The atmosphere of Mars: pressure or density? The atmosphere of Mars - chemical composition, weather conditions and climate in the past.

Today, not only science fiction writers, but also real scientists, businessmen, and politicians talk about flights to Mars and its possible colonization. Probes and rovers have provided answers about geological features. However, for manned missions it is necessary to understand whether Mars has an atmosphere and what its structure is.

General information

Mars has its own atmosphere, but it is only 1% of Earth's. Like Venus, it consists mainly of carbon dioxide, but again, much thinner. The relatively dense layer is 100 km (for comparison, the Earth has 500 - 1000 km, according to various estimates). Because of this, there is no protection from solar radiation, and temperature regime practically not regulated. There is no air on Mars as we know it.

Scientists have established the exact composition:

Carbon dioxide - 96%.
Argon - 2.1%.
Nitrogen - 1.9%.

Methane was discovered in 2003. The discovery spurred interest in the Red Planet, with many countries launching exploration programs that led to talk of flight and colonization.

Due to the low density, the temperature regime is not regulated, so the differences average 100 0 C. During the daytime, fairly comfortable conditions of +30 0 C are established, and at night the surface temperature drops to -80 0 C. The pressure is 0.6 kPa (1 /110 from the earth's indicator). On our planet, similar conditions occur at an altitude of 35 km. This main danger for a person without protection, it is not the temperature or gases that will kill him, but the pressure.

There is always dust near the surface. Due to the low gravity, clouds rise up to 50 km. Strong temperature changes lead to winds with gusts of up to 100 m/s, so dust storms It's common on Mars. They do not pose a serious threat due to the low concentration of particles in the air masses.

What layers does the atmosphere of Mars consist of?

The force of gravity is less than that of Earth, so Mars’ atmosphere is not so clearly divided into layers according to density and pressure. The homogeneous composition remains until the 11 km mark, then the atmosphere begins to separate into layers. Above 100 km the density decreases to minimum values.

Troposphere - up to 20 km.
Stratomesosphere - up to 100 km.
Thermosphere - up to 200 km.
Ionosphere - up to 500 km.

The upper atmosphere contains light gases - hydrogen, carbon. Oxygen accumulates in these layers. Individual particles of atomic hydrogen spread over distances of up to 20,000 km, forming a hydrogen corona. There is no clear division between the extreme regions and outer space.

Upper atmosphere

At an elevation of more than 20-30 km, the thermosphere is located - the upper regions. The composition remains stable up to an altitude of 200 km. There is a high content of atomic oxygen here. The temperature is quite low - up to 200-300 K (from -70 to -200 0 C). Next comes the ionosphere, in which ions react with neutral elements.

Lower atmosphere

Depending on the time of year, the boundary of this layer changes, and this zone is called the tropopause. Further extends the stratomesosphere, whose average temperature is -133 0 C. On Earth, it contains ozone, which protects from cosmic radiation. On Mars, it accumulates at an altitude of 50-60 km and then is practically absent.

Atmospheric composition

The earth's atmosphere consists of nitrogen (78%) and oxygen (20%), in small quantities argon, carbon dioxide, methane, etc. are present. Such conditions are considered optimal for the emergence of life. The composition of the air on Mars is significantly different. The main element of the Martian atmosphere is carbon dioxide - about 95%. Nitrogen accounts for 3%, and argon 1.6%. Total oxygen - no more than 0.14%.

This composition was formed due to the weak gravity of the Red Planet. The most stable was heavy carbon dioxide, which is constantly replenished as a result of volcanic activity. Light gases are dispersed in space due to low gravity and lack of magnetic field. Nitrogen is held by gravity in the form of a diatomic molecule, but is split under the influence of radiation, and flies into space in the form of single atoms.

The situation is similar with oxygen, but in the upper layers it reacts with carbon and hydrogen. However, scientists do not fully understand the specifics of the reactions. According to calculations, the amount of carbon monoxide CO should be greater, but in the end it is oxidized to carbon dioxide CO2 and sinks to the surface. Separately, molecular oxygen O2 appears only after the chemical decomposition of carbon dioxide and water in the upper layers under the influence of photons. It refers to substances that do not condense on Mars.

