Solar system mars. Mars is a mysterious red planet. Rotation axis and seasons

Mars is the fourth planet in our solar system and the second smallest after Mercury. Named after the ancient Roman god of war. Its nickname "Red Planet" comes from the reddish hue of the surface, which is due to the predominance of iron oxide. Every few years, when Mars is in opposition to Earth, it is most visible in the night sky. For this reason, people have observed the planet for many millennia, and its appearance in the sky has played a large role in the mythology and astrological systems of many cultures. In the modern era, it has become a treasure trove of scientific discoveries that have expanded our understanding of the solar system and its history.

Size, orbit and mass of Mars

The radius of the fourth planet from the Sun is about 3396 km at the equator and 3376 km in the polar regions, which corresponds to 53% And although it is about half as large, the mass of Mars is 6.4185 x 10²³ kg, or 15.1% of the mass of our planet. The axis tilt is similar to that of Earth and is equal to 25.19° to the orbital plane. This means that the fourth planet from the Sun also experiences the change of seasons.

At its greatest distance from the Sun, Mars orbits at a distance of 1.666 AU. e., or 249.2 million km. At perihelion, when it is closest to our star, it is 1.3814 AU away from it. e., or 206.7 million km. The Red Planet takes 686,971 Earth days, equivalent to 1.88 Earth years, to orbit the Sun. In Martian days, which on Earth are equal to one day and 40 minutes, a year lasts 668.5991 days.

Soil composition

With an average density of 3.93 g/cm³, this characteristic of Mars makes it less dense than Earth. Its volume is about 15% of the volume of our planet, and its mass is 11%. Red Mars is a consequence of the presence of iron oxide on the surface, better known as rust. The presence of other minerals in the dust ensures the presence of other shades - gold, brown, green, etc.

This terrestrial planet is rich in minerals containing silicon and oxygen, metals and other substances that are usually found in rocky planets. The soil is slightly alkaline and contains magnesium, sodium, potassium and chlorine. Experiments conducted on soil samples also show that its pH is 7.7.

Although liquid water cannot exist on it due to its thin atmosphere, large concentrations of ice are concentrated within the polar ice caps. In addition, the permafrost belt extends from the pole to 60° latitude. This means that water exists beneath most of the surface as a mixture of its solid and liquid states. Radar data and soil samples confirmed the presence also in mid-latitudes.

Internal structure

The 4.5 billion-year-old planet Mars consists of a dense metallic core surrounded by a silicon mantle. The core is made of iron sulfide and contains twice as many light elements as the Earth's core. The average thickness of the crust is about 50 km, the maximum is 125 km. If we take into account that the earth's crust, the average thickness of which is 40 km, is 3 times thinner than the Martian crust.

Current models of its internal structure suggest that the core has a radius size of 1700-1850 km and is composed primarily of iron and nickel with approximately 16-17% sulfur. Due to its smaller size and mass, the gravity on the surface of Mars is only 37.6% that of Earth. here it is 3.711 m/s², compared to 9.8 m/s² on our planet.

Surface characteristics

Red Mars is dusty and dry from above, and geologically it closely resembles Earth. It has plains and mountain ranges, and even the largest sand dunes in the solar system. The highest mountain, the Olympus shield volcano, and the longest and deepest canyon, the Valles Marineris, are also located here.

Impact craters are typical elements of the landscape that dot the planet Mars. Their age is estimated at billions of years. Due to the slow rate of erosion, they are well preserved. The largest of them is the Hellas Valley. The circumference of the crater is about 2300 km, and its depth reaches 9 km.

Gullies and channels can also be discerned on the surface of Mars, and many scientists believe that water once flowed through them. Comparing them with similar formations on Earth, it can be assumed that they were at least partially formed by water erosion. These canals are quite large - 100 km wide and 2 thousand km long.

Moons of Mars

Mars has two small moons, Phobos and Deimos. They were discovered in 1877 by astronomer Asaph Hall and bear the names of mythical characters. Following the tradition of taking their names from classical mythology, Phobos and Deimos are the sons of Ares, the Greek god of war who was the prototype of the Roman Mars. The first of them personifies fear, and the second - confusion and horror.

Phobos is about 22 km in diameter, and the distance to Mars from it is 9234.42 km at perigee and 9517.58 km at apogee. This is below synchronous altitude, and the satellite takes only 7 hours to orbit the planet. Scientists estimate that in 10-50 million years, Phobos may fall to the surface of Mars or disintegrate into a ring structure around it.

