The Experts below are selected from a list of 2088 Experts worldwide ranked by ideXlab platform

H B Niemann - One of the best experts on this subject based on the ideXlab platform.

  • laboratory simulations of the titan surface to elucidate the Huygens Probe gcms observations
    42nd Annual Lunar and Planetary Science Conferece, 2011
    Co-Authors: Melissa G Trainer, H B Niemann, Daniel N. Harpold, Sushil K. Atreya, T Owen, W T Kasprzak
    Abstract:

    The Cassini/Huygens mission has vastly increased the information we have available to stndy Satnro's moon Titan. The complete mission has included an array of observational methods including remote sensing techniques, upper atmosphere in-situ saropling, and the descent of the Huygens Probe directly through the atmosphere to the surface [1,2]. The instruments on the Huygens Probe remain the ouly source of in-situ measurements at the surface of Titan, and work evaluating these measurements to create a pict.rre of the surface environment is ongoing. In particular, the Gas Chromatograph Mass Spectrometer (GCMS) experiment on Huygens found that although there were no heavy hydrocarbons detected in the lower atmosphere, a rich spectrum of mass peaks arose once the Probe landed on the surface [3,4], However, to date it has not been possible to extract the identity and abundances of the many minor components of the spectra due to a lack of temperatnre- and instrumentappropriate data for the relevant species. We are performing laboratory stndies designed to elucidate the spectrum collected on Titan's surface, utilizing a cryogenic charober maintained at appropriate temperature and pressure conditions. The experiments will simulate the temperatnre rise experienced by the surface, which led to an enhanced signal of volatiles detected by the Huygens GCMS. The objective of this study is to exaroine the characteristics of various surface analogs as measured by the Huygens GCMS flight spare instrument, which is currently housed in our laboratory at NASA Goddard Space Flight Center (GSFC). This identification cannot be adequately accomplished through theoretical work alone since the thermodynamic properties of many species at these temperatnres (94 K, HASI measurement [5]) are not known.

  • composition of titan s lower atmosphere and simple surface volatiles as measured by the cassini Huygens Probe gas chromatograph mass spectrometer experiment
    Journal of Geophysical Research, 2010
    Co-Authors: H B Niemann, J E Demick, D Gautier, J A Haberman, Daniel N. Harpold, W T Kasprzak, Tobias Owen, Jonathan I. Lunine, Sushil K. Atreya, François Raulin
    Abstract:

    [1] The Cassini-Huygens Probe gas chromatograph mass spectrometer (GCMS) determined the composition of the Titan atmosphere from ∼140 km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N2), methane (CH4), and molecular hydrogen (H2) were determined. Traces were detected on the surface of evaporating methane, ethane (C2H6), acetylene (C2H2), cyanogen (C2N2), and carbon dioxide (CO2). The methane data showed evidence that methane precipitation occurred recently. The methane mole fraction 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 fraction was (1.01 ± 0.16) × 10−3 in the atmosphere and (9.90 ± 0.17) × 10−4 on the surface. Isotope ratios 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 fractions of 36Ar and radiogenic 40Ar are (2.1 ± 0.8) × 10−7 and (3.39 ± 0.12) × 10−5, respectively. 22Ne has been tentatively identified at a mole fraction of (2.8 ± 2.1) × 10−7. Krypton and xenon were below the detection threshold of 1 × 10−8 mole fraction. Science data were not retrieved from the gas chromatograph subsystem as the abundance of the organic trace gases in the atmosphere and on the ground did not reach the detection threshold. Results previously published from the GCMS experiment are superseded by this publication.

  • composition of titan s lower atmosphere and simple surface volatiles as measured by the cassini Huygens Probe gas chromatograph mass spectrometer experiment
    Journal of Geophysical Research, 2010
    Co-Authors: H B Niemann, J E Demick, D Gautier, J A Haberman, Daniel N. Harpold, W T Kasprzak, Tobias Owen, Jonathan I. Lunine, Sushil K. Atreya, F Raulin
    Abstract:

