Philippe Lognonné

Université Paris Cité, Institut de physique du globe de Paris, CNRS

Biography 

Philippe Lognonné, 62 years, is professor in Geophysics at University Paris Cité and planetary seismologist at the Institut de physique du globe de Paris. He performs his research in the Planetary and Space Science team he founded in 1996 and is director of the French National Observation Service in Planetary seismology responsible for future FarSide Lunar Seismic Suite data distribution (and analysis).    
His researches are related to long period seismology, to the seismic coupling of telluric planets with their atmosphere and ionosphere, including for tsunami mitigation on Earth and to Planetary Geophysics and seismology, including lunar and Mars seismology. 
He started Mars seismology just after his PhD in 1989 and was from 1991 to 1996 co-Principal Investigator of the seismometer onboard the Russian Mars96 Small stations, lost after mission launch in November 1996. He then succeeded, together with Dr. Bruce Banerdt, from the Jet Propulsion Laboratory and an international team, to get the NASA InSight mission selected in NASA Discovery program. As principal investigator of the SEIS experiment he contributed with his team to the success of InSight, on Mars from December 2018 until December 2022, and to the first discovery of both the seismicity and internal structure of the red planet.  
He is now focusing his research to lunar seismology, as lead co-investigator of the VBB seismometer in the JPL lead Farside Seismic Suite experiment to the Moon (to land on the Moon in late summer 2027 in the Schrödinger basin) and as co-investigator of the Chinese Lunar Seismograph, which will land on the Moon in summer 2025 onboard Changh’7. He is also leading the ERC funded LISTEN FLASH project, which will support all future lunar seismic missions by monitoring flashes generated by lunar impacts, in order to locate, time and calibrate them for better seismic analysis. 

Abstract: Planetary seismology in the solar system

41 years after the end of Apollo’s seismometer operation on the Moon, seismology came back in planetary science with the landing of the NASA InSight mission and its very broad band seismometer SEIS. This mission did not only discovered the Martian Interior and demonstrated an ongoing seismo-tectonic activity around the Martian Cerberus Fossae province, but also contributed to a rebirth of seismology in planetary science. 5 years after the end of SEIS operation, 3 lunar missions will deploy seismometer in 2026 (LS on CSA Chang’E 7) and 2027 (FSS on NASA CP12, LEMS on NASA Artemis 3) and two other missions will deploy seismometer on Titan in 2034 (NASA dragonfly) and on the Earth flyby asteroid Apophis in 2029 (ESA RAMSES). Other projects plan additional seismometers on the Moon, Europa, Enceladus and proposes alternative seismic investigations on Venus. Projects also propose to implement seismic investigations for searching for lunar resources or to use seismometers for ultra-sensitive gravitational wave detectors on the Moon.

We first present science achievement and lesson learned from SEIS, the international instrument of NASA’InSight mission. More than 1300 events were detected during two Martian years, including a Mw=4.7 marsquake, several tens of tele seismic events with determined distance, about 10 impacts confirmed by orbital crater imaging, two with very large craters and a thousand of regional crustal high frequency quakes. This data set provided models for the subsurface, for the crust below InSight and between InSight and several epicenters, for the mantle and determined the core radius. SEIS was nevertheless able to detect the small and most frequent quakes only during about half of the night, when the ground deformation noise generated by the wind carried pressure waves was minimum. And even if the seismic records of the largest M~4.7 quake suggest weakly excited normal modes, these data are far from those requested for Normal modes detection. This shed light on the direction of improvements which might be implemented in future missions.

We then present and review the perspectives of future missions and provide, based on the InSight lessons learned, a critical analysis on their goals and associated requirements. We here also present and discuss mission aiming to detect seismic signals on Venus through atmospheric balloons or airglow orbital remote sensing or for Earth-based observations of Jovian seismology. A final focus is then given on the future of a potential international lunar seismic network, possibly coupled with Earth based and Space based monitoring of Lunar Impact flashes, which will be the new arena of Planetary seismology in the next 5 years and prior the landing of Dragon Fly on Titan.