Observatoire de Paris Institut national de recherche scientifique français Univerité Pierre et Marie Curie Université Paris Diderot - Paris 7

Sauf exception, les séminaires ont lieu sur le site de Meudon, dans la salle de conférence du bâtiment 17.

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Séminaires passés

  • Lundi 4 mars 2024 à 16h00 (Salle de conférence du bâtiment 17)

    A Brief Introduction about China Planetary Explorations and Tianwen-2 mission

    Dr. Shanhong Liu, Associate Professor, Key Laboratory of Science and Technology on Aerospace Flight Dynamics (BACC) in Beijing (China)

    China’s planetary exploration mission will be shortly introduced. Some typically planetary radio science results will be reviewed. Then, this report will introduce the Tianwen-2 mission, China’s follow-up mission to the Tianwen-1 Mars exploration. The Tianwen-2 mission focuses on near-earth asteroid and main-belt comet research. Targeting asteroid 2016HO3 and main-belt comet 311P, the report will delve into their characteristics, scientific goals, and exploration strategies. It aims to analyze orbital dynamics, gravitational fields, and material composition, which can unravel the solar system’s formation and evolution. Additionally, the mission’s outline and payload details will be briefly outlined.


  • Lundi 4 mars 2024 à 14h00 (Salle de conférence du bâtiment 17)

    Plasma and radio waves missions in Japan : Arase, BepiColombo, and JUICE - from Earth, via Mercury, to Jupiter

    Pr KASABA (PPARC and Graduate School of Science de Tohoku Univervity, Japan)

    In plasma and radio waves sensing, we are now running Plasma Wave Experiment (PWE) aboard Arase spacecraft which are investigating Geospace. This spacecraft have provided continuous observations of the inner magnetosphere, which extension until FY2032 has been approved. With good particle measurements, we are revealing electron and ion waves which can contribute to the acceleration and loss of energetic particles in Geospace.

    Associated with this mission, we are also running two major collaborations with Europe including LESIA colleagues. The first is Plasma Wave Investigation (PWI) aboard the Mio spacecraft of BepiColombo, ESA-JAXA joint mission to Mercury, which will observe Mercury on the orbit from the end of 2025. The second is Radio and Plasma Wave Investigations (RPWI) aboard ESA JUpiter ICy moons Explorer (JUICE) mission to Jupiter, which will observe Jovian system on the orbit from 2031. In both Japan and Europe, main players are overlapped and collaborating strongly in both missions and beyond.

    In this presentation, we show (1) Recent progress by Arase, (2) recent Mercury flyby studies of BepiColombo/Mio PWI, and (3) recent status of JUICE RPWI, focusing to Lunar-Earth flyby plans in this Aug which is linked to the feasibility studies on Jovian orbit.


  • Mardi 27 février 2024 à 16h00 (Salle de conférence du bâtiment 17)

    The polar regions of Jupiter

    Vincent HUE (Laboratoire d’Astrophysique de Marseille)

    The polar atmosphere of Jupiter is a complex region were chemistry, dynamics and magnetospheric-coupling are intertwined. Several decades of ground-based observations and spacecraft measurements (Voyager, Cassini, Juno) are progressively revealing how rich and complex these regions are. Species such as HCN, CO, H2O were brought in large amount during the Shoemaker-Levy 9 impact in 1994 and provide important dynamical tracers, as they have spread across the atmosphere over the last 30 years. Hydrocarbons originate from methane-photolysis and are affected by auroral precipitations, leading to the formation of aerosols across the polar cap. Magnetosphere-ionosphere coupling generates powerful electrojets that drag the neutral stratosphere underneath. I will review our current understanding of these regions, based on observations from Cassini, Juno, ALMA, Gemini, and IRTF.


