 1–2 km above the mean level 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 main part is occupied by relatively smooth plains, probably formed as a result of lava flooding and erosion. This difference between the hemispheres remains a matter of debate. The boundary between the hemispheres follows approximately a great circle inclined at 30° to the equator. The boundary is wide and irregular and forms a slope towards the north. Along it there are the most eroded areas of the Martian surface.

Two alternative hypotheses have been put forward to explain the asymmetry of the hemispheres. According to one of them, at an early geological stage, the lithospheric plates "came together" (perhaps by accident) into one hemisphere, like the Pangea continent on Earth, and then "frozen" in this position. Another hypothesis involves the collision of Mars with space body the size of Pluto.

A large number of craters in the southern hemisphere suggests that the surface here is ancient - 3-4 billion years. There are several types of craters: large craters with a flat bottom, smaller and younger cup-shaped craters similar to the moon, craters surrounded by a rampart, and elevated craters. The latter two types are unique to Mars - rimmed craters formed where liquid ejecta flowed over the surface, and elevated craters formed where a crater ejecta blanket protected the surface from wind erosion. The largest feature of impact origin is the Hellas Plain (about 2100 km across).

In a region 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) and flooding with liquid lava. Chaotic landscapes are often found at the head of large channels cut by water. The most acceptable hypothesis for their joint formation is the sudden melting of subsurface ice.

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 a height of 10 km above the average level. There are three large shield volcanoes on it - Mount Arsia, Mount Pavlina and Mount Askriyskaya. On the edge of Tharsis is the highest mountain on Mars and in the solar system, Mount Olympus. Olympus reaches 27 km in height in relation to its base and 25 km in relation to the average level of the surface of Mars, and covers an area of 550 km in diameter, surrounded by cliffs, in places reaching 7 km in height. The volume of Mount Olympus is 10 times the volume of the largest volcano on Earth, Mauna Kea. Several smaller volcanoes are also located here. Elysium - a hill up to six kilometers above the average level, with three volcanoes - the dome of Hecate, Mount Elysius and the dome of Albor.

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

The appearance of Mars varies greatly depending on the time of year. First of all, changes in the polar caps are striking. They grow and shrink, creating seasonal phenomena in the atmosphere and on the 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 of the hemispheres recedes in spring, details of the planet's surface begin to darken. To a terrestrial observer, the darkening wave appears to be propagating from the polar cap towards the equator, although the orbiters do not record any significant changes.

The polar caps are made up of two components: seasonal carbon dioxide and secular water ice. According to the Mars Express satellite, the thickness of the caps can range from 1 m to 3.7 km. Mars Odysseus discovered on Mars' south polar cap active geysers. As NASA experts believe, jets of carbon dioxide with spring warming break up to a great height, taking dust and sand with them.

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 at the same time is 10-40 m/s, sometimes up to 100 m/s. The wind raises a large amount of dust from the surface, which leads to dust storms. Strong dust storms almost completely hide the surface of the planet. Dust storms have a noticeable effect on the temperature distribution in the Martian atmosphere.

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

On Mars, there are many geological formations that resemble water erosion, in particular, dried up river beds. According to one hypothesis, these channels could have formed as a result of short-term catastrophic events and are not evidence of a long-term existence. river system. However, recent evidence suggests that the rivers have flowed for geologically significant periods of time. In particular, inverted channels (that is, channels elevated above the surrounding area) have been found. 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 channel shifting in the river delta as the surface gradually rises.

Data from NASA's Spirit and Opportunity rovers also provide evidence for the presence of water in the past (minerals found that could only form as a result of prolonged exposure to water). The device "Phoenix" discovered deposits of ice directly in the ground.

Several unusual deep wells have been found on the Tharsis volcanic upland. Judging by the image of the Martian 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 about the volcanic origin of these formations has been put forward.

The elemental composition of the surface layer of the Martian soil, according to the data of the 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%), which give the soil a reddish color. There are significant impurities of sulfur compounds, calcium, aluminum, magnesium, sodium (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 Earth's, and plants could theoretically be grown on them. “In fact, we found that the soil on Mars meets the requirements and also contains necessary elements for the origin and maintenance of life in the past, present and future. “We were pleasantly surprised by the data received. This type of soil is also widely represented on Earth - any villager deals with it daily in the garden. A high (significantly higher than expected) content of alkalis was noted in it, and ice crystals were found. Such soil is quite suitable for growing various plants, such as asparagus. There is nothing here to make life impossible. On the contrary: with each new study, we find additional evidence in favor of the possibility of its existence, ”said Sam Kunaves, lead research chemist of the project.

There is also a significant amount of water ice in the ground at the landing site of the apparatus.

Unlike Earth, there is no movement on Mars lithospheric plates. As a result, volcanoes can exist for a much longer time and reach gigantic sizes.

Modern models 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 1800 km thick and a core with a radius of 1480 km. The density in the center of the planet should reach 8.5 g/cm³. The core is partially liquid and consists mainly of iron with an admixture of 14-17% (by mass) of 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 mantle of Mars is much smaller than on Earth, which means that it has fewer phase transitions. It is assumed that the phase transition of olivine to 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. For some regions of Mars, a detailed geological map has been compiled.

According to observations from orbit and analysis of the collection of Martian meteorites, the surface of Mars consists mainly of basalt. There is some evidence to suggest that, on part of the Martian surface, the material is more quartz-bearing than normal 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. A significant part of the deeper layer consists of granular iron oxide dust.

Mars has a magnetic field, but it is weak and 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 planet's crust are magnetized and that there has been a reversal of the magnetic poles of these parts in the past. The magnetization of these parts turned out to be similar to strip magnetic anomalies in the oceans.

One theory, published in 1999 and re-examined in 2005 (using the unmanned Mars Global Surveyor), is that these bands 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 decline 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 rotated at a distance of 50-75 thousand kilometers around Mars and caused instability in its core. The asteroid then dropped to its Roche limit and collapsed. However, this explanation itself contains ambiguities, and is disputed in the scientific community.

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. It is believed that the loss of the magnetic field occurred about 4 billion years ago. Due to the weakness of the magnetic field, the solar wind penetrates the Martian atmosphere almost unhindered, and many of the photochemical reactions under the action of solar radiation, which occur on Earth in the ionosphere and above, on Mars can be observed almost at its very surface.

The geological history of Mars includes the following three epochs:
Noachian Epoch (named after "Noachian Land", a region of Mars): Formation of the oldest extant surface of Mars. It continued in the period 4.5 billion - 3.5 billion years ago. During this epoch, the surface was scarred by numerous impact craters. The plateau of the province of Tharsis was probably formed during this period with intense water flow later.
Hesperian epoch: 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 Epoch (named after the "Amazonian Plain" on Mars): from 2.9 - 3.3 billion years ago to the present day. The regions formed during this epoch have very few meteorite craters, but otherwise they are completely different. Mount Olympus was formed during this period. At this time, lava flows were pouring in other parts of Mars.

The natural satellites of Mars are Phobos and Deimos. Both were discovered by the American astronomer Asaph Hall in 1877. Phobos and Deimos are irregularly shaped and very small. According to one hypothesis, they may represent asteroids captured by the gravitational field of Mars, like (5261) Eureka from the Trojan group of asteroids. 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, therefore they are always turned to the planet by the same side. The tidal influence of Mars gradually slows down the movement of Phobos, and eventually will lead to the fall of the satellite to Mars (while maintaining the current trend), or to its disintegration. On the contrary, Deimos is moving away from Mars.

Phobos (top) and Deimos (bottom).

