Mars and Venus are similar to 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 once rivers flowed there, which means that there was an atmosphere. Perhaps life on Mars existed long before the earth or would be possible after terraforming (changes in climatic conditions). This requires the presence of a magnetic field in Mars.
Dimensions, mass and orbits of the planets
The red planet is significantly smaller than the Earth in size. According to the calculations of scientists 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 at the equator is 0.53 Earth's, and the surface density is 37.6%.
The orbital paths of the planets are fundamentally different, but the sidereal revolution is similar. This means that the year on Mars lasts almost 687 days, and the day - 24 hours 40 minutes. The axial tilt is almost the same - 25 degrees at Mars, at the Earth two degrees less. This similarity means that seasonality can be expected from the red planet.
The 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 Mars. That is, the red planet consists of lighter elements. The Earth has a stone core, covered with a liquid top, as well as a silicate mantle and a solid surface crust. As for Mars, scientists are still not completely sure about the structure of its core. It is known that the Martian core consists of iron and nickel, 16-17% - from 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 the 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-dust cloud, from which the Earth was formed. According to another, it appeared as a result of intense asteroid and comet bombing, which was subjected to a young planet. Some scholars 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 true to one degree or another.
On Mars, too, once there was water in liquid form, which is a necessary condition for the development of life. But now it is a cold and deserted planet, on which there is a lot of iron oxide, which gives the surface of Mars a red tint. 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, ranges, plateaus. The largest mountain on Mars is called Olympus, and the deepest abyss is the Mariner Valley. Both planets during the formation were subjected to meteorite and asteroid attacks, but on Mars, traces were preserved much better due to the lack of precipitation and air pressure. The age of individuals totals billions of years. On Earth, such formations gradually collapsed.
Atmosphere Composition and Temperature
The earth has a dense atmosphere, divided into five layers. Mars has a very subtle and high pressure atmosphere. The Earth’s atmosphere consists mainly of nitrogen (78%) and 21% of oxygen (the remaining 1% is made up of other substances in a gaseous state), and on the red planet the composition is predominantly carbon dioxide (96%), nitrogen and argon (almost 2 %, the remaining 1% - other gases).
This had an effect on temperature. The average Earth temperature is +14 degrees Celsius, the maximum is 70.7 degrees, the minimum is -89.2 degrees. Mars is much colder. The average temperature drops to -46 degrees Celsius, the minimum reaches -143 degrees, and the planet warms up to a maximum of 35 degrees. In addition, the atmosphere of the red planet contains a lot of dust.
Does Mars have a magnetic field
A magnetic field emanates from the core of the planet and creates a protective region that deflects electric charges from the original trajectory. All charges from the Sun or another object do not threaten the planet on which there is such a protective field. Earth has a magnetic field, but does Mars have such protection? In this respect, the planet is different from Earth.
What is the magnetic field on Mars? Once the global protective envelope around the planet existed, but with time it disappeared for a number of reasons. Now there is a magnetic field on Mars, it is vast, but does not capture the entire surface of the planet. There are localized areas where the field is more pronounced. The radius of the magnetic field of Mars in some places is 0.2-0.4 Gauss, which is approximately equal to terrestrial indicators.
Scientists are trying to explain such 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 due to the core. 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 the 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 formation of a magnetic field leads to a constant movement of electric charges.
Recently, it is believed that 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 unstable. Over 160 million years, the poles have changed about 100 times. The last time this happened about 720 thousand years ago, and when it happens next time is unknown.
The magnetic field of Mars in comparison with the earth is insufficient to ensure life. But a potentially habitable planet should at least have a metal core. This will create the prerequisites for the formation of a magnetic field. As for Mars, there is a magnetic field (albeit "in the remainder"), there is a metal core. This means that in theory, life on the planet either existed before, or is possible subject to some changes.
Field Theories
Why is there no magnetic field on Mars? What catastrophe "broke" the protective shell or what caused the metal core of the planet to 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 (as on Earth), but it was "pierced" by a collision with any 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 is completely contrary to the first. Mars could begin to exist without a magnetic field. After the planet was born, the iron core in the center for a long time remained motionless and did not create magnetic pulses. But once the strongest magnetic field of the gas giant of the solar system of Jupiter, capable of repelling not only small asteroids, but also huge objects, pushed 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 flows appeared on Mars, which caused the planetary core to move and provoked the formation of a magnetic field. As the cosmic body approached Mars, the field intensified, but after several million years the body collapsed, so that the magnetic field gradually began to disappear. That is what is now being observed by researchers.
Why NASA wants to create an artificial field
Does Mars have a magnetic field that will colonize the planet? It is already clear that there is no such protective force, but scientists continue to research. Recently, there was information that NASA wants to create an artificial magnetic field on Mars, so that the planet’s atmosphere becomes denser. This should greatly simplify future exploration of the red planet and possible colonization.
How to create a magnetic field on Mars? The authors of the report presented at the planetological 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. The module will include special magnets that can create a field of 1-2 tesla. About the same magnets were installed at the Large Hadron Collider.
The field forms a “tail” that covers the entire planet. This field will be very weak, but in theory this will be enough. According to NASA, after this, the atmosphere of the planet will begin to thicken. Upon reaching a density equal to terrestrial, the average temperature on Mars will rise to +4 degrees Celsius, and the snow caps at the poles will melt. There is enough water in them so that moderate seas appear.
The authors of the report avoiding the cost of developing and maintaining the space module on Mars and where it will take energy from. By the ratio of cost and efficiency, the method is not compared with other projects. For example, there was an idea to develop 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 atmospheric losses of Mars. But the causes of nitrogen loss are unlikely to be associated with the wind alone, so scientists are not in a hurry to implement projects yet, but continue to research.
From the history of the exploration of Mars
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 also calculated the trajectory of the planet. In the Babylonian theory, the position of Mars in the night sky was clarified, for the first time, temporary measurements of planetary motion were obtained.
The map of the surface of Mars was first made by the Dutch astronomer H. Huygens. Several drawings in which dark areas were displayed, he made in 1659. The existence of an ice cap at the poles was suggested by the Italian astronomer J. Cassini in 1666. He calculated the period of rotation of the planet around its axis - 24 hours 40 minutes. It has the correct value; this result differs by less than three minutes.
Since the sixties of the last century, several AWS have been sent to Mars. Using orbital and ground-based telescopes, remote sensing of the planet from the Earth continued 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, 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 still turned out to be advanced for its time.
The Americans launched the Mariner 4 in 1964 to Mars. The spacecraft took pictures of the surface and investigated the composition of the atmosphere. The first artificial satellite of the planet was the Mariner-9, launched in 1971. The search for life in soil samples was carried out in 1975 by two identical spacecraft in the framework of the Viking program. Further, the Hubble telescope was used to systematically study the planet.
Existence of life on mars
Scientists study the work of the planet’s magnetic field in the sense that this may indicate the existence of life on Mars. Numerous observations have generated around this topic a real "Martian fever" at the end of the nineteenth century. Then Nikola Tesla observed some unidentified signal while studying radio interference in the atmosphere.
He suggested that this could be a signal from other planets, for example, from Mars. He himself could not decipher the meaning of the signals, but he was sure that they arose not by chance. The Tesla 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 caught the Martian signal.
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, gas quickly decomposes, so there must be a source of its appearance. Such may be the vital activity of bacteria or geological activity (given the fact that active volcanoes on Mars could not be detected, this is not the cause of the appearance of gas).
Currently, the problems for maintaining life on Mars are the lack of liquid water, the magnetosphere, and too thin atmosphere. 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 and the surface.