Free Astronomy Magazine March-April 2015

ASTROBIOLOGY C uriosity’s path from Bradbury Landing, its land- ing point, to Yellowknife Bay, where, down- stream of Glenelg, it photographed possible traces of fossils of bacterial colonies. The num- bers shown along the route indicate the Martian days (sols) elapsed from its landing. [NASA/JPL-Cal- tech/University of Arizona] billions of years ago. According to NASA scientists involved in the planning and im- plementation of the mission, that area showed particularly promising characteri- stics for achieving the primary objective assigned to Curiosity, namely to ascertain the potential habitability of Mars in a di- stant past. To this end the rover has been equipped with a series of scientific instruments allo- wing it to recognize in the atmosphere and soil of the planet all those chemical ele- ments that are notoriously linked to life, either because they constitute its building blocks, or because in certain situations they represent the by-product of biological ac- tivities. Particularly relevant in this sense are the recent discoveries of some impor- tant organic compounds (carbon-based molecules), among which methane (CH 4 ), present in the atmosphere and indicative of possible forms of metabolism. Thus far, though, only interesting clues, but nothing having closely to do with hy- pothetical present or past Martian forms of life, given that organic compounds can also be produced through abiotic processes. Curiosity remained in the Yellowknife Bay area for almost a year, where it studied some layered structures collectively named the “Yellowknife Bay formation”, consi- sting of three different rock outcrops, lo- cated at different levels: Glenelg Member (1.7 meters thick), Gillespie Lake Member