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Huygens Probe Gas Chromatograph Mass Spectrometer
(GCMS)
Jianfeng Xie ASTR/GEOL/ATOC 5835
11/15/2011
Science ObjecKves
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Titan's atmosphere
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Titan’s atmosphere hypothesized by scienKsts
Nitrogen (N2) and methane (CH4) were well established as the major atmospheric consKtuents aUer the Voyager 1 encounter
Voyager 1 spacecraU (1977,1980)
Cassini-‐Huygens Probe
• Cassini launched: October 15, 1997 • Arrives at Saturn: July 1, 2004 • Huygens Probe Release: December 25, 2004
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• Entry and Landing: January 14, 2005 • Probe mass: 318 kg • 6 instruments on the probe • Probe and instruments survived impact • Sent data for 90 minutes on surface
GCMS locaKon in Probe
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GCMS Outlet
GCMS Inlet
GCMS ConfiguraKon
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Exhaust Tube
Pressurized Housing
Moun?ng Flange
Outlet Break off
Thermal Inlet Isolator
Inlet Break off
Ion Pump HV Supplies
Center Sec?on
Prom Board
Other Instruments
• ONMS – The Pioneer Venus orbiter neutral mass spectrometer (1978)
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• GPMS – Galileo Probe Mass Spectrometer (1989)
• NMS – Planet-‐B Neutral Mass
Spectrometer (1998)
GC and MS
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GC Column
• Gas Chromatograph (GC)
• Quadrupole Mass Spectrometer (MS)
Ion Source
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Gas Chromatograph
Mass Spectrometer
Ion Source
Ion Source
Ion Lens Assembly
Filament Assembly
Electron Beam Lens Assembly
Electron Beam energy: 25 eV and 70 eV
Sample CollecKon and Processing
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GCMS Cutaway View
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Other GCMS Components
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ACP (Aerosol Collector Pyrolyzer)
Geder Pump
Hydrogen Reservoir
Pressure Regulator
Enrichment Cell
Microvalves
Gas Flow
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GCMS CharacterisKcs • Quadrupole mass spectrometer with a dual, secondary electron
mul<plier detec<on system; 5 electron impact ion sources; and 3
gas chromatographic columns
• Sample trapping and enrichment system
• 6 ion pumps and 8 geDers
• 17.3 kg mass, 41 W average power
• Mass range 2-‐141 u
• Dynamic range >1x108
• Resolu<on 1x10-‐6 for adjacent half masses
up to 60 u, less for higher masses
• Sensi<vity limit: 1x1014 counts/s/mbar source pressure
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GCMS Descent Sequence
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a. Ambient atmospheric pressure
b. Pressure in the direct sampling ion source
c. ACP ion source dedicated sampling ?me
d. Opera?ng ?me of the ion sources for GC columns
Instrument Performance • The instrument executed the pre-‐programmed sequence as
expected
• Data were taken from about 146 km al<tude to the surface
• 2h27m descent opera<on yielding 5634 mass spectra
• 1h10m surface opera<on yielding 2692 mass spectra
• Ion source 5 failed to operate early in the descent
• Loss of data from one gas chromatograph column which
resolved CO and N2
• Loss of channel A effected <me resolu<on and signal
sta<s<cs, no loss of essen<al data
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ScienKfic Results Summary • Height profiles of molecular nitrogen (N2), methane (CH4), and
molecular hydrogen (H2) were determined. • Traces were detected on the surface of evaporaKng methane,
ethane(C2H6), acetylene (C2H2), cyanogen (C2N2), and carbon dioxide (CO2).
• The methane data showed evidence that methane precipitaKon occurred recently.
• The methane mole fracKon was (1.48 ± 0.09) × 10-‐2 in the lower stratosphere (139.8–75.5 km) and (5.65 ±0.18) × 10-‐2 near the surface (6.7 km to the surface).
• The molecular hydrogen mole fracKon was (1.01 ± 0.16) × 10-‐3 in the atmosphere and (9.90 ± 0.17) × 10-‐4 on the surface.
