Please consult the online calendar, as cancelations can occur!
Resurfacing and texturing of rubble-pile minor planets
Ishan SHARMA (Indian Institute of Technology, Kanpur)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Summary
Many asteroids, small moons and trans-Neptunian objects (TNOs) are now thought to be rubble piles, i.e. granular aggregates that are held together mainly by their self-gravity. The study of their dynamics and physics thus necessitates an investigation into the mechanics of self-gravitating and rotating granular aggregates in space. I will present some of our recent work into the processes by which the surfaces of such objects may be reshaped and textured by landslides and seismic shaking that may be induced by impact events.
Connection details
Zoom link
Meeting ID: 876 7331 0489
Passcode: 856642
In-person directions
The IPGP Planetary and Space Sciences seminar series is held in the building Lamarck B that is part of the Université Paris Cité - Campus des Grands Moulins near the BnF (Bibliothèque Nationale de France). You do not need a badge to enter this building. You only need to go to 35 rue Hélène Brion, and once in the lobby of the main entrance, take the elevators on the right to the 5th floor. Exit the elevator and take the corridor to the right. The seminar room is number 522.
Thermal Tides in the Martian Atmosphere
Siteng FAN (Laboratoire de Météorologie Dynamique, LMD)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Summary
Atmospheric thermal tides are planetary-scale harmonic responses driven by diurnal solar forcing and influenced by planetary topography. As results of solar heating absorbed directly by the atmosphere and exchanged with the surface, thermal tides in the Martian atmosphere usually have large amplitudes due to its low heat capacity, and dominate the diurnal temperature variations throughout the thin atmosphere. In this talk, I will present results of the analysis of thermal tides and their seasonal variations using temperature profiles retrieved from infrared spectra obtained by the TIRVIM Fourier-spectrometer, part of the Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter (TGO) and the Emirates Mars InfraRed Spectrometer (EMIRS) instrument onboard the Emirates Mars Mission (EMM) Hope spacecraft. Design of non-Sun-synchronous orbits of these spacecrafts enable the analysis of diurnal temperature variations with a full local time coverage obtained within a short period of time. Wave mode decomposition is applied to these diurnal variations to derive the tide amplitudes and phases. The results show good agreements with predictions made by the Mars Planetary Climate Model (PCM), previously known as the Laboratoire de Météorologie Dynamique (LMD) Mars Global Circulation Model (GCM), except for decent differences in phases. Possible tide excitation sources are also examined through a series of sensitivity tests using Mars PCM. This work provides valuable information on understanding physical processes in the Martian atmosphere on a diurnal scale.
Connection details
Zoom link
Meeting ID: 876 7331 0489
Passcode: 856642
In-person directions
The IPGP Planetary and Space Sciences seminar series is held in the building Lamarck B that is part of the Université Paris Cité - Campus des Grands Moulins near the BnF (Bibliothèque Nationale de France). You do not need a badge to enter this building. You only need to go to 35 rue Hélène Brion, and once in the lobby of the main entrance, take the elevators on the right to the 5th floor. Exit the elevator and take the corridor to the right. The seminar room is number 522.
Ring moon morphology and libration measurements
Nicolas Rambaux (Sorbonne Université, IMCCE-Observatoire de Paris)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Summary
The Cassini-Huygens space mission made a series of observations of Saturn’s small satellites during its grand finale stage. This talk will discuss the shape analysis of the small Saturnian satellites in order to describe their global figure and large-scale topography, as well as to deduce fundamental quantities, gravity field, and amplitude of the diurnal libration by assuming that the bodies are homogeneous. These predicted librations are then compared with recent measurements obtained by astrometry to discuss the internal structure of such bodies.
Connection details
Zoom link
Meeting ID: 876 7331 0489
Passcode: 856642
In-person directions
The IPGP Planetary and Space Sciences seminar series is held in the building Lamarck B that is part of the Université Paris Cité - Campus des Grands Moulins near the BnF (Bibliothèque Nationale de France). You do not need a badge to enter this building. You only need to go to 35 rue Hélène Brion, and once in the lobby of the main entrance, take the elevators on the right to the 5th floor. Exit the elevator and take the corridor to the right. The seminar room is number 522.
Please consult the online calendar, as cancelations can occur!
