Why Mars didn’t survive?
To answer that question we have to understand what is important for survival to organisms. We can compare with our beloved Earth. We have water, atmosphere, rocky surface, required minerals, magnetic field, ozone layer, complex molecules and the right temperature. These factors lead to the basic needs for an organism to survive. Our neighbour Mars has few of these properties at a much lower proportion. It is believed that Mars and our sister Venus had these properties but were stripped of them over millions of years.
Water is an essential part of reactions as it is a good solvent for chemical reactions. Nowadays most of the water on Mars has been lost and the left over is impure. Liquid water cannot be present at such low pressures presented by the thin Martian atmosphere. Ox-bows and many other examples of water movement have been noticed on the Martian surface by the rovers sent to mars including glaciers towards the poles, with seasonal flows as shown in the image below.
However, in our oceans we would find a lot of limestone as excess Co2 from the atmosphere dissolves into the ocean creating an equilibrium. This forms carbonic acid, which undergoes several reactions to form limestone in which fossils are embedded overtime. However, the rovers made an unexpected discovery of sulfur deposits in dried up riverbeds. This meant with Co2 the Martian atmosphere was also polluted with So2 . Sulfuric acid formed which was far more acidic than carbonic acid which lowered the pH drastically, preventing several basic reactions in this pH. However overtime if life prospered this problem could have been tackled but due to several unfortunate events, we don’t have neighbours.
One of the most important factors for life is the atmosphere, which prevents harmful cosmic radiation from harming us and contains the most important gas known as oxygen for us to respire. It also has other gases, which are important like Co2 without which our planet would be freezing to about -50C, and it is also the gas which plants use for photosynthesis. Atmosphere dilutes oxygen, has the ozone layer to protect us from harmful UV rays, and has many other beneficial implications. However, Mars had this but lost it due to a process known as Sputtering.
Without required gases or molecules, organisms cannot survive. At half the diameter, lower density and small core, Mars’s core cooled fast which resulted in loss of magnetic field.
Thus unlike Earth, Mars had no defensive mechanism against the solar wind and radiation. Our magnetic field deflects the solar wind,which have a large magnetic field, which is received from the sun’s massive magnetic field. However as Mars lost its magnetic field 4 billion years back, it was bombarded by large amount of radiation. The high-energy photon beams and other higher frequency radiation ionized the molecules in the atmosphere. This happens at much lower rate on our planet as our atmosphere helps to block the radiation and most gas is near the surface so cannot escape as high escape velocity is required. Solar wind would use its magnetic force to create an electromagnetic effect on these ionized molecules and carry them away from the planet. As mars has a lower mass, it has a lower escape velocity than Earth according to Newtonian Equations of gravitational forces. However, large molecules like Co2 needed lots more energy to achieve this velocity. However, over the years, some molecules reached the required energy level and during solar flares (which were 20 times more violent in the early stages of Sun), helped these molecules escape. Till this day 100g of molecules is lost to solar wind every second! The number was larger when Mars had a thriving atmosphere. This meant that there was not enough pressure for water so no marine organism lived. All the life forms would have died without the atmosphere, other than tough bacterial life, which still might exist near sulfuric vents known as extremophiles. These species can survive a variety of temperatures even upwards of 100C and can breathe Hydrogen Sulfide. Other than these main reasons, there are other issues but the loss of magnetic field was by far the most important and those issues would elongate this blog.
For now, let us hope that large figures like Elon Musk can colonize Mars and take another great leap for mankind.
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