    The Cassini-Huygens Probe Gas Chromatograph Mass Spectrometer (GCMS) determined the composition of the Titan atmosphere from ~140km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N2), methane (CH4) and molecular hydrogen (H2) were determined. Traces were detected on the surface of evaporating methane, ethane (C2H6), acetylene (C2H2), cyanogen (C2N2) and carbon dioxide (CO2). The methane data showed evidence that methane precipitation occurred recently. The methane mole fraction was (1.48+/-0.09) x 10(exp -2) in the lower stratosphere (139.8 km to 75.5 km) and (5.65+/-0.18) x 10(exp -2) near the surface (6.7 km to the surface). The molecular hydrogen mole fraction was (1.01+/-0.16) x 10(exp -3) in the atmosphere and (9.90+/-0.17) x 10(exp -4) on the surface. Isotope ratios were 167.7+/-0.6 for N-14/N-15 in molecular nitrogen, 91.1+/-1.4 for C-12/C-13 in methane and (1.35+/-0.30) x 10(exp -4) for D/H in molecular hydrogen. The mole fractions of Ar-36 and radiogenic Ar-40 are (2.1+/-0.8) x 10(exp -7) and (3.39 +/-0.12) x 10(exp -5) respectively. Ne-22 has been tentatively identified at a mole fraction of (2.8+/-2.1) x 10(exp -7) Krypton and xenon were below the detection threshold of 1 x 10(exp -8) mole fraction. Science data were not retrieved from the gas chromatograph subsystem as the abundance of the organic trace gases in the atmosphere and on the ground did not reach the detection threshold. Results previously published from the GCMS experiment are superseded by this publication.

  • titan s damp ground constraints on titan surface thermal properties from the temperature evolution of the Huygens gcms inlet
    Meteoritics & Planetary Science, 2006
    Co-Authors: H B Niemann, Ralph D Lorenz, Dan Harpold, S H Way, J C Zarnecki
    Abstract:

    A simple thermal model is developed to determine the temperature history of the inlet tube of the Huygens Probe gas chromatograph mass spectrometer (GCMS) after its fortuitous emplacement on the surface of Saturns moon Titan. The model parameters are adjusted to match the recorded temperature history of a nearby heater, taking into account heat losses by conduction to the rest of the Probe and to Titans cold atmosphere. The model suggests that after impact when forced convective cooling ceased, the inlet temperature rose from ~110 K to an asymptotic value of only ~145 K. This requires that the inlet was embedded in a surface that acted as an effective heat sink, most plausibly interpreted as wet or damp with liquid methane. The data appear inconsistent with a tar or dry, fine-grained surface, and the inlet was not warm enough to devolatilize methane hydrate.

  • results from the gas chromatograph mass spectrometer gcms experiment on the cassini Huygens Probe
    European geosciences union general assembly, 2006
    Co-Authors: H B Niemann, Sushil K. Atreya, J. A. Haberman, D. N. Harpold, T Owen, E Raaen, W Kasprzak, J Demickmontelara, S Way
    Abstract:

    The 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 m/z 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, methane, 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.

Ralph D Lorenz - One of the best experts on this subject based on the ideXlab platform.

  • evolution of the Huygens Probe spin during parachute descent
    Journal of Spacecraft and Rockets, 2021
    Co-Authors: Ralph D Lorenz, J P Lebreton, Annie Leroy, Miguel Perezayucar
    Abstract:

    The anomalous spin of the Huygens Probe on Titan is simulated with a simple model, which is also applied to the (also anomalous) spin history from a terrestrial parachute drop test. The model consi...

  • large eddy simulation of titan s near surface atmosphere convective turbulence and flow over dunes with application to Huygens and dragonfly
    Icarus, 2021
    Co-Authors: Adam Lavely, Ralph D Lorenz, Sven Schmitz
    Abstract:

    Abstract The planetary boundary layer (PBL) on Titan is modeled using large-eddy simulation (LES) to quantify the turbulence structures and statistics in the atmospheric surface layer. The results at three different stability states over a flat surface indicate similar velocity fluctuations to the limited observations taken by the Huygens Probe during descent, and are much weaker than those characteristic of the convective PBL on Earth and Mars. Additionally, turbulence statistics are calculated using topographical configurations representative of Titan’s dunes, thereby quantifying the acceleration of the mean flow over the dune crest. The resolution available with the LES is relevant for future science missions to Titan, including the Dragonfly rotorcraft lander recently selected for the NASA New Frontiers program.