Both satellites have a shape approaching a triaxial ellipsoid, Phobos (26.6 × 22.2 × 18.6 km) is somewhat larger than Deimos (15 × 12.2 × 10.4 km). The surface of Deimos looks much smoother due to the fact that most of the craters are covered with fine-grained matter. Obviously, on Phobos, which is closer to the planet and more massive, the substance ejected during meteorite impacts either hit the surface again or fell on Mars, while on Deimos it remained in orbit around the satellite for a long time, gradually settling and hiding uneven terrain.

The popular idea that Mars was inhabited by intelligent Martians became widespread in the late 19th century. Schiaparelli's observations of the so-called canals, combined with Percival Lowell's book on the same subject, popularized the idea of a planet that was getting drier, colder, dying, and had an ancient civilization doing irrigation work.

Numerous other sightings and announcements by famous people gave rise to the so-called "Mars Fever" around this topic. In 1899, while studying atmospheric interference in a radio signal using receivers at the Colorado Observatory, inventor Nikola Tesla observed a repeating signal. He then speculated that it might 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, it was a greeting from one planet to another.

Tesla's theory was enthusiastically supported by Lord Kelvin, who, visiting the US in 1902, said that he thought Tesla had picked up the Martian signal sent to the US. However, Kelvin then vehemently denied this statement before he left America: "In fact, I said that the inhabitants of Mars, if they exist, can certainly see New York, in particular 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 semi-major axis of the orbit of Mars. During perihelion, Mars is within 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 terrestrial life.

The lack of a magnetosphere and the extremely thin atmosphere of Mars are also a problem for sustaining life. There is a very weak movement of heat flows on the surface of the planet, it is poorly isolated 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 inside planets.

Evidence suggests that the planet was previously much more prone to life than it is now. However, to date, the remains of organisms have not been found on it. Under the Viking program, carried out in the mid-1970s, a series of experiments were conducted to detect microorganisms in the Martian soil. It has shown positive results, such as a temporary increase in CO2 release when soil particles are placed in water and nutrient media. However, then this evidence of life on Mars was disputed by some scientists. This led to their lengthy dispute with NASA scientist Gilbert Lewin, who claimed that the Viking had discovered life. After re-evaluating the Viking data in the light of current scientific knowledge about extremophiles, it was determined that the experiments carried out were not perfect enough to detect these life forms. Moreover, these tests could even kill the organisms, even if they were contained in the samples. Tests conducted by the Phoenix Program have shown that the soil has a very alkaline pH and contains magnesium, sodium, potassium and chloride. The nutrients in the soil are sufficient to support life, but life forms must be protected from intense ultraviolet light.

Interestingly, in some meteorites of Martian origin, formations were found that resemble the simplest bacteria in shape, although they are inferior to the smallest terrestrial organisms in size. One of these meteorites is ALH 84001, found in Antarctica in 1984.

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

After the landings 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 period of revolution of Mars and its satellites, the picture of the night sky of Mars (and astronomical phenomena observed from the planet) differs from the earth's and in many ways seems unusual and interesting.

During sunrise and sunset, the Martian sky at the zenith has a reddish-pink color, and in close proximity to the disk of the Sun - from blue to purple, 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 color scheme of the earth's sky is the properties of the thin, rarefied atmosphere of Mars containing suspended dust. On Mars, Rayleigh scattering of rays (which on Earth is the cause of the blue color of the sky) plays an insignificant role, its effect is weak. Presumably, the yellow-orange coloration 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 acquires a purple hue as a result of light scattering on microparticles of water ice in clouds (the latter is a rather rare phenomenon).

Earth is an inner planet to Mars, just like Venus is to 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 stellar magnitude of about −2.5) greenish star, next to which the yellowish and dimmer (about 0.9) star of the Moon will be easily distinguishable. In 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 will easily separate the Moon and the Earth: in a week the “stars” of the Moon and the Earth will merge into a single star inseparable by the eye, in another week the Moon will again be visible at maximum distance, but on the other side of the Earth. Periodically, 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 viewed from Mars will vary significantly depending on the relative position of the Earth and Mars, and, accordingly, the distance between the planets. In the epoch of oppositions, it will be about 17 minutes of arc, at the maximum distance of Earth and Mars - 3.5 minutes of arc. Earth, like other planets, will be observed in the constellation band of the Zodiac. An astronomer on Mars will also be able to observe the passage of the Earth across the disk of the Sun, the next one will occur on November 10, 2084.

The angular size of the Sun, observed from Mars, is less than that visible from the Earth and is 2/3 of the latter. Mercury from Mars will be practically 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, in second place is Jupiter (its four largest satellites can be observed without a telescope), in third is Earth.

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

The brightness of both Phobos and Deimos is sufficient for objects on the surface of Mars to cast sharp shadows at night. Both satellites have a relatively small inclination of the orbit to the equator of Mars, which excludes 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. sh. or south of 70.4°S sh.; for Deimos these values are 82.7°N. sh. and 82.7°S sh. On Mars, an eclipse of Phobos and Deimos can be observed when 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.

North Pole on Mars, due to the tilt of the planet's axis, it 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 star of the sixth magnitude BD +52 2880 (its other designations - HR 8106, HD 201834, SAO 33185). South Pole the world (coordinates 9h 10m 42s and −52 ° 53.0) is a couple of degrees from the star Kappa Sails (apparent magnitude 2.5) - it, in principle, can be considered the South Pole Star of Mars.

The zodiac 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 before how to re-enter the western part of Pisces.

Due to the proximity of Mars to Earth, its colonization in the foreseeable future is an important task for humanity. Relatively close to Earth natural conditions make this task easier. In particular, on Earth there are such places explored by man, in which the natural conditions are in many ways similar to those on Mars. Atmospheric pressure at an altitude of 34,668 meters - the highest point reached by a balloon with a crew on board (May 1961) - roughly corresponds to the pressure on the surface of Mars. Extremely low temperatures in the Arctic and Antarctica are comparable even to the lowest temperatures on Mars, and on the equator of Mars in the summer months it is as warm (+30 ° C) as on Earth. Also on Earth there are deserts similar in appearance to the Martian landscape.

However, there are several significant differences between Earth and Mars. In particular, the magnetic field of Mars is weaker than the earth's by about 800 times. Together with a rarefied atmosphere, this increases the amount of ionizing radiation reaching its surface. Radiation measurements carried out by the American unmanned spacecraft The Mars Odyssey showed that the radiation background in the orbit of Mars is 2.2 times higher than the radiation background at 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 exposure received as a result of being in such a background for three years, approaches the established safety limits for astronauts. On the surface of Mars, the radiation background will most likely be somewhat lower and may vary significantly depending on the terrain, altitude and local magnetic fields.

Mars has a certain economic potential for colonization. In particular, the southern hemisphere of Mars was not subjected to melting, unlike the entire surface of the Earth - therefore, the rocks of the southern hemisphere inherited the quantitative composition of the non-volatile component of the protoplanetary cloud. According to calculations, it should be enriched with those elements (relative to the Earth) that on Earth “drowned” in its core during the melting of the planet: metals of the copper, iron and platinum groups, tungsten, rhenium, uranium. The export of rhenium, platinum metals, silver, gold and uranium to the Earth (in the event of an increase in prices for it to the level of silver prices) has good prospects, but for its implementation it requires the presence of a surface reservoir with liquid water for enrichment processes.

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 (the opposition of Mars, from an earthly point of view, which repeats every 780 days), and about 20 minutes. at the maximum removal of the planets (the conjunction of Mars with the Sun); see Configuration (astronomy).

However, to date, no practical steps have been taken towards the colonization of Mars.

The exploration of Mars began a long time ago, even 3.5 thousand years ago, in ancient Egypt. The first detailed accounts of the position of Mars were made by Babylonian astronomers, who developed a number of mathematical methods to predict the position of the planet. Using the data of the Egyptians and Babylonians, ancient Greek (Hellenistic) philosophers and astronomers developed a detailed geocentric model to explain the movement of the planets. A few 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 for Mars, coinciding with the observed one.