Scientists believe that millions of years ago the amount of oxygen was comparable to that on Earth - 15-20%. It is not yet known exactly why conditions changed. However, individual atoms do not evaporate so actively, and due to more weight it even accumulates. To some extent, the reverse process is observed.

Other important elements:

Ozone is practically absent, there is one area of accumulation 30-60 km from the surface.
Water content is 100-200 times less than in the driest region of the Earth.
Methane - emissions observed unknown nature, and so far the most discussed substance for Mars.

Methane on Earth is classified as a nutrient, so it could potentially be associated with organic matter. The nature of the appearance and rapid destruction has not yet been explained, so scientists are looking for answers to these questions.

What happened to Mars' atmosphere in the past?

Over the millions of years of the planet's existence, the atmosphere changes in composition and structure. As a result of research, evidence has emerged that liquid oceans existed on the surface in the past. However, now the water remains in small quantities in the form of steam or ice.

Reasons for the disappearance of fluid:

Low atmospheric pressure is unable to keep water in a liquid state long time as it happens on Earth.
Gravity is not strong enough to hold the vapor clouds.
Due to the absence of a magnetic field, matter is carried away by solar wind particles into space.
With significant temperature changes, water can only be preserved in a solid state.

In other words, the atmosphere of Mars is not dense enough to retain water as a liquid, and the small force of gravity is not able to retain hydrogen and oxygen.
According to experts favorable conditions for life on the Red Planet could have formed about 4 billion years ago. Perhaps there was life at that time.

The following reasons for destruction are named:

Lack of protection from solar radiation and gradual depletion of the atmosphere over millions of years.
A collision with a meteorite or other cosmic body that instantly destroyed the atmosphere.

The first reason for this moment is still more likely, since no traces of a global catastrophe have yet been found. Similar conclusions were drawn thanks to the study of the autonomous station Curiosity. The Mars rover determined the exact composition of the air.

The ancient atmosphere of Mars contained a lot of oxygen

Today, scientists have little doubt that there used to be water on the Red Planet. On numerous views of the outlines of the oceans. Visual observations are confirmed by specific studies. Mars rovers took soil tests in the valleys of former seas and rivers, and chemical composition confirmed initial assumptions.

Under current conditions, any liquid water on the surface of the planet will instantly evaporate because the pressure is too low. However, if oceans and lakes existed in ancient times, the conditions were different. One of the assumptions is a different composition with an oxygen fraction of about 15-20%, as well as an increased proportion of nitrogen and argon. In this form, Mars becomes almost identical to our home planet - with liquid water, oxygen and nitrogen.

Other scientists have suggested the existence of a full-fledged magnetic field that can protect against the solar wind. Its power is comparable to that of Earth, and this is another factor that speaks in favor of the presence of conditions for the origin and development of life.

Causes of atmosphere depletion

The peak of development occurred in the Hesperia era (3.5-2.5 billion years ago). On the plain was salty ocean, comparable in size to the Northern Arctic Ocean. The temperature at the surface reached 40-50 0 C, and the pressure was about 1 atm. There is a high probability of the existence of living organisms during that period. However, the period of “prosperity” was not long enough for complex, much less intelligent, life to arise.

One of the main reasons is the small size of the planet. Mars smaller than Earth, so gravity and magnetic field are weaker. As a result, the solar wind actively knocked out particles and literally cut off the shell layer by layer. The composition of the atmosphere began to change over the course of 1 billion years, after which climate change became catastrophic. The decrease in pressure led to evaporation of the liquid and temperature changes.

When we talk about climate change, we sadly shake our heads - oh, how much our planet has changed over the past Lately, how polluted its atmosphere is... However, if we want to see a true example of how fatal climate change can be, then we will have to look for it not on Earth, but beyond its borders. Mars is very suitable for this role.

What was here millions of years ago cannot be compared with the picture of today. These days, Mars has a bitterly cold surface, low pressure, and a very thin and tenuous atmosphere. Before us lies only a pale shadow of the former world, the surface temperature of which was not much lower than the current temperature on earth, and across the plains and gorges rushed deep rivers. Perhaps there was even organic life here, who knows? All this is a thing of the past.

What is the atmosphere of Mars made of?