The role of planet formation in the composition of planetary bodies
Amy Bonsor (University of Cambridge)
IPGP, 1 rue Jussieu 75005 Paris (Salle 310)
TBD
Miki Nakajima (University of Rochester)
IPGP, 1 rue Jussieu 75005 Paris (Salle 310)
Ring moon morphology and libration measurements
Nicolas Rambaux (Observatoire de Paris, IMCEE)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Summary
The Cassini-Huygens space mission made a series of observations of Saturn’s small satellites during its grand finale stage. This talk will discuss the shape analysis of the small Saturnian satellites in order to describe their global figure and large-scale topography, as well as to deduce fundamental quantities, gravity field, and amplitude of the diurnal libration by assuming that the bodies are homogeneous. These predicted librations are then compared with recent measurements obtained by astrometry to discuss the internal structure of such bodies.
Connection details
Zoom link
Meeting ID: 876 7331 0489
Passcode: 856642
In-person directions
The IPGP Planetary and Space Sciences seminar series is held in the building Lamarck B that is part of the Université Paris Cité - Campus des Grands Moulins near the BnF (Bibliothèque Nationale de France). You do not need a badge to enter this building. You only need to go to 35 rue Hélène Brion, and once in the lobby of the main entrance, take the elevators on the right to the 5th floor. Exit the elevator and take the corridor to the right. The seminar room is number 522.
Les anneaux de Jupiter (Cécile Ferrari, IPGP). Actualités d’INSU.
“Seismic detection of the Martian core” by Simon Stähler and members of the InSight science team (2021) awarded the 2023 AAAS Newcomb Cleveland prize for the best paper published in the journal Science. Watch the video.
Titan Through Time workshop #6. The Titan Through Time workshop is an important venue for the Titan research community to exchange research results and ideas about the Titan Science System. The 6th workshop will be held June 13-15 at the Université Paris Cité, Campus Grands Moulins. The abstract submission deadline is April 15.
Ph.D. topic: Simulation of Martian Ground Ice. The project aims to significantly advance our understanding of very shallow ground ice on Mars, which has been found to be much more widespread than once thought. Contact: Frédéric Schmidt, GEOPS – GEOsciences Paris-Saclay, Université Paris-Saclay, Orsay, France.
Please consult the online calendar, as cancelations can occur!
Seismic attenuation in the Martian lithosphere from InSight-SEIS data: separation and stratification of scattering and absorption processes (Ph.D. defense)
Sabrina Menina (Institut de Physique du Globe de Paris)
IPGP amphithéâtre, 1 rue Jussieu, 75005, Paris
Connection details
Zoom : https://u-paris.zoom.us/j/7568613007?pwd=MExoWDA2VDAvOVMrR1h2QzZJSVNVdz09
Summary
Since its deployment at the surface of Mars in 2019, the SEIS seismometer of the InSight mission has detected hundreds of Very high Frequency (VF; > 1 Hz) seismic events. They are characterized by emergent P and S arrivals, a broad maximum and a very slow energy decay known as “coda” that can last up to 1 hour. The objective of this thesis is to use these seismic data to constrain a 1-D model of the regional attenuation properties of the Martian lithosphere in order to estimate the characteristics of the heterogeneities and the volatile content as a function of depth.
To achieve this goal, we first examined the statistical and energetic characteristics of the VF signals. In addition to the energy equipartition observed through the stabilization of the vertical/horizontal kinetic energy ratio in the coda, our analysis shows that these signals are in general depolarized and follow a Gaussian probability distribution. We interpret these observations as direct consequences of multiple scattering. In order to characterize the shape of the envelopes of the VF signals, we measured the delay time (td) between the arrival of the direct S-wave and the maximum of the energy and the quality factor of the coda (Qc), which characterizes the rate of energy decay. We observed that the td measurements are almost frequency-independent, a characteristic which distinguishes Mars from other planets. We found that Qc increases linearly with frequency and shows intermediate values between the Earth and the Moon.
We subsequently estimated the attenuation properties of the Martian lithosphere. For this, we quantified the scattering quality factor (Qsc), which contains information about the heterogeneities of the medium and the extent of fractures at depth, as well as the absorption quality factor (Qμ) which is related to the presence of volatiles in the medium. To separate the two processes, we modeled the energy envelopes of the VF seismograms using a multiple-scattering approach. The direct problem is based on elastic radiative transfer theory, while the inversion combines a grid search approach with an optimization by the Levenberg-Marquardt algorithm. We first applied our method to the distant VF events by considering a statistically uniform medium (half-space). This first study revealed very high values for Qμ, which are characteristic of a dry environment. Moreover, we observed a rapid decrease of the attenuation with the epicentral distance, which we interpreted as an indication of the stratification of the medium properties. To further investigate this hypothesis, we applied our method not only to distant VFs but also to nearby impacts, in the case of a medium stratified in both velocity and attenuation. In this model, we assume that a strongly heterogeneous layer lies on top of a transparent medium. Our inversions indicate that a strongly diffusive and globally dry layer (Qsc and Qμ of the order of 50 and 3500 at 7.5 Hz) with a minimum thickness of 20 km under the InSight landing site (northern plains) and with high S-wave velocities (3 km/s) can explain the shape of the energetic envelopes of the near impacts. However, the thickness of this layer has to be extended to at least 60 km to recover the shape of the envelopes of the distant VF. The correlation between the thickness of the diffusive layer at the surface of Mars and the depth of the Moho suggests that the main source of heterogeneity is the crust itself and not a very thick megaregolith as is the case on the Moon. In this framework, the numerical simulations suggest that the sources of distant VF events are essentially superficial and localized on the southern highlands of Mars.
