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Mars - the atmosphere of the planet: layers of the atmosphere, chemical composition, pressure, density, comparison with the Earth, the amount of methane, ancient planet, research with photo.
BUTatmosphere of mars is only 1% of the earth, so there is no protection from the Red Planet solar radiation, as well as normal temperature conditions. The composition of the atmosphere of Mars is represented by carbon dioxide (95%), nitrogen (3%), argon (1.6%) and small impurities of oxygen, water vapor and other gases. It is also filled with small dust particles, which make the planet appear red.
Researchers believe that earlier atmospheric layer was dense, but collapsed 4 billion years ago. Without a magnetosphere, the solar wind crashes into the ionosphere and reduces atmospheric density.
This led to a low pressure indicator - 30 Pa. The atmosphere extends for 10.8 km. It contains a lot of methane. Moreover, strong emissions are noticeable in specific areas. There are two locations, but the sources have not yet been discovered.
270 tons of methane are released per year. Which means we are talking about some active subsurface process. Most likely, this is volcanic activity, comet impacts or serpentinization. The most attractive option is methanogenic microbial life.
Now you know about the presence of the atmosphere of Mars, but, unfortunately, it is set to exterminate the colonists. It prevents liquid water from accumulating, is open to radiation, and is extremely cold. But in the next 30 years, we are still focused on development.
Dissipation of planetary atmospheres
Astrophysicist Valery Shematovich on the evolution of planetary atmospheres, exoplanetary systems and the loss of the Martian atmosphere:
| Carbon dioxide | 95,32 % |
| Nitrogen | 2,7 % |
| Argon | 1,6 % |
| Oxygen | 0,13 % |
| Carbon monoxide | 0,07 % |
| water vapor | 0,03 % |
| Nitric oxide(II) | 0,013 % |
| Neon | 0,00025 % |
| Krypton | 0,00003 % |
| Xenon | 0,000008 % |
| Ozone | 0,000003 % |
| Formaldehyde | 0,0000013 % |
Atmosphere of Mars- the gaseous envelope surrounding the planet Mars. Significantly differs from the earth's atmosphere both in chemical composition and in physical parameters. The pressure at the surface is 0.7-1.155 kPa (1/110 of the earth's, or equal to the earth's at an altitude of more than thirty kilometers from the Earth's surface). The approximate thickness of the atmosphere is 110 km. The approximate mass of the atmosphere is 2.5 10 16 kg. Mars has a very weak magnetic field (compared to Earth's), and as a result, the solar wind causes dissipation atmospheric gases into space at a speed of 300 ± 200 tons per day (depending on current solar activity and distance from the Sun). 
Chemical composition
4 billion years ago, the atmosphere of Mars contained an amount of oxygen comparable to its share on the young Earth.
Temperature fluctuations
Since the atmosphere of Mars is very rarefied, it does not smooth out daily fluctuations in surface temperature. Temperatures at the equator range from +30°C during the day to -80°C at night. Temperatures can drop to -143°C at the poles. However, diurnal temperature fluctuations are not as significant as on the atmosphereless Moon and Mercury. Low density does not prevent the atmosphere from forming large-scale dust storms and tornadoes, winds, fogs, clouds, and affecting the climate and the surface of the planet.
The first measurements of the temperature of Mars using a thermometer placed at the focus of a reflecting telescope were made back in the early 1920s. Measurements by W. Lampland in 1922 gave an average surface temperature of Mars of 245 (−28°C), E. Pettit and S. Nicholson in 1924 obtained 260 K (−13°C). A lower value was obtained in 1960 by W. Sinton and J. Strong: 230 K (−43°C).
annual cycle
The mass of the atmosphere during the year varies greatly due to the condensation in the polar caps of large volumes of carbon dioxide in winter and evaporation in summer.