Nowadays he even rejects the possibility of living beings living here. Martian weather is shaped by many factors, including the cyclical growth and melting of ice caps, water vapor in the atmosphere and seasonal dust storms. Sometimes, giant dust storms cover the entire planet at once and can last for months, turning the sky deep red.

Mars' atmosphere is about 100 times thinner than Earth's and is 95 percent carbon dioxide. The exact composition of the Martian atmosphere is:

Carbon dioxide: 95.32%
Nitrogen: 2.7%
Argon: 1.6%
Oxygen: 0.13%
Carbon monoxide: 0.08%

In addition, in small quantities there are: water, nitrogen oxides, neon, heavy hydrogen, krypton and xenon.

How did the atmosphere of Mars originate? Just like on Earth - as a result of degassing - the release of gases from the bowels of the planet. However, the gravity on Mars is much less than on Earth, so most of the gases escape into space, and only a small part of them is able to stay around the planet.

What happened to Mars' atmosphere in the past?

At the dawn of existence solar system, that is, 4.5-3.5 billion years ago, Mars had a fairly dense atmosphere, due to which water could exist in liquid form on its surface. Orbital photographs show the outlines of vast river valleys, the outlines of an ancient ocean on the surface of the red planet, and Mars rovers have found samples more than once chemical compounds, which prove to us that the eyes do not lie - all these relief details on Mars, familiar to the human eye, were formed under the same conditions as on Earth.

There was water on Mars without a doubt, there are no questions here. The only question is why did she eventually disappear?

The main theory on this matter looks something like this: once upon a time Mars had a light that effectively reflected solar radiation, however, over time it began to weaken and about 3.5 billion years ago practically disappeared (individual local centers of the magnetic field, with a power quite comparable to the earth’s, still exist on Mars). Since Mars is almost half the size of Earth, its gravity is much weaker than that of our planet. The combination of these two factors (loss of magnetic field and weak gravity) led to this. that the solar wind began to “knock out” light molecules from the planet’s atmosphere, gradually thinning it. So, in a matter of millions of years, Mars found itself in the role of an apple, from which the skin was carefully cut off with a knife.

The weakened magnetic field could no longer effectively “quench” cosmic radiation, and the sun from a source of life turned into a killer for Mars. And the thinned atmosphere could no longer retain heat, so the temperature on the surface of the planet dropped to an average of -60 degrees Celsius, reaching +20 degrees only on a summer day at the equator.

Although the atmosphere of Mars is now about 100 times thinner than Earth's, it is still thick enough for weather formation processes to actively occur on the red planet, precipitation to occur, clouds and winds to arise.

"Dust Devil" - a small tornado on the surface of Mars, photographed from the planet's orbit

Radiation, dust storms and other features of Mars

Radiation near the surface of the planet poses a danger, however, according to NASA data obtained from the collection of analyzes by the Curiosity rover, it follows that even during a 500-day period of stay on Mars (+360 days on the way), astronauts (taking into account protective equipment) would receive “ dose of radiation equal to 1 sievert (~100 roentgens). This dose is dangerous, but it certainly will not kill an adult “on the spot.” It is believed that 1 sievert of radiation exposure increases an astronaut's risk of developing cancer by 5%. According to scientists, for the sake of science you can go to great hardships, especially the first step to Mars, even if it promises health problems in the future... This is definitely a step towards immortality!

On the surface of Mars, seasonally, hundreds of dust devils (tornadoes) rage, raising into the atmosphere dust from iron oxides (rust, in simple terms) which abundantly covers the Martian wastelands. Martian dust is very fine, which, combined with low gravity, leads to the fact that a significant amount of it is always present in the atmosphere, reaching especially high concentrations in autumn and winter in the northern, and in spring and summer in the southern hemispheres of the planet.

Dust storms on Mars- the largest in the solar system, capable of covering the entire surface of the planet and sometimes lasting for months. The main seasons for dust storms on Mars are spring and summer.

The mechanism of such powerful weather phenomena have not been fully studied, but is most likely explained by the following theory: when big number dust particles rise into the atmosphere, this leads to its sharp heating to a high altitude. Warm masses of gases rush towards the cold regions of the planet, generating wind. Martian dust, as already noted, is very light, so strong winds kick up even more dust, which in turn heats the atmosphere even more and generates even stronger winds, which in turn kick up even more dust... and so on!

