From UPSC perspective, the following things are important :
Prelims level : Methanogens on saturn's moon
Mains level : Hunt for extra-terrestrial life
NASA’s Cassini spacecraft has detected an unusually high concentration of methane, along with carbon dioxide and dihydrogen, in the moons of Saturn by flying through their plumes.
What is the new observation?
- The spacecraft has found that Titan has methane in its atmosphere and Enceladus has a liquid ocean with erupting plumes of gas and water.
Are there methane-producing organisms on Earth?
- Most of the methane on Earth has a biological origin.
- Microorganisms called methanogens are capable of generating methane as a metabolic byproduct.
- They do not require oxygen to live and are widely distributed in nature.
- They are found in swamps, dead organic matter, and even in the human gut.
- They are known to survive in high temperatures and simulation studies have shown that they can live in Martian conditions.
- Methanogens have been widely studied to understand if they can be a contributor to global warming.
Could there be methanogens on Enceladus?
- We cannot conclude that life exists in the Enceladus ocean.
- It is the probability that Enceladus’ hydrothermal vents could be habitable to Earth-like microorganisms.
- There can be life hypotheses.
What other processes could have produced the methane?
- Methane could be formed by the chemical breakdown of organic matter present in Enceladus’ core.
- Hydrothermal processes could help the formation of carbon dioxide and methane.
- On Earth, hydrothermal vents on seafloors are known to release methane, but this happens at a very slow rate.
- This hypothesis is plausible but only if Enceladus was formed through the accretion of organic-rich material from comets.
- The results suggest that methane production from hydrothermal vents is not sufficient to explain the high methane concentration detected by Cassini in the plumes.
- An additional amount of methane produced via biological methanogenesis could match Cassini’s observations.