  • Huygens Probe a retrospective and lessons for the future
    IEEE Aerospace Conference, 2017
    Co-Authors: Ralph D Lorenz
    Abstract:

    The Huygens Probe mission is reviewed with particular attention to system and instrument behaviors that were not in accord with expectations. These include the radio system, radar altimeters, the descent spin and attitude behavior, and instrument operations. Lessons for future missions are drawn.

  • the electrical properties of titan s surface at the Huygens landing site measured with the pwa hasi mutual impedance Probe new approach and new findings
    Icarus, 2016
    Co-Authors: Michel Hamelin, R. Grard, K. Schwingenschuh, C Beghin, Jose Juan Lopezmoreno, Anthony Lethuillier, Alice Le Gall, I Jernej, V Brown, Ralph D Lorenz
    Abstract:

    Ten years after the successful landing of the Huygens Probe on the surface of Titan, we reassess the derivation of ground complex permittivity using the PWA-MIP/HASI measurements (Permittivity, Waves and Altimetry-Mutual Impedance Probe/Huygens Atmospheric Structure Instrument) at the frequencies 45, 90 and 360 Hz. For this purpose, we have developed a numerical method, namely “the capacity-influence matrix method”, able to account for new insights on the Huygens Probe attitude at its final resting position. We find that the surface of Titan at the landing site has a dielectric constant of 2.5±0.3 and a conductivity of 1.2±0.6 nS/m, in agreement with previously published results but with much more reliable error estimates. These values speak in favour of a photochemical origin of the material in the first meter of the subsurface. We also propose, for the first time, a plausible explanation for the sudden change observed by PWA-MIP ∼11 min after landing: this change corresponds to a drop in the ground conductivity, probably due to the removal of a superficial conductive layer in association with the release of volatile materials warmed by the Huygens Probe.

  • gravity waves in titan s lower stratosphere from Huygens Probe in situ temperature measurements
    Icarus, 2014
    Co-Authors: Ralph D Lorenz, Leslie A Young, F Ferri
    Abstract:

    Abstract The Huygens Probe recorded atmospheric temperatures during its parachute descent through the atmosphere of Titan. A careful analysis of these data reveals for the first time spectacular but hitherto-unreported small-scale variations in stratospheric temperatures that we interpret as gravity waves, consistent with detection of such waves at higher altitudes by other means. The structures have a vertical wavelength of 3–8 km and a peak–peak amplitude of ∼2 K that is roughly constant over altitudes from ∼140 km, where measurements began, to ∼60 km. This altitude, below which no significant temperature waves are seen, coincides with a local maximum in the zonal wind profile, and is close to where the Brunt–Vaisala frequency is highest. It seems possible that the zonal wind field influences the vertical gravity wave propagation.

Sushil K. Atreya - One of the best experts on this subject based on the ideXlab platform.

  • laboratory simulations of the titan surface to elucidate the Huygens Probe gcms observations
    42nd Annual Lunar and Planetary Science Conferece, 2011
    Co-Authors: Melissa G Trainer, H B Niemann, Daniel N. Harpold, Sushil K. Atreya, T Owen, W T Kasprzak
    Abstract:

    The Cassini/Huygens mission has vastly increased the information we have available to stndy Satnro's moon Titan. The complete mission has included an array of observational methods including remote sensing techniques, upper atmosphere in-situ saropling, and the descent of the Huygens Probe directly through the atmosphere to the surface [1,2]. The instruments on the Huygens Probe remain the ouly source of in-situ measurements at the surface of Titan, and work evaluating these measurements to create a pict.rre of the surface environment is ongoing. In particular, the Gas Chromatograph Mass Spectrometer (GCMS) experiment on Huygens found that although there were no heavy hydrocarbons detected in the lower atmosphere, a rich spectrum of mass peaks arose once the Probe landed on the surface [3,4], However, to date it has not been possible to extract the identity and abundances of the many minor components of the spectra due to a lack of temperatnre- and instrumentappropriate data for the relevant species. We are performing laboratory stndies designed to elucidate the spectrum collected on Titan's surface, utilizing a cryogenic charober maintained at appropriate temperature and pressure conditions. The experiments will simulate the temperatnre rise experienced by the surface, which led to an enhanced signal of volatiles detected by the Huygens GCMS. The objective of this study is to exaroine the characteristics of various surface analogs as measured by the Huygens GCMS flight spare instrument, which is currently housed in our laboratory at NASA Goddard Space Flight Center (GSFC). This identification cannot be adequately accomplished through theoretical work alone since the thermodynamic properties of many species at these temperatnres (94 K, HASI measurement [5]) are not known.

