Scientists Seek Scent of Life in Methane at Mars

This article was written in 2004, so it may be a bit out of date, but it is really interesting. According to this article, the presence of methane in an atmosphere is a likely indication of life, as it often is produced as the bi-product of biological processes like fermentation. Active volcanoes also may produce amounts of methane. Methane usually would not stay in an atmosphere more than a couple hundred years because it reforms into other compounds over time, such as water and carbon dioxide, so without a means of continuous production, methane often disappears out of the atmosphere. However, a probe from the European Space Agency, or ESA, designed to discover the presence of various molecules and particles through the reading of spectral analysis, discovered traces of methane in the atmosphere of Mars. Every atom or molecule we have encountered emits a specific wavelength of energy that takes up a known location in the color spectrum. By looking at these emissions, one can detect which elements are present. The probe picked up emissions that are known to have come from methane. Does this indicate the presence of life, or perhaps an active volcano on Mars, or could there be some other explanation?