Free Astronomy Magazine May-June 2016

ASTRONAUTICS dedicated to the study of atmospheric gases and one instrument for mapping the sub- surface water ice. The orbiter's main task is to unravel the mystery of the presence of small amounts of methane in the Martian atmosphere. Such presence has been con- firmed as from 2009, both by previous probes and by observations from Earth. Since this is a molecule with a comparative- ly short life on geological scale and since it is generally the result of the decomposition of various organic substances in the ab- sence of oxygen, as well as the by-product of living beings’ metabolism, it goes with- out saying that discovering the origin of such presence is extremely interesting. The release of methane into the Martian atmosphere appears to be varying with the seasons and could be associated with rela- tively restricted surface regions. For all we know today, the source of that gas could be a natural geological process, such as the oxidation of certain minerals exposed to the atmosphere, or another type of chemical reaction, or indeed the biological activity of basic forms of life. From an altitude of about 400 km above the Martian surface, the TGO will be able E xoMars Trace Gas Orbiter (TGO) and Schia- parelli (attached to its top) dur- ing a vibration re- sistance test. [ESA – S. Corvaja] Below, an over- view of the two probes, showing the position of the TGO’s four groups of instru- ments. [ESA/ATG medialab]