  • composition of titan s lower atmosphere and simple surface volatiles as measured by the cassini Huygens Probe gas chromatograph mass spectrometer experiment
    Journal of Geophysical Research, 2010
    Co-Authors: H B Niemann, J E Demick, D Gautier, J A Haberman, Daniel N. Harpold, W T Kasprzak, Tobias Owen, Jonathan I. Lunine, Sushil K. Atreya, François Raulin
    Abstract:

    [1] The Cassini-Huygens Probe gas chromatograph mass spectrometer (GCMS) determined the composition of the Titan atmosphere from ∼140 km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N2), methane (CH4), and molecular hydrogen (H2) were determined. Traces were detected on the surface of evaporating methane, ethane (C2H6), acetylene (C2H2), cyanogen (C2N2), and carbon dioxide (CO2). The methane data showed evidence that methane precipitation occurred recently. The methane mole fraction 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 fraction was (1.01 ± 0.16) × 10−3 in the atmosphere and (9.90 ± 0.17) × 10−4 on the surface. Isotope ratios 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 fractions of 36Ar and radiogenic 40Ar are (2.1 ± 0.8) × 10−7 and (3.39 ± 0.12) × 10−5, respectively. 22Ne has been tentatively identified at a mole fraction of (2.8 ± 2.1) × 10−7. Krypton and xenon were below the detection threshold of 1 × 10−8 mole fraction. Science data were not retrieved from the gas chromatograph subsystem as the abundance of the organic trace gases in the atmosphere and on the ground did not reach the detection threshold. Results previously published from the GCMS experiment are superseded by this publication.

  • composition of titan s lower atmosphere and simple surface volatiles as measured by the cassini Huygens Probe gas chromatograph mass spectrometer experiment
    Journal of Geophysical Research, 2010
    Co-Authors: H B Niemann, J E Demick, D Gautier, J A Haberman, Daniel N. Harpold, W T Kasprzak, Tobias Owen, Jonathan I. Lunine, Sushil K. Atreya, F Raulin
    Abstract:

    The Cassini-Huygens Probe Gas Chromatograph Mass Spectrometer (GCMS) determined the composition of the Titan atmosphere from ~140km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N2), methane (CH4) and molecular hydrogen (H2) were determined. Traces were detected on the surface of evaporating methane, ethane (C2H6), acetylene (C2H2), cyanogen (C2N2) and carbon dioxide (CO2). The methane data showed evidence that methane precipitation occurred recently. The methane mole fraction was (1.48+/-0.09) x 10(exp -2) in the lower stratosphere (139.8 km to 75.5 km) and (5.65+/-0.18) x 10(exp -2) near the surface (6.7 km to the surface). The molecular hydrogen mole fraction was (1.01+/-0.16) x 10(exp -3) in the atmosphere and (9.90+/-0.17) x 10(exp -4) on the surface. Isotope ratios were 167.7+/-0.6 for N-14/N-15 in molecular nitrogen, 91.1+/-1.4 for C-12/C-13 in methane and (1.35+/-0.30) x 10(exp -4) for D/H in molecular hydrogen. The mole fractions of Ar-36 and radiogenic Ar-40 are (2.1+/-0.8) x 10(exp -7) and (3.39 +/-0.12) x 10(exp -5) respectively. Ne-22 has been tentatively identified at a mole fraction of (2.8+/-2.1) x 10(exp -7) Krypton and xenon were below the detection threshold of 1 x 10(exp -8) mole fraction. Science data were not retrieved from the gas chromatograph subsystem as the abundance of the organic trace gases in the atmosphere and on the ground did not reach the detection threshold. Results previously published from the GCMS experiment are superseded by this publication.

  • results from the gas chromatograph mass spectrometer gcms experiment on the cassini Huygens Probe
    European geosciences union general assembly, 2006
    Co-Authors: H B Niemann, Sushil K. Atreya, J. A. Haberman, D. N. Harpold, T Owen, E Raaen, W Kasprzak, J Demickmontelara, S Way
    Abstract:

    The 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 m/z 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, methane, 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.