There is no rain on Mars, and where would it come from in the cold of -60 degrees? But sometimes it snows. True, such snow consists not of water, but of carbon dioxide crystals, and its properties are more reminiscent of fog rather than snow (the “snowflakes” are too small), but rest assured - this is real snow! Just with local specifics.

In general, “snow” falls almost throughout the entire territory of Mars, and this process is cyclical - at night carbon dioxide freezes and turns into crystals, falling to the surface, and during the day it thaws and returns to the atmosphere again. However, in the northern and south poles planets, in winter period, frost reigns down to -125 degrees, so once it falls in the form of crystals, the gas no longer evaporates and lies in a layer until spring. Considering the size of the snow caps on Mars, is it necessary to say that in winter the concentration of carbon dioxide in the atmosphere drops by tens of percent? The atmosphere becomes even more rarefied, and as a result retains even less heat... Mars is plunging into winter.

Since Mars is further from the Sun than the Earth, it can occupy a position in the sky opposite to the Sun, then it is visible all night. This position of the planet is called confrontation. For Mars, it repeats every two years and two months. Since the orbit of Mars is more elongated than the Earth’s, during oppositions the distances between Mars and the Earth can be different. Once every 15 or 17 years, the Great Confrontation occurs, when the distance between Earth and Mars is minimal and amounts to 55 million km.

Canals on Mars

The photograph of Mars taken from the Hubble Space Telescope clearly shows characteristics planets. Against the red background of the Martian deserts, the bluish-green seas and the bright white polar cap are clearly visible. Famous channels not visible in the photo. At this magnification they are really invisible. After large-scale photographs of Mars were obtained, the mystery of the Martian canals was finally resolved: the canals are an optical illusion.

Of great interest was the question of the possibility of existence life on Mars. Studies carried out in 1976 on the American Viking MS apparently gave a final negative result. No traces of life have been found on Mars.

However, there is currently a lively discussion on this issue. Both sides, both supporters and opponents of life on Mars, present arguments that their opponents cannot refute. There is simply not enough experimental data to resolve this issue. We can only wait until the ongoing and planned flights to Mars will provide material confirming or refuting the existence of life on Mars in our time or in the distant past. Material from the site

Mars has two small satellite— Phobos (Fig. 51) and Deimos (Fig. 52). Their dimensions are 18×22 and 10×16 km, respectively. Phobos is located at a distance of only 6000 km from the surface of the planet and orbits it in about 7 hours, which is 3 times less than a Martian day. Deimos is located at a distance of 20,000 km.

There are a number of mysteries associated with satellites. So, their origin is unclear. Most scientists believe that these are relatively recently captured asteroids. It is difficult to imagine how Phobos survived the impact of a meteorite, which left a crater with a diameter of 8 km. It is not clear why Phobos is the blackest body known to us. Its reflectivity is 3 times less than soot. Unfortunately, several spacecraft flights to Phobos ended in failure. The final solution to many issues of both Phobos and Mars is postponed until the expedition to Mars, planned for the 30s of the 21st century.

Mars is a planet in the solar system, one of the first discovered by humanity. To date, of all eight planets, it is Mars that has been studied in the most detail. But this does not stop researchers, but, on the contrary, arouses increasing interest in the “Red Planet” and its study.

Why is it called that?

The planet got its name from Mars, one of the most revered gods ancient roman pantheon, which in turn is a reference to Greek god Ares, patron of cruel and treacherous war. This name was not chosen by chance - the reddish surface of Mars resembles the color of blood and involuntarily makes us remember the ruler of bloody battles.

The names of the planet's two satellites also bear deep meaning. The words “Phobos” and “Deimos” translated from Greek mean “Fear” and “Horror”; these were the names of the two sons of Ares, who, according to legend, always accompanied their father in battle.

Brief history of the study

For the first time, humanity began to observe Mars not 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 astronomers of the Babylonian kingdom took over the baton. Scientists from Babylon were able to more accurately determine the location of the planet and measure the time of its movement. Next were the Greeks. They managed to create an accurate geocentric model and, with its help, understand the movement of the planets. Then scientists in Persia and India were able to estimate the size of the Red Planet and its distance to Earth.