Deimos has a diameter of about 12 km, and its distance to Mars is 23455.5 km at perigee and 23470.9 km at apogee. The satellite makes a full revolution in 1.26 days. Mars may also have additional satellites, the sizes of which are less than 50-100 m in diameter, and there is a ring of dust between Phobos and Deimos.

According to scientists, these moons were once asteroids, but then they were captured by the planet's gravity. The low albedo and composition of both moons (carbonaceous chondrite), which is similar to asteroid material, support this theory, and Phobos' unstable orbit would seem to suggest a recent capture. However, both moons' orbits are circular and in the plane of the equator, which is unusual for captured bodies.

Atmosphere and climate

The weather on Mars is due to the presence of a very thin atmosphere, which consists of 96% carbon dioxide, 1.93% argon and 1.89% nitrogen, as well as traces of oxygen and water. It is very dusty and contains particulate matter measuring 1.5 microns in diameter, which turns the Martian sky dark yellow when viewed from the surface. Atmospheric pressure varies between 0.4-0.87 kPa. This is equivalent to about 1% of the Earth's at sea level.

Due to the thin layer of gaseous shell and greater distance from the Sun, the surface of Mars warms up much worse than the surface of the Earth. On average it is -46 °C. In winter it drops to -143 °C at the poles, and in summer at noon at the equator it reaches 35 °C.

Dust storms are raging on the planet, which turn into small tornadoes. More powerful hurricanes occur when dust rises and is heated by the Sun. The winds intensify, creating storms whose scales are measured in thousands of kilometers and their duration is several months. They effectively hide almost the entire surface area of ​​Mars from view.

Traces of methane and ammonia

Traces of methane were also found in the planet's atmosphere, the concentration of which is 30 parts per billion. It is estimated that Mars should produce 270 tons of methane per year. Once released into the atmosphere, this gas can only exist for a limited period of time (0.6-4 years). Its presence, despite its short lifetime, indicates that an active source must exist.

Possible possibilities include volcanic activity, comets, and the presence of methanogenic microbial life forms beneath the planet's surface. Methane can be produced through non-biological processes called serpentinization, involving water, carbon dioxide and olivine, which is common on Mars.

Express also detected ammonia, but with a relatively short lifetime. It is not clear what produces it, but volcanic activity has been suggested as a possible source.

Planet exploration

Attempts to find out what Mars is began in the 1960s. Between 1960 and 1969, the Soviet Union launched 9 unmanned spacecraft to the Red Planet, but all of them failed to reach their target. In 1964, NASA began launching Mariner probes. The first were Mariner 3 and Mariner 4. The first mission failed during deployment, but the second, launched 3 weeks later, successfully completed the 7.5-month journey.

Mariner 4 took the first close-up images of Mars (showing impact craters) and provided precise data on atmospheric pressure at the surface and noted the absence of a magnetic field and radiation belt. NASA continued the program with another pair of flyby probes, Mariner 6 and 7, which reached the planet in 1969.

In the 1970s, the USSR and the United States competed to see who would be the first to launch an artificial satellite into orbit around Mars. The Soviet M-71 program included three spacecraft - Kosmos-419 (Mars-1971C), Mars-2 and Mars-3. The first heavy probe crashed during launch. The subsequent missions, Mars 2 and Mars 3, were a combination of an orbiter and a lander and became the first extraterrestrial landings (other than the Moon).

They were successfully launched in mid-May 1971 and flew from Earth to Mars for seven months. On November 27, the Mars-2 lander made an emergency landing due to an onboard computer failure and became the first man-made object to reach the surface of the Red Planet. On December 2, Mars 3 made a routine landing, but its transmission was interrupted after 14.5 seconds of broadcast.

Meanwhile, NASA continued the Mariner program, and Probes 8 and 9 were launched in 1971. Mariner 8 crashed into the Atlantic Ocean during launch. But the second spacecraft not only reached Mars, but also became the first to be successfully launched into its orbit. While the planet-scale dust storm lasted, the satellite managed to take several photographs of Phobos. As the storm subsided, the probe captured images that provided more detailed evidence that water once flowed on the surface of Mars. A feature called the Snows of Olympus (one of the few objects that remained visible during the planetary dust storm) was determined to also be the tallest feature in the solar system, leading to its renaming as Mount Olympus.