Topographic map of Mars.

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 details: the seas of Aphrodite, Eritrean, Adriatic, Cimmerian; lakes of the Sun, Lunar and Phoenix.

The heyday of telescopic observations of Mars came at the end of the 19th - the middle of the 20th century. It is largely due to public interest and well-known scientific disputes around the observed Martian channels. Among the astronomers of the pre-space era who made telescopic observations of Mars during this period, the most famous are Schiaparelli, Percival Lovell, Slifer, Antoniadi, Barnard, Jarry-Deloge, 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 wrong after flights of automatic probes to Mars.

Orbital characteristics:
Perihelion
206.62×106 km
1.3812 a. e.
Aphelion
249.23×106 km
1.6660 a. e.
Major axle (a)
227.92×106 km
1.5236 a. e.
Orbital eccentricity (e)
0,093315
sidereal period
686.971 days
1.8808 Earth years
Sol 668.5991
Synodic period of circulation
779.94 days
Orbital speed (v)
24.13 km/s (average)
Inclination (i)
1.85061° (relative to the plane of the ecliptic)
5.65° (relative to solar equator)
Ascending node longitude (Ω)
49.57854°
Periapsis argument (ω)
286.46230°

Satellites:
2 (Phobos and Deimos)
physical characteristics
flattening
0,00589
Equatorial radius
3396.2 km
Polar radius
3376.2 km
Medium radius
3386.2 km
Surface area (S)
144,798,465 km²
Volume (V)
1.6318×1011 km³
0.151 Earth
Weight (m)
6.4185×1023 kg
0.107 Earth
Average density (ρ)
3.9335 g/cm³
Acceleration of gravity at the equator (g)
3.711 m/s² (0.378 g)
Second escape velocity (v2)
5.027 km/s
Equatorial rotation speed
868.22 km/h
Rotation period (T)
24 hours 39 minutes and 36 seconds
Axis Tilt
24.94°
Right ascension north pole (α)
21 h 10 min 44 s
317.68143°
North Pole Declination (δ)
52.88650°
Albedo
0.250 (Bond)
0.150 (geom.albedo)

Temperature:

min. avg. Max.

Worldwide 186 K 227 K 268 K

Atmosphere:
Atmosphere pressure
0.6-1.0 kPa (0.006-0.01 atm)
Compound:
95.32% ar. gas

2.7% Nitrogen
1.6% Argon
0.2% oxygen
0.07% Carbon monoxide
0.03% Water vapor
0.01% Nitric oxide

Mars is the fourth largest 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 referred to as the "red planet" because of the reddish hue of the surface given to it by iron oxide.

Mars is a terrestrial planet with a rarefied atmosphere (the pressure at the surface is 160 times less than the earth's). The features of the surface relief of Mars can be considered impact craters like those of the moon, as well as volcanoes, valleys, deserts and polar ice caps like those of the 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.

The great oppositions of Mars, 1830-2035

Year	the date	Distance a. e.
1830	September 19	0,388
1845	August 18	0,373
1860	July 17th	0,393
1877	September 5	0,377
1892	August 4	0,378
1909	September 24	0,392
1924	August 23	0,373
1939	July 23	0,390
1956	10 September	0,379
1971	August 10	0,378
1988	September 22nd	0,394
2003	August 28	0,373
2018	July 27	0,386
2035	September 15th	0,382

Mars is the fourth farthest from the Sun (after Mercury, Venus and Earth) and the seventh largest (exceeds only Mercury in mass and diameter) planet of 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), the volume is 0.15 of the volume of the Earth, and the average linear diameter- 0.53 of the diameter of the Earth (6800 km).

The relief of Mars has many unique features. The Martian extinct volcano Mount Olympus is the highest mountain in the solar system, and the Mariner Valley is the largest canyon. In addition, in June 2008, three papers published in the journal Nature provided evidence for the existence of the largest known impact crater in the solar system in the northern hemisphere of Mars. It is 10,600 km long and 8,500 km wide, about four times larger than the largest impact crater previously discovered on Mars, near its south pole.

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

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

The geological data they collected suggests that most of the surface of Mars was previously covered with water. Observations over the past decade have made it possible to detect weak geyser activity in some places on the surface of Mars. According to observations from the Mars Global Surveyor spacecraft, some parts of the south polar cap of Mars are gradually receding.

Mars can be seen from Earth with the naked eye. Its apparent stellar magnitude reaches 2.91m (at the closest approach to the Earth), yielding in brightness only to Jupiter (and even then not always during the great confrontation) and Venus (but only in the morning or evening). As a rule, during the great opposition, orange Mars is the brightest object in the earth's night sky, but this happens only 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), the period of revolution around the Sun is 687 Earth days. The orbit of Mars has a rather noticeable eccentricity (0.0934), so the distance to the Sun varies from 206.6 to 249.2 million km. The orbital inclination of Mars is 1.85°.

Mars is closest to Earth during opposition, when the planet is in the opposite direction from the Sun. Oppositions are repeated every 26 months at different points in the orbit of Mars and the Earth. But once every 15-17 years, the opposition occurs at a time when Mars is near its perihelion; in these so-called great oppositions (the last 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

Size comparison 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 roughly equal to the land area of Earth.

The polar radius of Mars is about 20 km less than the equatorial one, although the period of rotation of the planet is longer than that of the Earth, which gives reason to assume a change in the rate of rotation of Mars with time.

The mass of the planet is 6.418 1023 kg (11% of the mass of the Earth). The free fall acceleration 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, which is inclined to the perpendicular plane of the orbit at an angle of 24°56?. The tilt of the axis of rotation of Mars causes the change of seasons. 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 fall on the part of Mars' orbit that is farthest from the Sun. Therefore, on Mars, northern summers are long and cool, while southern summers are short and hot.

Atmosphere and climate

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

The temperature on the planet ranges from -153 at the pole in winter to over +20 °C at the equator at noon. The average temperature is -50°C.

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

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

Atmosphere pressure

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

Unlike the Earth, the mass of the Martian atmosphere varies greatly during the year due to the melting and freezing of the polar caps containing carbon dioxide. During winter, 20-30 percent of the entire atmosphere is frozen on the polar cap, which consists 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 to find the highest atmospheric pressure on Mars

At the landing site of the AMC Mars-6 probe in the Eritrean 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 count the heights and depths on Mars. According to the data of this device, obtained during the descent, the tropopause is located at an altitude of about 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 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 sufficiently high 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 top of the highest 27 km volcano Olympus, the pressure can be between 0.5 and 1 mbar (Zurek 1992).

Before landing on the surface of Mars, the pressure was measured by attenuating radio signals from the AMS Mariner-4, Mariner-6 and Mariner-7 when they entered the Martian disk - 6.5 ± 2.0 mb at the average surface level, which is 160 times less than the earthly; the same result was shown by the spectral observations of AMS Mars-3. At the same time, 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 the pressure of the atmosphere using photographic photometry - by the distribution of brightness along the diameter of the disk in different ranges of light waves. For this purpose, the French scientists B. Lyo and O. Dollfus made observations of the polarization of the light scattered by the Martian atmosphere. 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

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

According to NASA (2004), the average temperature is ~210 K (-63 °C). According to Viking landers, the daily temperature range is from 184 K to 242 K (from -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 the Mars-6 landing probe, the average temperature of the Mars troposphere is 228 K, in the troposphere the temperature decreases by an average of 2.5 degrees per kilometer, and the stratosphere above the tropopause (30 km) has an almost constant temperature of 144 K.