European astronomers made a huge breakthrough. Johannes Kepler, using Nikolai Kaepernick's model as a basis, was able to calculate the elliptical orbit of Mars, and Christiaan Huygens created the first map of its surface and noticed ice cap at the planet's north pole.

The advent of telescopes marked a heyday in the study of Mars. Slipher, Barnard, Vaucouleurs and many other astronomers became the greatest explorers of Mars before man entered space.

Human space exploration has made it possible to study the Red Planet more accurately and in detail. In the mid-20th century, with the help of interplanetary stations, precise images of the surface were taken, and ultra-powerful infrared and ultraviolet telescopes made it possible to measure the composition of the planet’s atmosphere and the speed of winds on it.

Subsequently, more and more accurate studies of Mars followed from the USSR, the USA, and then other countries.

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

Characteristics of Mars

Mars is the fourth planet from the Sun, adjacent to the Earth on one side, and Jupiter on the other. In size it is one of the smallest and surpasses only Mercury.
The length of Mars' equator is slightly more than half the length of Earth's equator, and its surface area is approximately equal to the land area of Earth.
There is a change of seasons on the planet, but their duration varies greatly. For example, summer in the northern part is long and cold, and in the southern part it is short and warmer.
The length of a day is quite comparable to that on earth - 24 hours and 39 minutes, that is, a little more.

Surface of the planet

No wonder the second name of Mars is “Red Planet”. Indeed, from a distance its surface looks reddish. This shade of the planet's surface is given by the red dust contained in the atmosphere.

However, up close, the planet sharply changes its color and no longer looks red, but yellow-brown. Sometimes other shades can be mixed with these colors: golden, reddish, greenish. The source of these shades are colored minerals that are also present on Mars.

The main part of the planet’s surface is made up of “continents” - clearly visible light areas, and a very small part - “seas”, dark and poorly visible areas. Most of the "seas" are located in southern hemisphere Mars. The nature of the “seas” is still subject to controversy among researchers. But now scientists are most inclined to the following explanation: dark areas are simply irregularities on the surface of the planet, namely craters, mountains and hills.

The following fact is extremely interesting: the surface of the two hemispheres of Mars is very different.

The Northern Hemisphere consists largely of smooth plains, its surface is below average.

The southern hemisphere is mostly cratered, with a surface above average.

Structure and geological data

The study of the magnetic field of Mars and the volcanoes that are located on its surface led scientists to an interesting conclusion: once on Mars, as on Earth, there was a movement of lithospheric plates, which, however, is not observed now.

Modern researchers tend to think that internal structure Mars consists of the following components:

Crust (approximate thickness - 50 kilometers)
Silicate mantle
Core (approximate radius - 1500 kilometers)
The planet's core is partially liquid and contains twice as much light elements as the Earth's core.

All about the atmosphere

The atmosphere of Mars is very thin and consists mainly of carbon dioxide. In addition, it contains: nitrogen, water vapor, oxygen, argon, carbon monoxide, xenon and many other elements.

The thickness of the atmosphere is approximately 110 kilometers. Atmosphere pressure the planet's surface is more than 150 times smaller than Earth's (6.1 Millibars).

Temperatures on the planet fluctuate over a very wide range: from -153 to +20 degrees Celsius. The most low temperatures take place at the pole in winter time, the highest are at the equator at midday. Average temperatures are around -50 degrees Celsius.

Interestingly, a thorough analysis of the Martian meteorite “ALH 84001” led scientists to believe that a very long time ago (billions of years ago) the atmosphere of Mars was denser and wetter, and the climate was warmer.

Is there life on Mars?

There is still no clear answer to this question. There is now scientific evidence that supports both theories.

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

Instant 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 accurate answer, since the amount of necessary data is too small.

The mass of Mars is 10 times less than the mass of Earth.
The first person to see Mars through a telescope was Galileo Galilei.
Mars was originally the Roman god of the harvest, not war.
The Babylonians called the planet "Nergal" (in honor of their deity of evil).
IN ancient india Mars was named "Mangala" ( Indian god 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.