In 1973, the Soviet Union sent four more probes: the 4th and 5th Mars orbiters, and the orbiters and landers Mars 6 and 7. All interplanetary stations except Mars 7 transmitted data , and the Mars-5 expedition turned out to be the most successful. Before the transmitter housing depressurized, the station managed to transmit 60 images.

By 1975, NASA had launched Viking 1 and 2, consisting of two orbiters and two landers. The mission to Mars was aimed at searching for traces of life and observing its meteorological, seismic and magnetic characteristics. Results from biological experiments aboard the Viking landers were inconclusive, but a reanalysis of the data published in 2012 suggested evidence of microbial life on the planet.

Orbiters have provided additional evidence that water once existed on Mars - large floods created deep canyons thousands of kilometers long. Additionally, areas of braided streams in the southern hemisphere suggest that precipitation once occurred there.

Resumption of flights

The fourth planet from the sun was not explored until the 1990s, when NASA sent the Mars Pathfinder mission, which consisted of a spacecraft that landed a station with the traveling Sojourner probe. The device landed on Mars on July 4, 1987 and became proof of the viability of technologies that would be used in future expeditions, such as air-cushion landing and automatic obstacle avoidance.

The next mission to Mars, the MGS mapping satellite, reached the planet on September 12, 1997, and began operations in March 1999. Over the course of one full Martian year, from a low altitude in almost polar orbit, it studied the entire surface and atmosphere and sent back more data about the planet than all previous missions combined.

On November 5, 2006, MGS lost contact with Earth and NASA's efforts to restore it were terminated on January 28, 2007.

In 2001, the Mars Odyssey Orbiter was sent to find out what Mars is. Its goal was to search for evidence of water and volcanic activity on the planet using spectrometers and thermal imagers. In 2002, it was announced that the probe had detected large quantities of hydrogen - evidence of the existence of huge deposits of ice in the top three meters of soil within 60° of the south pole.

On June 2, 2003, Mars Express was launched, a spacecraft consisting of a satellite and the Beagle 2 lander. It entered orbit on December 25, 2003, and the probe entered the planet's atmosphere on the same day. Before ESA lost contact with the lander, Mars Express Orbiter confirmed the presence of ice and carbon dioxide at the south pole.

In 2003, NASA began exploring the planet under the MER program. It used two rovers, Spirit and Opportunity. The mission to Mars had the task of examining various rocks and soils in order to find evidence of the presence of water.

The Mars Reconnaissance Orbiter (MRO) was launched on 08/12/05 and reached the planet's orbit on 03/10/06. The spacecraft carries scientific instruments designed to detect water, ice and minerals on and below the surface. In addition, MRO will support future generations of space probes by daily monitoring Mars' weather and surface conditions, searching for future landing sites, and testing a new telecommunications system that will speed up communications with Earth.

On August 6, 2012, NASA's Mars Science Laboratory MSL and the Curiosity rover landed in Gale Crater. With their help, many discoveries were made regarding local atmospheric and surface conditions, and organic particles were also discovered.

On November 18, 2013, in another attempt to find out what Mars is, the MAVEN satellite was launched, the purpose of which is to study the atmosphere and relay signals from robotic rovers.

Research continues

The fourth planet from the Sun is the most studied in the solar system after Earth. Currently, the Opportunity and Curiosity stations operate on its surface, and 5 spacecraft operate in orbit - Mars Odyssey, Mars Express, MRO, MOM and Maven.

These probes were able to transmit incredibly detailed images of the Red Planet. They helped discover that there was once water there, and confirmed that Mars and Earth are very similar - they have polar caps, seasons, an atmosphere and the presence of water. They also showed that organic life can exist today and most likely existed in the past.

Humanity's obsession with discovering what Mars is continues unabated, and our efforts to study its surface and unravel its history are far from over. In the coming decades, we will likely continue to send rovers there and will send a man there for the first time. And over time, given the availability of the necessary resources, the fourth planet from the Sun will one day become habitable.

And the seventh largest:

Orbital distance from the Sun: 227,940,000 km (1.52 AU)

Diameter: 6794 km

Mars has been known since prehistoric times. The planet has been carefully studied using ground-based observatories.

The first spacecraft to visit Mars was Mariner 4 (USA) in 1965. Others followed, such as Mars 2 (USSR), the first spacecraft to land on Mars, followed by two Viking spacecraft (USA) with landers in 1976.

