Methane — a colorless substance, without smell or taste, so common in the Solar System that is found in large amounts in the atmosphere of Jupiter and Saturn, forms a whole seas and lakes on Titan, and, possibly, covers the surface of the distant dwarf planet Sedna. On Earth this gas is most often used in industry, for example, for the manufacture of rocket fuel. What else might be interested in this stuff and why scientists believe that methane can solve the mystery of the origin of life on the planet?
How is the methane?
Researchers have long noticed the methane released from deep-sea vents. But while gas is abundant in the atmosphere, where it is produced by living beings, the source of methane on the sea floor was a mystery.
The scientists were able to perform more than 160 samples of rocks found at the bottom of the ocean. Almost every sample contained traces of methane, which helped the researchers to prove the fact that the scale of the oceanic deposits of organic matter is many times the amount of methane contained in the atmosphere of the planet.
But as methane in such quantities may be on the bottom of the ocean?
Despite the fact that methane is considered an organic substance that scientists have isolated a 4 fundamentally different modes of its origin in nature. Thus, biogenic methane is formed during the chemical transformation of organic matter, the abiogenic methane is formed by chemical reactions between some inorganic compounds, bacterial methane is a result of microorganisms that is formed as a thermogenic in nature as the result of thermochemical processes.
In order to solve the mystery of the origin of the vast reservoirs of methane beneath the ocean, the researchers analyzed found on the multi-kilometer depth of the rocks using Raman spectroscopy.
Raman spectroscopy is a method of investigation of matter, in which through needed to study the sample is passed the beam of light dissipated upon contact with the breed. The rays received in the course of the experiment, are collected into a single beam and passed through a special filter that separates the weak from the strong rays. It is the weak rays are called romanovskij, which allow to judge about the structure of a substance.
As a result of the experiment revealed that in all samples of deep-sea rocks containing large amounts of various minerals and gases which are formed due to the movement of sea water in the trap of a hot olivine (or magma). When olivine freezes, the water as a result of serpentinization is converted into hydrogen and methane.
In other words, the huge methane pools on seafloor are not formed by living organisms, but as a result of geological processes.
Why methane is a sign of the presence of life?
Astronomers distinguish 4 markers of potentially habitable exoplanets. In addition to the presence of methane in the atmosphere, scientists are also searching for water, carbon dioxide and oxygen. If water, oxygen and carbon dioxide all can be more or less clear, why the scientists needed the methane?
The fact that the methanogens were the first living organisms developed in the primary broth of the Earth. Using methane compounds for energy, these microscopic organisms are given the opportunity for the emergence and evolution of other inhabitants of the planet.
Despite the fact that the presence of all markers has yet been found on any of the open planet, awareness of the fact that life on Earth originated from methane, allows the researchers to take a new look at the question of the possible presence of life on other planets.