Mars, the fourth planet farthest from the Sun, has been the object of close attention of world science for a long time. This planet is very similar to the Earth with one, small, but fateful exception - the atmosphere of Mars is no more than one percent of the volume of the earth's atmosphere. The gas envelope of any planet is the determining factor that shapes its appearance and conditions on the surface. It is known that all solid worlds solar system formed under approximately the same conditions at a distance of 240 million kilometers from the Sun. If the conditions for the formation of the Earth and Mars were almost the same, then why are these planets so different now?
It's all about the size - Mars, formed from the same material as the Earth, once had a liquid and hot metal core, like our planet. Proof - many extinct volcanoes on But the "red planet" is much smaller than Earth. Which means it cools down faster. When the liquid core finally cooled down and solidified, the process of convection ended, and with it the magnetic shield of the planet, the magnetosphere, also disappeared. As a result, the planet remained defenseless against the destructive energy of the Sun, and the atmosphere of Mars was almost completely blown away by the solar wind (a giant stream of radioactive ionized particles). The "Red Planet" has turned into a lifeless, dull desert...
Now the atmosphere on Mars is a thin rarefied gas shell, unable to resist the penetration of the deadly one that burns the surface of the planet. The thermal relaxation of Mars is several orders of magnitude smaller than that of Venus, for example, whose atmosphere is much denser. The atmosphere of Mars, which has a too low heat capacity, forms more pronounced daily average wind speed indicators.
The composition of the atmosphere of Mars is characterized by a very high content (95%). The atmosphere also contains nitrogen (about 2.7%), argon (about 1.6%) and a small amount of oxygen (no more than 0.13%). The atmospheric pressure of Mars is 160 times higher than that at the surface of the planet. Unlike the Earth's atmosphere, the gaseous envelope here is of a pronounced changeable character, due to the fact that the planet's polar caps, containing great amount carbon dioxide, melt and freeze during one annual cycle.
According to data received from the Mars Express research spacecraft, the atmosphere of Mars contains some methane. The peculiarity of this gas is its rapid decomposition. This means that somewhere on the planet there must be a source of replenishment of methane. There can be only two options here - either geological activity, traces of which have not yet been discovered, or the vital activity of microorganisms, which can turn our idea of the presence of centers of life in the solar system.
A characteristic effect of the Martian atmosphere is dust storms that can rage for months. This dense air blanket of the planet consists mainly of carbon dioxide with minor inclusions of oxygen and water vapor. Such a lingering effect is due to the extremely low gravity of Mars, which allows even a super-rarefied atmosphere to lift billions of tons of dust from the surface and hold for a long time.
When we talk about climate change, we shake our heads sadly - oh, how much our planet has changed over recent times 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. Mars is very suitable for this role.
What was here millions of years ago cannot be compared with the picture of today. Today, Mars is a bitter cold on the surface, low pressure, a very thin and rarefied 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 through the plains and gorges rushed deep rivers. Maybe even here organic life, who knows? All this is in the past.
What is the atmosphere of Mars made of?
Now it even rejects the possibility of living beings living here. Martian weather is shaped by many factors, including the cyclic growth and melting of ice caps, atmospheric water vapor, and seasonal dust storms. Sometimes, giant dust storms cover the entire planet at once and can last for months, turning the sky a deep red.
The atmosphere of Mars is about 100 times thinner than that of Earth, and 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 come about? Just like on Earth - as a result of degassing - the release of gases from the bowels of the planet. However, the force of gravity on Mars is much less than on Earth, so most of gases escape into world space, and only a small part of them is able to stay around the planet.
What happened to the atmosphere of Mars in the past?
At the dawn of the existence of the solar system, that is, 4.5-3.5 billion years ago, Mars had a sufficiently dense atmosphere, due to which water could be in liquid form on its surface. Orbital photos show the outlines of vast river valleys, the outlines of an ancient ocean on the surface of the red planet, and rovers have repeatedly found samples of chemical compounds that prove to us that the eyes do not lie - all these familiar human eye the details of the relief on Mars were formed in the same conditions as on Earth.
There was no doubt that there was water on Mars, there are no questions here. The only question is, why did she end up disappearing?
