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1. First Steps Towards a New Saturn Ionosphere Model Including Ring-Planet Coupling and Electrodynamics

Author

Omakshi Agiwal, Luke Moore, Carlos Martinis, Ingo Mueller-Wodarg, and Joe Huba

Abstract

The Cassini Grand Finale revealed that there is still much that we do not understand about Saturn’s upper atmosphere. In-situ observations reveal highly complex coupling between the planetary atmosphere and rings and inter-hemispheric electrodynamic coupling at latitudes that are magnetically connected to the intra D-ring region in the magnetosphere. Current Saturn models are ill-suited to treating electrodynamics and ring-planet interactions at Saturn. Thus, we adapt SAMI, a well-known terrestrial ionosphere model that is flux-tube based and already includes electrodynamics, to Saturn, with the aim of using it in conjunction with existing Saturn models such as the STIM-GCM (Saturn Thermosphere Ionosphere Model) to decipher the long-standing unexplained morphologies in Saturn’s ionosphere and investigate the ring-atmosphere coupling and electrodynamics revealed by the Cassini end-of-mission data. We will present initial results having adapted SAMI to Saturn, showing the full extent of the atmospheric chemistry and model capabilities at present. We will discuss future directions of development towards the construction of the new model capable of resolving the complex ring-atmosphere coupling and electrodynamics, and the possibility of adapting this model to other planets.

Published
2022
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2. Phosphine gas in the cloud decks of Venus

Author

Sara Seager, Jim Hoge, Janusz J. Petkowski, David L. Clements, Jane Greaves, E’lisa Lee, Paul B. Rimmer, Anita M. S. Richards, Per Friberg, Sukrit Ranjan, William Bains, Hideo Sagawa, Clara Sousa-Silva, Emily Drabek-Maunder, Zhuchang Zhan, Iain Coulson, Ingo Mueller-Wodarg, Helen J. Fraser, Annabel Cartwright, Greaves, JS [0000-0002-3133-413X], Richards, AMS [0000-0002-3880-2450], Rimmer, PB [0000-0002-7180-081X], Sagawa, H [0000-0003-2064-2863], Seager, S [0000-0002-6892-6948], Petkowski, JJ [0000-0002-1921-4848], Sousa-Silva, C [0000-0002-7853-6871], Mueller-Wodarg, I [0000-0001-6308-7826], Friberg, P [0000-0002-8010-8454], Apollo - University of Cambridge Repository, Science and Technology Facilities Council (STFC), Imperial College Trust, and Science and Technology Facilities Council

Subjects
010504 meteorology & atmospheric sciences, sub-01, FOS: Physical sciences, SULFUR, Venus, Cloud computing, 5109 Space Sciences, Astronomy & Astrophysics, 01 natural sciences, Astrobiology, Atmosphere, chemistry.chemical_compound, CHEMISTRY, 0103 physical sciences, LOWER ATMOSPHERE, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), SPECTRUM, geography, Science & Technology, geography.geographical_feature_category, biology, sub-99, business.industry, Nearest neighbour, Astronomy and Astrophysics, biology.organism_classification, Lightning, Trace gas, LIFE, Volcano, chemistry, WATER-VAPOR, 5101 Astronomical Sciences, 13. Climate action, Physical Sciences, PH3, ENCELADUS, CHEMICAL KINETIC-MODEL, business, 51 Physical Sciences, 5107 Particle and High Energy Physics, Phosphine, Astrophysics - Earth and Planetary Astrophysics
Abstract

Measurements of trace gases in planetary atmospheres help us explore chemical conditions different to those on Earth. Our nearest neighbour, Venus, has cloud decks that are temperate but hyperacidic. Here we report the apparent presence of phosphine (PH3) gas in Venus’s atmosphere, where any phosphorus should be in oxidized forms. Single-line millimetre-waveband spectral detections (quality up to ~15σ) from the JCMT and ALMA telescopes have no other plausible identification. Atmospheric PH3 at ~20 ppb abundance is inferred. The presence of PH3 is unexplained after exhaustive study of steady-state chemistry and photochemical pathways, with no currently known abiotic production routes in Venus’s atmosphere, clouds, surface and subsurface, or from lightning, volcanic or meteoritic delivery. PH3 could originate from unknown photochemistry or geochemistry, or, by analogy with biological production of PH3 on Earth, from the presence of life. Other PH3 spectral features should be sought, while in situ cloud and surface sampling could examine sources of this gas. The detection of ~20 ppb of phosphine in Venus clouds by observations in the millimetre-wavelength range from JCMT and ALMA is puzzling, because according to our knowledge of Venus, no phosphine should be there. As the most plausible formation paths do not work, the source could be unknown chemical processes—maybe even life?

Published
2020
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3. A pole-to-pole pressure–temperature map of Saturn’s thermosphere from Cassini Grand Finale data

Author

Ingo Mueller-Wodarg, Tommi Koskinen, A. Jouchoux, Robert A. West, Larry W. Esposito, and Zarah Brown

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), 010504 meteorology & atmospheric sciences, Atmospheric wave, FOS: Physical sciences, Astronomy and Astrophysics, Zonal and meridional, Atmospheric sciences, 01 natural sciences, Physics::Geophysics, Latitude, Planet, Drag, Saturn, Physics::Space Physics, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Thermosphere, 010303 astronomy & astrophysics, Physics::Atmospheric and Oceanic Physics, Geology, Pressure gradient, Astrophysics - Earth and Planetary Astrophysics, 0105 earth and related environmental sciences
Abstract