Characteristics: The atmosphere of Mars is more rarefied than the air shell of the Earth. Its composition resembles the atmosphere of Venus and is 95% carbon dioxide. About 4% comes from nitrogen and argon. Oxygen and water vapor in the Martian atmosphere are less than 1% (see exact composition). The average atmospheric pressure at surface level is about 6.1 mbar. This is 15,000 times less than on Venus, and 160 times less than at the surface of the Earth. In the deepest depressions the pressure reaches 10 mbar.
The average temperature on Mars is significantly lower than on Earth - about -40° C. Under the most favorable conditions in summer, on the daytime half of the planet the air warms up to 20° C - a completely acceptable temperature for the inhabitants of the Earth. But winter night frost can reach up to -125° C. When winter temperature even carbon dioxide freezes into dry ice. Such sudden temperature changes are caused by the fact that the thin atmosphere of Mars is not able to retain heat for a long time. The first measurements of the temperature of Mars using a thermometer placed at the focus of a reflecting telescope were carried out back in the early 20s. Measurements by V. Lampland in 1922 gave average temperature surface of Mars -28°C, E. Pettit and S. Nicholson obtained -13°C in 1924. A lower value was obtained in 1960. W. Sinton and J. Strong: -43°C. Later, in the 50s and 60s. Numerous temperature measurements were accumulated and generalized at various points on the surface of Mars, in different seasons and times of day. From these measurements it followed that during the day at the equator the temperature could reach +27°C, but by the morning it could reach -50°C.

There are also temperature oases on Mars; in the areas of the Phoenix “lake” (solar plateau) and the land of Noah, the temperature difference ranges from -53° C to +22° C in summer and from -103° C to -43° C in winter. So, Mars is very cold world, however, the climate there is not much harsher than in Antarctica. When the first photographs from the surface of Mars taken by Viking were transmitted to Earth, scientists were very surprised to see that the Martian sky was not black, as expected, but pink. It turned out that dust hanging in the air absorbs 40% of the incoming sunlight, creating a color effect.
Dust storms: One of the manifestations of temperature differences is winds. Strong winds often blow over the surface of the planet, the speed of which reaches 100 m/s. Low gravity allows even thin air currents to raise huge clouds of dust. Sometimes quite large areas on Mars are covered in enormous dust storms. Most often they occur near the polar ice caps. A global dust storm on Mars prevented the Mariner 9 probe from photographing the surface. It raged from September 1971 to January 1972, raising about a billion tons of dust into the atmosphere at an altitude of more than 10 km. Dust storms most often occur during periods of great opposition, when summer in the southern hemisphere coincides with Mars' passage through perihelion. The duration of storms can reach 50-100 days. (Previously, the changing color of the surface was explained by the growth of Martian plants).
Dust Devils: Dust devils- another example of temperature-related processes on Mars. Such tornadoes are very on Mars. They raise dust into the atmosphere and are caused by temperature differences. Reason: during the day, the surface of Mars warms up quite a bit (sometimes to positive temperatures), but at an altitude of up to 2 meters from the surface, the atmosphere remains just as cold. This difference causes instability, raising dust into the air - dust devils are formed.
Water vapor: There is very little water vapor in the Martian atmosphere, but at low pressure and temperature it is in a state close to saturation and often collects in clouds. Martian clouds are rather featureless compared to those on Earth. Only the largest of them are visible through a telescope, but observations from spacecraft have shown that clouds of a wide variety of shapes and types are found on Mars: cirrus, wavy, leeward (near large mountains and under the slopes of large craters, in places protected from the wind). There is often fog over lowlands - canyons, valleys - and at the bottom of craters during the cold season. In the winter of 1979, a thin layer of snow fell in the Viking 2 landing area, which remained for several months.
Seasons: Today it is known that of all the planets in the solar system, Mars is the most similar to Earth. It was formed approximately 4.5 billion years ago. Mars' rotation axis is inclined to its orbital plane by approximately 23.9°, which is comparable to the Earth's 23.4° axis tilt, and therefore, like on Earth, the seasons change there. Seasonal changes are most pronounced in the polar regions. In winter, the polar caps occupy a significant area. The boundary of the northern polar cap can move away from the pole by a third of the distance to the equator, and the boundary of the southern cap covers half of this distance. This difference is caused by the fact that in the northern hemisphere, winter occurs when Mars passes through the perihelion of its orbit, and in the southern hemisphere, when it passes through aphelion. Because of this, winter in the southern hemisphere is colder than in the northern hemisphere. And the length of each of the four Martian seasons varies depending on its distance from the Sun.
With the onset of spring, the polar cap begins to “shrink,” leaving behind gradually disappearing islands of ice. At the same time, a so-called darkening wave is spreading from the poles to the equator. Modern theories explain it by the fact that spring winds transport large masses of soil with different reflective properties along the meridians.