Turbulence in the atmosphere of Mars and Titan
Aymeric Spiga (Laboratoire de Météorologie Dynamique, Sorbonne Université)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Summary
Mars and Titan have both vastly distinct environments from the Earth’s, yet they exhibit atmospheric turbulent phenomena akin to the ones we experience at the surface of our planet. What is particularly interesting on Mars and Titan is that turbulence is somewhat a distant exotic cousin of Earth’s atmospheric turbulence, with many different aspects that allows for a rich comparative study. This study can be placed in a context of planetary exploration and multi-disciplinary planetary science.
Connection details
Zoom link
Meeting ID: 876 7331 0489
Passcode: 856642
In-person directions
The IPGP Planetary and Space Sciences seminar series is held in the building Lamarck B that is part of the Université Paris Cité - Campus des Grands Moulins near the BnF (Bibliothèque Nationale de France). You do not need a badge to enter this building. You only need to go to 35 rue Hélène Brion, and once in the lobby of the main entrance, take the elevators on the right to the 5th floor. Exit the elevator and take the corridor to the right. The seminar room is number 522.
Insights into the Origin of Volatile Elements in Terrestrial Planets through Zinc and Copper Isotopic Analyses of Ryugu Samples
Frédéric Moynier (Institut de Physique du Globe de Paris)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Summary
The samples collected by the Hayabusa2 spaceship from Ryugu are incredibly valuable due to their pristine nature, potentially escape terrestrial contamination, and therefore are providing a unique opportunity to study planetary building blocks. In this presentation, I will share the first stable isotopic composition data obtained from Ryugu’s samples for Zn and Cu, which are moderately volatile elements. Through this analysis, we have discovered that materials similar to Ryugu contributed approximately 30% of the budget of Zn and Cu to Earth, and approximately 5% of the total mass of the Earth. This shed light on the origins of these essential elements and provide insight into the formation and evolution of our planet.
Connection details
Zoom link
Meeting ID: 876 7331 0489
Passcode: 856642
In-person directions
The IPGP Planetary and Space Sciences seminar series is held in the building Lamarck B that is part of the Université Paris Cité - Campus des Grands Moulins near the BnF (Bibliothèque Nationale de France). You do not need a badge to enter this building. You only need to go to 35 rue Hélène Brion, and once in the lobby of the main entrance, take the elevators on the right to the 5th floor. Exit the elevator and take the corridor to the right. The seminar room is number 522.
Ring moon morphology and libration measurements
Nicolas Rambaux (Observatoire de Paris, IMCEE)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Summary
The Cassini-Huygens space mission made a series of observations of Saturn’s small satellites during its grand finale stage. This talk will discuss the shape analysis of the small Saturnian satellites in order to describe their global figure and large-scale topography, as well as to deduce fundamental quantities, gravity field, and amplitude of the diurnal libration by assuming that the bodies are homogeneous. These predicted librations are then compared with recent measurements obtained by astrometry to discuss the internal structure of such bodies.
Connection details
Zoom link
Meeting ID: 876 7331 0489
Passcode: 856642
In-person directions
The IPGP Planetary and Space Sciences seminar series is held in the building Lamarck B that is part of the Université Paris Cité - Campus des Grands Moulins near the BnF (Bibliothèque Nationale de France). You do not need a badge to enter this building. You only need to go to 35 rue Hélène Brion, and once in the lobby of the main entrance, take the elevators on the right to the 5th floor. Exit the elevator and take the corridor to the right. The seminar room is number 522.
Please consult the online calendar, as cancelations can occur!