According to researchers from the Carl Sagan Center, the process of warming has been going on 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 liquid water existed on the surface of Mars and it rained. The 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 whirlwinds

Dust swirls 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 whirlwinds were recorded. These are air turbulences that occur near the surface of the planet and raise a large amount of sand and dust into the air. Vortices are often observed on the Earth (in English speaking countries they are called dust demons - dust devil), but on Mars they can reach much larger sizes: 10 times higher and 50 times wider than on Earth. In March 2005, a vortex cleared the solar panels off the Spirit rover.

Surface

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

The hemispheres of Mars are quite different in the nature of the surface. In the southern hemisphere, the surface is 1-2 km above the mean level 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 main part is occupied by relatively smooth plains, probably formed as a result of lava flooding and erosion. This difference between the hemispheres remains a matter of debate. The boundary between the hemispheres follows approximately a great circle inclined at 30° to the equator. The boundary is wide and irregular and forms a slope towards the north. Along it there are the most eroded areas of the Martian surface.

A large number of craters in the southern hemisphere suggests that the surface here is ancient - 3-4 billion years. There are several types of craters: large craters with a flat bottom, smaller and younger cup-shaped craters similar to the moon, craters surrounded by a rampart, and elevated craters. The last two types are unique to Mars - rimmed craters formed where liquid ejecta flowed over the surface, and elevated craters formed where a crater ejecta blanket protected the surface from wind erosion. The largest feature of impact origin is the Hellas Plain (about 2100 km across).

Mariner Valleys on Mars

According to others (Faure and Mensing, 2007), the height of Olympus is 21,287 meters above zero 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 (depression in the center of the volcano) is 70 km wide and 3 km deep.

The Tharsis Upland is also crossed by many tectonic faults, often very complex and extended. The largest of them - the Mariner valleys - stretches in the 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. On its steep slopes, the largest landslides in the solar system occur. The Mariner Valleys are the largest known canyon in the solar system. The canyon, which was discovered by the Mariner 9 spacecraft in 1971, could cover the entire territory of the United States, from ocean to ocean.

A 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 region, taken by the Spirit rover November 23-28, 2005.

Ice and polar ice caps

North polar cap in summer, photo by Mars Global Surveyor. A long wide fault that cuts through the cap on the left - Northern Fault

The polar caps consist of two components: seasonal - carbon dioxide and secular - water ice. According to the Mars Express satellite, the thickness of the caps can range from 1 m to 3.7 km. The Mars Odyssey spacecraft discovered active geysers on the south polar cap of Mars. As NASA experts believe, jets of carbon dioxide with spring warming break up to a great height, taking dust and sand with them.

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

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 the French astronomer E. Lie observed a wave of darkening around the melting spring polar cap, which was then interpreted by the spreading hypothesis melt water and vegetation growth. Spectrometric measurements that were carried out at the beginning of the 20th century. at the Lovell Observatory in Flagstaff, 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 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 was called the Mitchell Mountains, located near the south pole of Mars, looks like a white island when the polar cap melts, since glaciers melt later in the mountains, including on Earth.

Channels of "rivers" and other features

On Mars, there are many geological formations that resemble water erosion, in particular, dried up river beds. According to one hypothesis, these channels could have formed as a result of short-term catastrophic events and are not proof of the long-term existence of the river system. However, recent evidence suggests that the rivers have flowed for geologically significant periods of time. In particular, inverted channels (that is, channels elevated above the surrounding area) have been found. 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 channel shifting 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 over the delta was more than 60 km long.

Data from NASA's Spirit and Opportunity rovers also testify to the presence of water in the past (minerals have been found that could only form as a result of prolonged exposure to water). The device "Phoenix" discovered deposits of ice directly in the ground.

In addition, dark stripes have been found on the slopes of hills, indicating the appearance of liquid salt water on the surface in our time. They appear shortly after the onset of the summer period and disappear by winter, “flow around” various obstacles, merge and diverge. "It's hard to imagine that such structures could form not from fluid flows, but from something else," said NASA employee Richard Zurek.

Priming

There is also a significant amount of water ice in the ground at the landing site of the apparatus. The Mars Odyssey orbiter also discovered that there are deposits of water ice under the surface of the red planet. 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 a movement of lithospheric plates. This is confirmed by the features 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 Mariner Valley. 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 possibly did not allow them to reach heights, as on Mars. On the other hand, the difference in the maximum height of volcanoes can be explained by the fact that, due to the lower gravity on Mars, it is possible to build higher structures that would not collapse under their own weight.

Comparison of the structure of Mars and other terrestrial planets

Modern 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 1800 km thick, and a core with a radius of 1480 km. The density in 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) of sulfur, and the content of light elements is twice as high as in the core of the Earth. 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 mantle of Mars is much smaller than on Earth, which means that it has fewer phase transitions. It is assumed that the phase transition of olivine to 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. For some regions of Mars, a detailed geological map has been compiled.

Mars magnetic field

Mars has a weak magnetic field.

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 gammas, at the pole 120 gammas, which is 500 times weaker than the earth's. According to AMS Mars-5, the magnetic field strength at the equator was 64 gamma, 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 planet's crust are magnetized and that there has been a reversal of the magnetic poles of these parts in the past. The magnetization of these parts turned out to be similar to strip magnetic anomalies in the oceans.

Geological history

Global mosaic of 102 Viking 1 orbiter images 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. It is believed that the loss of the magnetic field occurred about 4 billion years ago. Due to the weakness of the magnetic field, the solar wind penetrates the atmosphere of Mars almost unhindered, and many of the photochemical reactions under the influence of solar radiation that occur on Earth in the ionosphere and above can be observed on Mars almost at its very surface.

The geological history of Mars includes the following three epochs:

Noachian Epoch (named after "Noachian Land", a region of Mars): the formation of the oldest extant surface of Mars. It continued in the period 4.5 billion - 3.5 billion years ago. During this epoch, the surface was scarred by numerous impact craters. The plateau of the province of Tharsis was probably formed during this period with intense water flow later.

Hesperian 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 regions formed during this epoch have very few meteorite craters, but otherwise they are completely different. Mount Olympus was formed during this period. At this time, lava flows were pouring in other parts of Mars.

Moons of Mars

The natural satellites of Mars are Phobos and Deimos. Both were discovered by the American astronomer Asaph Hall in 1877. Phobos and Deimos are irregularly shaped and very small. According to one hypothesis, they may represent asteroids captured by the gravitational field of Mars, like (5261) Eureka from the Trojan group of asteroids. 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 have a shape approaching a triaxial ellipsoid, Phobos (26.6x22.2x18.6 km) is somewhat larger than Deimos (15x12.2x10.4 km). The surface of Deimos looks much smoother due to the fact that most of the craters are covered with fine-grained matter. Obviously, on Phobos, which is closer to the planet and more massive, the substance ejected during meteorite impacts either hit the surface again 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 in the late 19th century.

Schiaparelli's observations of the so-called canals, combined with Percival Lowell's book on the same subject, popularized the idea of a planet that was getting drier, colder, dying, and had an ancient civilization doing irrigation work.

Tesla's theory was strongly supported by the famous British physicist William Thomson (Lord Kelvin), who, visiting the USA in 1902, said that in his opinion Tesla had picked up the Martian signal sent to the USA. However, Kelvin then vehemently denied this statement before he left America: "In fact, I said that the inhabitants of Mars, if they exist, can certainly see New York, in particular the light from electricity."

Evidence suggests that the planet was previously much more prone to life than it is now. However, to date, the remains of organisms have not been found on it. Under the Viking program, carried out in the mid-1970s, a series of experiments were conducted to detect microorganisms in the Martian soil. It has shown positive results, such as a temporary increase in CO2 release when soil particles are placed in water and nutrient media. 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 Lewin, who claimed that the Viking had discovered life. After re-evaluating the Viking data in the light of current scientific knowledge about extremophiles, it was determined that the experiments carried out were not perfect enough to detect these life forms. Moreover, these tests could even kill the organisms, even if they were contained in the samples. Tests conducted by the Phoenix Program have shown that the soil has a very alkaline pH and contains magnesium, sodium, potassium and chloride. The nutrients in the soil are sufficient to support life, but life forms must be protected from intense ultraviolet light.

