of methane-producing and methane-consuming microorganisms. Even if rover missions determine that microscopic Martian life is the seasonal source of the methane, the life forms probably reside far below the surface, outside of the rover's reach. Potential sinks It was initially thought that methane is chemically unstable in an oxidizing atmosphere with UV radiation and so its lifetime in the Martian atmosphere should be about 400 years, but in 2014, it was concluded that the strong methane sinks are not subject to atmospheric oxidation, suggesting an efficient physical-chemical process at the surface that "consumes" methane, generically called a "sink". A hypothesis postulates that the methane is not consumed at all, but rather condenses and evaporates seasonally from clathrates. Another hypothesis is that methane reacts with tumbling surface sand quartz (silicon dioxide ) and olivine to form covalent Si – bonds. The researchers showed that these solids can be oxidized and gases are ionized during the erosion processes. Thus, the ionized methane reacts with the mineral surfaces and bonds to them. Images See also Atmosphere of Mars Climate of Mars Life on Mars Weather of Mars References Atmosphere of Mars Mars Astrobiology