Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury. Also known as the "Red Planet," Mars is the only other planet besides Earth considered to have the potential to support life. The atmosphere of Mars consists of four layers: exosphere; the upper atmosphere, which has very high temperature caused by heating from the Sun; middle atmosphere, where Mars' jetstream flows; and lower atmosphere, which is generally a warmer region. The atmospheric pressure on the surface of Mars averages 600 Pa, which is 0.6% of Earth’s atmospheric pressure (101.3 kPa). Additionally, the atmospheric mass of Mars is only 25 teratons, compared to Earth’s 5,146 teratons. However, like Earth, Mars’ atmosphere is composed of several gases including carbon dioxide, argon, nitrogen, as well as traces of other gases such as oxygen and carbon monoxide.
Atmospheric Composition Of Mars
Carbon dioxide (CO2) is the major component of Mars’ atmosphere, accounting for approximately 95.32%. Each of the planet's poles remains in continual darkness during its hemisphere's winter, and the surface becomes so cold that up to 25% of the atmosphere's carbon dioxide condenses into solid carbon dioxide ice. When the poles are exposed to sunlight, especially during summer, the dry ice sublimes back to the gaseous form. The condensing and subliming of carbon dioxide lead to significant annual variations in atmospheric composition and pressure near the Martian poles. The proportion of carbon dioxide on Mars is much higher compared to Earth because plants on Earth convert carbon dioxide into oxygen, resulting in higher amounts of oxygen and lower levels of carbon dioxide. Research conducted by NASA suggests that the atmosphere of Mars was once denser, thicker, wetter, and composed of carbon dioxide. This type of atmosphere would have raised the temperature above the freezing point of water, resulting in running water that may have formed several channels and outflow valleys that characterize the planet's surface.
The atmosphere of Mars contains more argon (Ar) than other planets, accounting for about 1.6%, while Earth's atmosphere contains less than 1%. The amount of argon in Mars’ atmosphere is constant since the gas does not condense. However, its relative concentration can change depending on whether carbon dioxide moves in or out of the atmosphere. According to recent satellite data, atmospheric argon increases in the South Pole during autumn and decreases during spring.
Nitrogen (N) is the second most abundant gas in the atmosphere of Mars, accounting for about 1.9%. However, researchers think the planet contains more nitrogen, some of which may be hidden and stored in Martian soil in the form of nitrate salt. However, scientists have only measured the amount of nitrogen within the atmosphere. Based on the analysis of meteorites on Mars, its atmosphere has rich isotope 15N.
Traces of methane (CH4) also exist in the atmosphere of Mars. Methane on Mars quickly breaks down due to its chemical reaction with other gases, as well as radiation from the Sun. However, the believed persistent presence of methane in Mars' atmosphere suggests the existence of a source that continuously replenishes the gas.
Learn about some fascinating facts about Mars in this article.