Flickering in the days of confrontation with an ominous blood-red color and causing primitive mystical fear of a mysterious and mysterious star, which the ancient Romans named in honor of the god of war, Mars (among the Greeks Ares), it would hardly have been a woman's name. The Greeks also called it Phaeton for its "radiant and shining" appearance, to which the surface of Mars owes its bright color and "moon" relief with volcanic craters, dents from the impacts of giant meteorites, valleys and deserts.
Orbital characteristics
The eccentricity of the elliptical orbit of Mars is 0.0934, thus causing a difference in the maximum (249 million km) and minimum (207 million km) distances to the Sun, due to which the amount of solar energy entering the planet varies between 20-30%.
The orbital speed averages 24.13 km / s. Mars completely bends around the Sun for 686.98 Earth days, which is twice as much as the Earth’s period, and turns around its own axis in much the same way as the Earth (in 24 hours 37 minutes). According to various estimates, the angle of inclination of the orbit to the plane of the ecliptic is determined from 1.51 ° to 1.85 °, and the inclination of the orbit to the equator is 1.093 °. Relative to the equator of the Sun, the orbit of Mars is inclined at an angle of 5.65 ° (and the Earth - about 7 °). A significant inclination of the planet's equator to the orbit plane (25.2 °) leads to significant seasonal changes in climate.
Physical parameters of the planet
Mars among the planets of the solar system in size is in seventh place, and in remoteness from the sun it occupies the fourth position. The planet’s volume is 1.638 × 1011 km³, and the weight is 0.105-0.108 of the Earth’s mass (6.44 * 1023 kg), yielding it in a density of about 30% (3.95 g / cm 3 ). The acceleration of gravity in the equatorial region of Mars is determined in the range from 3.711 to 3.76 m / s². The surface area is estimated at 144.8 million square kilometers. Atmospheric pressure ranges from 0.7-0.9 kPa. The speed required to overcome gravity (second space) is 5,072 m / s. In the southern hemisphere, the surface of Mars is 3-4 km higher at the average level than in the northern.
Climatic conditions
The total mass of the atmosphere of Mars is about 2.5 * 1016 kg, but during the year it varies greatly due to the melting or “freezing” of the polar caps containing carbon dioxide . The average pressure at the surface level (about 6.1 mbar) is almost 160 times less than near the surface of our planet, but in deep trenches it reaches 10 mbar. According to various sources, seasonal pressure drops range from 4.0 to 10 mbar.
At 95.32%, the atmosphere of Mars consists of carbon dioxide, about 4% falls on argon and nitrogen, and oxygen and water vapor are less than 0.2%.
A highly diluted atmosphere cannot retain heat for a long time. Despite the “hot color” that Mars stands out among others, the temperature on the surface drops in winter to -160 ° C at the pole, and at the equator in summer, during the daytime the surface can only warm up to + 30 ° C.
The climate is seasonal, as on Earth, but the elongation of the orbit of Mars leads to significant differences in the duration and temperature of the seasons. The cool spring and summer of the northern hemisphere in aggregate last significantly more than half of the Martian year (371 Mars days), and winters are short and mild with autumn. Southern summers are hot and short, and winters are cold and long.
Seasonal climate changes are most clearly manifested in the behavior of polar caps stacked with ice mixed with finely dispersed, dusty rock particles. The front of the northern polar cap can be removed from the pole by almost a third of the distance to the equator, and the border of the southern cap reaches half of this distance.
With a thermometer located exactly in the focus of the reflecting telescope aimed at Mars, the temperature on the planet’s surface was already determined at the beginning of the 1920s. The first measurements (until 1924) showed values from -13 to -28 ° C, and in 1976 the lower and upper temperature limits were specified by the Viking spacecraft that landed on Mars.
Martian dust storms
The "exposure" of dust storms, their magnitude and behavior allowed to uncover the secret that Mars has long kept. The surface of the planet mysteriously changes color, fascinating observers from ancient times. The cause of "chameleonism" was dust storms.
Sudden changes in temperature of the Red Planet are causing a frenzy of violent winds, the speed of which reaches 100 m / s, and low gravity, despite the thinness of the air, allows the winds to lift huge masses of dust to a height of more than 10 km.
The emergence of dust storms also contributes to a sharp increase in atmospheric pressure caused by the evaporation of frozen carbon dioxide in winter polar caps.
Dust storms, as shown by images of the surface of Mars, spatially gravitate to polar caps and can cover enormous areas, lasting up to 100 days.
