Schröder C (2015) Mössbauer spectroscopy in astrobiology. Spectroscopy Europe, 27 (2), pp. 10-13. http://www.spectroscopyeurope.com/articles/55-articles/3467-moessbauer-spectroscopy-in-astrobiology
First paragraph: Astrobiology is the study of the origin, evolution and distribution of life in the universe. As such, the field begins very much on Earth before venturing out to search for life in space. This search is guided by a follow-the-water strategy because water is the most important prerequisite for the carbon-based life we know of from our own example. Two of the hot spots for this search within our Solar System are our neighbour Mars and Jupiter's icy moon Europa. Mars continues to reveal more and more morphological and mineralogical evidence for abundant water on its surface more than 3.5billion years ago -a time when life is thought to have begun on Earth. While the planet has become cold and arid, whiffs of methane show that it is still active in some ways today. A biological origin of the methane has not yet been ruled out and there may be niches left on Mars that would support microbial life at the present day. Europa, on the other hand, is thought to carry a sub-surface ocean covered by many kilometres of solid ice which might be able to sustain life.
Spectroscopy Europe: Volume 27, Issue 2