Temperatures of the outer planet thermospheres exceed those predicted by solar heating alone by several hundred degrees. Enough energy is deposited at auroral regions to heat the entire thermosphere, but models predict that equatorward distribution is inhibited by strong Coriolis forces and ion drag. A better understanding of auroral energy deposition and circulation are critical to solving this so-called energy crisis. Stellar occultations observed by the Ultraviolet Imaging Spectrograph instrument during the Cassini Grand Finale were designed to map the thermosphere from pole to pole. We analyze these observations, together with earlier observations from 2016 and 2017, to create a two-dimensional map of densities and temperatures in Saturns thermosphere as a function of latitude and depth. The observed temperatures at auroral latitudes are cooler and peak at higher altitudes and lower latitudes than predicted by models, leading to a shallower meridional pressure gradient. Under modified geostrophy, we infer slower westward zonal winds that extend to lower latitudes than predicted, supporting equatorward flow from approximately 70 to 30 degrees latitude in both hemispheres. We also show evidence of atmospheric waves in the data that can contribute to equatorward redistribution of energy through zonal drag., 25 pages, 6 figures, including Supplementary Information

Published
2020
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4. Addendum: Phosphine gas in the cloud deck of Venus

Author

E’lisa Lee, Anita M. S. Richards, Helen J. Fraser, Annabel Cartwright, Janusz J. Petkowski, Per Friberg, Jane Greaves, Clara Sousa-Silva, David L. Clements, Paul B. Rimmer, Ingo Mueller-Wodarg, Jim Hoge, Sara Seager, William Bains, Emily Drabek-Maunder, Sukrit Ranjan, Zhuchang Zhan, Iain Coulson, and Hideo Sagawa

Subjects
biology, business.industry, Addendum, Astronomy and Astrophysics, Venus, Cloud computing, biology.organism_classification, Deck, Astrobiology, chemistry.chemical_compound, chemistry, Environmental science, business, Phosphine
Published
2021
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5. Titan After Cassini-Huygens

Author

Rosaly M.C. Lopes, Charles Elachi, Ingo Mueller-Wodarg, Anezina Solomonidou, Rosaly M.C. Lopes, Charles Elachi, Ingo Mueller-Wodarg, and Anezina Solomonidou

Abstract

Titan After Cassini-Huygens is the most up-to-date and comprehensive coverage of our knowledge on Titan, including results and insights from the joint NASA/European Space Agency/Italian Space Agency mission Cassini-Huygens and the conclusions drawn by experts following detailed analysis of the mission data. Our knowledge of Titan has increased substantially due to observations from the Cassini-Huygens mission, which ended in 2017. Since then, observations from Earth, as well as laboratory and theoretical studies, have continued to add to our knowledge. These conclusions, combined with the latest ground-based and theoretical research, provide the most recent understanding of the science of Titan, covering the origin and evolution of Titan, its magnetic and plasma environment, surface, interior structure, geology, atmosphere, and the astrobiological potential for the oceans on the moon.The first book of the new COSPAR book series, Titan After Cassini-Huygens, is an integral reference for scientists, researchers, and academics working on Titan or ocean worlds. Part of the COSPAR Book SeriesEdited by Jean-Louis Fellous, former Executive Director of COSPAR (Committee on Space Research; 2008–2019) - Details the total knowledge of Titan from Cassini-Huygens and subsequent observations from Earth, as well as laboratory and theoretical studies from the last decade - Covers all aspects of Titan, including origin and evolution, magnetic and plasma environment, surface, interior structure, geology, atmospheric science and astrobiological potential - Provides detailed, referenceable data from investigators of the Cassini spacecraft and Huygens probe, as well as the ALMA radio telescope observatory

Published
2025

6. Preface to the special issue of PSS on 'Surfaces, atmospheres and magnetospheres of the outer planets and their satellites and ring systems: Part XI'

Author

J. Castillo, G. Strazzulla, Athena Coustenis, Sushil K. Atreya, Linda Spilker, Ingo Mueller-Wodarg, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), University of Michigan [Ann Arbor], University of Michigan System, Human Computer Technology Laboratory (HCTLab), Universidad Autónoma de Madrid (UAM), INAF - Osservatorio Astrofisico di Catania (OACT), Istituto Nazionale di Astrofisica (INAF), and Universidad Autonoma de Madrid (UAM)

Subjects
Physics, [PHYS]Physics [physics], Outer planets, Space and Planetary Science, Astronomy, Astronomy and Astrophysics, Ring (chemistry), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ComputingMilieux_MISCELLANEOUS, Astrobiology
Abstract

International audience

Published
2016
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7. Response of Saturn's ionosphere to solar radiation: Testing parameterizations for thermal electron heating and secondary ionization processes

Author

Ingo Mueller-Wodarg, Luke Moore, Marina Galand, and Michael Mendillo

Subjects
Physics, Range (particle radiation), Space and Planetary Science, Ionization, Saturn, Astronomy and Astrophysics, Plasma, Electron, Ionosphere, Atmospheric sciences, Computational physics, Ion, Latitude
Abstract

We evaluate the effectiveness of two parameterizations in Saturn's ionosphere over a range of solar fluxes, seasons, and latitudes. First, the parameterization of the thermal electron heating rate, Q * e , introduced in [Moore, L., Galand, M., Mueller-Wodarg, I., Yelle, R.V., Mendillo, M., 2008. Plasma temperatures in Saturn's ionosphere. J. Geophys. Res. 113, A10306. doi:10.1029/2008JA013373 .] for one specific set of conditions, is found to produce ion and electron temperatures that agree with self-consistent suprathermal electron calculations to within 2% on average under all conditions considered. Next, we develop a new parameterization of the secondary ion production rate at Saturn based on the calculations of [Galand, M., Moore, L., Mueller-Wodarg, I., Mendillo, M., 2009. Modeling the photoelectron secondary ionization process at Saturn. accepted. J. Geophys. Res.]; it is found to be accurate to within 4% on average. The demonstrated effectiveness of these two parameterizations over a wide range of input conditions makes them good candidates for inclusion in 3D Saturn thermosphere–ionosphere general circulation models (TIGCMs).

