Ion Neutral Mass Spectrometer Results from the First Flyby of Titan

Waite, J. H.; Niemann, H. B.; Yelle, R. V.; Kasprzak, W. T.; Cravens, T. E.; Luhmann, J. G.; McNutt, R. L.; Ip, W.-H.; Gell, D. A.; Haye, V. de La; Müller-Wordag, I.; Magee, B.; Borggren, N.; Ledvina, S. A.; Fletcher, Greg; Walter, E. M.; Miller, Ryan; Scherer, S.; Thorpe, Rob; Xu, Jing; Block, Bruce; Arnett, Ken

doi:10.1126/science.1110652

Cited by 423 publications

(381 citation statements)

References 18 publications

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“…Waite et al 2005;Vuitton et al 2007;Cui et al 2009) supports the above production scheme and allows one to evaluate it quantitatively, although key reaction rates (k i ) are still uncertain. The dissociative recombination rate of HCNH + depends on the electron temperature.…”

Section: Discussionmentioning

confidence: 99%

“…As a matter of fact, and as one of the major discoveries of the Cassini mission at Titan, numerous heavy organic molecules have been detected in Titan's upper atmosphere by Cassini Ion Neutral Mass Spectrometer (INMS), (e.g. Waite et al 2005;Vuitton et al 2007). Despite these impressive results, from which a completely new view of Titan's ion-neutral chemistry emerged, INMS cannot distinguish between species of identical mass, in particular between isomers.…”

Section: Introductionmentioning

confidence: 99%

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First detection of hydrogen isocyanide (HNC) in Titan’s atmosphere

Moreno

Lellouch

Lara

et al. 2011

A&A

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We report on the first identification of hydrogen isocyanide (HNC) in Titan's atmosphere, from observations using the HIFI instrument on the Herschel Space Observatory. An emission line from the HNC J = 6 → 5 rotational transition at 543.897 GHz was measured in Titan on June 14 and December 31, 2010. Radiative transfer modeling indicates that the bulk of HNC is located above 400 km, with a column density in the range (0.6−1.5) × 10 13 cm −2 , but the observations cannot establish its vertical profile. In particular HNC could be restricted to the upper thermosphere (∼1000 km), in which case its local abundance relative to HCN could be as high as ∼0.3. HNC is probably formed mostly at ionospheric levels (950-1150 km) from dissociative recombination of HCNH + and possibly other heavier nitrile ions. Ionospheric loss of HNC occurs by protonation with XH + ions. Additional formation (e.g. from N( 4 S) + 3 CH 2 ) and loss routes (e.g. from isomerization to HCN) in the neutral atmosphere remain to be investigated.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

First detection of hydrogen isocyanide (HNC) in Titan’s atmosphere

Moreno

Lellouch

Lara

et al. 2011

A&A

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“…The CSN operational mode uses an enhancement chamber in front of the mass spectrometer that concentrates atmospheric molecules resulting in higher sensitivity (Waite et al 2005). Radical recombination on chamber walls is a common phenomenon in spaceflight mass spectrometers (Hedin et al 1973;Kasprzak et al 1980).…”

Section: Distribution and Formation Of Benzene (A ) Benzene Distributionmentioning

confidence: 99%

Composition and chemistry of Titan's thermosphere and ionosphere

Vuitton

Yelle

Lavvas

2008

Phil. Trans. R. Soc. A.

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Titan has long been known to harbour the richest atmospheric chemistry in the Solar System. Until recently, it had been believed that complex hydrocarbons and nitriles were produced through neutral chemistry that would eventually lead to the formation of micrometre sized organic aerosols. However, recent measurements by the Cassini spacecraft are drastically changing our understanding of Titan's chemistry. The Ion and Neutral Mass Spectrometer (INMS) and the Cassini Plasma Spectrometer (CAPS) revealed an extraordinary complex ionospheric composition. INMS detected roughly 50 positive ions with m/z!100 and a density higher than 0.1 cm K3 . CAPS provided evidence for heavy (up to 350 amu) positively and negatively charged (up to 4000 amu) ions. These observations all indicate that Titan's ionospheric chemistry is incredibly complex and that molecular growth starts in the upper atmosphere rather than at lower altitude. Here, we review the recent progress made on ionospheric chemistry. The presence of heavy neutrals in the upper atmosphere has been inferred as a direct consequence of the presence of complex positive ions. Benzene (C 6 H 6 ) is created by ion chemistry at high altitudes and its main photolysis product, the phenyl radical (C 6 H 5 ), is at the origin of the formation of aromatic species at lower altitude.

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“…The instruments baselined for the Kronos Probe investigation have a solid heritage from previous probe missions such as Galileo [55] (Fig. 9) and Cassini/ Huygens [56].…”

Section: Elemental and Isotopic Measurements Of Saturn's Atmospherementioning

confidence: 99%

Kronos: exploring the depths of Saturn with probes and remote sensing through an international mission

et al. 2008

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Kronos is a mission aimed to measure in situ the chemical and isotopic compositions of the Saturnian atmosphere with two probes and also by remote sensing, in order to understand the origin, formation, and evolution of giant planets in general, including extrasolar planets. Xe/ 129 Xe isotopic ratios will be measured by mass spectrometry on two probes entering the atmosphere of Saturn at two different locations near mid-latitudes, down to a pressure of 10 Bar. The global composition of Saturn will be investigated through these measurements, together with microwave radiometry determination of H 2 O and NH 3 and their 3D variations. The dynamics of Saturn's atmosphere will be investigated from: (1) measurements of pressure, temperature, vertical distribution of clouds and wind speed along the probes' descent trajectories, and (2) determination of deep winds, differential rotation and convection with combined probe, gravity and radiometric measurements. Besides these primary goals, Kronos will also measure the intensities and characteristics of Saturn's magnetic field inside the D ring as well as Saturn's gravitational field, in order to constrain the abundance of heavy elements in Saturn's interior and in its central core. Depending on the preferred architecture (flyby versus orbiter), Kronos will be in a position to measure the properties of Saturn's innermost magnetosphere and to investigate the ring structure in order to understand how these tiny structures could have formed and survived up to the present times.

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Ion Neutral Mass Spectrometer Results from the First Flyby of Titan

Cited by 423 publications

References 18 publications

First detection of hydrogen isocyanide (HNC) in Titan’s atmosphere

First detection of hydrogen isocyanide (HNC) in Titan’s atmosphere

Composition and chemistry of Titan's thermosphere and ionosphere

Kronos: exploring the depths of Saturn with probes and remote sensing through an international mission

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