Astronomical observations from the surface of Mars

Sky color on Mars

At noon, the sky of Mars is yellow-orange. The reason for such differences from the color scheme of the earth's sky is the properties of the thin, rarefied atmosphere of Mars containing suspended dust. On Mars, Rayleigh scattering of rays (which on Earth is the cause of the blue color of the sky) plays an insignificant role, its effect is weak. Presumably, the yellow-orange coloration 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 clouds (the latter is a rather rare phenomenon).

sun and planets

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 of about -2.5) greenish star, next to which the yellowish and dimmer (about 0.9) star of the Moon will be easily distinguishable. In 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 will easily separate the Moon and the Earth: in a week the “stars” of the Moon and the Earth will merge into a single star inseparable by the eye, in another week the Moon will again be visible at maximum distance, but on the other side of the Earth. Periodically, 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 viewed from Mars will vary significantly depending on the relative position of the Earth and Mars, and, accordingly, the distance between the planets. During the epoch of oppositions, it will be about 17 minutes of arc, at the maximum distance of Earth and Mars - 3.5 minutes of arc. Earth, like other planets, will be observed in the constellation band of the Zodiac. An astronomer on Mars will also be able to observe the passage of the Earth across the disk of the Sun, the next one will occur on November 10, 2084.

Moons - Phobos and Deimos

Passage of Phobos across the disk of the Sun. Pictures of Opportunity

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

Celestial sphere

The north pole on Mars, due to the tilt of the planet's axis, is 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 star of the sixth magnitude BD +52 2880 (other its designations are HR 8106, HD 201834, SAO 33185. The south celestial pole (coordinates 9h 10m 42s and -52° 53.0) is a couple of degrees from the star Kappa Parusov (apparent magnitude 2.5) - it, in principle , can be considered the South Pole Star of Mars.

History of the study of Mars

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 details: the seas of Aphrodite, Eritrean, Adriatic, Cimmerian; lakes of the Sun, Lunar and Phoenix.

The heyday of telescopic observations of Mars came at the end of the 19th - the middle of the 20th century. It is largely due to public interest and well-known scientific disputes around the observed Martian channels. Among the astronomers of the pre-space era who made telescopic observations of Mars during this period, the best known 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 wrong after automatic probes flew to Mars.

Mars colonization

Estimated view of Mars after terraforming

Relatively close to terrestrial natural conditions make this task somewhat easier. In particular, there are places on Earth where natural conditions are similar to those on Mars. Extremely low temperatures in the Arctic and Antarctica are comparable to even the lowest temperatures on Mars, and the equator of Mars during the summer months is as warm (+20 °C) as on Earth. Also on Earth there are deserts similar in appearance to the Martian landscape.

But there are significant differences between Earth and Mars. In particular, the magnetic field of Mars is weaker than the earth's by about 800 times. Together with a rarefied (hundreds of times in comparison with the Earth) atmosphere, this increases the amount of ionizing radiation reaching its surface. Measurements carried out by the American unmanned vehicle The Mars Odyssey showed that the radiation background in the orbit of Mars is 2.2 times higher than the radiation background at 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 staying in such a background for three years is approaching the established safety limits for astronauts. On the surface of Mars, the radiation background 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 others. celestial bodies close to the earth. According to the 4Frontiers corporation, they are enough to supply not only Mars itself, but also the Moon, the 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 for the colonization of Mars, however, colonization is being developed, for example, the Centenary Spacecraft project, the development of a habitation module for staying on the Deep Space Habitat planet.

The main characteristics of Mars

Atmosphere of Mars

The composition and other parameters of the Martian atmosphere have been determined quite accurately by now. The atmosphere of Mars is composed of carbon dioxide (96%), nitrogen (2.7%) and argon (1.6%). Oxygen is present in negligible amounts (0.13%). Water vapor is presented as traces (0.03%). The pressure at the surface is only 0.006 (six thousandths) of the pressure at the Earth's surface. Martian clouds are made up of water vapor and carbon dioxide and look something like cirrus clouds above the Earth.

The color of the Martian sky is reddish due to the presence of dust in the air. Extremely rarefied air does not transfer heat well, so there is a large temperature difference in different parts of the planet.

Despite the rarefaction of the atmosphere, its lower layers represent a rather serious obstacle for spacecraft. So, the conical protective shells of the descent vehicles "Mariner-9"(1971) during the passage of the Martian atmosphere from its uppermost layers to a distance of 5 km from the surface of the planet, they were heated to a temperature of 1500 ° C. The Martian ionosphere extends from 110 to 130 km above the surface of the planet.

On the movement of Mars

Mars can be seen from Earth with the naked eye. Its apparent stellar magnitude reaches −2.9m (at its closest approach to the Earth), second only to Venus, the Moon and the Sun in brightness, but most of the time Jupiter is brighter than Mars for an earthly observer. Mars moves around the Sun in an elliptical orbit, then moving away from the star at 249.1 million km, then approaching it up to a distance of 206.7 million km.

If you carefully observe the movement of Mars, you can see that during the year the direction of its movement across the sky changes. By the way, ancient observers noticed this. At a certain point, it seems that Mars is moving in the opposite direction. But this movement is only apparent from the Earth. Mars, of course, cannot perform any reverse movement in its orbit. And the appearance of a reverse movement is created because the orbit of Mars in relation to the orbit of the Earth is external, and average speed orbit around the Sun is higher for the Earth (29.79 km/s) than for Mars (24.1 km/s). At the moment when the Earth begins to overtake Mars in its movement around the Sun, and it seems that Mars began the reverse or, as astronomers call it, retrograde motion. The diagram of the reverse (retrograde) movement illustrates this phenomenon well.

The main characteristics of Mars

Name of parameters	Quantitative indicators
Average distance to the Sun	227.9 million km
Minimum distance to the Sun	206.7 million km
Maximum distance to the Sun	249.1 million km
Equator diameter	6786 km (Mars is almost half the size of the Earth in size - its equatorial diameter is ~ 53% of the Earth's)
Average orbital speed around the Sun	24.1 km/s
Period of rotation around its own axis (Sidereal equatorial period of rotation)	24h 37 min 22.6 s
Period of revolution around the sun	687 days
Known natural satellites	2
Mass (Earth = 1)	0.108 (6.418 × 10 23 kg)
Volume (Earth = 1)	0,15
Average density	3.9 g/cm³
Average surface temperature	minus 50°C (temperature difference is from -153°C at the pole in winter and up to +20°C at the equator at noon)
Axis Tilt	25°11"
Orbital inclination with respect to the ecliptic	1°9"
Surface pressure (Earth = 1)	0,006
Composition of the atmosphere	CO 2 - 96%, N - 2.7%, Ar - 1.6%, O 2 - 0.13%, H 2 O (vapors) - 0.03%
Acceleration of free fall at the equator	3.711 m/s² (0.378 Earth)
parabolic speed	5.0 km/s (for Earth 11.2 km/s)

The table shows with what high accuracy the main parameters of the planet Mars are determined. This is not surprising, given that astronomical observations and research are now using the most modern scientific methods and high precision equipment. But with a completely different feeling, we treat such facts from the history of science, when scientists of past centuries, who often did not have any astronomical instruments at their disposal, except for the simplest telescopes with a small increase (maximum 15-20 times), made accurate astronomical calculations and even discovered the laws of motion of celestial bodies.