Published
2009
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8. Titan : Interior, Surface, Atmosphere, and Space Environment

Author

Ingo Müller-Wodarg, Caitlin A. Griffith, Emmanuel Lellouch, Thomas E. Cravens, Ingo Müller-Wodarg, Caitlin A. Griffith, Emmanuel Lellouch, and Thomas E. Cravens

Subjects
SCIENCE / Astronomy
Abstract

Titan, the largest of Saturn's moons, shares remarkable similarities with Earth. Its thick atmosphere is composed primarily of nitrogen; it features the most complex organic chemistry known outside of Earth and, uniquely, hosts an analog to Earth's hydrological cycle, with methane forming clouds, rain and seas. Using the latest data from the ongoing Cassini–Huygens missions, laboratory measurements and numerical simulations, this comprehensive reference examines the physical processes that shape Titan's fascinating atmospheric structure and chemistry, weather, climate, circulation and surface geology. The text also surveys leading theories about Titan's origin and evolution, and assesses their implications for understanding the formation of other complex planetary bodies. Written by an international team of specialists, chapters offer detailed, comparative treatments of Titan's known properties and discuss the latest frontiers in the Cassini–Huygens mission, offering students and researchers of planetary science, geology, astronomy and space physics an insightful reference and guide.

Published
2014

9. The EChO science case

Author

Giovanna Tinetti, Pierre Drossart, Paul Eccleston, Paul Hartogh, Kate Isaak, Martin Linder, Christophe Lovis, Giusi Micela, Marc Ollivier, Ludovic Puig, Ignasi Ribas, Ignas Snellen, Bruce Swinyard, France Allard, Joanna Barstow, James Cho, Athena Coustenis, Charles Cockell, Alexandre Correia, Leen Decin, Remco de Kok, Pieter Deroo, Therese Encrenaz, Francois Forget, Alistair Glasse, Caitlin Griffith, Tristan Guillot, Tommi Koskinen, Helmut Lammer, Jeremy Leconte, Pierre Maxted, Ingo Mueller-Wodarg, Richard Nelson, Chris North, Enric Pallé, Isabella Pagano, Guseppe Piccioni, David Pinfield, Franck Selsis, Alessandro Sozzetti, Lars Stixrude, Jonathan Tennyson, Diego Turrini, Mariarosa Zapatero-Osorio, Jean-Philippe Beaulieu, Denis Grodent, Manuel Guedel, David Luz, Hans Ulrik Nørgaard-Nielsen, Tom Ray, Hans Rickman, Avri Selig, Mark Swain, Marek Banaszkiewicz, Mike Barlow, Neil Bowles, Graziella Branduardi-Raymont, Vincent Coudé du Foresto, Jean-Claude Gerard, Laurent Gizon, Allan Hornstrup, Christopher Jarchow, Franz Kerschbaum, Géza Kovacs, Pierre-Olivier Lagage, Tanya Lim, Mercedes Lopez-Morales, Giuseppe Malaguti, Emanuele Pace, Enzo Pascale, Bart Vandenbussche, Gillian Wright, Gonzalo Ramos Zapata, Alberto Adriani, Ruymán Azzollini, Ana Balado, Ian Bryson, Raymond Burston, Josep Colomé, Martin Crook, Anna Di Giorgio, Matt Griffin, Ruud Hoogeveen, Roland Ottensamer, Ranah Irshad, Kevin Middleton, Gianluca Morgante, Frederic Pinsard, Mirek Rataj, Jean-Michel Reess, Giorgio Savini, Jan-Rutger Schrader, Richard Stamper, Berend Winter, L. Abe, M. Abreu, N. Achilleos, P. Ade, V. Adybekian, L. Affer, C. Agnor, M. Agundez, C. Alard, J. Alcala, C. Allende Prieto, F. J. Alonso Floriano, F. Altieri, C. A. Alvarez Iglesias, P. Amado, A. Andersen, A. Aylward, C. Baffa, G. Bakos, P. Ballerini, M. Banaszkiewicz, R. J. Barber, D. Barrado, E. J. Barton, V. Batista, G. Bellucci, J. A. Belmonte Avilés, D. Berry, B. Bézard, D. Biondi, M. Błęcka, I. Boisse, B. Bonfond, P. Bordé, P. Börner, H. Bouy, L. Brown, L. Buchhave, J. Budaj, A. Bulgarelli, M. Burleigh, A. Cabral, M. T. Capria, A. Cassan, C. Cavarroc, C. Cecchi-Pestellini, R. Cerulli, J. Chadney, S. Chamberlain, N. Christian Jessen, A. Ciaravella, A. Claret, R. Claudi, A. Coates, R. Cole, A. Collur, D. Cordier, E. Covino, C. Danielski, M. Damasso, H. J. Deeg, E. Delgado-Mena, C. Del Vecchio, O. Demangeon, A. De Sio, J. De Wit, M. Dobrijévi, P. Doel, C. Dominic, E. Dorfi, S. Eales, C. Eiroa, M. Espinoza Contreras, M. Esposito, V. Eymet, N. Fabrizio, M. Fernández, B. Femenía Castella, P. Figueira, G. Filacchione, L. Fletcher, M. Focardi, S. Fossey, P. Fouqué, J. Frith, M. Galand, L. Gambicorti, P. Gaulme, R. J. García López, A. Garcia-Piquer, W. Gear, J. -C. Gerard, L. Gesa, E. Giani, F. Gianotti, M. Gillon, E. Giro, M. Giuranna, H. Gomez, I. Gomez-Leal, J. Gonzalez Hernandez, B. GonzÁlez Merino, R. Graczyk, D. Grassi, J. Guardia, P. Guio, J. Gustin, P. Hargrave, J. Haigh, E. Hébrard, U. Heiter, R. L. Heredero, E. Herrero, F. Hersant, D. Heyrovsky, M. Hollis, B. Hubert, R. Hueso, G. Israelian, N. Iro, P. Irwin, S. Jacquemoud, G. Jones, H. Jones, K. Justtanont, T. Kehoe, F. Kerschbaum, E. Kerins, P. Kervell, D. Kipping, T. Koskinen, N. Krupp, O. Lahav, B. Laken, N. Lanza, E. Lellouch, G. Leto, J. Licandro Goldaracena, C. Lithgow Bertelloni, S. J. Liu, U. Lo Cicero, N. Lodieu, P. Lognonné, M. Lopez Puertas, M. A. Lopez Valverde, I. Lundgaard Rasmussen, A. Luntzer, P. Machado, C. Mac Tavish, A. Maggio, J. P. Maillard, W. Magnes, J. Maldonado, U. Mall, J. B. Marquette, P. Mauskopf, F. Massi, A. S. Maurin, A. Medvedev, C. Michaut, P. Miles Paez, M. Montalto, P. Montañés Rodríguez, M. Monteiro, D. Montes, H. Morais, J. C. Morale, M. Morales-Calderón, G. Morello, A. Moro Martín, J. Moses, A. Moya Bedon, F. Murgas Alcaino, E. Oliva, G. Orton, F. Palla, M. Pancrazzi, E. Pantin, V. Parmentier, H. Parviainen, Y. Pena Ramirez, J. Peralta, S. Perez-Hoyos, R. Petrov, S. Pezzuto, R. Pietrzak, E. Pilat-Lohinger, N. Piskunov, R. Prinja, L. Prisinzano, I. Polichtchouk, E. Poretti, A. Radioti, A. Ramos, T. Rank-Luftinger, P. Read, K. Readorn, R. Rebolo Lopez, J. Rebordao, M. Rengel, L. Rezac, M. Rocchetto, F. Rodler, J. Sanchez Bejar, A. Sanchez Lavega, E. Sanroma, N. Santos, J. Sanz Forcada, G. Scandariato, F.- X. Schmider, A. Scholz, S. Scuderi, J. Sethenadh, S. Shore, A. Showman, B. Sicardy, P. Sitek, A. Smith, L. Soret, S. Sousa, A. Stiepen, M. Stolarski, G. Strazzulla, H. M. Tabernero, P. Tanga, M. Tecsa, J. Temple, L. Terenzi, M. Tessenyi, L. Testi, S. Thompson, H. Thrastarson, B. W. Tingley, M. Trifoglio, J. Martin Torres, A. Tozzi, D. Turrini, R. Varley, F. Vakili, M. de Val-Borro, M. L. Valdivieso, O. Venot, E. Villaver, S. Vinatier, S. Viti, I. Waldmann, D. Waltham, D. Ward-Thompson, R. Waters, C. Watkins, D. Watson, P. Wawer, A. Wawrzaszk, G. White, T. Widemann, W. Winek, T. Wi.niowski, R. Yelle, Y. Yung, and S. N. Yurchenko