This was followed by a 20-year break in spacecraft launches to Mars, and on July 4, 1997, the Mars Pathfinder successfully landed

In 2004, the Opportunity rover landed on Mars, conducted geological research and sent many images back to Earth.

In 2008, the Phoenix spacecraft landed on the northern plains of Mars to search for water.

Then three orbital stations were sent into Mars orbitMars Reconnaissance Orbiter, Mars Odyssey and Mars Express, which are currently in operation.

The MSL Curiosity (CIF) spacecraft successfully landed on Mars on August 6, 2012. The landing was broadcast live on the NASA website. The device landed in a given area - in the Gale crater.
The Mars rover "Curiosity" (from the English "curiosity", "curiosity") was launched on November 26, 2011. It is the largest robotic vehicle in the entire history of Mars exploration - its mass is more than 900 kilograms.
One of the main tasks of Curiosity is to analyze the chemical composition of soil on the surface and at shallow depths. Its analytical instruments include a quadrupole mass spectrometer, gas chromatograph and X-ray spectrometers. In addition, it is equipped with the Russian-made DAN neutron detector, designed to search for ice under the surface of the planet.

The orbit of Mars is elliptical. This significantly affects the temperature with a difference of 30 C , from the side of the Sun, measured at the aphelion of the orbit and perihelion. This has a big impact on the climate of Mars. While the average temperature on Mars is about -55 C, the surface temperature of Mars ranges from -133 C at the winter pole to almost 27 C at the day side during the summer.

Even though Mars is much smaller than Earth, its area is approximately the same as Earth's land surface area.

Mars has one of the most diverse and interesting terrains of any planet:

Mount Olympus : The largest mountain in the solar system, its height is 24 km above the surrounding plain. The foot of the mountain is 500 km in diameter and is framed by cliffs 6 km high.

Tarsis: A huge bulge on the surface of Mars, measuring about 4000 km across and 10 km high.

Valles Marineris: a system of canyons 4000 km long and from 2 to 7 km deep;

Plain of Hellas: a meteorite crater in the southern hemisphere more than 6 km deep and 2000 km in diameter.

Much of the surface of Mars is covered with very old craters, but there are also much younger rift valleys, ridges, hills and plains.

The southern hemisphere is covered with craters, much like the Moon. The Northern Hemisphere consists of plains that are much younger, smaller in height, and have a much more complex history. A sharp change in altitude of several kilometers occurs at the border of the hemispheres. The reasons for this global dichotomy and the presence of sharp boundaries are unknown.

A cross-section of the planet looks something like this: the crust in the southern hemisphere is about 80 km and about 30 km in the northern hemisphere, the core is very dense, about 1700 km in radius.

The relatively low density of Mars compared to other terrestrial planets indicates that its core may contain a relatively large proportion of sulfur and iron (iron and iron sulfide).

Mars, like Mercury and the Moon, has no currently active tectonic strata and no signs of recent horizontal surface movement. On Earth, evidence of this movement are folded mountains.

There are currently no signs of ongoing volcanic activity. However, data from the Mars Global Surveyor spacecraft indicate that Mars very likely had tectonic activity at some point in the past.

There is very clear evidence of erosion in many places on Mars, including large floods and small river systems. In the past, there was some kind of liquid on the surface of the planet.

There may have been seas and even oceans on Mars; the Mars Global Surveyor has provided very clear images of a layered soil system. It is rather caused by the presence of fluid in the past. The age of channel erosion is estimated to be approximately 4 billion years.

Mars Express in early 2005 sent back images of a dry sea that had been filled with liquid as recently as perhaps 5 million years ago.

Early in its history, Mars was much more like Earth. As on Earth, almost all of the carbon dioxide was used to form carbonate rocks.

Mars has a very thin atmosphere, consisting mainly of small amounts of remaining carbon dioxide (95.3%), nitrogen (2.7%), argon (1.6%), traces of oxygen (0.15%), water (0 .03%).

The average surface pressure on Mars is only about 7 millibars (less than 1% of the pressure on Earth), but it varies greatly with altitude. So, 9 millibars in the deepest depressions and 1 millibar at the top of Mount Olympus.

However, Mars experiences very strong winds and huge dust storms that sometimes cover the entire planet for months at a time.