Turbulence in the atmosphere of Mars and Titan
Aymeric Spiga (Laboratoire de Météorologie Dynamique, Sorbonne Université)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Summary
Mars and Titan have both vastly distinct environments from the Earth’s, yet they exhibit atmospheric turbulent phenomena akin to the ones we experience at the surface of our planet. What is particularly interesting on Mars and Titan is that turbulence is somewhat a distant exotic cousin of Earth’s atmospheric turbulence, with many different aspects that allows for a rich comparative study. This study can be placed in a context of planetary exploration and multi-disciplinary planetary science.
Connection details
Zoom link
Meeting ID: 876 7331 0489
Passcode: 856642
In-person directions
The IPGP Planetary and Space Sciences seminar series is held in the building Lamarck B that is part of the Université Paris Cité - Campus des Grands Moulins near the BnF (Bibliothèque Nationale de France). You do not need a badge to enter this building. You only need to go to 35 rue Hélène Brion, and once in the lobby of the main entrance, take the elevators on the right to the 5th floor. Exit the elevator and take the corridor to the right. The seminar room is number 522.
Please consult the online calendar, as cancelations can occur during this season of strikes!
InSight et SEIS : Premier bilan après 4 années de surveillance sismique de Mars
Philippe Lognonné (Univ. Paris Cité, IPGP, CNRS)
Ecole Normale Supérieure, Salle Jaurès, 29 rue d’Ulm, 75005 Paris
Summary
Pendant près de 4 ans, la mission NASA InSight, portée par le Jet Propulsion Laboratory, a exploré la structure interne de Mars avec son instrument principal, le sismomètre SEIS sous responsabilité scientifique de l’IPGP et maitrise d’œuvre CNES. Avec plus de 1300 événements sismiques, dont plus de 30 de magnitude supérieure à 3, le plus fort de magnitude 4,7, il a permis d’identifier une forte activité sismique dans Cerberus Fossae et d’inverser les mécanismes au foyer pour une demi-douzaine de séismes. Ces analyses sismiques, ainsi que les modélisations récentes du champ de gravité, suggèrent que cette région de Mars pourrait être le siège d’un panache mantellique encore actif. SEIS a également détecté de nombreux impacts de météorites, confirmés par l’imagerie orbitale, y compris pour quelques impacts dont les cratères dépassent 100m de diamètre. Pour la première, ces données ont permis d’élaborer des modèles sismiques de la croûte, du manteau et du noyau, et ce pour une autre planète tellurique que la Terre, nous permettant de mieux comparer la structure interne de Mars à celle la Terre et de la Lune, tant pour la taille de leurs noyaux que celle de leur lithosphère thermique, permettant ainsi de poser de nouvelles bases en planétologie et sismologie comparée.
Nous concluons en présentant les futures missions de sismologie planétaire, tant sur la Lune, avec la mission FarSide Seismic Suite et les perspectives d’Artemis, que sur les satellites des planètes géantes, Titan pour Saturne ou Europe pour Jupiter, ainsi que les perspectives sur la Lune de détection d’ondes gravitationnelles avec des capteurs sismiques.
Turbulence in the atmosphere of Mars and Titan
Aymeric Spiga (Laboratoire de Météorologie Dynamique, Sorbonne Université)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Summary
Mars and Titan have both vastly distinct environments from the Earth’s, yet they exhibit atmospheric turbulent phenomena akin to the ones we experience at the surface of our planet. What is particularly interesting on Mars and Titan is that turbulence is somewhat a distant exotic cousin of Earth’s atmospheric turbulence, with many different aspects that allows for a rich comparative study. This study can be placed in a context of planetary exploration and multi-disciplinary planetary science.
Connection details
Zoom link
Meeting ID: 876 7331 0489
Passcode: 856642
In-person directions
The IPGP Planetary and Space Sciences seminar series is held in the building Lamarck B that is part of the Université Paris Cité - Campus des Grands Moulins near the BnF (Bibliothèque Nationale de France). We are not at the main IPGP campus near the Jardin des Plantes and the Jussieu metro station. You do not need a badge to enter this building. You only need to go to 35 rue Hélène Brion, and once in the lobby of the main entrance, take the elevators on the right to the 5th floor. Exit the elevator and take the corridor to the right. The seminar room is number 522.