For example, let's recall that the Italian astronomer Giandomenico Cassini already in 1666 (!) determined the time of rotation of the planet Mars around its axis. His calculations gave a result of 24 hours and 40 minutes. Compare this result with the period of rotation of Mars around its axis, determined with the help of modern technical means (24 hours 37 minutes 23 seconds). Are our comments needed here?

Or such an example. Johannes Kepler at the very beginning of the 17th century, he discovered the laws of planetary motion, having neither precise astronomical instruments nor a mathematical apparatus for calculating the areas of such geometric shapes like an ellipse and an oval. Suffering from a visual defect, he made the most accurate astronomical measurements.

Similar examples show great importance activity and enthusiasm in science, as well as devotion to the cause that a person serves.

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Mars is the fourth planet from the Sun and the last of the terrestrial planets.

The planet got its name due to its bright red color. AT Ancient Greece and Rome, red was associated with blood and war, so the name was given in honor of the god of war - Mars.
On closer inspection, the color of the surface of Mars is more orange than red. This shade occurs due to the high content of iron oxide. Scientists suggest that contact with oxygen led to the oxidation of iron, and strong dust storms eventually carried rusty particles over the entire surface.

With all this, Mars is the second smallest planet in the solar system after Mercury.

Dimensions of the Earth, Mars and Moon

Main characteristics

Weight:	6.4 * 1023 kg (0.107 Earth masses)
Equator diameter:	6794 km (0.53 Earth diameter)
Axis Tilt:	25°
Density:	3.93 g/cm³
Surface temperature:	-50°C
Period of circulation	around the axis (day): 24 hours 39 minutes 35 seconds; around the Sun in orbit (year): 687 days
Distance from the Sun (average):	1.53 a. e. = 228 million km
Orbital speed: Orbital inclination to the ecliptic:	24.1 km/s
Acceleration of gravity	3.7 m/s2
Satellites:	Phobos and Deimos

The structure of Mars

Scientists can only guess what the structure of Mars is based on data from orbiters, studies of meteorites and experience of studying other planets. There is reason to believe that Mars, like the Earth, has a three-layer structure:

Nucleus. Most likely, most of the core is iron, sulfur and nickel. Knowledge of the density of the planet and the strength of the magnetic field allows us to think that the core of Mars is solid and much smaller than the earth's, about 2000 km.
Mantle similar in composition to Earth. Perhaps it contains such radioactive elements as uranium, thorium and potassium. Their decay heats the mantle up to 1500°.
Bark Mars is heterogeneous in thickness: the layer increases from the northern hemisphere to the southern. It mainly consists of volcanic basalt.

Surface

Thanks to robotic vehicles sent to Mars, it was possible to draw up a detailed map of it. As it turned out, the surface of Mars is very similar to the Earth. There are plains and mountains, crevices and volcanoes.

Plains.

Most of Mars, and especially its northern hemisphere, is covered by desert low-lying plains. One of them is considered the largest lowland in the entire solar system, and its relative smoothness may be a consequence of the presence of water here in the distant past.

Canyons.

A whole network of canyons covers the surface of Mars. They are concentrated mainly on the equator. These canyons got their name - the Mariner Valley - in honor of the space station of the same name, which recorded them in 1971. The length of the valley is comparable to the length of Australia and occupies about 4000 km, and sometimes goes 10 km deep.

Volcanoes.

There are many volcanoes on Mars, including Olympus Olympus is the largest volcano in the solar system. Its height reaches 27 km, which is 3 times the height of Everest.

Volcano Olympus on Mars

To date, not a single active volcano has been discovered, but the presence of volcanic rocks and ash speaks of their former activity.

River basins.

On the surface of the plains of Mars, scientists have found depressions that look like traces of rivers flowing here. Perhaps earlier the temperature here was much higher, which allowed water to exist in liquid form.

Water

Until the middle of the last century, scientists believed that liquid water could be found on Mars, and this gave reason to say that life exists on the red planet. This theory was based on the fact that light and dark areas were clearly visible on the planet, which very much resembled seas and continents, and dark long lines on the map of the planet looked like river valleys. But, after the very first flight to Mars, it became obvious that water, due to too low atmospheric pressure, cannot be in a liquid state on seventy percent of the planet.

Riverbeds on Mars

It is suggested that it did exist: this fact is evidenced by the found microscopic particles of the mineral hematite and other minerals, which are usually formed only in sedimentary rocks and clearly succumbed to the influence of water.

Also, many scientists are convinced that the dark stripes on the mountain heights are traces of the presence of liquid salt water at the present time: water flows appear at the end of summer and disappear at the beginning of winter. The fact that this is water is evidenced by the fact that the stripes do not go over the obstacle, but flow around them, sometimes at the same time they diverge, and then merge again (they are very clearly visible on the map of the planet). Some features of the relief indicate that the riverbeds shifted during the gradual uplift of the surface and continued to flow in a direction convenient for them.

one more interesting fact, indicating the presence of water in the atmosphere, are thick clouds, the appearance of which is associated with the fact that the uneven topography of the planet directs air masses upward, where they cool, and the water vapor in them condenses into ice crystals.

Moons of Mars

Mars orbits two of its moons: Phobos and Deimos. Asaph Hall found them in 1877 and named them after characters from Greek mythology. These are the sons of the god of war Ares: Phobos - fear, a Deimos - horror. Martian satellites are shown in the photo.

The diameter of Phobos is 22 km, and the distance is 9234.42 - 9517.58 km. It needs 7 hours for an orbital passage, and this time is gradually decreasing. Researchers believe that in 10-50 million years the satellite will crash into Mars or be destroyed by the planet's gravity and form a ring structure.

Deimos has a diameter of 12 km and rotates at a distance of 23455.5 - 23470.9 km. The orbital route takes 1.26 days. Mars may also have additional moons with a width of 50-100 m, and a dust ring can form between two large ones.

It is believed that previously the satellites of Mars were ordinary asteroids that succumbed to planetary gravity. But they have circular orbits, which is unusual for captured bodies. They may also have formed from material torn from the planet at the start of creation. But then their composition should have resembled a planetary one. A strong impact could also have occurred, repeating the scenario with our Moon.

Atmosphere and temperature of the planet Mars

The red planet has a thin atmospheric layer, which is represented by carbon dioxide (96%), argon (1.93%), nitrogen (1.89%) and oxygen impurities with water. It contains a lot of dust, the size of which reaches 1.5 micrometers. Pressure - 0.4-0.87 kPa.

The large distance from the Sun to the planet and the thin atmosphere have led to the fact that the temperature of Mars is low. It fluctuates between -46°C to -143°C in winter and can warm up to 35°C in summer at the poles and at noon on the equatorial line.

There are suggestions that in the past the atmosphere could have been denser, and the climate warm and humid, and liquid water existed on the surface of Mars and it rained. The proof of this hypothesis is the analysis of the meteorite ALH 84001, which showed that about 4 billion years ago the temperature of Mars was 18 ± 4 °C.

Mars is notable for the activity of dust storms that can mimic mini-tornadoes. They are formed due to solar heating, where warmer air currents rise and form storms that stretch for thousands of kilometers.

The analysis in the atmosphere also found traces of methane with a concentration of 30 parts per million. So, he was released from specific territories. Studies show that the planet is capable of creating up to 270 tons of methane per year. It reaches the atmospheric layer and persists for 0.6-4 years until complete destruction. Even a small presence suggests that a gas source is hiding on the planet.

Suggestions have hinted at volcanic activity, comet impacts, or the presence of microorganisms below the surface. Methane can also be created in a non-biological process - serpentinization. It contains water, carbon dioxide and the mineral olivine.

In 2012, some calculations were made on methane using the Curiosity rover. If the first analysis showed a certain amount of methane in the atmosphere, then the second showed 0. But in 2014, the rover encountered a 10-fold surge, which indicates a localized release.