The main theory on this matter looks something like this: once upon a time, Mars had an effectively reflecting solar radiation, but over time it began to weaken and almost disappeared about 3.5 billion years ago (separate local foci magnetic field, and in terms of power quite comparable to the earth, there is on Mars even now). Since the size of Mars is almost half that 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 atmosphere of the planet, gradually thinning it. So, in a matter of millions of years, Mars turned into the role of an apple, from which the skin was carefully cut with a knife.
The weakened magnetic field could no longer effectively “extinguish” cosmic radiation, and the sun turned from a source of life into a killer for Mars. And the thinned atmosphere could no longer retain heat, so the temperature on the planet's surface dropped to an average value of -60 degrees Celsius, only on a summer day at the equator, reaching +20 degrees.
Although the atmosphere of Mars is now about 100 times thinner than Earth's, it is still thick enough for the weather formation processes to actively occur on the red planet, precipitation fell, clouds and winds arose.
"Dust Devil" - a small tornado on the surface of Mars, photographed from the orbit of the planet
Radiation, dust storms and other features of Mars
Radiation near the surface of the planet is dangerous, however, according to NASA data obtained from the collection of analyzes by the Curiosity rover, it follows that even for a 500-day period of stay on Mars (+360 days on the way), astronauts (including protective equipment) would receive " dose" of radiation equal to 1 sievert (~100 roentgens). This dose is dangerous, but certainly will not kill an adult "on the spot." It is believed that 1 sievert of radiation received increases the 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 into immortality!
On the surface of Mars, seasonally, hundreds of dust devils (tornadoes) rage, raising dust from iron oxides (rust, in a simple way) into the atmosphere, 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 hemispheres, 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 going for months. The main dust storm seasons on Mars are spring and summer.
The mechanism of such powerful weather phenomena is not fully understood, but with big share probability is explained by the following theory: when a large number of dust particles rise into the atmosphere, this leads to its sharp heating by great height. Warm masses of gases rush towards the cold regions of the planet, generating wind. Martian dust, as already noted, is very light, so a strong wind raises even more dust, which in turn heats the atmosphere even more and generates even stronger winds, which in turn raise even more dust ... and so on!
There is no rain on Mars, and where can they come from in the cold at -60 degrees? But sometimes it snows. True, such snow consists not of water, but of carbon dioxide crystals, and its properties are more like fog than snow (the “snowflakes” are too small), but be sure that this is real snow! Just with local specifics.
In general, "snow" goes almost throughout the territory of Mars, and this process is cyclic - 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, at the north and south poles of the planet, in winter period, frost reigns down to -125 degrees, therefore, having once fallen out 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, delays even more less heat… Mars is sinking into winter.
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 planet terrestrial group with a rarefied atmosphere (the pressure near 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 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 largest planet from the Sun (after Mercury, Venus and Earth) and the seventh largest (surpasses 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 Earth's volume, and the average linear diameter is 0.53 of the Earth's diameter (6800 km).
The relief of Mars has many unique features. Martian extinct volcano Mount Olympus - the most high 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 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 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 besides Earth.
The surface of Mars this moment explored 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 a 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.
The minimum distance from Mars to 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.
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). Acceleration free fall at the equator it is 3.711 m/s (0.378 Earth); first space 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 salts).
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.
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 approximate thickness of the atmosphere is 110 km.
According to NASA (2004), the atmosphere of Mars consists of 95.32% carbon dioxide; it also contains 2.7% nitrogen, 1.6% argon, 0.13% oxygen, 210 ppm water vapor, 0.08% carbon monoxide, 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. When enough 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 AMC observations 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
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 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 at the Carl Sagan Center, recent decades Mars is in the process of warming. 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 lift into the air a large number of sand and dust. 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 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, early geological stage lithospheric plates "came together" (perhaps by accident) into one hemisphere, like the continent Pangea on Earth, and then "frozen" in this position. Another hypothesis involves the collision of Mars with space body the size of Pluto.
