On the colonisation and alteration of stony meteorites by microorganisms from the Nullarbor Plain, Australia: Applications for future astrobiology exploration on Mars TAITALASTAIR WILLIAM 2017 Meteorites have very narrow chemical and isotopic ranges, which make them ideal ‘standards’ with which to remove ambiguity associated with finding positive biosignatures in complex and incompletely understood environmental settings, such as the surface of Mars. This thesis examines meteorites from the Nullarbor Plain, Australia, to see whether they can be colonised and altered by microorganisms from the soil in a detectable way. This technique could be used to explore for life on Mars, where meteorites have already been found.