Electron conductivity and density profiles derived from the mutual impedance probe measurements performed during the descent of Huygens through the atmosphere of Titan

Hamelin, Michel; Béghin, C.; Grard, R.; López-Moreno, J. J.; Schwingenschuh, K.; Simões, F.; Trautner, R.; Berthelier, Jean‐Jacques; Brown, V.; Chabassière, M.; Falkner, P.; Ferri, F.; Fulchignoni, M.; Jernej, I.; Jeronimo, J. M.; Molina‐Cuberos, G. J.; Rodrigo, R.; Tokano, Tetsuya

doi:10.1016/j.pss.2007.04.008

Cited by 53 publications

(78 citation statements)

References 18 publications

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“…The result of this total ionization, presented in Fig. 4, shows that the GCR ionize mainly at an altitude of 65 km, which is consistent with Huygens observations (López-Moreno et al 2008;Hamelin et al 2007) as shown in Paper I. The main ion produced is N + 2 , followed by CH + 4 , CH + 3 , and N + .…”

Section: The Cosmic-ray Total Ion Productionsupporting

confidence: 88%

“…The remaining presence of that gap ensures that there are still two separate layers of ionization caused by cosmic rays and Saturn's protons, which is consistent with our previous conclusions. The cosmic ray ionization peak, at 65 km altitude, agrees with the Huygens data, which indicates that an ion layer peaks at this altitude (Paper I; López-Moreno et al 2008;Hamelin et al 2007, and references herein). The second difference is the altitude and the intensity of the peak due to electron precipitation at an altitude of 900 km, to account for the influence of magnetic field lines, explained in Paper II (Gronoff et al 2009b), we assumed a dip angle of 20 • for the electron precipitation.…”

Section: Revised Evaluation Of the Total Ionization Profilesupporting

confidence: 71%

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Ionization processes in the atmosphere of Titan

Gronoff

Mertens

Lilensten

et al. 2011

A&A

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Context. The Cassini-Huygens mission has revealed the importance of particle precipitation in the atmosphere of Titan thanks to in-situ measurements. These ionizing particles (electrons, protons, and cosmic rays) have a strong impact on the chemistry, hence must be modeled. Aims. We revisit our computation of ionization in the atmosphere of Titan by cosmic rays. The high-energy high-mass ions are taken into account to improve the precision of the calculation of the ion production profile. Methods. The Badhwahr and O'Neill model for cosmic ray spectrum was adapted for the Titan model. We used the TransTitan model coupled with the Planetocosmics model to compute the ion production by cosmic rays. We compared the results with the NAIRAS/HZETRN ionization model used for the first time for a body that differs from the Earth. Results. The cosmic ray ionization is computed for five groups of cosmic rays, depending on their charge and mass: protons, alpha, Z = 8 (oxygen), Z = 14 (silicon), and Z = 26 (iron) nucleus. Protons and alpha particles ionize mainly at 65 km altitude, while the higher mass nucleons ionize at higher altitudes. Nevertheless, the ionization at higher altitude is insufficient to obscure the impact of Saturn's magnetosphere protons at a 500 km altitude. The ionization rate at the peak (altitude: 65 km, for all the different conditions) lies between 30 and 40 cm −3 s −1 . Conclusions. These new computations show for the first time the importance of high Z cosmic rays on the ionization of the Titan atmosphere. The updated full ionization profile shape does not differ significantly from that found in our previous calculations (Paper I: Gronoff et al. 2009, 506, 955) but undergoes a strong increase in intensity below an altitude of 400 km, especially between 200 and 400 km altitude where alpha and heavier particles (in the cosmic ray spectrum) are responsible for 40% of the ionization. The comparison of several models of ionization and cosmic ray spectra (in intensity and composition) reassures us about the stability of the altitude of the ionization peak (65 km altitude) with respect to the solar activity.

