Mars and Venus are similar to the Earth, so scientists do not lose hope of finding life on neighboring planets. For Mars, this is more likely. The Curiosity rover was able to find out for sure that rivers once flowed there, which means that there was an atmosphere. Perhaps life on Mars existed long before Earth or will be possible after terraforming (changes in climatic conditions). This requires the presence of a magnetic field near Mars.
Sizes, masses and orbits of planets
The red planet is much smaller than the Earth in size. According to scientists' calculations and the data that were obtained in the process of numerous studies, up to six objects of the same volume as Mars would fit in the Earth. The radius of the fourth planet from the Sun along the equator is 0.53 Earth's, and the surface density is 37.6%.
The orbital paths of the planets are radically different, but the sidereal turnover is similar. This means that a year on Mars lasts almost 687 days, and a day is 24 hours 40minutes. The axial tilt is almost the same - 25 degrees for Mars, the Earth is two degrees less. This similarity means that seasonality can be expected from the red planet.
Structure and composition of Earth and Mars
Representatives of terrestrial planets (Venus, Earth and Mars) are similar in structure. This is a metal core with a mantle and crust, but the density of the Earth is higher than that of Mars. That is, the red planet consists of lighter elements. The Earth has a rocky core topped with liquid, as well as a silicate mantle and a solid surface crust. As for Mars, scientists are not yet completely sure about the structure of its core. It is known that the Martian core consists of iron and nickel, 16-17% - of sulfur. The mantle of Mars is only 1300-1800 km (for comparison: the thickness of the earth's mantle is 2890 km), and the crust covers 50-125 km (near the Earth - 40 km). The mantle and crust of Earth and Mars are almost identical in structure, but differ in thickness.
Surface Features
About 70% of the Earth's surface is covered by the waters of the oceans. According to one version, liquid water was part of the gas and dust cloud from which the Earth was formed. According to another, it appeared as a result of intense asteroid and comet bombardment, which the young planet underwent. Some scientists are of the opinion that water was released from hydrated minerals during the formation of the Earth. There are other hypotheses, and it is possible that all of them are more or less true.
Mars also once had liquid water, whichis a necessary condition for the development of life. But now it is a cold and desolate planet, rich in iron oxide, which gives the surface of Mars a red hue. Water is available in the form of ice at the poles. A small amount accumulates below the surface.
Mars and Earth are similar in landscape. On the planets there are mountains and volcanoes, canyons and plains, gorges, ridges, plateaus. The largest mountain on Mars is called Olympus, and the deepest abyss is the Mariner Valley. Both planets were subjected to meteor and asteroid attacks during their formation, but traces on Mars are much better preserved due to the lack of precipitation and air pressure. Individuals are billions of years old. On Earth, such formations gradually collapsed.
Atmospheric composition and temperature
Earth has a dense atmosphere divided into five layers. Mars has a very thin atmosphere and high pressure. The Earth's atmosphere consists mainly of nitrogen (78%) and 21% of oxygen (the remaining 1% is other substances in the gaseous state), and on the red planet the composition is represented mainly by carbon dioxide (96%), nitrogen and argon (almost 2 %, the remaining 1% - other gases).
It had an effect on the temperature. The average earth temperature is +14 degrees Celsius, maximum - 70.7 degrees, minimum - -89.2 degrees. It's much colder on Mars. The average temperature drops to -46 degrees Celsius, the minimum reaches -143 degrees, and the maximum planet warms up to 35 degrees. Besides, inthe atmosphere of the red planet contains a lot of dust.
Does Mars have a magnetic field
The magnetic field emanates from the core of the planet and creates a protective area that deflects electrical charges from the original trajectory. All charges from the Sun or another object do not threaten a planet that has such a protective field. Earth has a magnetic field, but does Mars have such protection? In this respect, the planet differs from the Earth.
What is the magnetic field on Mars? Once upon a time, a global protective shell around the planet existed, but eventually disappeared for a number of reasons. Now there is a magnetic field on Mars, it is extensive, but does not capture the entire surface of the planet. There are localized areas where the field is stronger. The radius of the magnetic field of Mars in some places is 0.2-0.4 Gauss, which is approximately equal to the earth's indicators.
Scientists are trying to explain these features today. It was possible to find out, for example, that the magnetic field of Mars and the structure of the planet are interconnected. The field is weak because of the nucleus. The Martian core is motionless relative to the crust, which weakens the effect of that same protective field.
Comparison of magnetospheres
The magnetic field of the Earth and Mars does not allow ionized particles of the solar wind and other cosmic particles to break through to the surface. The field literally protects life on Earth. The presence of the field is explained by the rotation of the metal core in the liquid outer part. The constant movement of electric charges leads to the formation of a magnetic field.
Bmore recently, it has been thought that the magnetic forces change significantly or contribute to the leakage of oxygen from the atmosphere. This may be true, because the magnetic poles can change places over time, they are not permanent. For 160 million years, the poles have changed about 100 times. The last time it happened was about 720,000 years ago, and when it will happen next time is unknown.
The magnetic field of Mars, in comparison with the Earth's, is insufficient to support life. But a potentially habitable planet must at least have a metallic core. This will create prerequisites for the formation of a magnetic field. As for Mars, there is a magnetic field (albeit "in the balance"), there is also a metallic core. This means that in theory, life on the planet either existed before, or is possible subject to some changes.
