Gas chromatography in space exploration - Capillary and micropacked columns for in situ analysis of Titan's atmosphere

The gas chromatography-mass spectrometry (GC-MS) experiment using capillary and micropacked columns is one of the main instruments of the Huygens prob e of the Cassini-Huygens mission launched in October 1997 for the in situ a nalysis of Titan's atmosphere. Because of its composition and density the s tudy of the atmosphere of Titan is of primary interest for understanding th e prebiotic chemistry in the primitive Earth's environment. We describe her e the GC subsystem of the GC-MS instrument with a particular emphasis on it s exobiological implications. The GC subsystem includes three columns which operate in parallel: a carbon molecular sieve micropacked column is used f or the separation of CO, N-2 and other permanent gases; a capillary column will separate the light hydrocarbons up to C-3; a second capillary column w ith a cyanopropyl dimethyl polysiloxane stationary phase will analyze the C -4-C-8 hydrocarbons and the low-molecular mass nitriles up to C-4. These he avier compounds will mainly result from the pyrolysis of the aerosols prese nt in the atmosphere of Titan by using the aerosol collector pyrolyser inst rument. (C) 1999 Published by Elsevier Science B.V. All rights reserved.