Another dusty attraction that Mars owes to abnormal temperature changes is tornadoes, which, unlike terrestrial “colleagues”, walk not only in desert regions, but also host the slopes of volcanic craters and shock craters, meaning up to 8 km. Their tracks were giant branchy-striped drawings, which for a long time remained mysterious.
Dust storms and tornadoes occur mainly during great confrontations, when summer in the southern hemisphere falls on the period of Mars passing through the planet’s orbit (perihelion) closest to the Sun.
Images of the surface of Mars taken by the Mars Global Surveyor spacecraft , which has been in orbit around the planet since 1997, turned out to be very productive for tornadoes.
Some tornadoes leave traces, sweeping away or sucking in a loose surface layer of finely dispersed soil particles, others do not even leave “fingerprints”, while others, frantically, draw intricate figures, for which they were called dust devils. Vortices work, as a rule, alone, but also do not refuse from group “representations”.
Relief features
Probably, everyone who, armed with a powerful telescope, first looked at Mars, the surface of the planet immediately resembled a lunar landscape, and in many areas this is true, but still the geomorphology of Mars is peculiar and unique.
Regional features of the relief of the planet due to the asymmetry of its surface. The prevailing plain surfaces of the northern hemisphere are 2–3 km lower than the conditionally zero level, and in the southern hemisphere the surface is 3-4 km higher than the base level complicated by craters, valleys, canyons, hollows, and hills. The transition zone between two hemispheres 100–500 km wide is morphologically expressed by a strongly eroded giant ledge almost 2 km high, covering almost 2/3 of the planet around the circumference and traced by a fault system.
The prevailing relief forms characterizing the surface of Mars are represented by dotted craters of various genesis, elevations and depressions, shock structures of circular depressions (multi-ring basins), linearly elongated elevations (ridges) and steeply inclined basins of irregular shape.
Widespread flat-topped elevations with steep edges (table mountains), extensive flat craters (shield volcanoes) with eroded slopes, winding valleys with tributaries and arms, flattened hills (plateaus) and areas of randomly alternating canyon-like valleys (labyrinths).
Mars is also characterized by failed depressions with a chaotic and shapeless relief, long, complex steps (faults), a series of subparallel ridges and furrows, as well as vast plains of a completely “earthly” appearance.
Annular crater basins and large (over 15 km across) craters are the determining morphological structures for most of the southern hemisphere.
The highest regions of the planet with the names of Farsis and Elysius are in the northern hemisphere and represent huge volcanic highlands. The Farsida Plateau, towering almost 6 km above the plain surroundings, stretches for 4000 km in longitude and extends for 3000 km in latitude. On the plateau are 4 giant volcanoes ranging in height from 6.8 km (Mount Alba) to 21.2 km (Mount Olympus, diameter 540 km). The peaks of the mountains (volcanoes) of Pavlina / Pavonis (Pavonis), Askrian (Ascraeus) and Arsia (Arsia) are at an altitude of 14, 18 and 19 km, respectively. Mount Alba stands apart to the northwest of a strict series of other volcanoes and is a shield volcanic structure with a diameter of about 1,500 km. Volcano Olympus (Olympus) - the highest mountain not only on Mars, but in the entire solar system.
From the east and west, two vast meridional lowlands adjoin the province of Farsida. The surface marks of the western plain with the name Amazonia are close to the planet's zero level, and the lowest parts of the eastern depression (Chris plain) are 2-3 km below the zero level.
In the equatorial region of Mars, the second largest volcanic plateau of Elysius is located, measuring about 1,500 km in diameter. The plateau rises above the base for 4–5 km and carries three volcanoes (actually Mount Elysius, the dome of Albor and Mount Hekate). The highest mountain, Elysius, has grown to 14 km.
A giant rift-like system of valleys (canyons) Mariner extends to the east of the Farsid plateau in the near-equatorial region (almost 5 km), which exceeds the length of one of the largest Grand Canyons in the world by almost 10 times, and 7 times wider and deeper. The width of the valleys averages 100 km, and the almost steep ledges of their sides reach a height of 2 km. The linearity of the structures indicates their tectonic origin.
Within the elevations of the southern hemisphere, where the surface of Mars is simply dotted with craters, there are the largest circular shock depressions on the planet with the names Argir (about 1,500 km) and Hellas (2,300 km).
