Year: 2018-19
Aparna RVM
Grade: 12
City: Kozhikode, Kerala
"Ever imagined the vastness of space? What if there is a planet just like home, hiding somewhere in the corners of the cosmos? The curious question of the possibility of extraterrestrial life drives humanity to dive into the wonders of the cosmic ocean. I think Saturn’s moon Titan with liquid hydrocarbon lakes, underground oceans, sand dunes and cryovolcanoes is the best place to start our voyage.
It’s the liquid lakes and thick and chemically active atmosphere that help Titan stand out from the crowd. According to the observations made by Cassini spacecraft, almost 2% of Titan’s total surface is covered in liquid. Even if Titan is blessed with water, it’s rock-hard at about 94K. Instead Titan’s lakes are composed of liquid methane. Moreover the hydrological cycle, seasonal weather patterns etc. are analogous to that of Earth. The alluvial fans observed by Cassini’s SAR instruments tell us about the intense rainfall there. Cassini mission has also found that Titan has a liquid ocean composed of water and ammonia at its core-mantle boundary.
Scientists believe that life could still be possible in Titan, even in the absence of water. The discovery of ‘carbon chained anions’, the building blocks of complex organic molecules, in Titan’s atmosphere was the turning point of the journey. Titan could be home to a completely new set of methane based organisms, with different cell structure. This type of organisms will have a rigid and flexible outer membrane called ‘azotosome’ (or ‘nitrogen body’) that replaces the liposomes seen in organisms of our planet. They can withstand the harsh methane atmosphere and the bitter cold. Studies conducted by NASA shows that Acrylonitrile (known as vinyl cyanide); an organic compound found in cryogenic methane, showcased the key features of a cellular membrane, like its resistance to decomposition, and can possibly form an azotosome. A miniature pulsed proton-NMR spectrometer that can function even at 77K, could be used in future missions for the analysis of liquid hydrocarbons.
Cryovolcanoes are the significant source of atmospheric methane. The lava is composed of water and ammonia. It gives us a great insight on Titan’s interior. When Tholins, the organic materials produced when gases react with cosmic radiations, mix with this liquid water, they are likely to form aminoacids. We could also include techniques like Radar interferometry that investigates more about the topography of these volcanoes.
Likewise, Sand Dunes that stretch thousands of kilometers are repositories of organic materials. The grains of sand are not made up of silicates as on Earth, but scientists believe that they are tiny water crystals, coated with hydrocarbons. Even comparing the pattern of the dunes in both worlds helps us reveal the wind patterns on Titan.
Titan is truly a land of surprises. Learning more about Titan could give us a golden ticket to explore new forms of life, and even get clues on beginning of earth. Studying methane lakes and cryovolcanoes may help us rewrite the slogan ‘water is life’ with a groundbreaking concept ‘life can evolve anywhere!'"