Subjects
13. Climate action, 7. Clean energy
Published
2015
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10. Preface

Author

Roger V. Yelle and Ingo Mueller-Wodarg

Subjects
symbols.namesake, General Mathematics, General Engineering, symbols, General Physics and Astronomy, Environmental science, Titan (rocket family), Atmospheric sciences, Space environment
Published
2008
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11. Surfaces, atmospheres and magnetospheres of the outer planets and their satellites and ring systems: Part VIII

Author

J. Castillo, Sushil K. Atreya, Ingo Mueller-Wodarg, P. Coll, Linda Spilker, Athena Coustenis, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor] (AOSS), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Human Computer Technology Laboratory (HCTLab), Universidad Autónoma de Madrid (UAM), and Universidad Autonoma de Madrid (UAM)

Subjects
Physics, [PHYS]Physics [physics], Outer planets, 010504 meteorology & atmospheric sciences, Astronomy, Astronomy and Astrophysics, Ring (chemistry), 01 natural sciences, Astrobiology, Space and Planetary Science, 0103 physical sciences, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

International audience

Published
2013
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12. Response of Saturn's auroral ionosphere to electron precipitation: Electron density, electron temperature, and electrical conductivity

Author

Marina Galand, Michael Mendillo, Steve Miller, Luke Moore, and Ingo Mueller-Wodarg

Subjects
Atmospheric Science, Electron density, Soil Science, Energy flux, Electron precipitation, Magnetosphere, Aquatic Science, Oceanography, Physics::Geophysics, Geochemistry and Petrology, Saturn, Earth and Planetary Sciences (miscellaneous), Earth-Surface Processes, Water Science and Technology, Physics, Ecology, Paleontology, Forestry, Geophysics, Computational physics, Space and Planetary Science, Physics::Space Physics, Electron temperature, Astrophysics::Earth and Planetary Astrophysics, Ionosphere, Thermosphere
Abstract