Topographic map Mars, according to Mars Global Surveyor, 1999
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).
In an area of chaotic landscape near the hemispheric boundary, the surface has experienced large areas of fracture and compression, sometimes followed by erosion (due to landslides or catastrophic release of groundwater), as well as 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.
Mariner Valleys on Mars
In the northern hemisphere, in addition to vast volcanic plains, there are two areas of large volcanoes - Tharsis and Elysium. Tharsis is a vast volcanic plain with a length of 2000 km, reaching 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.
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 circumference of the planet), 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
Appearance Mars varies greatly with the seasons. 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.
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 has 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
The spring melting of the polar caps leads to a sharp increase in atmospheric pressure and displacement large masses 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.
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 hypothesis of the spreading of melt water and the growth of vegetation. 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, when the polar cap melts, looks like white island, since glaciers melt later in the mountains, including on Earth.
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.
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 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.
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.
Priming
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 the necessary elements for the emergence and maintenance of life both in the past, in the present and in the future," said Sam Kunaves, lead research chemist of the project. Also, according to him, many people can find this alkaline type of soil in “their backyard”, and it is quite suitable for growing asparagus.
There is also a significant amount of water ice in the ground at the landing site 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 maximum height 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 internal structure 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. Supposed, phase transition olivine to spinel modification begins at rather great 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 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 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 various 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 retested in 2005 (using the unmanned Mars Global Surveyor) suggests 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 ambiguous points, and is disputed in scientific community.
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 Martian atmosphere almost unhindered, and many of the photochemical reactions under the influence 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 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 little 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
natural satellites 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 captured gravitational field Mars asteroids 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.
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 material ejected during meteorite impacts either struck again on the surface or fell on Mars, while on Deimos it long time remained in orbit around the satellite, gradually settling and hiding the unevenness of the relief.
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.
Other numerous sightings and announcements 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 the idea came to him 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 strongly supported by the famous British physicist William Thomson (Lord Kelvin), who, visiting the United States in 1902, said that in his opinion Tesla had picked up the signal of the Martians sent to the United States. 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 inside this zone, but a thin atmosphere with low pressure prevents the appearance of liquid water over a large area on 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 particle bombardment solar wind 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 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 certificate life on Mars has been 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. Nutrients in the soil is 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.
Astronomical observations from the surface of Mars
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 astronomical position Mars in the solar system, 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.
Sky color on Mars
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 takes on 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 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 satellite can be observed without a telescope), on the third - the Earth.
Earth in relation to Mars is inner planet, just like Venus is to Earth. Accordingly, from Mars, the Earth is observed as morning or evening Star, rising before dawn or visible in the evening sky after sunset.
The maximum elongation of the Earth in the sky of Mars will be 38 degrees. To the naked eye, the Earth will be visible as a bright (maximum visible magnitude 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 on 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. Naked eye distinguishes the largest detail of the relief of Phobos - the crater Stickney. Deimos rises in the east and sets in the west, looks like bright Star without a noticeable visible disk, 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.
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). South Pole 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 South polar star 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.
History of the study of Mars
The exploration of Mars began a long time ago, even 3.5 thousand years ago, in Ancient Egypt. The first detailed reports on the position of Mars were made by Babylonian astronomers, who developed a series 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.
In 1659, Francesco Fontana, looking at Mars through a telescope, made the first drawing of the planet. He pictured black spot in the center of a well-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 fell on late XIX- mid-twentieth 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 incorrect after flights of automatic probes to Mars.
Mars colonization
Estimated view of Mars after terraforming
Relatively close to Earth natural conditions make this task a little 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 most low temperatures on Mars, and on the equator of Mars in the summer months it 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 compared to the Earth) atmosphere, this increases the amount of ionizing radiation. 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 the minerals common on Mars is more diverse than that of other celestial bodies near the Earth. According to 4Frontiers Corporation, they are enough to supply not only Mars itself, but also the Moon, Earth and 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.
