Celestial Mechanics

Satellites in our Solar System show very interesting characteristics, both in their interior structure and their dynamics. For some of them, these two aspects are strongly related: it is the case of the four Galilean satellites of Jupiter, where tidal dissipation and mean motion resonances generate spectacular phenomena, such as Io's volcanism. As part of my research, I investigate the long-term orbital evolution of these satellites driven by the tidal dissipation, focusing on the stability of the Laplace resonance between Io, Europa and Ganymede, and possible captures of Callisto into resonance. Moreover, I study the tilting of gas giants of our Solar System through spin-orbit resonances. In recent works, we propose that such resonances were achieved later than previously thought, because of the fast tidal migration of the satellites.

Space Missions

So far, several interplanetary missions have reached celestial bodies of our solar system. Radio science experiments onboard spacecrafts provide extremely accurate data that allow to improve our knowledge of celestial bodies. As part of my research, I work on the processing of the radio science data of Juno, a NASA mission which is currently orbiting around Jupiter. Using Orbit14, an orbit determination software developed by the Celestial Mechanics Group of Pisa, we estimate the gravitational field's coefficients and other parameters that allow to constrain the interior of the planet. I am also currently involved in preliminary studies for the Italian contribution to the future NASA space mission to Uranus. In particular, I study the dynamics of the Uranian moons in order to reconstruct their thermo-orbital history and give support to the radio science experiment of the mission.

Computational Fluid Dynamics

In the case of a volcanic eruption the magma flows from the cone to the areas below. A possible model that can predict the path of the fluid is described by the Shallow Water equations, which consider a low fluid thickness and a 2-dimensional motion. In order to obtain realistic simulations, it is necessary to consider a suitable rheology, that adds friction forces to the model. A few years ago, I joined a project of the INGV, under the supervision of Dr. de' Michieli Vitturi, for which we developed a numerical solver for the Shallow Water equations (IMEX_SfloW2D software, open source), in order to study Etna eruption events. The program can take a DEM (Digital Elevation Model) in input, to perform realistic simulations on 3D topographies; moreover, it has simple input options to define the initial state of the fluid.

Ph.D Thesis

For my Ph.D I worked on two main projects. First, I developed a secular model of the Galilean satellites' dynamics suitable for studying the long-term evolution of the system. Then, I performed simulations and covariance analyses of the orbit determination experiments of the future JUICE mission to the Jovian system.

Here you can download the pdf file
The Galilean satellites’ dynamics and the estimation of the Jovian system’s dissipation from JUICE data.

