The role of ion‐molecule reactions in the growth of heavy ions in Titan's ionosphere

Westlake, J. H.; Waite, J. H.; Carrasco, Nathalie; Richard, M. S.; Cravens, T. E.

doi:10.1002/2014ja020208

Cited by 53 publications

(38 citation statements)

References 45 publications

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“…This technique has been previously used at Titan (Coates et al, ; Crary et al, ; Desai et al, ) and at Enceladus (Coates et al, ; Hill et al, ; Jones et al, ). The along‐track ion velocity term v

_{i}

has not previously been accounted for at Enceladus but has been accounted for at Titan (Crary et al, ; Westlake et al, ), the addition of this term is explained in section .…”

Section: Methodsmentioning

confidence: 99%

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Fast and Slow Water Ion Populations in the Enceladus Plume

et al. 2020

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Ion velocities have been measured during the Enceladus E3 and E5 flybys using the Cassini Plasma Spectrometer (CAPS) instrument on the Cassini spacecraft. Data from three sensors in the CAPS instrument have been examined from two flybys that occurred during 2008. Positive ion measurements from the CAPS Ion Beam Spectrometer and Ion Mass Spectrometer have been used to measure positive ion velocities. The CAPS Electron Spectrometer has been used to complement the positive ion findings with measurements of negative ion velocities. Two velocities for the positive ions are found, with the fast ions (2.3–5.8 km/s) originating from the high‐speed neutral gas emission and slow ions (0.2–2.2 km/s) associated with the low‐speed thermal gas emission from Enceladus. Negative ions were found to be near stationary or northerly traveling, implying a deceleration mechanism within the plume. A tentative detection of fast negative ions was also recorded for one of the flybys. These findings will aid in future modeling of plume dynamics.

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_{i}

has not previously been accounted for at Enceladus but has been accounted for at Titan (Crary et al, ; Westlake et al, ), the addition of this term is explained in section .…”

Section: Methodsmentioning

confidence: 99%

“…CAPS Ion Beam Spectrometer (IBS) data have been previously used to study the composition of Titan's atmosphere, reinforcing arguments on hydrocarbon detections made by INMS in addition to creating composition altitude profiles and quantifying their abundance (Crary et al, ; Westlake et al, ).…”

Section: Introductionmentioning

confidence: 99%

Fast and Slow Water Ion Populations in the Enceladus Plume

et al. 2020

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“…3) Large negative ions with masses greater than 5000 u measured by the CAPS Electron Spectrometer (ELS; panel C) that increase in complexity at altitudes below 1000 km . Westlake et al (2014) demonstrated with correlation analysis that the molecular growth between ions and neutral species below 200 u appears to take place in large part due to addition reactions of C 2 compounds (C 2 H 2 and C 2 H 4 ). Westlake et al (2014), Waite et al (2006), and Lavvas et al…”

Section: Reactions In the Higher Layers Of Titan's Atmosphere And Ionmentioning

confidence: 98%

Laboratory Studies of Methane and Its Relationship to Prebiotic Chemistry

et al. 2017

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To examine how prebiotic chemical evolution took place on Earth prior to the emergence of life, laboratory experiments have been conducted since the 1950s. Methane has been one of the key molecules in these investigations. In earlier studies, strongly reducing gas mixtures containing methane and ammonia were used to simulate possible reactions in the primitive atmosphere of Earth, producing amino acids and other organic compounds. Since Earth's early atmosphere is now considered to be less reducing, the contribution of extraterrestrial organics to chemical evolution has taken on an important role. Such organic molecules may have come from molecular clouds and regions of star formation that created protoplanetary disks, planets, asteroids, and comets. The interstellar origin of organics has been examined both experimentally and theoretically, including laboratory investigations that simulate interstellar molecular reactions. Endogenous and exogenous organics could also have been supplied to the primitive ocean, making submarine hydrothermal systems plausible sites of the generation of life. Experiments that simulate such hydrothermal systems where methane played an important role have consequently been conducted. Processes that occur in other Solar System bodies offer clues to the prebiotic chemistry of Earth. Titan and other icy bodies, where methane plays significant roles, are especially good targets. In the case of Titan, methane is both in the atmosphere and in liquidospheres that are composed of methane and other hydrocarbons, and these have been studied in simulation experiments. Here, we review the wide range of experimental work in which these various terrestrial and extraterrestrial environments have been modeled, and we examine the possible role of methane in chemical evolution. Key Words: Methane-Interstellar environments-Submarine hydrothermal systems-Titan-Origin of life. Astrobiology 17, 786-812.

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“…Currently formation of complex molecules, ions, and haze is poorly constrained. The present lack of constraints on the aerosol chemical composition precludes clear benchmarks for further synthetic organic solids studies in the laboratory (Cable et al, 2012;Gautier et al, 2014;Sebree et al, 2014;Westlake et al, 2014). A mission dedicated to Titan is essential to determine haze composition, how its formation in the ionosphere links to other levels, if its composition changes with altitude, how it affects climate, and its role in the methane cycle and surface composition, morphology and alteration.…”

Section: Complex Chemistry and Haze Formationmentioning

confidence: 99%

Science goals and mission concept for the future exploration of Titan and Enceladus

Tobie¹,

Teanby²,

Coustenis³

et al. 2014

Planetary and Space Science

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Saturn's moons, Titan and Enceladus, are two of the Solar System's most enigmatic bodies and are prime targets for future space exploration. Titan provides an analogue for many processes relevant to the Earth, more generally to outer Solar System bodies, and a growing host of newly discovered icy exoplanets. Processes represented include: atmospheric dynamics, complex organic chemistry, meteorological cycles (with methane as a working fluid), astrobiology, surface liquids and lakes, geology, fluvial and aeolian erosion, and interactions with an external plasma environment. In addition, exploring Enceladus over multiple targeted flybys will give us a unique opportunity to further study the most active icy moon in our Solar System as revealed by Cassini and to analyse in situ its active plume with highly capable instrumentation addressing its complex chemistry and dynamics. Enceladus' plume likely represents the most accessible samples from an extra-terrestrial liquid water environment in the Solar system, which has far reaching implications for many areas of planetary and biological science. Titan with its massive atmosphere and Enceladus with its active plume are prime planetary objects in the Outer Solar System to perform in situ investigations. In the present paper, we describe the science goals and key measurements to be

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The role of ion‐molecule reactions in the growth of heavy ions in Titan's ionosphere

Cited by 53 publications

References 45 publications

Fast and Slow Water Ion Populations in the Enceladus Plume

Fast and Slow Water Ion Populations in the Enceladus Plume

Laboratory Studies of Methane and Its Relationship to Prebiotic Chemistry

Science goals and mission concept for the future exploration of Titan and Enceladus

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