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Section: The Cosmic-ray Total Ion Productionsupporting

confidence: 88%

Section: Revised Evaluation Of the Total Ionization Profilesupporting

confidence: 71%

Ionization processes in the atmosphere of Titan

Gronoff

Mertens

Lilensten

et al. 2011

A&A

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“…These authors concluded that in order to explain the observed disk emissions, the scattered stellar light from Titan's disk is the most likely scenario. It is worth mentioning, however, that according to Gronoff et al (2011), the ionization by each Z-group of cosmic rays in the atmosphere of Titan results in the formation of an ionization layer peaking at 65 km altitude, independently of the solar activity, in consistency with the Huygens measurements (Hamelin et al 2007;López-Moreno et al 2008). The observed correlation between cosmic ray ionization altitudes and aerosol layers urges for further investigations in this direction in the future.…”

Section: The Role Of Galactic Cosmic Rays and Transient Eventssupporting

confidence: 64%

“…Each source has a main ionization altitude that creates several ionospheric layers above 50 km (Hamelin et al 2007;Cravens et al 2008Cravens et al , 2009López-Moreno et al 2008, and references therein). The ion production rates in Titan's ionosphere, for the dayside (Richard et al 2015a and references therein) and nightside (Richard et al 2015b and references therein), have been extensively studied.…”

Section: Space Weather At the Saturnian Moonsmentioning

confidence: 99%

Planetary space weather: scientific aspects and future perspectives

Plainaki

Lilensten

Radioti

et al. 2016

J. Space Weather Space Clim.

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In this paper, we review the scientific aspects of planetary space weather at different regions of our Solar System, performing a comparative planetology analysis that includes a direct reference to the circum-terrestrial case. Through an interdisciplinary analysis of existing results based both on observational data and theoretical models, we review the nature of the interactions between the environment of a Solar System body other than the Earth and the impinging plasma/radiation, and we offer some considerations related to the planning of future space observations. We highlight the importance of such comparative studies for data interpretations in the context of future space missions (e.g. ESA JUICE; ESA/JAXA BEPI COLOMBO). Moreover, we discuss how the study of planetary space weather can provide feedback for better understanding the traditional circumterrestrial space weather. Finally, a strategy for future global investigations related to this thematic is proposed.

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“…Each source has a main ionization altitude that creates several ionosphere layers above 50 km (Cravens et al 2008(Cravens et al , 2009Hamelin et al 2007;López-Moreno et al 2008, and references therein). While Titan can be inside or outside of the Saturn's magnetosphere, particle precipitation, hence ionization can be very variable depending on the position of the satellite and local plasma conditions.…”

Section: Introductionmentioning

confidence: 99%

Ionization processes in the atmosphere of Titan

Gronoff¹,

Lilensten²,

Desorgher

et al. 2009

A&A

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Context. The Cassini probe regularly passes in the vicinity of Titan, revealing new insights into particle precipitation thanks to the electron and proton spectrometer. Moreover, the Huygens probe has revealed an ionized layer at 65 km induced by cosmic rays. The impact of these different particles on the chemistry of Titan is probably very strong. Aims. In this article, we compute the whole ionization in the atmosphere of Titan: from the cosmic rays near the ground to the EUV in the upper atmosphere. The meteoritic layer is not taken into account. Methods. We used the transTitan model to compute the electron and EUV impact, and the planetocosmics code to compute the influence of protons and oxygen ions. We coupled the two models to study the influence of the secondary electrons obtained by planetocosmics through the transTitan code. The resulting model improves the accuracy of the calculation through the transport of electrons in the atmosphere. Results. The whole ionization is computed and studied in details. During the day, the cosmic ray ionization peak is as strong as the UV-EUV one. Electrons and protons are very important depending the precipitation conditions. Protons can create a layer at 500 km, while electrons tend to ionize near 800 km. The oxygen ion impact is near 900 km. The results shows few differences to precedent models for the nightside T5 fly-by of Cassini, and can highlight the sources of the different ion layers detected by radio measurements. Conclusions. The new model successfully computes the ion production in the atmosphere of Titan. For the first time, a full electron and ion profile has been computed from 0 to 1600 km, which compares qualitatively with measurements. This result can be used by chemical models.

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Electron conductivity and density profiles derived from the mutual impedance probe measurements performed during the descent of Huygens through the atmosphere of Titan

Cited by 53 publications

References 18 publications

Ionization processes in the atmosphere of Titan

Ionization processes in the atmosphere of Titan

Planetary space weather: scientific aspects and future perspectives

Ionization processes in the atmosphere of Titan

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