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Results from the Gas Chromatograph Mass Spectrometer (GCMS) Experiment on the Cassini-Huygens ProbeThe Gas Chromatograph Mass Spectrometer was one of six instruments on the Cassini-Huygens Probe mission to Titan. The GCMS measured in situ the chemical composition of the atmosphere during the probe descent and served as the detector for the pyrolization products for the Aerosol Collector Pyrolyser (ACP) experiment to determine the composition of the aerosol particles. The GCMS collected data from an altitude of 146 km to ground impact. The Probe and the GCMS survived impact and collected data for 1 hour and 9 minutes on the surface. Mass spectra were collected during descent and on the ground over a range of mlz from 2 to 141. The major constituents of the lower atmosphere were confirmed to be N2 and CH4. The methane mole fraction was uniform in the stratosphere. It increased below the tropopause, at about 32 km altitude, monotonically toward the surface, reaching a plateau at about 8 km at a level near saturation. After surface impact a steep increase of the methane signal was observed, suggesting evaporation of surface condensed methane due to heating by the GCMS sample inlet heater. The measured mole fraction of Ar-40 is 4.3x10(exp -5) and of Ar-36 is 2.8x10(exp -7). The other primordial noble gases were below 10(exp -8) mole fraction. The isotope ratios of C-12/C-13 determined from methane measurements are 82.3 and of N-14/N-15 determined from molecular nitrogen are 183. The D/H isotope ratio determined from the H2 and HD measurements is 2.3x10(exp -4). Carbon dioxide, ethane, acetylene and cyanogen were detected evaporating from the surface in addition to methane. The GCMS employed a quadrupole mass filter with a secondary electron multiplier detection system and a gas sampling system providing continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns, a chemical scrubber and a hydrocarbon enrichment cell. The GCMS gas inlet was heated to prevent condensation, and to evaporate volatiles from the surface after impact.
Document ID
20080045296
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Niemann, Hasso
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Atreya, S.
(Michigan Univ. MI, United States)
Demick-Monelara, J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Haberman, J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Harpold, D.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kasprzak, W.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Owen, T.
(Hawaii Univ. HI, United States)
Raaen, E.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Way, S.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 24, 2013
Publication Date
July 9, 2006
Subject Category
Space Sciences (General)
Meeting Information
Meeting: AOGS meeting
Country: Singapore
Start Date: July 9, 2006
End Date: July 14, 2006
Distribution Limits
Public
Copyright
Other

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