Apparently none of the caps disappear completely. Before Mars was explored using interplanetary probes, it was assumed that its polar regions were covered with frozen water. More accurate modern ground-based and space measurements have discovered the composition Martian ice also frozen carbon dioxide. In summer it evaporates and enters the atmosphere. The winds carry it to the opposite polar cap, where it freezes again. This cycle of carbon dioxide and different sizes polar ice caps explains the variability of pressure in the Martian atmosphere.
A Martian day, called a sol, is 24.6 hours long, and its year is sol 669.
Climate influence: The first attempts to find direct evidence in the Martian soil of the presence of the basis for life - liquid water and elements such as nitrogen and sulfur - were unsuccessful. An exobiological experiment conducted on Mars in 1976 after the American Viking interplanetary station, carrying an automatic biological laboratory (ABL), landed on its surface, did not bring evidence of the existence of life. Absence organic molecules on the studied surface could be caused by intense ultraviolet radiation The sun, since Mars does not have a protective ozone layer, and the oxidizing composition of the soil. That's why upper layer The Martian surface (about a few centimeters thick) is barren, although there is an assumption that in the deeper, subsurface layers, conditions that existed billions of years ago have been preserved. A definite confirmation of these assumptions was the recently discovered microorganisms on Earth at a depth of 200 m - methanogens that feed on hydrogen and breathe carbon dioxide. A special experiment carried out by scientists proved that such microorganisms could survive in harsh conditions. Martian conditions. The hypothesis of a warmer ancient Mars with open bodies of water - rivers, lakes, and maybe seas, as well as a denser atmosphere - has been discussed for more than two decades, since it would be possible to “inhabit” such an inhospitable planet, and even in the absence of water very difficult. In order for liquid water to exist on Mars, its atmosphere would have to be very different from the current one.

Changeable Martian climate

Modern Mars is a very inhospitable world. A rarefied atmosphere, also unsuitable for breathing, terrible dust storms, lack of water and sharp temperature changes throughout the day and year - all this indicates that it will not be so easy to populate Mars. But rivers once flowed on it. Does this mean that Mars had a different climate in the past?
There are several facts to support this claim. Firstly, very old craters have been practically erased from the face of Mars. The modern atmosphere could not cause such destruction. Secondly, there are numerous traces of flowing water, which is also impossible given the current state of the atmosphere. A study of the rate of formation and erosion of craters made it possible to establish that the strongest wind and water destroyed them about 3.5 billion peta ago. Many ravines are approximately the same age.
Unfortunately, it is currently not possible to explain what exactly led to such serious climate changes. After all, in order for liquid water to exist on Mars, its atmosphere had to be very different from the current one. Perhaps the reason for this lies in the abundant release of volatile elements from the bowels of the planet in the first billion years of its life or in a change in the nature of the movement of Mars. Due to its large eccentricity and proximity to the giant planets, the orbit of Mars, as well as the tilt of the planet’s rotation axis, can experience strong fluctuations, both short-period and quite long-term. These changes cause the amount of solar energy absorbed by the surface of Mars to decrease or increase. In the past, the climate may have experienced strong warming, as a result of which the density of the atmosphere increased due to the evaporation of the polar caps and the melting of underground ice.
Assumptions about the variability of the Martian climate are confirmed by recent observations from the Hubble Space Telescope. It made it possible to produce very precise measurements characteristics of the Martian atmosphere and even predict Martian weather. The results were quite unexpected. The planet's climate has changed greatly since the Viking landers landed in 1976: it has become drier and colder. This may be due to the strong storms that occurred in the early 70s. raised a huge number of tiny dust particles into the atmosphere. This dust prevented Mars from cooling and water vapor evaporating into space, but then settled and the planet returned to its normal state.