Telescopic observations have shown that Mars has permanent caps at both poles, visible even with a small telescope. They consist of water ice and solid carbon dioxide ("dry ice"). Ice caps have a layered structure with alternating layers of ice and varying concentrations of dark dust.

The Viking spacecraft (USA) carried out studies from landers to determine the existence of life on Mars. The results have been somewhat mixed, but most scientists now believe they have no evidence of life on Mars. Optimists point out that only two tiny soil samples have been analyzed, and not from the most favorable locations.

Large, but not global, weak magnetic fields exist in various regions of Mars. This unexpected discovery was made by the Mars Global Surveyor a few days after it entered Mars orbit. These may be remnants of a previously global magnetic field.

If there was a magnetic field on Mars, then the existence of life on it becomes more likely.

Characteristics of Mars:

Weight (10 24 kg): 0.64185

Volume (10 10 km cubic): 16,318

Equatorial radius: 3397 km

Polar radius: 3375 km

Volumetric average radius: 3390 km

Average density: 3933 kg/m 3

Radius: 1700 km

Gravity (ed.) (m/s): 3.71

Gravity acceleration (ed.) (m/s): 3.69

Second escape velocity (km/s): 5.03

Albedo: 0.250

Visual albedo: 0.150

Solar Energy (W/m 2 ): 589,2

Black body temperature (k): 210.1

Number of natural satellites: 2

Mars orbital parameters

Semi-major axis (distance from the Sun) (106 km): 227.92

Sidereal orbital period (days): 686.98

Tropical orbital period (days): 686.973

Perihelion (106 km): 206.62

Aphelion (106 km): 249.23

Synodic period (days): 779.94

Maximum orbital speed (km/s): 26.5

Minimum orbital speed (km/s): 21.97

Orbital inclination (degrees): 1,850

Period of rotation around its axis (hours): 24.6229

Daylight hours (hours): 24.6597

Axle Tilt (degrees): 25.19

Minimum distance to Earth (106 km): 55.7

Maximum distance to Earth (106 km): 401.3

Atmospheric parameters

Surface pressure (bar): 6.36 mb (varies from 4 to 8.7 mb depending on meson)

Density of the atmosphere near the surface (kg/m3): 0.020

Atmospheric altitude (km): 11.1

Average temperature (k): - 55 C

Temperature range: -133С - +27С

Basic parameters of Mars satellites

Atmospheric composition 95.72% Ang. gas
0.01% Nitric oxide

Mars- the fourth most distant planet from the Sun and the seventh largest planet in the solar system. This planet is named after Mars, the ancient Roman god of war, corresponding to the ancient Greek Ares. Mars is sometimes called the “Red Planet” because of the reddish hue of its surface given by iron(III) oxide.

Basic information

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

Currently (February 2009), the orbital exploration constellation in orbit around Mars has three operational spacecraft: Mars Odyssey, Mars Express and Mars Reconnaissance Orbiter, and this is more than around any other planet except Earth. The surface of Mars is currently being explored by two rovers: Spirit And Opportunity. There are also several inactive landers and rovers on the surface of Mars that have completed their missions. Geological data collected by all of these missions suggests that much of the surface of Mars was previously covered by water. Observations over the past decade have revealed weak geyser activity in some places on the surface of Mars. Based on observations from NASA spacecraft "Mars Global Surveyor", some parts of Mars' southern polar cap are gradually retreating.

Mars has two natural satellites, Phobos and Deimos (translated from ancient Greek as “fear” and “terror” - the names of the two sons of Ares who accompanied him in battle), which are relatively small and irregular in shape. They may be asteroids captured by the gravitational field of Mars, similar to asteroid 5261 Eureka from the Trojan group.

Mars can be seen from Earth with the naked eye. Its apparent magnitude reaches −2.91 m (at its closest approach to the Earth), second in brightness only to Jupiter, Venus, the Moon and the Sun.

Orbital characteristics

The minimum distance from Mars to Earth is 55.75 million km, the maximum is about 401 million km. 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 fairly noticeable eccentricity (0.0934), so the distance to the Sun varies from 206.6 to 249.2 million km. The inclination of Mars' orbit is 1.85°.

The atmosphere consists of 95% carbon dioxide; it also contains 2.7% nitrogen, 1.6% argon, 0.13% oxygen, 0.1% water vapor, 0.07% carbon monoxide. The Martian ionosphere extends from 110 to 130 km above the planet's surface.