  • Lundi 19 février 2024 à 16h00 (Salle de conférence du bâtiment 17)

    Timing of Explosive Volcanic Eruptions on Mercury

    Mireia LEON-DASI (LESIA)

    Volcanism plays a major role in Mercury’s geological processes, and understanding this activity is crucial to delimit the evolution of the planet. The presence of large pyroclastic deposits contrasts with formation models which predict a volatile depleted crust and mantle, especially in the recent past. Constraining the timing of these volcanic eruptions and the extent of the resulting pyroclastic deposits is fundamental to refine our knowledge of Mercury’s internal evolution and improve the formation models. Using a Deep Learning approach with MESSENGER/MASCS spectra we delimit the extent of irregular pyroclastic deposits and update the area of these features. Moreover, we study the evolution of the spectral properties of pyroclastic deposits over time, using the degradation state of the vent as a reference for the deposit age. We observe a trend between the deposit spectra and the vent degradation characterized by a rapid initial darkening and flattening over time followed by stabilization. The oldest deposits reach a steady state with no further spectral changes. To explain these temporal variations in spectral properties, we propose three potential processes : space weathering, mixing with the background and changes in pyroclast size over time. We examine the implications of space weathering on spectral properties and discuss the eruption timeline for each scenario. Finally, we introduce the ongoing lab measurement campaign to study the effect of grain size and composition on the spectral properties of Mercury analogs, with the aim of improving our knowledge of how different processes can affect the spectra of this planet.


  • Lundi 12 février 2024 à 16h00 (Salle de conférence du bâtiment 17)

    Deciphering Remote Sensing Data from Micro- to Macro-Scale : Infrared Laboratory Investigations in Support of Solar System Exploration

    Giovanni Poggiali (LESIA)

    Several Solar System bodies target of past, present and future space missions are characterized by dark rocky surfaces and complex mixtures of several component with different grain size regolith material. Space missions with their payloads of scientific instrumentation are our gateway to the knowledge of these surfaces, and in recent years the gap is being further closed with the study of samples returned to Earth. Meanwhile, analyzing analogous materials, like minerals mixtures and meteorites, remains one of the pivotal laboratory investigations to support remote sensing interpretation. It also represents one of the most challenging experiments, in particular when multiple components are used in the mixtures. We will review briefly the state of art of laboratory investigations and present in several results from different works that share the common goal of studying how the complex mixing of different grain size and dark materials can affect the behavior of infrared spectra in the near- to mid-infrared range (1.25-25 μm).


  • Lundi 22 janvier 2024 à 16h00 (Salle de conférence du bâtiment 17)

    Mercure : une surface volcanique soumise à l’altération spatiale

    Emma Caminiti, doctorante du pôle planétologie

    La surface de Mercure est soumise à l’altération spatiale de par l’absence d’atmosphère dense. Le bombardement météoritique, l’irradiation du vent solaire, les températures extrêmes ainsi qu’un volcanisme intense ont fortement modifiés la surface au cours du temps. Les données spectrales obtenues par la mission NASA/MESSENGER ont permis de mieux contrainte l’évolution de la surface de Mercure ; cependant les propriétés spectrales ont grandement été influencées par l’irradiation solaire pouvant induire un biais lors de leur interprétation. Des expériences de laboratoire simulant l’irradiation du vent solaire permettent de contraindre les changements spectraux liés à l’environnement. Une meilleure compréhension du rôle de l’altération spatiale sur les propriétés spectrales est essentielle aux vues de l’arrivée imminente de la sonde ESA/JAXA/BepiColombo.

    Mercury’s surface is subject to space weathering due to the absence of a dense atmosphere. Meteorite bombardment, solar wind irradiation, extreme temperatures and intense volcanism have intensely modified the surface over time. The spectral data obtained by the NASA/MESSENGER mission have enabled us to better constrain the evolution of the surface however, the spectral properties have been greatly influenced by solar irradiation, which can lead to a bias in their interpretation. Laboratory experiments simulating solar wind irradiation are used to constrain spectral changes induced by the environment. A better understanding of the role of space weathering on spectral properties is essential in preparation for the imminent arrival of the ESA/JAXA/BepiColombo mission.