The Hellas plain is deeper than all the depressions of the planet (almost 7000 m below the average level), and the excess of the Argir plain in relation to the level of the surrounding hill is 5.2 km. A similar rounded lowland, the plain of Isis (1,100 km across), is located in the equatorial region of the eastern hemisphere of the planet and in the north is adjacent to the plain of Elysius.
About 40 such multi-ring basins are known on Mars, but smaller.
IN the northern hemisphere is the largest lowland on the planet (Northern Plain), bordering the polar region. The plains are below the surface of the planet.
Aeolian landscapes
It would be difficult in a few words to characterize the surface of the Earth, referring to the planet as a whole, but to get an idea of what surface Mars can be, if you just call it lifeless and dry, reddish-brown, rocky-sandy desert, because the dissected relief of the planet is smoothed by loose alluvial deposits.
Aeolian landscapes, composed of sand-fine-aleurite dusty material and formed as a result of wind activity, cover almost the entire planet. These are ordinary (like on the ground) dunes (transverse, longitudinal and diagonal) ranging in size from the first hundreds of meters to 10 km, as well as layered aeolian-glacial deposits of polar caps. The special relief "created by Aeolus" is confined to enclosed structures - the bottoms of large canyons and craters.
The morphological activity of the wind, which determines the peculiar features of the surface of Mars, manifested itself in intense erosion (deflation), which led to the formation of characteristic, "engraved" surfaces with cellular and linear structures.
Layered eolian-glacial formations composed of ice mixed with sediments cover the polar caps of the planet. Their power is estimated at several km.
Geological characteristics of the surface
According to one of the existing hypotheses of the modern composition and geological structure of Mars, the inner core of a small size, consisting mainly of iron, nickel and sulfur, was first melted from the primary substance of the planet. Then, a lithosphere with a thickness of about 1000 km, with a crust uniform in composition, formed around the core, in which volcanic activity is likely to continue today, with the release of ever new portions of magma. The thickness of the Martian crust is estimated at 50–100 km.
Since man began to peer at the brightest stars, scientists, like all people who are not indifferent to universal neighbors, among other mysteries, have been primarily interested in what surface Mars has.
Almost the entire planet is covered with a layer of brownish-yellowish-red dust with an admixture of fine aleurite and sandy material. The main components of loose soil are silicates with a large admixture of iron oxides, giving the surface a reddish tint.
According to the results of numerous studies performed by spacecraft, fluctuations in the elemental composition of loose deposits of the surface layer of the planet are not so significant as to suggest a wide variety of mineral composition of rocks that make up the Martian crust.
The average content of silicon (21%), iron (12.7%), magnesium (5%), calcium (4%), aluminum (3%), sulfur (3.1%), as well as potassium and chlorine established in the soil (<1%) indicated that the bulk of loose surface deposits are the products of the destruction of igneous and volcanic rocks of the main composition, close to the basalts of the earth. Initially, scientists doubted the significant differentiation of the stone shell of the planet in mineral composition, however, studies of the Martian bedrocks conducted within the framework of the Mars Exploration Rover (USA) project led to the sensational discovery of analogues of terrestrial andesites (rocks of medium composition).
This discovery, later confirmed by numerous finds of similar rocks, made it possible to judge that Mars, like the Earth, may have a differentiated crust, as evidenced by the significant contents of aluminum, silicon and potassium.
Based on the huge number of images taken by spacecraft and allowing us to judge what the surface of Mars consists of, in addition to igneous and volcanogenic rocks, the presence of volcanic-sedimentary rocks and sedimentary deposits, which are recognizable by the characteristic tiled segregation and stratification of exposure fragments, is obvious on the planet.
The nature of the stratification of rocks may indicate their formation in the seas and lakes. Areas of sedimentary rocks are recorded in many places on the planet and most often they are found in extensive craters.
Scientists do not exclude the “dry” precipitation of their Martian dust with their further lithification (petrification).
Permafrost formations
A special place in the morphology of the surface of Mars is occupied by permafrost formations, most of which appeared at different stages of the geological history of the planet as a result of tectonic movements and the influence of exogenous factors.
Based on the study of a large number of satellite images, scientists unanimously concluded that water plays a significant role in the formation of the appearance of Mars along with volcanic activity. Volcanic eruptions led to the melting of the ice cover, which, in turn, served to the development of water erosion, traces of which are visible today.