[1] In the high‐latitude regions of Saturn, the ionosphere is strongly coupled to the magnetosphere through the exchange of energy. The influx of energetic particles from Saturn’s magnetosphere enhances the ionospheric densities and temperatures, affects the electrodynamical properties of the ionosphere, and contributes to the heating of the thermosphere. It is therefore critical to accurately model the energy deposition of these magnetospheric particles in the upper atmosphere in order to evaluate key ionospheric quantities of the coupled magnetosphere‐ionosphere system. We present comprehensive results of ionospheric calculations in the auroral regions of Saturn using our Saturn Thermosphere‐Ionosphere Model (STIM). We focus on solar minimum conditions during equinox. The atmospheric conditions are derived from the STIM 3‐D General Circulation Model. The ionospheric component is self‐consistently coupled to the solar and auroral energy deposition component. The precipitating electrons are assumed to have a Maxwellian distribution in energy with a mean energy Em and an energy flux Q0. In the presence of hard electron precipitation (1 0.04 mW m −2 , the ionospheric conductances are found to be proportional to the square root of the energy flux, but the response of the ionosphere is not instantaneous and a time delay needs to be applied to Q0 when estimating the conductances. In the presence of soft electron precipitation (Em < 500 eV) with Q0 ≤ 0.2 mW m −2 , the ionospheric conductances at noon are found to be primarily driven by the Sun. However, soft auroral electrons are efficient at increasing the ionospheric total electron content and at heating the thermal electron population.

Published
2011
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13. Latitudinal variations in Saturn's ionosphere: Cassini measurements and model comparisons

Author

Michael Mendillo, Ingo Mueller-Wodarg, Luke Moore, Arvydas J. Kliore, and Marina Galand

Subjects
Physics, Atmospheric Science, Ecology, Total electron content, TEC, Equator, Paleontology, Soil Science, Forestry, Aquatic Science, Oceanography, Atmospheric sciences, Latitude, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Saturn, Middle latitudes, Earth and Planetary Sciences (miscellaneous), Radio occultation, Ionosphere, Earth-Surface Processes, Water Science and Technology
Abstract

[1] We present a study of latitudinal variations in Saturn’s ionosphere using Cassini Radio Science Subsystem (RSS) measurements and Saturn‐Thermosphere‐Ionosphere‐Model (STIM) simulations. On the basis of Cassini RSS observations, the peak electron density (NMAX) and the total electron content (TEC) both exhibit a clear increase with latitude, with a minimum at Saturn’s equator. When compared with these RSS trends, current model simulations overestimate NMAX and TEC at low latitudes and underestimate those parameters at middle and high latitudes. STIM is able to reproduce the RSS values for NMAX and TEC at low latitude when an additional low‐latitude loss process, such as a water influx, is introduced near Saturn’s equator. The lack of auroral precipitation processes in the model likely explains some model/data discrepancies at high latitude; however, most of the high‐latitude RSS data are from latitudes outside of Saturn’s typical main auroral oval. Using Cassini RSS electron density altitude profiles combined with ion density fractions and neutral background parameters calculated in STIM, we also present estimates of the latitudinal variations of Saturn’s Pedersen conductance, SP. We find SP to be driven by ion densities in Saturn’s lower ionosphere and to exhibit a latitudinal trend with a peak at mid‐latitude. Model calculations are able to reproduce low‐latitude conductances when an additional loss process is introduced, as before, but consistently underestimate most of the mid‐ and high‐latitude conductances derived from Cassini observations, perhaps indicating a missing ionization source within the model.

Published
2010
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14. The science of EChO

