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Scientists have been trying to explore the possibilities of life in our solar system beyond planet Earth. A suitable candidate to explore is the Red Planet, Mars, as it is considered to be the most Earth-like planet. The advent of exploring Mars began from various Rover missions, leading to a better understanding of the Red Planet’s past.
Furthermore, the results of these past missions have suggested that Mars once had a wetter surface and thicker atmosphere, which could have sustained microbial life. Over the past few decades, the race to explore Mars has exponentially gained a tremendous pace. Many space agencies are gearing up for upcoming missions to explore the evolution of the atmosphere and surface of Mars. Some of the highlights include NASA’s Perseverance Mission slated for launch in July 2020.
To understand what potential key the Martian environment holds and the importance of such mobile missions, we spoke with Dr. Abhay Deshpande, a senior scientist (physicist) working for the Government of India, as well as with the Honorary Secretary of Khagol Mandal , a collective Benefit of astronomy enthusiasts who organize various sky observation programs, conferences and study tours.
Why is there renewed interest among the space community on Mars?
The Martian rock found in Antarctica.
(NASA / JSC / Stanford))
In recent times, there is a growing curiosity among everyone due to various interesting news that emerged from various Mars Missions. It all started more than three decades ago, when in the Alan Hill region of Antarctica a piece of rock was found and identified as Meteorite. It was identified that this special rock does not come from the asteroid belt, but from Mars.
About 17 million years ago, a meteorite hit the surface of Mars and created an impact crater. But the impact was so strong that, due to the intense blast wave, one of the Martian rocks probably exploded in space and continued to roam the solar system. By chance, 13,000 years ago, it was attracted to Earth and hit Earth near Antarctica. Luckily, this rock was found during an expedition in Antarctica and passed to NASA as a meteorite for sample studies.
The main increase in popularity of this famous meteorite occurred in 1996 when NASA declared that this rock, ALH 84001, was not an ordinary meteorite, but it is a rare sample that descends directly from Mars.
On careful analysis, it shows some structures that are probably traces of life from Mars! This surprising announcement sparked public interest and all nations began to wonder about sending missions to Mars. This started the race to Mars with NASA flying multiple missions to Mars with Pathfinder carrying “Sojourner” in 1997 becoming the first Rover on Mars with the ability to experiment. Spirit and Opportunity followed in 2004 and finally Curiosity in 2012.
Life on Mars has eluded us for so many years, but now we have confirmed that there was indeed water on Mars.
How similar / different is the atmosphere of Mars from that of Earth?
This illustration shows NASA’s Perseverance rover operating on the surface of Mars. Perseverance will land in the Jezero crater on the red planet.
(NASA / JPL-Caltech)
The main reason for not finding water, and therefore life on Mars, is that the atmosphere there is very thin compared to Earth. In fact, atmospheric pressure is less than 1% of that of Earth. Just to compare what it means, if you start to fly high and reach three times the height of the mount. Everest, then the pressure at that height will be slightly higher than that of the surface of Mars. Due to this very low pressure, the retention of water on the surface of Mars in liquid form is not possible. It evaporates quickly. One of the most striking features is that the normal value of the pressure on the surface of Mars is very close to the pressure of the Triple Point of water. This is very interesting for a slight variation in pressure, which makes the existence of water possible and will result in abundant liquid water. However, at present, the pressure is not enough to retain the water in liquid form.
From a compositional point of view, we know that more than 95% of the Martian atmosphere contains carbon dioxide (CO2). We know that CO2 is a good candidate to cause the greenhouse effect. It means that the heat leaving the planet can be trapped in the atmosphere and will help retain it on the planet. Since CO2 is a good and abundant greenhouse gas on Mars, it should be able to heat the atmosphere and the surface. Why do not you do it?
The answer is found if we look closely at other parameters. The temperature of a planet depends not only on the composition of the atmosphere but also on the atmospheric density, water content, inclination and eccentricity of the orbit. Many other parameters can also affect, but these are the main actors. The atmosphere is thin and there are no sea or large sources of water on the surface. The orbit is also more elongated compared to Earth, and therefore the seasonal variation in temperature is also severe. Day and night temperatures vary more than 70 degrees C. With such extreme variations, is the planet really habitable?
Why is it important to study current and ancient atmospheric conditions on Mars?
We have discussed in detail the current atmosphere. The key question for Mars is that there was life before and there will be life possible in the future. Both questions have to do with what was there in the past and what will be there in the future and, therefore, are key to understanding Mars.
We now believe that Mars once had a thicker atmosphere with plenty of water. The water beds on Mars are a remaining proof of the existence of flowing water. At some point, the atmosphere suddenly changed and decreased. Many gases escaped and CO2 became dominant. Efforts are underway to determine how long the thick atmosphere existed and answers may be found in upcoming missions.
Can we transform the Martian atmosphere and make it favorable for us?
The artist’s concept shows the Mars helicopter on the Martian surface.
(NASA / JPL-Caltech)
This idea has been under consideration for quite some time. The central theme is called “Terraforming”. The root of the idea lies in the fact that the atmospheric pressure on the surface of Mars is very close to the triple point of water. So if we can increase the pressure on the planet, then there is a possibility that water may exist on the planet in the future. Furthermore, if we increase the total CO2 content, then the greenhouse effect can further increase and lead to better conditions to stay on the planet.
But where would we get the CO2 from? The answer is that there is a large amount of CO2 trapped in the polar caps of Mars and also trapped along with various minerals near the ground. Now, if we are able to get all this CO2, then we can activate a mechanism and release this CO2 into the atmosphere. The question was how much CO2 will be found. NASA’s mission, Mars Reconnaissance Mission, Mars Odyssey, and MAVEN, were used to study the problem.
For the region of the polar caps, the scheme could spread the dust on the caps to absorb more solar radiation. Otherwise we can use explosives to evaporate the caps and CO2 will be released into the atmosphere. If full caps are melted to obtain the maximum CO2, the pressure will increase to double the current pressure.
To trap CO2 near the ground, we can burn it. Imagine that we are mining to a depth of almost 100 meters and heating the entire surface of Mars. This will help release the gas into the atmosphere. Rover data from previous missions predicted the distribution of minerals around the surface. Based on these estimates, it was concluded that this Herculean task of mining around you will increase the pressure to 5% of Earth’s pressure. So if we manage to do all these complex things, we can raise the Martian pressure from the present value to 610 Pascals (or 4.57 mm-Hg) to 7092 Pa (or 53.2 mm-Hg). However, this is only 7% of Earth’s pressure, while at the location of Mars for water to survive freely in liquid form on the surface, almost the same pressure is needed as on Earth. Therefore, it was concluded that even if we are able to squeeze whole CO2 anywhere on the surface of Mars and we are able to release it into the atmosphere, exercise will not help us obtain favorable conditions on the Martian surface.
However, the idea of transforming the entire habitat of Mars to be suitable is a symbol of human efforts to colonize new planets. Unfortunately, we have extensive experience in totally changing the habitat around us. In the past 50 years, we have degraded our environment so rapidly that the concept of altering the course of nature as we wish is no longer considered novelty. We have done it here and we will surely do it there!
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This article was produced in collaboration with Khagol Mandal.