Publications

Durante D., Cappuccio P., Di Stefano I., Zannoni M., Gomez Casajus L., Lari G., Falletta M., Buccino D. R., Iess L., Park R. S., Bolton S. J. (2024) Testing general relativity with Juno at Jupiter. The Astrophysical Journal 971, 145 . DOI: https://doi.org/10.3847/1538-4357/ad5ff5
Lari G., Saillenfest M. (2024) The nature of the Laplace resonance between the Galilean moons. Celestial Mechanics and Dynamical Astronomy 136, 19. DOI: https://doi.org/10.1007/s10569-024-10191-6 (mentioned in this informative article)
Cuk M., El Moutamid M., Lari G., Neveu M., Nimmo F., Noyelles B., Rhoden A., Saillenfest M. (2024) Long-term evolution of the Saturnian system. Space Science Reviews 220, 20. DOI: https://doi.org/10.1007/s11214-024-01049-2
Lari G., Zannoni M., Durante D., Park R. S., Tommei G. (2024) Determination of Jupiter's pole orientation from Juno radio science data. Aerospace 11, 124. DOI: https://doi.org/10.3390/aerospace11020124
Lari G., Saillenfest M., Grassi C. (2023) Dynamical history of the Galilean satellites for a fast migration of Callisto. Monthly Notices of the Royal Astronomical Society 518, 3023-3035. DOI: https://doi.org/10.1093/mnras/stac3299
Saillenfest M., Rogoszinski Z., Lari G., Baillé K., Boué G., Crida A., Lainey V. (2022) Tilting Uranus via the migration of an ancient satellite. Astronomy and Astrophysics 668, A108. DOI: https://doi.org/10.1051/0004-6361/202243953 (see also informative articles: eng, eng2, ita)
Durante D., Guillot T., Iess L., Stevenson D. J., Mankovich C. R., Markham S., Galanti E., Kaspi Y., Zannoni M., Gomez Casajus L., Lari G., Parisi M., Buccino D. R., Park R. S., Bolton S. J. (2022) Juno spacecraft gravity measurements provide evidence for normal modes of Jupiter. Nature Communications 13, 4632. DOI: https://doi.org/10.1038/s41467-022-32299-9 (see also informative articles: eng, ita)
Lari G., Schettino G., Serra D., Tommei G. (2022) Orbit determination methods for interplanetary missions: development and use of the Orbit14 software. Experimental Astronomy 53, 159-208. DOI: https://doi.org/10.1007/s10686-021-09823-8
Saillenfest M., Lari G. (2021) Future destabilisation of Titan as a result of Saturn's tilting. Astronomy and Astrophysics 654, A83. DOI: https://doi.org/10.1051/0004-6361/202141467 (see also informative articles: eng, ita)
Saillenfest M., Lari G., Boué G., Courtot A. (2021) The past and future obliquity of Saturn as Titan migrates. Astronomy and Astrophysics 647, A92. DOI: https://doi.org/10.1051/0004-6361/202039891 (see also A&A Highlight)
Saillenfest M., Lari G., Boué G. (2021) The large obliquity of Saturn explained by the fast migration of Titan. Nature Astronomy 5, 345-349. DOI: https://doi.org/10.1038/s41550-020-01284-x (see also Nature Research Highlight and informative articles: eng, eng2, eng3, ita, ita2, ita3, fra)
Saillenfest M., Lari G., Courtot A. (2020) The future large obliquity of Jupiter. Astronomy and Astrophysics 640, A11. DOI: https://doi.org/10.1051/0004-6361/202038432
Lari G., Saillenfest M., Fenucci M. (2020) Long-term evolution of the Galilean satellites: the capture of Callisto into resonance. Astronomy and Astrophysics 639, A40. DOI: https://doi.org/10.1051/0004-6361/202037445
Durante D., Parisi M., Serra D., Zannoni M., Notaro V., Racioppa P., Buccino D.R., Lari G., Gomez Casajus L., Iess L., Folkner W.M., Tommei G., Tortora P., Bolton S.J. (2020) Jupiter’s gravity field halfway through the Juno mission. Geophysical Research Letters 47, e2019GL086572. DOI: https://doi.org/10.1029/2019GL086572
Serra D., Lari G., Tommei G., Durante D., Gomez Casajus L., Notaro V., Zannoni M., Iess L., Tortora P., Bolton S.J. (2019) A Solution of Jupiter's Gravitational Field from Juno Data with the ORBIT14 Software. Monthly Notices of the Royal Astronomical Society 490, 766-772. DOI: https://doi.org/10.1093/mnras/stz2657
Lari G., Milani A. (2019) Chaotic orbit determination in the context of the JUICE mission. Planetary and Space Science 176, 104679. DOI: https://doi.org/10.1016/j.pss.2019.06.003
de' Michieli Vitturi M., Esposti Ongaro T., Lari G., Aravena A. (2019) IMEX_SfloW2D 1.0: a depth-averaged numerical flow model for pyroclastic avalanches. Geoscientific Model Development 12, 581-595. DOI: https://doi.org/10.5194/gmd-12-581-2019
Lari G. (2018) A semi-analytical model of the Galilean satellites' dynamics. Celestial Mechanics and Dynamical Astronomy, 130, 50. DOI: https://doi.org/10.1007/s10569-018-9846-4
Dirkx D., Gurvits L.I., Lainey V., Lari G., Milani A., Cimó G., Bocanegra-Bahamon T.M., Visser P.N.A.M. (2017) On the contribution of PRIDE-JUICE to Jovian system ephemerides. Planetary and Space Science 147, 14-27. DOI: https://doi.org/10.1016/j.pss.2017.09.004
Saillenfest M., Lari G. (2017) The long-term evolution of known resonant trans-Neptunian objects. Astronomy and Astrophysics 603, A79. DOI: https://doi.org/10.1051/0004-6361/201730525