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

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

According to researchers from the Carl Sagan Center, Mars is currently undergoing a warming process. Other experts believe that it is too early to draw such conclusions.

Surface

Description of the main regions

Topographic map of Mars

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

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

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

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

The large number of craters in the southern hemisphere suggests that the surface here is ancient - 3-4 billion years ago. years. Several types of craters can be distinguished: large craters with a flat bottom, smaller and younger bowl-shaped craters similar to the Moon, craters surrounded by ridges, and elevated craters. The last two types are unique to Mars - rimmed craters formed where liquid ejecta flowed across the surface, and raised craters formed where a blanket of crater ejecta protected the surface from wind erosion. The largest feature of impact origin is the Hellas Basin (approximately 2100 km across).

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

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 2000 km long, reaching an altitude of 10 km above average. It contains three large shield volcanoes - Arsia, Pavonis (Peacock) and Askreus. On the edge of Tharsis is Mount Olympus, the highest on Mars and in the Solar System. Olympus reaches 27 km in height, and covers an area 550 km in diameter, surrounded by cliffs that in some places reach 7 km in height. The volume of Olympus is 10 times greater than the volume of the largest volcano on Earth, Mauna Kea. There are also several smaller volcanoes located here. Elysium is an elevation up to six kilometers above the average level, with three volcanoes - Hecate, Elysium and Albor.

"River" beds and other features

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

Geology and internal structure

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

Phobos (top) and Deimos (bottom)

Current models of the internal structure of Mars suggest that Mars consists of a crust with an average thickness of 50 km (and a maximum thickness of up to 130 km), a silicate mantle with a thickness of 1800 km and a core with a radius of 1480 km. The density in the center of the planet should reach 8.5 /cm³. The core is partially liquid and consists mainly of iron with an admixture of 14-17% (by mass) sulfur, and the content of light elements is twice as high as in the Earth's core.

Moons of Mars

The natural satellites of Mars are Phobos and Deimos. Both of them were discovered by American astronomer Asaph Hall in 1877. Phobos and Deimos are irregular in shape and very small in size. According to one hypothesis, they may represent asteroids like 5261 Eureka from the Trojan group of asteroids captured by the gravitational field of Mars.

Astronomy on Mars

This section is a translation of the English Wikipedia article

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

Noon on Mars. Photo of the Pathfinder

Sunset on Mars. Photo of the Pathfinder

The color of the sky on Mars Earth and Moon Satellites - Phobos and Deimos

On a surface There are two rovers operating on the planet:

Planned missions

In culture

Books

• A. Bogdanov “Red Star”
• A. Kazantsev “Phaetians”
• A. Shalimov “The Price of Immortality”
• V. Mikhailov “Special need”
• V. Shitik “The Last Orbit”
• B. Lyapunov “We ​​are on Mars”
• G. Martynov “Starfarers” trilogy
• G. Wells “War of the Worlds”, a film of the same name in two film adaptations
• Simmons, Dan "Hyperion", tetralogy
• Stanislav Lem "Ananke"

Movies

• "Journey to Mars" USA, 1903
• "Journey to Mars" USA, 1910
• "Sky Ship" Denmark, 1917
• "Journey to Mars" Denmark, 1920
• "Journey to Mars" Italy, 1920
• "The Ship Sent to Mars" USA, 1921
• “Aelita” directed by Yakov Protazanov, USSR, 1924.
• "Journey to Mars" USA, 1924
• "To Mars" USA, 1930
• "Flash Gordon: Mars Attacks Earth" USA, 1938
• "Scrappy's Journey to Mars" USA, 1938
• "Rocket X-M" USA, 1950
• “Flight to Mars” USA, 1951
• “The Sky is Calling” directed by A. Kozyr and M. Karyukov, USSR, 1959.
• “Mars” documentary, director Pavel Klushantsev, USSR, 1968.
• “First on Mars. The unsung song of Sergei Korolev” documentary, 2007
• "Martian Odyssey"

Other

• In the fictional universe of Warhammer 40,000, Mars is the capital world of the Adeptus Mechanicus organization, which supports the scientific and technological thought of the Imperium of Man.
• In the video game DOOM 3, the setting is the Red Planet.
• In the video game Red Faction 1.3, the setting is also the Red Planet.
• In the Mass Effect universe, a database of long-vanished aliens was found on the south pole of Mars, the decryption of which allowed people to enter the Galaxy.