Author

James Frith, Marina Galand, Emmanuel Lellouch, Antonino La Barbera, M. J. Barlow, Marcell Tessenyi, Peter Doel, Ignasi Ribas, Jesus Maldonado Prado, Sergey N. Yurchenko, David M. Kipping, Pactrick Guio, Roy van Boekel, Peter H. Hauschildt, Remco de Kok, Antonio Maggio, Maria R. Zapatero-Osorio, David Pinfield, Emanuele Pace, Mercedes Lopez Morales, Raman K. Prinja, Géza Kovács, Mark G. Swain, Angioletta Coradini, Richard P. Nelson, Patrick Gaulme, Julianne I. Moses, Ingo Mueller-Wodarg, Jean-Philippe Beaulieu, Alan D. Aylward, Gáspár Á. Bakos, Thomas Widemann, Giovanni Strazzulla, Céline Cavarroc, Manuel Guedel, Caitlin A. Griffith, Olivier Hainaut, S. J. Fossey, Pascal Bordé, Ennio Poretti, Giorgio Savini, Jeroen Bouwman, Jean-Pierre Maillard, Eric Pantin, Mercedes López-Morales, Leen Decin, Miguel A. Lopez Valverde, Olivier Mousis, Peter A. R. Ade, Pieter Deroo, Olivier Demangeon, Kevin Heng, James Y-K. Cho, Angela Ciaravella, Amaya Moro-Martin, Daphne Stam, Tristan Guillot, Bruno Bézard, Franck Selsis, Roger V. Yelle, Lisa Kaltenegger, Pascal Fouqué, Alessandro Sozzetti, Alberto Adriani, Linda R. Brown, Giovanna Tinetti, Loredana Prisinzano, Giuseppina Micela, Thomas Henning, Vincent Coudé du Foresto, Craig B. Agnor, Ulrich Grözinger, Yuk Yung, Michael Meyer, Robert J. Hargreaves, Marc Ollivier, Ansgar Reiners, Ricardo Hueso, Enzo Pascale, Alan Smith, Nicholas Achilleos, Dimitar Sasselov, Robin Wordsworth, Jonathan Tennyson, Bruce Swinyard, Carlos Allende Prieto, Sergio Molinari, Manuel López-Puertas, Peter F. Bernath, David Heyrovsky, Ignas Snellen, Bruno Sicardy, Oliver Krause, Gautam Vasisht, Steve Miller, Christophe Lovi, Matthew James Griffin, Athena Coustenis, Napoléon Nguyen Tuong, Ingo Waldmann, Glenn S. Orton, Giuseppe Leto, B. Samuel, Patrick Kervella, Pierre F. L. Maxted, F. J. Martin-Torres, Lee Grenfell, Patrick G. J. Irwin, Stefano Pezzuto, Cristina Afonso, Olivier Grasset, Thérèse Encrenaz, Jonay I. González Hernández, Helmut Lammer, Davide Grassi, Serena Viti, Enric Palle, Tommi Koskinen, Jorge Sanz Forcada, Glenn J. White, Camilla Danielski, François Forget, Leigh N. Fletcher, Jean-Michel Reess, Arnaud Cassan, J. B. Marquette, Matteo Focardi, D. Montes, R. J. Barber, Sandrine Vinatier, Charles S. Cockell, Lars Stixrude, Pierre Drossart, University College of London [London] (UCL), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Astronomy [UCL London], Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Istituto di Fisica dello Spazio Interplanetario (INAF), Consiglio Nazionale delle Ricerche [Roma] (CNR), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Département d'Astrophysique (ex SAP) (DAP), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1, Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Institut d'Astrophysique de Paris (IAP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Liquides Ioniques et Interfaces Chargées (LI2C), Université Pierre et Marie Curie - Paris 6 (UPMC)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Palermo (OAPa), Istituto Nazionale di Astrofisica (INAF), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), SRON Netherlands Institute for Space Research (SRON), University of Calgary, Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), School of Physics and Astronomy [London], Queen Mary University of London (QMUL), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Astronomische Rechen-Institut [Heidelberg] (ARI), Zentrum für Astronomie der Universität Heidelberg (ZAH), Universität Heidelberg [Heidelberg]-Universität Heidelberg [Heidelberg], Planetary and Space Sciences Research Institute [Milton Keynes] (PSSRI), Centre for Earth, Planetary, Space and Astronomical Research [Milton Keynes] (CEPSAR), The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Department of Atmospheric, Oceanic and Planetary Physics [Oxford] (AOPP), University of Oxford [Oxford], Institut Pierre-Simon-Laplace (IPSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National d'Études Spatiales [Toulouse] (CNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Blackett Laboratory, Imperial College London, Istituto di Fisica dello Spazio Interplanetario (IFSI), Consiglio Nazionale delle Ricerche (CNR), Escuela Superior de Ingenieria, Universidad del Pais Vasco / Euskal Herriko Unibertsitatea [Espagne] (UPV/EHU), Harvard-Smithsonian Center for Astrophysics (CfA), Smithsonian Institution-Harvard University [Cambridge], Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Department of Science and Technology Studies [London] (STS), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Imperial College Healthcare NHS Trust, STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC), Department of Physics and Astronomy [Milton Keynes], The Open University [Milton Keynes] (OU), Université Nice Sophia Antipolis (1965 - 2019) (UNS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Universität Heidelberg [Heidelberg] = Heidelberg University-Universität Heidelberg [Heidelberg] = Heidelberg University, University of Oxford, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Harvard University-Smithsonian Institution, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Planétologie et Géodynamique UMR6112 (LPG), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centre National de la Recherche Scientifique (CNRS)-ESPCI ParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), California Institute of Technology (CALTECH)-NASA, École normale supérieure - Paris (ENS Paris)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National d'Études Spatiales [Toulouse] (CNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, and Harvard University [Cambridge]-Smithsonian Institution

Subjects
Solar System, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Luchtkwaliteit, 01 natural sciences, 7. Clean energy, Astrobiology, Air Quality, Kepler-47, Planet, formation [Planetary systems], 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, planets and satellites: formation, Kepler-62, 010303 astronomy & astrophysics, planetary systems, Astrophysics::Galaxy Astrophysics, QC, Physics, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, planets and satellites: general, Planetary system, Exoplanet, general [Planets and satellites], planetary systems: formation, Planetary systems, 13. Climate action, Space and Planetary Science, Terrestrial planet, Planetary systems: formation, Planets and satellites: formation, Planets and satellites: general, Astrophysics::Earth and Planetary Astrophysics, Circumstellar habitable zone, formation [Planets and satellites]
Abstract

The science of extra-solar planets is one of the most rapidly changing areas of astrophysics and since 1995 the number of planets known has increased by almost two orders of magnitude. A combination of ground-based surveys and dedicated space missions has resulted in 560-plus planets being detected, and over 1200 that await confirmation. NASA's Kepler mission has opened up the possibility of discovering Earth-like planets in the habitable zone around some of the 100,000 stars it is surveying during its 3 to 4-year lifetime. The new ESA's Gaia mission is expected to discover thousands of new planets around stars within 200 parsecs of the Sun. The key challenge now is moving on from discovery, important though that remains, to characterisation: what are these planets actually like, and why are they as they are?In the past ten years, we have learned how to obtain the first spectra of exoplanets using transit transmission and emission spectroscopy. With the high stability of Spitzer, Hubble, and large ground-based telescopes the spectra of bright close-in massive planets can be obtained and species like water vapour, methane, carbon monoxide and dioxide have been detected. With transit science came the first tangible remote sensing of these planetary bodies and so one can start to extrapolate from what has been learnt from Solar System probes to what one might plan to learn about their faraway siblings. As we learn more about the atmospheres, surfaces and near-surfaces of these remote bodies, we will begin to build up a clearer picture of their construction, history and suitability for life.The Exoplanet Characterisation Observatory, EChO, will be the first dedicated mission to investigate the physics and chemistry of Exoplanetary Atmospheres. By characterising spectroscopically more bodies in different environments we will take detailed planetology out of the Solar System and into the Galaxy as a whole.EChO has now been selected by the European Space Agency to be assessed as one of four M3 mission candidates.

