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Do you know? Why is the atmosphere of Mars mainly composed of carbon dioxide?
Mars is one of the fascinating planets in the solar system. Its unique climate and atmospheric composition have triggered countless scientific explorations and studies. Compared with the Earth, the atmosphere of Mars is thin and cold. It is mainly composed of carbon dioxide, accounting for about 95% of the composition. Unlike the stable environment of the Earth, Mars' climate changes and changes in the composition of its atmosphere show the evolution of the planet, which has a profound impact on the search for extraterrestrial life and future human exploration.
The atmosphere of Mars contains carbon dioxide (95%), molecular nitrogen (2.85%), and argon (2%), with trace amounts of water vapor, oxygen, carbon monoxide, hydrogen, and noble gases.
The average air pressure on Mars is 610 Pascals (approximately 0.088 psi), which is only 0.6% of Earth's air pressure. This thin atmosphere cannot support the existence of liquid water on the surface of Mars, which is one of the biggest challenges in finding water sources on Mars. However, scientists speculate that early in Mars' history, its atmosphere may have been much thicker than it is now, enough to support the existence of liquid water.
The average surface temperature of Mars is about -60 degrees Celsius, and carbon dioxide in the lithosphere is partially frozen in winter, which causes significant changes in air pressure.
During the cold winter, the density of Mars' atmosphere will drop by about 25%, which will better highlight Mars' seasonal changes. Further observations also revealed that the climate of Mars is rapidly changing. The temperature range ranges from -75 to 0 degrees Celsius, showing the extreme day and night climate of Mars.
Although Mars' atmosphere is mainly composed of carbon dioxide, its greenhouse effect is much weaker than that of Earth, only 5 °C, while Earth's can reach 33 °C.
The reason for this phenomenon is the low density of the Martian atmosphere and the extremely scarce water vapor content. In addition, the frequent dust storms and dust cyclones on Mars add a lot of mystery to this dry planet. Every about 5.5 Earth years, a circular dust storm occurs on Mars, causing drastic changes in its surface climate. The mechanism of dust storm formation is not yet fully understood. Scientists speculate that it may be slightly related to the gravitational pull of Mars' two satellites.
The Martian atmosphere is oxidizing, and photochemical reactions in the atmosphere will oxidize organic matter and convert it into carbon dioxide or carbon monoxide.
Although the recent ExoMars Trace Gas Orbiter failed to detect methane in the atmosphere of Mars, previous observations have found the presence of methane, adding a hint of possibility to the study of whether life exists on Mars. However, the interpretation of these methane data remains the subject of intense scientific debate.
The evolution of the Martian atmosphere and its impact
As Mars evolved, the quality and composition of its atmosphere also changed dramatically. The early thicker and warmer climate environment once provided the existence of liquid water on Mars. However, according to various observations and determinations of atmospheric composition, Mars' atmosphere has gradually changed over its long geological history, in part due to the escape and loss of light components such as hydrogen. Many scientists believe that Mars' atmosphere was once rich enough to sustain water.
The ratio of nitrogen to argon on Mars shows that the presence of these gases is closely related to the mass-selective escape process.
Phenomena such as the diffusion escape of nitrogen and the escape of hydrogen, coupled with Mars' current relatively low escape velocity, mean that Mars is still losing its atmosphere. Observations in recent years have shown that the dynamic escape rate of hydrogen will be adjusted by dust storms on Mars, demonstrating the complexity of climate interactions on Mars.
Main components of the Martian atmosphere
Currently, the proportion of carbon dioxide in the atmosphere of Mars is quite high. However, due to low air pressure and insufficient water vapor content, Mars' greenhouse effect is very weak. While water vapor plays an important role in Earth's greenhouse effect, Mars can only form similar clouds of water ice.
The atmosphere of Mars contains nitrogen (about 2.6%) and argon (about 1.9%) on average. The existence of these gases is also affected by the geological history of Mars and the external environment.
In addition to carbon dioxide, nitrogen and argon, the Martian atmosphere also contains trace amounts of oxygen and water vapor. The seasonal distribution of water vapor has allowed scientists to make a major breakthrough in exploring the early climate of Mars and whether it was suitable for biological existence.
The extreme environment and unique climate of Mars make it an object of great scientific research value. As future exploration missions proceed, can we truly understand the past and future of the red planet, and then find more distant simulations of mankind? What about the hesitation?