• Isotope raKos were 167.7 ± 0.6 for 14N/15N in molecular nitrogen, 91.1 ± 1.4 for 12C/13C in methane, and (1.35 ± 0.30) × 10-‐4 for D/H in molecular hydrogen.
• The mole fracKons of 36Ar and radiogenic 40Ar are (2.1 ± 0.8) × 10-‐7 and (3.39 ± 0.12) × 10-‐5, respecKvely.
• 22Ne has been tentaKvely idenKfied at a mole fracKon of (2.8 ± 2.1) × 10-‐7
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ScienKfic Results
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Upper Atmosphere Averaged Spectrum (130-‐120 km)
Lower Atmosphere Averaged Spectrum (20-‐10 km)
Averaged Surface Spectrum
Surface Response
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Surface Response of N2 and CH4
Surface Response of C2H6 and CO2
Rare Gas Experiment Averaged Spectrum (with Background Subtracted)
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The GCMS Team H. Niemann, Principle InvesKgator,
NASA GSFC
S. K Atreya2, S. J. Bauer3 K. Biemann10 ,G.R. Carignan2 , J.E. Demick1 ,T. Donahue2 ,R. L. Frost7 , D. Gau<er4 , J. A. Haberman1 , D.N. Harpold1 , D.M. Hunten5 , G. Israel6 , J. I. Lunine5 , W. T. Kasprzak1 , K. Mauersberger11 ,T.C. Owen8 , M. Paulkovich1 , F. Raulin9 , E. Raaen1 , S. H. Way1
1.Na<onal Aeronau<cs and Space Administra<on 2.University of Michigan, Ann Arbor, MI 48109-‐2143, USA 3. Ins<tute for Meteorology and Geophysics, University of Graz
4. LESIA, Observatoirede Paris-‐Meudon 5. Lunar and Planetary Laboratory, University of Arizona 6. Service d’Aéronomie duCNRS 7. University of Alabama, CMC 8. University of Hawaii 9. Laboratoire Interuniversitairedes Systèmes Atmosphériques, Université Paris 12 et Paris 7 10.MassachuseDs Ins<tute of Technology 11.Max Planck Ins<tute
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Companies Involved With GCMS Company Product/Services Aker Industries Microvalves Artech Industries Ceramic to Metal Brazing AutoFlow Products Pressure Regulator Collimated Holes Capillary Leaks Command Technology Machining EG&G Pressure Sciences Vacuum/Pressure Seals Electron Beam Engineering Electron Beam Welding Ergenics Hydrogen Storage F&M Machine Machining Form Grind Hyperbolic Rod Manufacturing Galileo Electro Op<cs Secondary Electron Mul<pliers Herme<c Seal Vacuum/Pressure Feedthrus Insaco Ceramic Insulators Kulite Semiconductor Pressure Transducers Laser Applica<ons Laser Welding Micro Machining Machining Restek Corp. GC Columns Reynolds Industries Ion Pump Feedthrus Spiralock Corp. Self-‐locking Taps Summit Machining Machining Supelco Adsorbent Material for Enrichment Cells Teledyne Electronics Hybrid Manufacturers University of Michigan Analog Electronics Westport Development Thin-‐walled Bellows
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References • Niemann, H. B. et al. The Gas Chromatograph Mass Spectrometer for the Huygens
probe. Space Sci. Rev. 104(1), 553–-‐591 (2002). • Niemann, H. B. et al. The abundances of consKtuents of Titan’s atmosphere from the
GCMS instrument on the Huygens probe. Nature. 438(8), (2005) • Niemann, H. B. et al. ComposiKon of Titan’s lower atmosphere and simple surface
volaKles as measured by the Cassini-‐Huygens probe gas chromatograph mass spectrometer experiment. J. Geophys. Res., 115, (2010)
• hdp://huygensgcms.gsfc.nasa.gov/ • hdp://www.hems-‐workshop.org/5thWS/Talks/Thursday/Harpold.pdf • hdp://www.chem.arizona.edu/massspec/intro_html/intro.html • hdp://www.machinerylubricaKon.com/Read/352/gas-‐chromatography • hdp://www.files.chem.vt.edu/chem-‐ed/ms/quadrupo.html • hdp://anthony.liekens.net/index.php/Main/Huygens
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