Published
2010
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15. Solar primary and secondary ionization at Saturn

Author

Luke Moore, Ingo Mueller-Wodarg, Benjamin Charnay, Marina Galand, and Michael Mendillo

Subjects
Atmospheric Science, Electron density, Electron spectrometer, Soil Science, Photoionization, Aquatic Science, Oceanography, Atmosphere, Geochemistry and Petrology, Ionization, Saturn, Earth and Planetary Sciences (miscellaneous), Electron ionization, Earth-Surface Processes, Water Science and Technology, Physics, Ecology, Paleontology, Forestry, Computational physics, Geophysics, Space and Planetary Science, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, Ionosphere, Atomic physics
Abstract

[1] Solar EUV and soft X-ray photons are a prime source of energy upon Saturn's upper atmosphere. In particular, they represent a significant source of ionization yielding the creation of an ionosphere, a region probed by the Cassini Radio Science Subsystem (RSS) experiment. During the past decade the only ionization process modeled at Saturn under solar illumination has been photoionization. We present the first detailed calculation of the ionization rate by suprathermal electrons (photoelectrons and their secondaries), applied to Saturn using realistic solar flux and neutral atmospheric input. The energy degradation model, describing the absorption of solar photons and the transport of suprathermal electrons, is self-consistently coupled with an ionospheric model providing the electron and ion densities and temperatures. The coupled model is applied to equinox conditions at 30°N latitude. We assess and compare the photoionization and electron-impact ionization rates. We discuss their sensitivity with solar flux models as well as solar activity. We find that the secondary production rate affects not only the bottom side of the ionosphere, as previously predicted, but also the main ionospheric peak. The electron density is increased by up to 30% at the peak with a decrease in the peak altitude by several hundreds of kilometers around local noon. Above the homopause, the largest increase in electron density is found after sunrise below the ionospheric peak. Finally, we compare the energy degradation of photoelectrons with auroral electrons and discuss the relevance of this study to the interpretation of observations by the Cassini RSS and Cassini Plasma Science/Electron Spectrometer instruments.

Published
2009
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16. Neutral Upper Atmosphere and Ionosphere Modeling

Author

Pierre-Louis Blelly, Jane L. Fox, Raymond G. Roble, Aaron J. Ridley, Michael R. Combi, Stephen W. Bougher, and Ingo Mueller-Wodarg

Subjects
Atmosphere, business.industry, Planet, Numerical modeling, Environmental science, Astrophysics::Earth and Planetary Astrophysics, Aerospace engineering, Ionosphere, business, Strengths and weaknesses
Abstract

Numerical modeling tools can be used for a number of reasons yielding many benefits in their application to planetary upper atmosphere and ionosphere environments. These tools are commonly used to predict upper atmosphere and ionosphere characteristics and to interpret measurements once they are obtained. Additional applications of these tools include conducting diagnostic balance studies, converting raw measurements into useful physical parameters, and comparing features and processes of different planetary atmospheres. This chapter focuses upon various classes of upper atmosphere and ionosphere numerical modeling tools, the equations solved and key assumptions made, specified inputs and tunable parameters, their common applications, and finally their notable strengths and weaknesses. Examples of these model classes and their specific applications to individual planetary environments will be described.

Published
2009
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17. Plasma temperatures in Saturn's ionosphere

Author

Luke Moore, Roger V. Yelle, Michael Mendillo, Ingo Mueller-Wodarg, and Marina Galand

Subjects
Atmospheric Science, Electron density, Soil Science, Plasma diffusion, Aquatic Science, Oceanography, Atmospheric sciences, Secondary electrons, Atmosphere, Geochemistry and Petrology, Saturn, Earth and Planetary Sciences (miscellaneous), Radio occultation, Earth-Surface Processes, Water Science and Technology, Physics, Ecology, Paleontology, Forestry, Geophysics, Space and Planetary Science, Physics::Space Physics, Electron temperature, Astrophysics::Earth and Planetary Astrophysics, Ionosphere, Atomic physics
Abstract

[1] We have calculated self-consistent electron and ion temperatures in Saturn's ionosphere using a series of coupled fluid and kinetic models developed to help interpret Cassini observations and to examine the energy budget of Saturn's upper atmosphere. Electron temperatures in the midlatitude topside ionosphere during solar maximum are calculated to range between 500 and 560 K during the Saturn day, approximately 80–140 K above the neutral temperature. Ion temperatures, calculated for only the major ions H+ and H3+, are nearly equal to the neutral temperature at altitudes near and below the height of peak electron density, while they can reach 500 K during the day at the topside. Plasma scale heights of the dusk electron density profile from radio occultation measurements of the Voyager 2 flyby of Saturn have been used to estimate plasma temperature as a comparison. Such an estimate agrees well with the temperatures calculated here, although there is a topside enhancement in electron density that remains unexplained by ionospheric calculations that include photochemistry and plasma diffusion. Finally, parameterizations of the heating rate from photoelectrons and secondary electrons to thermal, ambient electrons have been developed. They may apply for other conditions at Saturn and possibly at other giant planets and exoplanets as well.