  • The abundances of constituents of Titan's atmosphere from the GCMS instrument on the Huygens Probe
    Nature, 2005
    Co-Authors: H. B. Niemann, D Gautier, Sushil K. Atreya, S. J. Bauer, G. R. Carignan, J. E. Demick, R. L. Frost, J. A. Haberman, D. N. Harpold, D. M. Hunten
    Abstract:

    Saturn's largest moon, Titan, remains an enigma, explored only by remote sensing from Earth, and by the Voyager and Cassini spacecraft. The most puzzling aspects include the origin of the molecular nitrogen and methane in its atmosphere, and the mechanism(s) by which methane is maintained in the face of rapid destruction by photolysis. The Huygens Probe, launched from the Cassini spacecraft, has made the first direct observations of the satellite's surface and lower atmosphere. Here we report direct atmospheric measurements from the Gas Chromatograph Mass Spectrometer (GCMS), including altitude profiles of the constituents, isotopic ratios and trace species (including organic compounds). The primary constituents were confirmed to be nitrogen and methane. Noble gases other than argon were not detected. The argon includes primordial 36Ar, and the radiogenic isotope 40Ar, providing an important constraint on the outgassing history of Titan. Trace organic species, including cyanogen and ethane, were found in surface measurements.

D Gautier - One of the best experts on this subject based on the ideXlab platform.

  • composition of titan s lower atmosphere and simple surface volatiles as measured by the cassini Huygens Probe gas chromatograph mass spectrometer experiment
    Journal of Geophysical Research, 2010
    Co-Authors: H B Niemann, J E Demick, D Gautier, J A Haberman, Daniel N. Harpold, W T Kasprzak, Tobias Owen, Jonathan I. Lunine, Sushil K. Atreya, François Raulin
    Abstract:

    [1] The Cassini-Huygens Probe gas chromatograph mass spectrometer (GCMS) determined the composition of the Titan atmosphere from ∼140 km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N2), methane (CH4), and molecular hydrogen (H2) were determined. Traces were detected on the surface of evaporating methane, ethane (C2H6), acetylene (C2H2), cyanogen (C2N2), and carbon dioxide (CO2). The methane data showed evidence that methane precipitation occurred recently. The methane mole fraction 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 fraction was (1.01 ± 0.16) × 10−3 in the atmosphere and (9.90 ± 0.17) × 10−4 on the surface. Isotope ratios 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 fractions of 36Ar and radiogenic 40Ar are (2.1 ± 0.8) × 10−7 and (3.39 ± 0.12) × 10−5, respectively. 22Ne has been tentatively identified at a mole fraction of (2.8 ± 2.1) × 10−7. Krypton and xenon were below the detection threshold of 1 × 10−8 mole fraction. Science data were not retrieved from the gas chromatograph subsystem as the abundance of the organic trace gases in the atmosphere and on the ground did not reach the detection threshold. Results previously published from the GCMS experiment are superseded by this publication.

  • composition of titan s lower atmosphere and simple surface volatiles as measured by the cassini Huygens Probe gas chromatograph mass spectrometer experiment
    Journal of Geophysical Research, 2010
    Co-Authors: H B Niemann, J E Demick, D Gautier, J A Haberman, Daniel N. Harpold, W T Kasprzak, Tobias Owen, Jonathan I. Lunine, Sushil K. Atreya, F Raulin
    Abstract:

    The Cassini-Huygens Probe Gas Chromatograph Mass Spectrometer (GCMS) determined the composition of the Titan atmosphere from ~140km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N2), methane (CH4) and molecular hydrogen (H2) were determined. Traces were detected on the surface of evaporating methane, ethane (C2H6), acetylene (C2H2), cyanogen (C2N2) and carbon dioxide (CO2). The methane data showed evidence that methane precipitation occurred recently. The methane mole fraction was (1.48+/-0.09) x 10(exp -2) in the lower stratosphere (139.8 km to 75.5 km) and (5.65+/-0.18) x 10(exp -2) near the surface (6.7 km to the surface). The molecular hydrogen mole fraction was (1.01+/-0.16) x 10(exp -3) in the atmosphere and (9.90+/-0.17) x 10(exp -4) on the surface. Isotope ratios were 167.7+/-0.6 for N-14/N-15 in molecular nitrogen, 91.1+/-1.4 for C-12/C-13 in methane and (1.35+/-0.30) x 10(exp -4) for D/H in molecular hydrogen. The mole fractions of Ar-36 and radiogenic Ar-40 are (2.1+/-0.8) x 10(exp -7) and (3.39 +/-0.12) x 10(exp -5) respectively. Ne-22 has been tentatively identified at a mole fraction of (2.8+/-2.1) x 10(exp -7) Krypton and xenon were below the detection threshold of 1 x 10(exp -8) mole fraction. Science data were not retrieved from the gas chromatograph subsystem as the abundance of the organic trace gases in the atmosphere and on the ground did not reach the detection threshold. Results previously published from the GCMS experiment are superseded by this publication.

  • characterization of zonal winds in the stratosphere of titan with uves 2 observations coordinated with the Huygens Probe entry
    Journal of Geophysical Research, 2006
    Co-Authors: David Luz, D Gautier, J P Lebreton, Olivier Witasse, F Ferri, T Civeit, R Courtin, A Kaufer, L M Lara, T A Livengood
    Abstract:

    [1] The Huygens Probe has successfully entered Titan's atmosphere and landed on its surface on 14 January 2005. With the aim of characterizing the zonal wind flow in Titan's stratosphere close to the time of entry, coordinated observations were carried out at the Very Large Telescope on the nights of 7, 12, 14, and 15 January. As in our previous investigation (Luz et al., 2005), we used the UVES instrument, mounted on the Kueyen-UT2 telescope, simultaneously achieving high spectral resolving power and high spatial resolution. The field has been derotated in order to align the 0.3-arcsec aperture perpendicularly to Titan's rotation axis. In this configuration, spatial information in the east-west direction is preserved in a set of spectra in the direction perpendicular to dispersion. We present measurements of zonal winds obtained with the technique of absolute accelerometry. The observations were made in the wavelength range 4200–6200 A, probing between 115 and 280 km, with peak contributions at 200 and 170 km for the lower and upper parts of the domain. We detect prograde zonal winds with lower limits 46 and 53 ms−1 at these altitudes. These values are close to our previous measurements.

  • The abundances of constituents of Titan's atmosphere from the GCMS instrument on the Huygens Probe
    Nature, 2005
    Co-Authors: H. B. Niemann, D Gautier, Sushil K. Atreya, S. J. Bauer, G. R. Carignan, J. E. Demick, R. L. Frost, J. A. Haberman, D. N. Harpold, D. M. Hunten
    Abstract:

    Saturn's largest moon, Titan, remains an enigma, explored only by remote sensing from Earth, and by the Voyager and Cassini spacecraft. The most puzzling aspects include the origin of the molecular nitrogen and methane in its atmosphere, and the mechanism(s) by which methane is maintained in the face of rapid destruction by photolysis. The Huygens Probe, launched from the Cassini spacecraft, has made the first direct observations of the satellite's surface and lower atmosphere. Here we report direct atmospheric measurements from the Gas Chromatograph Mass Spectrometer (GCMS), including altitude profiles of the constituents, isotopic ratios and trace species (including organic compounds). The primary constituents were confirmed to be nitrogen and methane. Noble gases other than argon were not detected. The argon includes primordial 36Ar, and the radiogenic isotope 40Ar, providing an important constraint on the outgassing history of Titan. Trace organic species, including cyanogen and ethane, were found in surface measurements.