Talks, seminars and posters

The nature of the Laplace resonance between the Galilean moons (invited seminar). Celestial Mechanics and Dynamical Astronomy Seminar Series, online, 12 July 2024.

The long term orbital evolution of the Galilean satellites (invited talk). Exploring the Jovian satellite system: from formation to habitability, International Space Science Institute, Beijing (China), 3-7 June 2024.

Dynamical history of the Galilean satellites for a fast migration of Callisto (poster). Origins and habitability of the Galilean Moons, Aix-Marseille Université, Marseille (France), 24-26 October 2023.

Orbital evolution of the Galilean moons driven by a fast orbital expansion of Callisto (talk). CPS II IAU symposium 382, Université de Namur, Namur (Belgium), 3-7 July 2023.

Results of the Juno radio science experiment obtained with the Orbit14 software (talk). New Frontiers of Celestial Mechanics: theory and applications, Dipartimento di Matematica, Padova (Italy), 15-17 February 2023.

The long-term evolution of the obliquity of gas giants (talk). Juno Science Team Meeting, Laboratory for Atmospheric and Space Physics, Boulder (U.S.A. Colorado), 24-27 January 2023.

Dynamical history of the Galilean satellites for a fast migration of Callisto (talk). CELMEC VIII, Università Roma Tor Vergata, Roma (Italy), 5-9 September 2022.

On the long-term orbital evolution of Callisto in different tidal scenarios (talk). Theory, models and simulations in Celestial Mechanics, Dipartimento di Matematica, Pisa (Italy), 14-16 June 2022.

Tides from radio-science data (invited talk) and Past orbital evolution of the Galilean satellites for a fast migration of Callisto (poster). New Vision of the Saturnian System in the Context of a Highly Dissipative Saturn, International Space Science Institute, Bern (Switzerland), 9-13 May 2022.

On the stability of the Laplace resonance under tidal effects (invited seminar). I-CELMECH Seminars Series, online, 20 July 2020.

Dealing with chaos in the JUICE space mission (poster). AGU Fall Meeting 2019, Moscone Center, San Francisco (U.S.A., California), 9-13 December 2019.

The Galilean satellites’ evolution toward a 4-body mean motion resonance (poster). EPSC-DPS 2019, Centre International de Conférences de Genève, Geneva (Switzerland), 16-21 September 2019.

Orbital evolution of the Galilean satellites driven by tidal dissipation (talk). XV Congresso Nazionale di Scienze Planetarie, Polo delle Scienze Sociali, Firenze (Italy), 4-8 February 2019.

Long-term orbital evolution of the Galilean satellites due to the tidal dissipation (poster). AGU Fall Meeting 2018, Walter E. Washington Convention Center, Washington (U.S.A., District of Columbia), 10-14 December 2018.

Modeling the long-term dynamics of the Galilean satellites (talk). 2018AMC70, Dipartimento di Matematica, Pisa (Italy), 3-5 September 2018.

On the determination of Jupiter system's energy dissipation with JUICE space mission data (talk). CELMEC VII, Balletti Park Hotel, San Martino al Cimino (Italy), 4-8 September 2017.

Laplace Resonance and energy dissipation in the Jovian system (talk). First JUICE 3GM Meeting, Dipartimento di Ingegneria Meccanica e Aerospaziale, Roma (Italy), 15-16 January 2015.

Giacomo Lari

Research interests