Published
2008
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18. Titan interaction with Saturn's magnetosphere: Voyager 1 results revisited

Author

Adolfo F. Viñas, Ingo Mueller-Wodarg, Howard Smith, Richard E. Hartle, Robert E. Johnson, and E. C. Sittler

Subjects
Atmospheric Science, Gyroradius, Soil Science, Magnetosphere, Aquatic Science, Oceanography, Astrobiology, symbols.namesake, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Atmosphere of Titan, Earth-Surface Processes, Water Science and Technology, Physics, Ecology, Paleontology, Forestry, Plasma, Pickup Ion, Geophysics, Space and Planetary Science, symbols, Atomic physics, Ionosphere, Titan (rocket family), Exosphere
Abstract

[1] We investigate the details of Titan's interaction with Saturn's magnetosphere, which includes formation and location of an ionopause, mass loading via ion pickup, and the effects of finite gyroradii. We present new interpretations of the Voyager 1 plasma instrument measurements not addressed by Hartle et al. (1982). Pickup ions H+ and H2+ dominate in the outermost region with respect to Titan's “ionopause,” followed by CH4+ at intermediate distances and N2+ just outside the “ionopause.” Mass loading and slowing down of the ambient plasma is observed to increase as the pickup ion mass increases with decreasing radial distance from Titan's ionosphere. H2 and CH4 are molecules not originally included in the exosphere of Titan by Hartle and coworkers, and the pickup ions of H2+ and CH4+ are a new feature of our model calculations and should be present in Titan's exospheric region. Therefore Titan could be an important source of carbon to Saturn's magnetosphere. Finite gyroradius effects are identified in the plasma interaction with Titan's atmosphere, which results in an asymmetric removal of ambient plasma from Titan's exosphere region. The finite gyroradius effects also show that the observed hot keV ion component of the ambient plasma is a heavy ion such as N+/O+. A minimum “ionopause” altitude of 4800 km is estimated by a new approach using mass loading.

Published
2005
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19. Effects of ring shadowing on the detection of electrostatic discharges at Saturn

Author

M. L. Kaiser, John Clarke, William S. Kurth, Michael Mendillo, Luke Moore, and Ingo Mueller-Wodarg

Subjects
Physics, Electron density, Geophysics, Physics::Space Physics, Diurnal temperature variation, General Earth and Planetary Sciences, Astrophysics::Earth and Planetary Astrophysics, Astrophysics, Radio frequency, Ionosphere, Physics::Geophysics, Astrobiology, Latitude
Abstract

[1] A long-standing discrepancy exists in determinations from observations and modeling of the diurnal variation of the peak electron density of Saturn's ionosphere. Using a new Saturn-Thermosphere-Ionosphere-Model (STIM), we examine the suggestion by Burns et al. (1983) that Saturn's rings shadow its ionosphere causing radio penetration “holes”, thereby allowing lightning-induced radio signals (Saturn electrostatic discharges, SEDs) to escape. This lessens the need to invoke globally enhanced loss processes to account for Voyager era observations of nighttime peak density (Nmax) as low as 103 e/cm3 from the SEDs. We find radio frequency “windows” produced by ring shadowing that were narrow and confined to low latitudes during the Voyager era, but are now broadly distributed over northern mid-latitudes during the Cassini era. If lightning sources occur only at near-equatorial latitudes, then the far less frequent detection of SEDs by Cassini early in its mission would be consistent with the current ionospheric morphology.

Published
2005
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20. Comparative Aeronomy

Author

Andrew F. Nagy, A. Balogh, Thomas E. Cravens, Michael Mendillo, Ingo Müller-Wodarg, Andrew F. Nagy, A. Balogh, Thomas E. Cravens, Michael Mendillo, and Ingo Müller-Wodarg

Subjects
Upper atmosphere
Abstract

Andrew F. Nagy Originally published in the journal Space Science Reviews, Volume 139, Nos 1–4. DOI: 10. 1007/s11214-008-9353-0 © Springer Science+Business Media B. V. 2008 Keywords Aeronomy The term “aeronomy” has been used widely for many decades, but its origin has mostly been lost over the years. It was introduced by Sydney Chapman in a Letter to the Editor, entitled “Some Thoughts on Nomenclature”, in Nature in 1946 (Chapman 1946). In that letter he suggested that aeronomy should replace meteorology, writing that the word “meteor is now irrelevant and misleading”. This proposal was apparently not received with much support so in a short note in Weather in 1953 Chapman (1953)wrote: “If, despite its obvious convenience of brevity in itself and its derivatives, it does not commend itself to aeronomers, I think there is a case for modifying my proposal so that instead of the word being used to signify the study of the atmosphere in general, it should be adopted with the restricted sense of the science of the upper atmosphere, for which there is no convenient short word. ” In a chapter, he wrote in a 1960 book (Chapman 1960), he give his nal and de nitive de nition, by stating that “Aeronomy is the science of the upper region of the atmosphere, where dissociation and ionization are important”. The Workshop on “Comparative Aeronomy” was held at ISSI during the week of June 25–29, 2007.

Published
2008

21. A young person's guide to the planets

Author

Tom Stallard and Ingo Mueller-Wodarg

Subjects
Geophysics, Geochemistry and Petrology, Planet, Media studies, Ball (bearing), Astronomy and Astrophysics, Sociology, Young person
Abstract

The UK Planetary Forum's Young Person's Planetary Meeting was a chance for young researchers to meet, speak and discuss their research with others from across the UK and to build new research contacts. The one-day symposium was organized by the UKPF with support from the RAS. Andrew Ball, Ingo Mueller-Wodarg and Tom Stallard report.

Published
2004
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22. Comparative aeronomy in the solar system

Author

Ingo Mueller-Wodarg and Emma J. Bunce

Subjects
Physics, Solar System, Geophysics, Meteorology, Geochemistry and Petrology, Planet, Aeronomy, Astronomy, Astronomy and Astrophysics, Subject (documents)
Abstract

The coupled upper atmospheres, ionospheres and magnetospheres of the planets were the subject of a joint RAS–G/MIST discussion meeting hosted by the RAS on 10 January 2003, organized by Ingo Mueller-Wodarg and Emma Bunce. The scientific programme consisted of 10 presentations by speakers from the UK, France, USA and Australia.

Published
2003
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