The "Red Planet" Mars is the fourth planet in the solar system and the second smallest planet after Mercury. Mars is a terrestrial planet with a thin atmosphere. It consists of various geological features like the impact craters of the Moon and the valleys, deserts, clouds and polar ice caps like the Earth.
The atmosphere of Mars used to to thick in the past which could support liquid water on the surface. But over the time the atmosphere of Mars kept loosing into space which still continues today. The present day atmosphere of Mars is thin which cannot support liquid water and life as we know it.
The climate on Mars is influenced by various factors including the polar ice caps, water vapor and dust storms. At times, the dust storms on Mars can cover the whole planet, lasting for months. These planet wide dust storms occur every 5.5 Earth-years. However, the mechanism that cause such storms is still unknown.
What is the atmosphere of Mars composed of?
The atmosphere of Mars is 100 times thinner than the atmosphere of Earth, mainly carbon dioxide. The resulting air pressure on the surface of Mars is only about 610 pascals which is less than 1% of the atmospheric pressure on Earth.
The composition of the atmosphere of Mars is as follows :
- Carbon dioxide : 95.32 percent.
- Nitrogen : 2.6 percent.
- Argon : 1.9 percent.
- Trace amount of : water vapor, oxygen, carbon monoxide, hydrogen and other noble gases.
Weather and Climate on Mars :
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| Martian sunset by Spirit rover at Gusev Crater (May 2005) |
Early in its history, Mars had a thick atmosphere suitable for liquid water to flow on the surface. This is supported by the orbital images of the rivers and oceanic boundaries on the barren surface of Mars. At the same time, several rovers have found rock on Mars with water soaked in them(primarily hematite and clay.) However, due to some reason the thick atmosphere of Mars thinned to what it is in present.
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| Photomicrograph by Opportunity showing a gray hematite concretion, nicknamed "blueberries", indicative of the past existence of liquid water. |
The leading theory for the loss of atmosphere of Mars is that Mars' low gravity combined with its lack of magnetosphere made it vulnerable towards the solar wind - stream of highly energetic particles from Sun. The resulting pressure from the solar winds stripped the Martian atmosphere and took the lighter molecule with it. Other theories suggest that a large body collided with Mars in the past which lead to the loss of atmosphere.
Owing to its larger distance from Sun, Mars receives less solar energy that Earth, resulting in lower effective temperature (about 210 K) compared to Earth's (about 252 K). Even though the Martian atmosphere is composed of 95% carbon dioxide, the greenhouse effect on Mars (about 5°C) is much lower than Earth's (about 33°C). This is attributed due to less amount of other greenhouse gases.
The temperature on Mars varies greatly. The temperature can range between minus 143 degree Celsius near the poles to a comfortable 35 degree Celsius near the equator during midday.
The two polar cap of Mars contains frozen carbon dioxide mixed with water ice. During the pole's winters, the region is in darkness which leads to decomposition of 25-30% of atmospheric carbon dioxide into dry ice. This carbon dioxide sublimes when exposed to sunlight which leads to dust storms, winds and cloud formation. Clouds containing water ice have been photographed by Opportunity in 2004.
Due to lack of magnetosphere and thin atmosphere, the surface of Mars is bathe by solar radiation which has rendered the Martian surface highly contaminated. However, the amount of radiation which a astronaut will experience in a single mission to Mars is comparable to the radiation guidelines for astronauts of European Space Agency, although it is more than that of NASA's.
Mars has an oxidizing atmosphere, which means compounds like methane are highly unstable in the Martian atmosphere. Methane would break down due to UV radiation or react with other gases in the Martian atmosphere. However, many ground based telescopes and rovers have detected methane in the atmosphere of Mars. This implies that there must be a source that continuously replenishes methane in the atmosphere.
The concentration of methane in the atmosphere of Mars fluctuates between 0.24 ppb (parts per billion) to 0.65 ppb. However, in 2014 Curiosity rover detected a big spike in the concentration of methane in the atmosphere. During the late 2013 and early 2014 data take during two months had average methane concentration of 7.2 ppb.
The concentration of methane in the atmosphere can be due to non biological processes involving reaction between water in rocks and some gases. However, methanogenic microbial life in the subsurface of Mars is a potential source of methane.
NASA's Perseverance rover (Mars 2020 rover) is set to go to Mars to study potential past or present life and samples for future retrieval.
What do you think? Can there be life on Mars? Share in the comments down below.
Owing to its larger distance from Sun, Mars receives less solar energy that Earth, resulting in lower effective temperature (about 210 K) compared to Earth's (about 252 K). Even though the Martian atmosphere is composed of 95% carbon dioxide, the greenhouse effect on Mars (about 5°C) is much lower than Earth's (about 33°C). This is attributed due to less amount of other greenhouse gases.
The temperature on Mars varies greatly. The temperature can range between minus 143 degree Celsius near the poles to a comfortable 35 degree Celsius near the equator during midday.
The two polar cap of Mars contains frozen carbon dioxide mixed with water ice. During the pole's winters, the region is in darkness which leads to decomposition of 25-30% of atmospheric carbon dioxide into dry ice. This carbon dioxide sublimes when exposed to sunlight which leads to dust storms, winds and cloud formation. Clouds containing water ice have been photographed by Opportunity in 2004.
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| Water-ice clouds formed in the vicinity of the Arsia Mons volcano. The image was taken on 21 September 2018, but similar cloud formation events had been observed in the same site before. Photo credit: ESA |
Due to lack of magnetosphere and thin atmosphere, the surface of Mars is bathe by solar radiation which has rendered the Martian surface highly contaminated. However, the amount of radiation which a astronaut will experience in a single mission to Mars is comparable to the radiation guidelines for astronauts of European Space Agency, although it is more than that of NASA's.
Possibility of life on Mars :
In its early days, Mars could have harbored life. Some speculate that life may still be present on Mars. Oceans may have once covered the surface of Mars, which would have provided a good environment for life to develop.
Although, the present day Mars is barren, scientist suggest that there could possibly be water below the surface of Mars, which would provide a potential refuge to any existing life forms. And studies have shown large deposits of water ice below the Martian surface.
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| Artist's impression of how Mars may have looked four billion years ago. Image credit : ESO |
Mars has an oxidizing atmosphere, which means compounds like methane are highly unstable in the Martian atmosphere. Methane would break down due to UV radiation or react with other gases in the Martian atmosphere. However, many ground based telescopes and rovers have detected methane in the atmosphere of Mars. This implies that there must be a source that continuously replenishes methane in the atmosphere.
The concentration of methane in the atmosphere of Mars fluctuates between 0.24 ppb (parts per billion) to 0.65 ppb. However, in 2014 Curiosity rover detected a big spike in the concentration of methane in the atmosphere. During the late 2013 and early 2014 data take during two months had average methane concentration of 7.2 ppb.
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| Potential source and sinks of methane on Mars. |
The concentration of methane in the atmosphere can be due to non biological processes involving reaction between water in rocks and some gases. However, methanogenic microbial life in the subsurface of Mars is a potential source of methane.
NASA's Perseverance rover (Mars 2020 rover) is set to go to Mars to study potential past or present life and samples for future retrieval.
What do you think? Can there be life on Mars? Share in the comments down below.
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