Field disappearance theories
Why is there no magnetic field on Mars? What catastrophe "broke through" the protective shell or what made the planet's metal core freeze? Is there any way to restore the field? Currently, scientists are considering two main theories of the disappearance of the magnetic field of Mars.
According to the first theory, the planet once had a stable magnetic field (like on Earth), but it was “pierced” by a collision with some large object. This collision stopped the core of the planet, the field began to weaken, and then completely lost its scale. And today some parts of the planet remain more protected than others.
The second theory completely contradicts the first. Mars could startexistence without a magnetic field. After the birth of the planet, the iron core in the center remained motionless for a long time and did not create magnetic impulses. But once the strongest magnetic field of the gas giant of the solar system Jupiter, capable of repelling not only small asteroids, but also huge objects, repelled some cosmetic body and sent it to Mars.
As a result of the influence of tidal force over several tens of thousands of years, convective currents appeared on Mars, which forced the core of the planet to move and provoked the formation of a magnetic field. As the cosmic body approached Mars, the field increased, but after several million years the body collapsed, so that the magnetic field gradually began to disappear. This is what researchers are now seeing.
Why NASA wants to create an artificial field
Does Mars have a magnetic field that would allow colonization of the planet? It is already clear that there is no such protective force, but scientists continue their research. Recently there was information that NASA wants to create an artificial magnetic field on Mars so that the atmosphere of the planet becomes denser. This should greatly simplify future exploration of the red planet and eventual colonization.
How to create a magnetic field on Mars? The authors of the report presented at the planetary conference proposed to deploy the module at a point between Mars and the Sun, where the spacecraft can remain almost indefinitely without the use of engines. On the module will includespecial magnets capable of creating a field of 1-2 tesla. Approximately the same magnets were installed at the Large Hadron Collider.
The field forms a "tail" that will cover the entire planet. This field will be very weak, but in theory this will be enough. According to NASA, after that, the planet's atmosphere will begin to thicken. Upon reaching a density equal to Earth, the average temperature on Mars will rise to +4 degrees Celsius, and the snow caps at the poles will melt. They have enough water to form moderate seas.
The cost of developing and maintaining a space module on Mars and where it will take energy from, the authors of the report bypass. In terms of cost-effectiveness, the method is not comparable with other projects. For example, there was an idea to produce SF6 gas on Mars. Even a small concentration of this gas is enough to create a greenhouse effect and protect the planet's surface from aggressive ultraviolet rays.
None of NASA's concepts has been fully proven to date. These are only assumptions based on the fact that the solar wind was the source of Mars' atmospheric losses. But the reasons for the loss of nitrogen are unlikely to be related to wind alone, so scientists are not in a hurry to implement projects, but continue research.
From the history of Mars exploration
The first observations of the planet were made before the invention of the telescope. The existence of Mars was recorded in 1534 BC by ancient Egyptian astronomers. They calculated the trajectoryplanetary movements. In the Babylonian theory, the position of Mars in the night sky was refined, and time measurements of planetary motion were obtained for the first time.
The Dutch astronomer H. Huygens was the first to map the surface of Mars. Several drawings showing dark areas were made by him in 1659. The existence of an ice cap at the poles was suggested by the Italian astronomer J. Cassini in 1666. He also calculated the period of rotation of the planet around its axis - 24 hours 40 minutes. It is correct, this result differs by less than three minutes.
Since the sixties of the last century, several AMS have been sent to Mars. Remote sensing of the planet from Earth continued with the help of orbiting and ground-based telescopes to determine the composition of the surface, study the composition of the atmosphere and measure the speed of light.
The magnetic field of Mars, which is five hundred times weaker than the earth's, was recorded by the stations "Mars-2" and "Mars-3" in Soviet times. The Mars 2 and 3 spacecraft were launched in 1971. The main technical problem was not solved, but scientific research was still advanced for its time.
The Americans launched Mariner 4 to Mars in 1964. The spacecraft took pictures of the surface and examined the composition of the atmosphere. The first artificial satellite of the planet was Mariner 9, launched in 1971. The search for life in soil samples was carried out in 1975 by two identical spacecraft as part of the Viking program. In the future, for a systematicthe study of the planet used the capabilities of the Hubble telescope.
Existence of life on Mars
The work of the planet's magnetic field, scientists are also studying in the sense that it may indicate the existence of life on Mars. Numerous observations gave rise to a real "Martian fever" around this topic at the end of the nineteenth century. Then Nikola Tesla observed some unidentified signal while studying radio interference in the atmosphere.
He suggested that it could be a signal from other planets, like Mars. He himself could not decipher the meaning of the signals, but he was sure that they did not arise by chance. Tesla's hypothesis was supported by the British physicist William Thomson (Lord Kelvin). In 1902, during a visit to the United States, he said that Tesla had indeed picked up the signal from the Martians.
Scientific hypotheses on this issue have existed for a long time. Methane and organic molecules have been discovered on Mars. Under the conditions of the red planet, the gas decomposes rapidly, so there must be a source of its occurrence. This may be bacterial activity or geological activity (given the fact that active volcanoes on Mars could not be found, this is not the cause of the gas).
Currently, the problems for sustaining life on Mars are the lack of liquid water, the lack of a magnetosphere, and an atmosphere that is too thin. In addition, the planet is on the verge of "geological death". The end of volcanic activity will finally stop the cycle of chemical elements between the inner part of the planet andsurface.
