What are the chances of Mars bearing life? Huge…one must say, because scientists have just discovered that life may exist beneath the layers of Mars- albeit, hidden.
Philosophers and scientists have often discussed and debated over the fact that life must have and may still exist on other planets in and out of our solar system; unaware to the humankind. One of the hottest topic of research in the scientific community is the existence of life on Mars, our very own Red Planet. One of the recent studies aims at understanding cross-contamination of planets during inter-planetary missions i.e. whether living organisms can be transferred to and from planets via spacecrafts. As observed from the Martian samples brought back during the inter-planetary missions, there is a strong possibility that some microbial species are indeed present on the surface of our nearest neighbour, dormant and invisible to us. With the increase in number of such inter-planetary missions cross-contamination is a strong and exciting and possibility.
However, Mars has an extremely low temperature of approximately 210K (or almost -60 degrees), and lacks a magnetosphere (the layer around the planet responsible for absorbing high radiations) of its own. Its surface is very much vulnerable to Ultra-Violet and galactic cosmic radiations. In such a scenario, it is difficult for most earthly species to survive on Mars. For example, if you were to be posted there without a protective gear, you would die of extreme cold as well as cancer pretty soon!
How then, would microbial species be able to survive there, even if any cross-contamination occurs? In order to understand this, a group of scientists from the North Western University along with others, replicated the conditions present in the Martian environment in a lab, and tested whether certain microbial species were able to survive them. Indeed, around 6 different types of microbial species were found to survive them, with a species called D. radiodurans being able to tolerate radiations as high as 140 kGy- this is equivalent to billions of years of radiations already present in the environment of Mars!
Now, this gives us a slight hint that some of these species may be alive on the Martian surface and buried deep between its rocks and crevices.
Amazing, isn’t it? Let’s implore more.
In an extremely dry climate such as that present on Mars, water levels inside cells decrease sharply, leading to the drying of the cell, and the cell enters into a stage of dormancy or hibernation. These cells are revived only when the external aqueous environment is restored. This strategy of longer-duration dormancy and subsequent revival could also be used by microbes to survive the harsh Martian conditions, as although the Martian surface is dry frequent meteorite impacts have given rise to periodic melts of the surface, which can help in the revival of the microbes. Further, in some species, such as the D. radiodurans mentioned above, there is presence of phenomenon known as: Holliday junctions, in which two homologous or identical DNA strands are permanently linked together, facilitating the process of DNA repair and survival of the species.
Thus, in all probability, DNA-based life forms may exist, and may even be able to survive and thrive on Mars. Thanks to the above study, we now have a slightly wider perspective on the never-ending search for extraterrestrial life and a higher possibility of finding our nearest neighbours!
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