Mars appeared relatively simultaneously with the rest of the planets of the solar system. The characteristic features and peculiarities of the Red Planet are explained by the history of its origin and formation. The history of Mars is a mystery, and many hypotheses have been put forward in attempts to unravel it.

How Mars was formed

The history of Mars has become the subject of debate among scientists around the world. According to official data, the formation of the Red Planet occurred simultaneously with other planets of the solar system about 4.6 billion years ago.

The Martian chronicles indicate that the formation of Mars in the asteroid belt occurred long before the crust stabilized and the atmosphere was created.

The origin of Mars is explained by the leading theory of the accretion model, which holds that all planets in the solar system were once a large, cold cloud of gas and dust called a nebula. As a result of its own gravity, the nebula was flattened, forming a rotating disk. As a result of rotational movements, the matter of this disk was shifted to the center, forming the star Sun.

The remaining particles stuck together to form planetesimals. Planetesimals are a collection of celestial bodies located in the orbit of a developing star, which have the property of increasing mass due to the adhesion of small particles. One such formation is Mars.

According to this theory, the planet Mars should have dimensions close to those of Earth. However, because gas and dust are unevenly distributed throughout the universe, Mars formed in a region with low levels of planetary building blocks. As a result, the planet is much smaller in size than Earth.

Like all planets, Mars was hot when it formed. The planet's interior melted and denser elements, such as iron, sank toward the center to form the core. Light silicates formed the mantle, less dense silicates formed the crust.

The formation of Mars as a solid celestial body occurred about 4.1 billion years ago. At this time, particles of space debris fell on the planet: meteoroids and comets, which provoked tectonic activity on Mars.

However, being far from the Sun and having a relatively small size, Mars cooled quickly, and its core froze about 4.2 billion years ago.

And the question of how old Mars can be answered by calculating its history from the very beginning of the emergence of its planetary characteristics. According to these calculations, the age of Mars is 4.6 billion years.

Geological history of Mars

As a result of studies of the density of impact craters on the red planet, the geological history of the structure of Mars was divided into four periods. These historical eras of the planet have the names of places that have their own characteristic features of the structure of the planet’s surface: large craters, wide spills of lava flows on Mars.

Scale of geological formation of Mars millions of years ago

The Martian Chronicles distinguishes four periods in the history of Mars, from the earliest to the present day.

• The Prenoian period represents the period from the beginning of accretion and the formation of the first planetary features, until the formation of the third largest crater in the solar system - the Hellas basin. It dates back to 4.6-4.5 billion years ago. The geological record of this time has been erased by erosion and the greater impact of the Martian hemispheric dichotomy. It is known that the dichotomous relief contrast formed in this geological period reaches from 1 to 3 km.
• The Noachian period dates back to the time frame 4.1 -3.7 billion years ago. It is characterized by the large-scale impact of meteorites and asteroids on the planet. It is assumed that the surface of Mars was covered with a large amount of water. At this time, the atmosphere of Mars was dense. Rivers and lakes occupied the southern part, and the northern part was covered by the ocean. Due to weathering, the surface was covered with clay minerals. This is an era of great volcanic activity. The Noachian period is credited with the formation of the Tharsis region, a concentration of the largest volcanoes in the solar system, 5,000 km wide.
• The Hesperia period lasted from 3.7 to 3 billion years ago and was characterized by the formation of vast lava plains. It was at this time that a large release of water occurred on the surface of the planet with the formation of water channels, which are now dried up and visible from images of planetary vehicles. This period was marked by the formation of the largest volcano in the solar system - Olympus.
• The Amazonian period begins 3 billion years ago and continues to the present day. At this time, the activity of volcanoes and erosion processes decreases. Icing begins and ice caps form.

The discovery of the planet and the study of the formation of Mars allows us to reasonably divide its history into periods and, thereby, explain all the processes that took place and their consequences, as a result of which we observe the planet in the form in which it now exists.

What ancient Mars looked like in the past

The Martian chronicles say that Mars was covered with a large number of oceans in the past. The volcanic activity of the planet contributed to the release of water to the surface of the planet. The density of the Martian atmosphere was sufficient to remain within the planet, which contributed to the creation of the greenhouse effect.

Ancient Mars had relief differences between two hemispheres, differing in height up to three kilometers. In the past, some of the largest volcanoes in the entire solar system formed and were active on Mars.