Geophysical evidence for an active mantle plume underneath Elysium Planitia on Mars
Adrien Broquet (Univ. of Arizona)
IPGP Origins seminar (online only)
Summary
Although the majority of volcanic and tectonic activity on Mars occurred during the first 1.5 billion years of its geologic history, recent volcanism, tectonism and active seismicity in Elysium Planitia reveal ongoing activity. However, this recent pulse in volcanism and tectonics is unexpected on a cooling Mars. In this talk, I will present observational evidence and geophysical models demonstrating that Elysium Planitia is underlain by an ~4,000-km-diameter active mantle plume head driving the regional volcanic and seismic activity. The inferred plume head characteristics are comparable to terrestrial plumes that are linked to the formation of large igneous provinces. These results demonstrate that the interior of Mars is geodynamically active today. Studies using data collected by InSight have to consider the presence of the plume.
Connection details
Zoom link
Meeting ID: 946 7946 3245
Passcode: C0sGse
The thermodynamic state of the protolunar disk after the giant impact
Razvan Caracas (Insitut de Physique du Globe de Paris)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Summary
We study the behavior of a multi-component silicate fluid with bulk silicate Earth composition at conditions typical for the giant impact that generated the protolunar disk. We find that the Earth’s protolunar disk reached the supercritical state of the silicate mantle. As such, the Earth, and most rocky planets, will traverse a temporary state that lacks a surface defined by a magma ocean-atmosphere boundary. The atomic structure of the silicate fluid varies with the radius within the disk due to strong pressure and temperature gradients. Fluffy short-lived chemical species dominate the outer parts of the disk, and long-lasting dense polymers abound in the deeper parts. During cooling, when the temperature and density profile of the disk intersect the liquid-vapor dome, liquid and vapor start to separate, the disk evolves as a two-phase system, and the central body starts to condense. The composition of the post-impact atmosphere is dominated by species along the mantle vapor curve.
Connection details
Zoom link
Meeting ID: 876 7331 0489
Passcode: 856642
In-person directions
The IPGP Planetary and Space Sciences seminar series is held in the building Lamarck B that is part of the Université Paris Cité - Campus des Grands Moulins near the BnF (Bibliothèque Nationale de France). We are not at the main IPGP campus near the Jardin des Plantes and the Jussieu metro station. You do not need a badge to enter this building. You only need to go to 35 rue Hélène Brion, and once in the lobby of the main entrance, take the elevators on the right to the 5th floor. Exit the elevator and take the corridor to the right. The seminar room is number 522.
Nudging virtual planets
Nicolas Coltice (Ecole Normale Supérieure, Paris)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Summary
Tectonics, climate, and landscapes are symptoms of underlying intrinsic properties of planets. Looking at the Earth in recent times, I will propose ways to nudge virtual planets towards real ones.
Connection details
Zoom link
Meeting ID: 876 7331 0489
Passcode: 856642
In-person directions
The IPGP Planetary and Space Sciences seminar series is held in the building Lamarck B that is part of the Université Paris Cité - Campus des Grands Moulins near the BnF (Bibliothèque Nationale de France). We are not at the main IPGP campus near the Jardin des Plantes and the Jussieu metro station. You do not need a badge to enter this building. You only need to go to 35 rue Hélène Brion, and once in the lobby of the main entrance, take the elevators on the right to the 5th floor. Exit the elevator and take the corridor to the right. The seminar room is number 522.
Where was the Moon? A fresh look at the tidal evolution of the early Earth-Moon system
Jun Korenaga (Yale University)
IMCCE, AstroGeo seminar (online only)
Summary
The early evolution of the Earth-Moon system prescribes the tidal environment of the Hadean Earth and holds the key to the formation mechanism of the Moon. Estimating its early state by backtracking from the present, however, suffers from considerable uncertainties associated with ocean tides. Tidal evolution during the solidification of Earth’s magma ocean, on the other hand, has the potential to provide robust constraints on the Earth-Moon system before the appearance of a water ocean. I will show how energy dissipation in a solidifying magma ocean results in limited lunar recession and suggest that the Moon was probably still at the distance of approximately 7-9 Earth radii at the beginning of subsolidus mantle convection. With a plausible range of ocean tides, the Moon must have gained nearly half of the present-day orbital distance during the Hadean, suggesting a rapidly changing tidal environment in the early Earth. Limited lunar recession during Earth’s magma ocean will also help to evaluate various hypotheses proposed for the origin of lunar inclination.
Connection details
Zoom link
Meeting ID: 88928171993
Razvan Caracas (Insitut de Physique du Globe de Paris)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Originally scheduled: 24 January 2023, 15:00
New date and time: January 31 2023, 15:00
Sébastien Charnoz (Institut de Physique du Globe de Paris)
IPGP Planetary and Space Sciences, Bâtiment Lamarck B, 35 rue Hélène Brion, Paris
Originally scheduled: 31 January 2023, 15:00
Will be rescheduled at a later date