Satellites also recorded the presence of ammonia, but its decomposition time is much shorter. A possible source is volcanic activity.

Brief history of learning

For the first time, mankind began to observe Mars by no means through telescopes. Even the ancient Egyptians noticed the Red Planet as a wandering object, which is confirmed by ancient written sources. The Egyptians were the first to calculate the trajectory of Mars relative to the earth.

Then the baton was taken over by the astronomers of the Babylonian kingdom. Scientists from Babylon were able to more accurately determine the location of the planet and measure the time of its movement. The Greeks were next. They managed to create an accurate geocentric model and use it to understand the movement of the planets. Then the scientists of Persia and India were able to estimate the size of the Red Planet and its distance from the Earth.

A huge breakthrough was made by European astronomers. Johannes Kepler, based on the model of Nikolai Kaepernik, was able to calculate the elliptical orbit of Mars, and Christian Huygens created the first map of its surface and noticed an ice cap at the planet's north pole.

The advent of telescopes was the heyday in the study of Mars. Slipher, Barnard, Vaucouleur, and many other astronomers became the greatest explorers of Mars before man went into space.

Man's spacewalk made it possible to study the Red Planet more accurately and in detail. In the middle of the 20th century, with the help of interplanetary stations, accurate pictures of the surface were taken, and super-powerful infrared and ultraviolet telescopes made it possible to measure the composition of the planet's atmosphere and the speed of the winds on it.

In the future, more and more accurate studies of Mars by the USSR, the USA, and then other states followed.

The study of Mars continues to this day, and the data obtained only fuel interest in its study.

Is there life on Mars?

There is still no single answer to this question. Currently, there are scientific data that become arguments in favor of both theories.

The presence of a sufficient amount of nutrients in the soil of the planet.
A large amount of methane on Mars, the source of which is unknown.
The presence of water vapor in the soil layer.

Against:

Instantaneous evaporation of water from the surface of the planet.
Vulnerable to solar wind bombardment.
The water on Mars is too salty and alkaline and unsuitable for life.
Intense ultraviolet radiation.

Thus, scientists cannot give an exact answer, since the amount of data required is too small.

In culture

To creation fantastic works about Mars, writers were pushed by the discussions of scientists that began at the end of the 19th century about the possibility that not just life exists on the surface of Mars, but a developed civilization. At this time, for example, the famous novel G. Wells "War of the Worlds", in which the Martians tried to leave their dying planet to conquer the Earth.

In 1938, in the United States, the radio news version of this work caused mass panic, when many listeners mistakenly accepted this "report" as the truth.

In 1966, the writers Arkady and Boris Strugatsky wrote a satirical "continuation" this work titled "The Second Invasion of the Martians".

Frame from the film "The Martian" 2015

Among the important works about Mars, it is also worth noting the novel published in 1950 Ray Bradbury "The Martian Chronicles", consisting of separate loosely interconnected short stories, as well as a number of stories adjacent to this cycle; the novel tells about the stages of human exploration of Mars and contacts with the dying ancient Martian civilization.

It is noteworthy that Jonathan Swift mentioned the satellites of Mars 150 years before they were actually discovered, in the 19th part of his novel "Gulliver's Travels" .

Also in cinematography, the theme of Mars is widely revealed, both in feature films and documentaries.

In creativity David Bowie Mars is mentioned intermittently in the early 1970s. So, the group with which he performs at this time is called Spiders From Mars, and a song called “Life on Mars?” appears on the Hunky Dory album.

Mars is also widely represented in the culture of ancient times.

The mass of Mars is less than the mass of the Earth by 10 times.
The first person to see Mars through a telescope was Galileo Galilei.
Scientists have discovered particles of Martian soil on Earth, which allowed them to explore the Red Planet even before the start space flights. These particles were literally "knocked out" of Mars by meteorites that crashed into the planet. Then, after millions of years, they fell to Earth.
The inhabitants of Babylon called the planet "Nergal" (after their evil deity).
AT ancient india Mars was called "Mangala" (Indian god of war).
In culture, Mars has become the most popular planet in the solar system.
The daily dose of radiation on Mars is equal to the annual dose on Earth.
In 1997, three Yemenis sued for NASA's invasion of Mars. They claimed that they inherited this planet from their ancestors thousands of years ago.
More than 100,000 people have applied for a one-way trip and want to be the first colonizers of the Red Planet in 2022 (Mars One expedition). The current population of Mars is seven robots.

When will humans be on Mars?

Mars is humanity's next goal, after going to the moon. For several years now, they have been discussing future missions and the prospect of creating a colony. But this task seems even more difficult, so a clear plan is needed. Can human turn out to be on Mars?

The concept of the first crewed mission was developed by Wernher von Braun. He was a former Nazi scientist and head of NASA's Mercury Project. In 1952, he proposed to create 10 vehicles (7 people each) that could deliver 70 people to the Red Planet.

But after all, it is not the flight itself that is important, but the organization of people living on Mars. In 1990, Robert Zubrin, who focused on colonization, proposed his Mars Direct project. The first missions were to build a site for a future settlement. Later it would be possible to go underground and develop the habitat already there.

In 1993, the Mars Design Reference from NASA appeared, which was edited 5 times until 2009. But the project never went beyond calculations and conversations.

Modern Ideas

Since 2004, American presidents have voiced their desire to conquer Mars. In 2015, a detailed plan was formed, where the delivery was based on the use of the Orion spacecraft and the SLS launch system. The project is based on 3 stages and 32 launches in 2018-2030s. During this time, it will be possible to transport the necessary equipment and equip the preparatory site. Until 2024, it is necessary to test Orion and SLS.

NASA also plans to catch the nearest asteroid and drag it to the Moon's orbit to test new equipment. This is an important mission that will help not only save the Earth from the fall of a dangerous space rock, but also use them to transform the planets (create a favorable environment for humans - terraforming Mars).

The first crew flight on Orion should take place in 2021-2023. At the second stage, a series of equipment delivery to the Red Planet will start. The third stage involves creating the necessary protective environment and checking all necessary devices.

But not only NASA has views of Mars. The ESA is also interested in exploring and colonizing the alien world. Aurora Program expects in the 2030s. send people on an Ariane-M rocket. In 2040-2060s. Roscosmos can visit the Red Planet. Back in 2011, Russia was running successful mission simulations. China has set itself the same time frame. One day we may come to the conclusion that people live on Mars.

In 2012, Dutch entrepreneurs announced that they were going to create a human base on Mars in 2023, which would later expand into a colony.

The MarsOne mission plans to deploy a telecommunications orbiter in 2018, a rover in 2020, and a settler base in 2023. It will be powered by solar panels with a length of 3000 m 2 . They will deliver 4 astronauts on a Falcon-9 rocket in 2025, where they will spend 2 years.

Mars colony project Mars one

Elon Musk, CEO of SpaceX, does not hide his desire for Mars. He is going to create a colony for 80,000 people. And this is only a small part of how many people are able to settle on Mars. To do this, he needs a special transportation system that would work in conveyor mode. He has already succeeded in creating a rocket reuse system.

In 2016, Musk announced that the first unmanned flight would take place in 2022, and the crewed flight in 2024. He believes that everything will require 10 billion dollars and it will be possible to launch 100 passengers. These will be tourist trips sent every 26 months (the window when Earth and Mars are closest).

The first missions may require sacrifice. But many have already expressed a desire to go one way. When will we see the first humans on Mars? There is no exact date, but evidence suggests that this will happen in the coming decades.

Mars, the fourth planet in the solar system, is the setting for many fantastic stories. Writers and directors often post here extraterrestrial civilizations, hostile or friendly to us. Research, however, shows that there is definitely no such highly developed life on Mars. This does not mean that the Red Planet is a boring and uninteresting place. On the contrary, many scientists in their thoughts are carried away here, trying to comprehend the secrets and explain the features of the fourth planet. Parameters such as the diameter of Mars, its mass, the acceleration of the first and second on the planet, and so on, are carefully collected and analyzed throughout the period of study of our neighbor. Let's get to know him better.