    Lien pour assister au séminaire :
    https://us02web.zoom.us/j/89077687967?pwd=RTdEeE9BaUN1ZmRkUUZKUU5HMVdRdz09


  • Lundi 11 décembre 2023 à 16h00 (Salle de conférence 204 du bâtiment 18)

    Observations de notre planète Terre par radiométrie microonde : caractérisation de sa surface et de son atmosphère

    Catherine Prigent (LERMA / Observatoire de Paris-PSL)

    L’observation de la Terre par radiométrie microonde depuis les satellites fournit des données essentielles pour la météorologie et l’étude des océans, des glaces, des continents. Le groupe télédétection du LERMA a développé une expertise dans ce domaine, allant du transfert radiatif à la production d’algorithmes d’inversion de paramètres géophysiques pour la climatologie. On donnera quelques exemples d’études récentes au LERMA, en insistant sur les thématiques d’intérêt en planétologie.

    On montrera aussi comment l’Europe a investi récemment dans ces observations microondes passives pour l’observation de la Terre, avec le lancement de plusieurs instruments innovants d’ici la fin de la décennie.


  • Vendredi 8 décembre 2023 à 10h30 (Salle 103a du bâtiment 14)

    The Plasma Observatory mission

    Karine Issautier (LESIA)


  • Vendredi 1er décembre 2023 à 11h00 (Salle de conférence du bâtiment 17)

    Space Weather : from the interplanetary space to Antarctic

    Sergio Dasso, directeur de recherche et professeur, CONICET et Université de Buenos Aires (FCEN-UBA)

    In this seminar I will present some results about Interplanetary Coronal Mass Ejections, ICMEs. Special emphasis will be made on the main dynamical processes occurring in the interplanetary medium from their solar launching to their arrival to the geo-space. These physical mechanisms can modify the level of ICMEs geoeffectiveness and the ICMEs impact on radiation level at ground level. Finally, I will briefly present a new Space Weather laboratory in an Argentine base at the Antarctic peninsula, from where the variability (e.g., the variaility produced by ICMEs near Earth) of the galactic cosmic rays flux at ground level can be observed in real time.

    Lien pour assister au séminaire :
    https://cnrs.zoom.us/j/95941251661?pwd=ZGp2TVI1RDZabDZkU1NTOUhlUHRYZz09


  • Lundi 27 novembre 2023 à 15h00 (Salle de conférence 204 du bâtiment 18)

    "Atelier nuages : LESIA’s approaches on modelling and characterizing clouds in planetary atmospheres"

    Óscar Carrión-González et Pablo Rodríguez-Ovalle, post-doctorant et doctorant au pôle planétologie

    Clouds and hazes are ubiquitous in the planetary atmospheres observed in the Solar System and beyond. Characterizing the properties of these aerosol layers provides unique information about the atmospheric structure and composition of a planet. However, the aerosol’s optical properties are generally correlated with those of other atmospheric components and even with non-atmospheric parameters of the planet. Accurately modelling clouds and hazes is thus a key to accurately characterizing (exo)planetary atmospheres.

    In this Théminaire ( 1h30 duration) we will have an open discussion on the different approaches taken at LESIA to model clouds and hazes in the atmospheres of Solar-System and extrasolar planets, and even retrieve chemical information on their nature. Several speakers have confirmed short presentations : Benjamin Charnay, Sandrine Vinatier, Joan Roy-Pérez (visiting from UPV/EHU, Spain), Óscar Carrión-González, Pablo Rodríguez-Ovalle, Lucas Teinturier. Additional speakers are welcome, and we warmly invite them to contact : oscar.carrion obspm.fr or pablo.ovalle obspm.fr to keep track of the planned duration.

    Lien pour assister au séminaire :
    https://us02web.zoom.us/j/82609724506?pwd=Y3JzbFhmN05nOWM0Q3NFaU1HY2JRdz09