The fact that the permafrost on Mars was formed already at the earliest stages of the geological history of the planet is evidenced not only by polar caps, but also by specific forms of relief similar to the landscape in permafrost zones on Earth.
The vortex-like formations that layered deposits in the polar regions of the planet look like on satellite images in the vicinity represent a system of terraces, ledges, and depressions that form the most diverse forms.
Deposits of polar caps with a thickness of several kilometers consist of layers of carbon dioxide and water ice mixed with silty and fine aleurite material.
The failure-subsidence relief forms characteristic of the equatorial zone of Mars are associated with the destruction of cryogenic strata.
Water on Mars
On most of the surface of Mars, water cannot exist in a liquid state due to low pressure, but in some regional areas with a total area of about 30% of the planet’s area, NASA experts allow the presence of liquid water.
Reliably established water reserves on the Red Planet are concentrated mainly in the near-surface permafrost layer (cryosphere) with a thickness of up to many hundreds of meters.
Scientists do not exclude the existence of relict lakes of liquid water and under the thickness of polar caps. Based on the estimated volume of the Mars cryolithosphere, water (ice) reserves are estimated at approximately 77 million km³, and given the probable volume of thawed rocks, this figure may decrease to 54 million km³.
In addition, there is an opinion that under the cryolithosphere there may be strata with enormous salt water reserves.
Many facts indicate the presence of water on the surface of the planet in the past. The main witnesses are minerals, the formation of which involves the participation of water. First of all, it is hematite, clay minerals and sulfates.
Martian clouds
The total amount of water in the atmosphere of the “withered” planet is more than 100 million times less than on Earth, and yet the surface of Mars can be covered with rare and inconspicuous, but real and even bluish clouds, though consisting of ice dust. Clouds form in a wide range of heights from 10 to 100 km and are concentrated mainly in the equatorial zone, rarely rising above 30 km.
Ice mists and clouds are also widespread near polar caps in winter (polar haze), but here they can "fall" below 10 km.
The clouds can turn a pale pinkish color when icy particles mix with dust raised from the surface.
Clouds of a wide variety of forms have been recorded, including wavy, striped and cirrus.
Martian landscape from a height of human growth
First time to see what the surface of Mars looks like from a height of a tall man (2.1 m) was allowed by a curiosity rover armed with a camera “arm” in 2012. Before the goggle of the robot appeared "sandy", gravelly-gravelly plain, dotted with small cobblestones, with rare flat outcrops, possibly of indigenous, volcanic rocks.
The dull and monotonous picture was enlivened on one side by a hilly ridge of the edge of the Gale Crater, and on the other - a sloping hulk of Mount Sharpe 5.5 km high, which was the object of spacecraft hunting.
When planning the route along the bottom of the crater, the authors of the project apparently did not suspect that the surface of Mars, taken by the Curiosity rover, would be so diverse and heterogeneous, contrary to the expectation of seeing only a dull and monotonous desert.
On the way to Mount Sharp, the robot had to overcome fractured, tile-like flat surfaces, gentle stepped slopes of volcanic-sedimentary (judging by the layered texture on the chips) rocks, as well as blocky collapses of dark bluish volcanics with a cellular surface.
The apparatus, along the way, fired at the “targets indicated above” (cobblestones) with laser pulses and drilled small wells (up to 7 cm deep) to study the material composition of the samples. The analysis of the obtained material, in addition to the contents of the rock-forming elements characteristic of the rocks of the basic composition (basalts), showed the presence of sulfur, nitrogen, carbon, chlorine, methane, hydrogen and phosphorus compounds, that is, “life components”.
In addition, clay minerals were found that were formed in the presence of water with a neutral acidity and a low salt concentration.
Based on this information, in conjunction with previously obtained information, scientists were inclined to conclude that billions of years ago there was liquid water on the surface of Mars, and the density of the atmosphere was much higher than modern.
Morning star of mars
Since the world circled the Earth’s blue crescent moon in May 2003, taken by the Mars Global Surveyor from the orbit of the Red Planet at a distance of 139 million km, it seems to many that this is what the Earth looks like from the surface of Mars.
But in reality, our planet looks from there approximately like we see Venus in the morning and evening hours, only a lonely (except for the faintly visible Moon) glowing in the brownish black of the Martian sky is a little bit brighter than Venus.
The first image of the Earth from the surface was taken at dawn from the Spirit rover in March 2004, and the Earth’s Curiosity spacecraft “posed by the moon” posed in 2012 and turned out to be even more beautiful than the first time.