The presence of clayey soils and water suggests that Mars was inhabited by living organisms, but which ones specifically can only be guessed at. Since no direct evidence of the population of organisms on the planet has been found.

The orbit of Mars is elongated, so the distance to the Sun changes by 21 million km throughout the year. The distance to Earth is also not constant. During the Great Oppositions of the Planets, which occur once every 15-17 years, when the Sun, Earth and Mars line up, Mars approaches the Earth at a maximum of 50-60 million km. The last Great Confrontation took place in 2003. The maximum distance of Mars from the Earth reaches 400 million km.

A year on Mars is almost twice as long as on Earth - 687 Earth days. The axis is inclined to the orbit - 65 °, which leads to the change of seasons. The period of rotation around its axis is 24.62 hours, i.e., only 41 minutes longer than the period of rotation of the Earth. The inclination of the equator to the orbit is almost like that of the Earth. This means that the change of day and night and the change of seasons on Mars proceeds almost the same as on Earth.

According to calculations, the core of Mars has a mass of up to 9% of the mass of the planet. It consists of iron and its alloys and is in a liquid state. Mars has a thick crust 100 km thick. Between them is a silicate mantle enriched in iron. The red color of Mars is precisely explained by the fact that its soil is half composed of iron oxides. The planet seemed to have “rusted.”

The sky above Mars is dark purple, and bright stars are visible even during the day in calm, calm weather. The atmosphere has the following composition (Fig. 46): carbon dioxide - 95%, nitrogen - 2.5%, atomic hydrogen, argon - 1.6%, the rest is water vapor, oxygen. In winter, carbon dioxide freezes, turning into dry ice. There are rare clouds in the atmosphere; there is fog over the lowlands and at the bottom of craters during the cold season.

Rice. 46. ​​Composition of the atmosphere of Mars

The average atmospheric pressure at surface level is about 6.1 mbar. This is 15,000 times less than , and 160 times less than the surface of the Earth. In the deepest depressions the pressure reaches 12 mbar. The atmosphere of Mars is very thin. Mars is a cold planet. The lowest recorded temperature on Mars is -139°C. The planet is characterized by sharp temperature changes. The temperature amplitude can be 75-60 °C. Mars has climate zones similar to those on Earth. In the equatorial zone, at noon the temperature rises to +20-25 °C, and at night drops to -40 °C. In the temperate zone, the temperature in the morning is 50-80 °C.

It is believed that several billion years ago Mars had an atmosphere with a density of 1-3 bar. At this pressure, water should be in a liquid state, and carbon dioxide should evaporate, and a greenhouse effect could occur (as on Venus). However, Mars gradually lost its atmosphere due to its low mass. The greenhouse effect decreased, permafrost and polar caps appeared, which are still observed today.

The tallest volcano in the solar system, Olympus Mons, is located on Mars. Its height is 27,400 m, and the diameter of the base of the volcano reaches 600 km. This is an extinct volcano that most likely erupted lava about 1.5 billion years ago.

General characteristics of the planet Mars

Currently, not a single active volcano has been found on Mars. There are other giant volcanoes near Olympus: Mount Askrian, Mount Pavolina and Mount Arsia, whose height exceeds 20 km. The lava that flowed out of them, before solidifying, spread in all directions, so the volcanoes are shaped more like cakes than cones. There are also sand dunes, giant canyons and faults, as well as meteorite craters on Mars. The most ambitious canyon system is the Valles Marineris, 4 thousand km long. In the past, rivers may have flowed on Mars, which left the channels observed today.

In 1965, the American Mariner 4 probe transmitted the first images of Mars. Based on these, as well as photographs from Mariner 9, the Soviet probes Mars 4 and Mars 5, and the American Viking 1 and Viking 2, which operated in 1974, the first map of Mars. And in 1997, an American spacecraft delivered a robot to Mars - a six-wheeled cart 30 cm long and weighing 11 kg. The robot was on Mars from July 4 to September 27, 1997, studying this planet. Programs about his movements were broadcast on television and the Internet.

Mars has two satellites - Deimos and Phobos.

The assumption about the existence of two satellites on Mars was made in 1610 by a German mathematician, astronomer, physicist and astrologer Johannes Kepler (1571 — 1630), who discovered the laws of planetary motion.

However, the satellites of Mars were discovered only in 1877 by an American astrologer Asaph Hall (1829-1907).