Orbit features

Mars - a description of the planet, perhaps, it is worth starting with this - in terms of distance from the Sun, it immediately follows the Earth. Its orbit has a length of almost 1.5 billion kilometers and, like most planets, is an ellipse. Beyond the orbit of Mars lies the main asteroid belt.

For one revolution around the star, the Red Planet takes much more time than the Earth - 687 days. The average distance of Mars from the Sun is about 228 million kilometers. For comparison, the same indicator for the Earth is 149.5 million km.

similarity

There are also parameters close in their values that characterize the Earth and Mars. The description of the planet always contains information about the period of rotation around the axis. As you know, for the Earth it is about 24 hours. In the case of the Red Planet, the figure is not much different - 24 hours 37 minutes 22.7 seconds. Due to such a rapid rotation, our neighbor has a somewhat flattened shape from the poles. As a result, the diameter of Mars at the equator is somewhat different from the same indicator for the poles. However, the same feature is characteristic of the Earth. The diameter of Mars in kilometers near the equator reaches 6739.8. This is approximately 53% of the similar parameter of our planet. The diameter of Mars, if measured at the poles, will be less than 42 km. This parameter is in the same ratio with the earth as the previous one.

The axis of the Red Planet has a rather large angle of inclination to the plane of the orbit (24 ° 56 ′), which provides Mars with another similarity to the Earth - the presence of a change of seasons. True, due to other features of the planet, the differences between the summer and winter periods are much sharper here.

Some other physical parameters

In general, according to the main characteristics, the Earth looks more impressive than Mars. The mass of the planet is 6.4185 × 10 23 kg - this is only 0.107 of the same parameter of the Earth.

The density of the substance that makes up Mars is 6.4185 × 10 23 kg. The value of free fall acceleration is 3.7 m/s 2 . The temperature conditions on the Red Planet are very different from those on Earth. At the equator, during the summer, the air can warm up to +30º during the day, and cool down to -80º in the winter at night. In the region of the poles, the temperature sometimes drops to -143º.

Surface

The planet Mars, the photo of which is delivered by almost all devices whose course runs past the Red Planet, is characterized by a rather interesting features surface topography. Here you can find a huge number of craters and traces of atmospheric and water activity that took place in antiquity.

The main feature of the surface is its division into two zones. The southern hemisphere resembles a lunar landscape. In general, the surface here rises to one or two kilometers above the average level. The northern part of the planet, on the contrary, is located below the average level. There are a small number of craters here, the main part of the space is occupied by more or less smooth plains, presumably formed as a result of erosion and lava flooding. The irregular and wide boundary separating the two zones runs along a great circle inclined at about 30º to the equator. The reason for this separation of the surface is still unclear to scientists.

Compound

The planet of the solar system Mars is in the same group space objects, which is the Earth. These are the so-called terrestrial planets. They are characterized by a rocky structure, in contrast to the gas giants, which are dominated by gaseous substances. The leading place among other elements in the composition of Mars is silicon (21%), followed by iron, magnesium, calcium and aluminum (12.7; 5; 4 and 3%, respectively). In addition, the level of sulfur on the Red Planet is quite high compared to the Earth - 3.1% of the total composition.

The planet Mars, whose photo is difficult to confuse with images of other objects, is known to have a reddish tint to the surface. This effect is provided by iron oxides and hydrates, which are part of the planet's soil along with silicates, which form its basis.

At the poles

The polar caps of the Red Planet are almost four kilometers thick. They are made up of water ice and carbon dioxide. The latter, under conditions of low temperatures prevailing here, condenses from the atmosphere. In the region of the southern polar cap, geysers were found, which are a mixture of dust and ice, ejected to a considerable height above the surface.

The polar caps begin to melt in spring. As a result, atmospheric pressure rises noticeably and there are very strong winds, contributing to the movement of impressive in volume gas masses to the opposite hemisphere. it sometimes reaches 100 m/s.

These movements cause dust storms, which are a characteristic feature of the planet. Dust storms make a significant contribution to the formation of conditions on Mars: they affect temperature changes and lead to soil erosion.

traces of water

One of the motivations forcing people to explore space is the desire to find, if not advanced life, then at least the conditions suitable for its occurrence. Mars has long been seen as one of the worthy candidates for this role. The data accumulated to date indicate that once upon a time there could have been one of the main conditions for the emergence of life on the Red Planet - water in a liquid state. Erosion has been discovered on Mars, resembling water in its characteristics. Pictures of the surface, transmitted by rovers, allowed scientists to see even the alleged beds of dry rivers. In addition, the devices found minerals on the Red Planet, for the formation of which positive temperatures and water-alkaline environment. However, scientists have not yet come to final conclusions about the watery past of Mars.

Atmosphere

Water vapor is also present in the air shell of the planet, but in small quantities - 0.1%. Basically (95%) the atmosphere of the planet consists of carbon dioxide, nitrogen (2.7%), argon (1.6%) and oxygen (0.13%) are also present here. Methane and heavy inert gases were also found in the atmosphere in even lower concentrations than the above substances.

Methane is considered one of the mysteries of Mars. This substance decomposes under the influence of sunlight, and for its accumulation in the atmosphere, even in such a small amount, a constant source of replenishment is needed. To date, there are two main candidates for this role: gas hydrates, heated by internal heat, and Martian bacteria, presumably existing in the deep layers of the lithosphere.

Records

Despite the fact that the diameter of Mars (in km), its mass and other parameters are inferior to those of the Earth, there are also objects here that amaze with their dimensions. Chief among them are volcanoes and mountains. The vast volcanic plain Tarsis is located in the northern hemisphere of the planet and stretches for two thousand kilometers. Volcanoes such as Arsia, Pavonis and Askreus are located here. Next to them, on the edge of Tarsis, is the main "attraction" of the Red Planet - Mount Olympus. Reaching a height of 27 km, it is considered the highest in the entire solar system. The diameter of the surface area occupied by Olympus is 550 km.

Rifts can also be found on the territory of Tarsis. The largest of them is the so-called 4.5 thousand kilometers long and 600 km wide with a depth of up to 10 km. On the slopes of the valley often occur the most impressive landslides in the solar system.

A magnetic field

If the diameter of the planet Mars and its other numerical characteristics are known exactly and are not in doubt, then some other parameters cause scientists a lot of questions. Among them is the planet's magnetic field. In fact, it does not exist: nothing protects Mars from exposure to sunlight. However, spacecraft studies have shown that there are zones on the planet with a fairly strong magnetic field. There is a version that Mars about 4 billion years ago had a powerful protection from the sun's rays, similar to the earth's, but then lost it.

The fixed remnants of the field are bands with variable polarity, stretching from west to east. Their width reaches thousands of kilometers. Such local magnetic fields are a mystery to scientists. Neither their origin nor the reason for this polarity is clear.

The diameter of Mars, however, was also a mystery to people some time ago. Exploration of the Red Planet continues and becomes more profound thanks to improving technology and new knowledge in the field of astrophysics. And therefore there is every reason to believe that one way or another they will be revealed and explained in the not so distant future.

The main characteristics of Mars

Atmosphere of Mars

On the movement of Mars

The main characteristics of Mars

Dear visitors!

The structure of Mars

Surface

Water

Moons of Mars

Atmosphere and temperature of the planet Mars

Brief history of learning

Is there life on Mars?

In culture

When will humans be on Mars?

Modern Ideas

Orbit features

similarity

Some other physical parameters

Surface

Compound

At the poles

traces of water

Atmosphere

Records

A magnetic field

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