  • the gas chromatograph mass spectrometer for the Huygens Probe
    International Conference on the Occaision of the 375th Birthday of Christiaan Huygens, 2004
    Co-Authors: H B Niemann, G. Israel, D Gautier, Sushil K. Atreya, D. M. Hunten, Siegfried Bauer, K Biemann, G R Carignan, T M Donahue, Jonathan I. Lunine
    Abstract:

    Titan is unique in the solar system, the only moon that has a dense atmosphere. The major constituents of the atmosphere, nitrogen and methane, are continuously broken apart by a combination of solar UV, impinging electrons from Saturn s magnetosphere, and a steady flux of cosmic rays. The resulting molecular fragments recombine and form a variety of new species, many of which were detected for the first time by Voyager1 . The ubiquitous, surface- hiding aerosol blanket manifests the existence of still more complex compounds. In addition to hydrocarbons and nitriles, the atmosphere is known to contain CO, CO2 and externally delivered H2O. The Gas Chromatograph Mass Spectrometer (GCMS) on the Huygens Probe will measure the chemical composition of the atmosphere of Titan from 170 Km altitude (approximately 1hPa) to the surface (approximately 1500hPa) and determine the isotope ratios of the major constituents. The GCMS will also analyze gas samples from the Aerosol Collector Pyrolyser (ACP) and may be able to obtain compositional information of several surface materials. The GCMS consists of a quadrupole mass spectrometer (QP) with a secondary electron multiplier ion detector, a three-column gas chromatograph (GC) and an elaborate gas sampling system. The gas sampling system will provide atmospheric samples to the QP for nearly continuous analysis during the Probe descent and batch samples at several altitudes for GC analysis. It also contains a chemical scrubber for noble gas analysis and an enrichment cell for trace constituent enhancement. In addition to the sampling of the atmosphere periodic gas samples, derived from the pyrolysis of aerosols, will be transferred from the ACP to the GCMS for direct QP and full GCMS analysis. The QP can analyze molecular masses from 2 to 141Dalton. The nominal detection threshold is at a mixing ratio of 10E-8. Data rate is 885 bits/sec. The mass of the instrument is 17.3 kg and the energy required for operation during the descent is 110 Watt-hours.

Jonathan I. Lunine - One of the best experts on this subject based on the ideXlab platform.

  • composition of titan s lower atmosphere and simple surface volatiles as measured by the cassini Huygens Probe gas chromatograph mass spectrometer experiment
    Journal of Geophysical Research, 2010
    Co-Authors: H B Niemann, J E Demick, D Gautier, J A Haberman, Daniel N. Harpold, W T Kasprzak, Tobias Owen, Jonathan I. Lunine, Sushil K. Atreya, François Raulin
    Abstract:

    [1] The Cassini-Huygens Probe gas chromatograph mass spectrometer (GCMS) determined the composition of the Titan atmosphere from ∼140 km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N2), methane (CH4), and molecular hydrogen (H2) were determined. Traces were detected on the surface of evaporating methane, ethane (C2H6), acetylene (C2H2), cyanogen (C2N2), and carbon dioxide (CO2). The methane data showed evidence that methane precipitation occurred recently. The methane mole fraction 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 fraction was (1.01 ± 0.16) × 10−3 in the atmosphere and (9.90 ± 0.17) × 10−4 on the surface. Isotope ratios 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 fractions of 36Ar and radiogenic 40Ar are (2.1 ± 0.8) × 10−7 and (3.39 ± 0.12) × 10−5, respectively. 22Ne has been tentatively identified at a mole fraction of (2.8 ± 2.1) × 10−7. Krypton and xenon were below the detection threshold of 1 × 10−8 mole fraction. Science data were not retrieved from the gas chromatograph subsystem as the abundance of the organic trace gases in the atmosphere and on the ground did not reach the detection threshold. Results previously published from the GCMS experiment are superseded by this publication.

  • composition of titan s lower atmosphere and simple surface volatiles as measured by the cassini Huygens Probe gas chromatograph mass spectrometer experiment
    Journal of Geophysical Research, 2010
    Co-Authors: H B Niemann, J E Demick, D Gautier, J A Haberman, Daniel N. Harpold, W T Kasprzak, Tobias Owen, Jonathan I. Lunine, Sushil K. Atreya, F Raulin
    Abstract:

    The Cassini-Huygens Probe Gas Chromatograph Mass Spectrometer (GCMS) determined the composition of the Titan atmosphere from ~140km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N2), methane (CH4) and molecular hydrogen (H2) were determined. Traces were detected on the surface of evaporating methane, ethane (C2H6), acetylene (C2H2), cyanogen (C2N2) and carbon dioxide (CO2). The methane data showed evidence that methane precipitation occurred recently. The methane mole fraction was (1.48+/-0.09) x 10(exp -2) in the lower stratosphere (139.8 km to 75.5 km) and (5.65+/-0.18) x 10(exp -2) near the surface (6.7 km to the surface). The molecular hydrogen mole fraction was (1.01+/-0.16) x 10(exp -3) in the atmosphere and (9.90+/-0.17) x 10(exp -4) on the surface. Isotope ratios were 167.7+/-0.6 for N-14/N-15 in molecular nitrogen, 91.1+/-1.4 for C-12/C-13 in methane and (1.35+/-0.30) x 10(exp -4) for D/H in molecular hydrogen. The mole fractions of Ar-36 and radiogenic Ar-40 are (2.1+/-0.8) x 10(exp -7) and (3.39 +/-0.12) x 10(exp -5) respectively. Ne-22 has been tentatively identified at a mole fraction of (2.8+/-2.1) x 10(exp -7) Krypton and xenon were below the detection threshold of 1 x 10(exp -8) mole fraction. Science data were not retrieved from the gas chromatograph subsystem as the abundance of the organic trace gases in the atmosphere and on the ground did not reach the detection threshold. Results previously published from the GCMS experiment are superseded by this publication.

  • an estimate of the chemical composition of titan s lakes
    arXiv: Earth and Planetary Astrophysics, 2009
    Co-Authors: Jonathan I. Lunine, Olivier Mousis, Daniel Cordier, P Lavvas, Veronique Vuitton
    Abstract:

    Hundreds of radar-dark patches interpreted as lakes have been discovered in the north and south polar regions of Titan. We have estimated the composition of these lakes by using the direct abundance measurements from the Gas Chromatograph Mass Spectrometer (GCMS) aboard the Huygens Probe and recent photochemical models based on the vertical temperature profile derived by the Huygens Atmospheric Structure Instrument (HASI). Thermodynamic equilibrium is assumed between the atmosphere and the lakes, which are also considered as nonideal solutions. We find that the main constituents of the lakes are ethane (C2H6) (~76-79%), propane (C3H8) (~7-8%), methane (CH4) (~5-10%), hydrogen cyanide (HCN) (~2-3%), butene (C4H8) (~1%), butane (C4H10) (~1%) and acetylene (C2H2) (~1%). The calculated composition of lakes is then substantially different from what has been expected from models elaborated prior to the exploration of Titan by the Cassini-Huygens spacecraft.

  • Results from the Huygens Probe on Titan
    The Astronomy and Astrophysics Review, 2009
    Co-Authors: Jean-pierre Lebreton, François Raulin, Tobias Owen, Jonathan I. Lunine, Athena Coustenis, Darrell Strobel
    Abstract:

    The Cassini–Huygens mission, comprising the NASA Saturn Orbiter and the ESA Huygens Probe, arrived at Saturn in late June 2004. The Huygens Probe descended under parachute in Titan’s atmosphere on 14 January 2005, 3 weeks after separation from the Orbiter. We discuss here the breakthroughs that the Huygens Probe, in conjunction with the Cassini spacecraft, brought to Titan science. We review the achievements ESA’s Huygens Probe put forward and the context in which it operated. The findings include new localized information on several aspects of Titan science: the atmospheric structure and chemical composition; the aerosols distribution and content; the surface morphology and composition at the Probe’s landing site; the winds, the electrical properties, and the implications on the origin and evolution of the satellite.

  • hydrocarbon lakes on titan distribution and interaction with a porous regolith
    Geophysical Research Letters, 2008
    Co-Authors: A G Hayes, Ralph D Lorenz, Oded Aharonson, P Callahan, C Elachi, Y Gim, Randolph L Kirk, K W Lewis, R M C Lopes, Jonathan I. Lunine
    Abstract:

    from <10 to more than 100,000 km 2 . The size and location of lakes provide constraints on parameters associated with subsurface transport. Using porous media properties inferred from Huygens Probe observations, timescales for flow into and out of observed lakes are shown to be in the tens of years, similar to seasonal cycles. Derived timescales are compared to the time between collocated SAR observations in order to considertheroleofsubsurfacetransportinTitan’shydrologic cycle. Citation: Hayes, A., et al. (2008), Hydrocarbon lakes on Titan: Distribution and interaction with a porous regolith,Geophys. Res. Lett., 35, L09204, doi:10.1029/2008GL033409.